I can't thank you enough for making your lectures available for free. It really warms my heart to see people that love to share knowledge. Many blessings to you!!
These lectures are a valuable contribution. You are enlarging our world and making something dangerous and mysterious more understandable. That which is understandable is less frightening. Knowledge is power and it also reduces fear. Thank you.
This man is phenomenal and his lectures are great! I’m a retired physician and know a lot of research but I have learned so much from these talks! It is amazing that these are free to view. I applaud the professor.
@@be_rt whoosh! In one ear, out the other. The only dogma is here is your ignorance and appeal to Koch's postulates which even Koch had to admit there were limitations and not all 4 postulates could be met. Introduce virual diseases and it's even more oblivious especially because the criterion was established before viruses was discovered.
I've taken over 70+ college courses and Professor Racaniello, you've given some of the best lectures I've seen. I'm giddy with knowledge! Wonderful information! Thank you!
Why has this only got 12k odd views! - All of humanity should be educating themselves on this stuff! - I'm just some random bank worker, but i have to say virus's are fascinating "things"
I think the viruses find us interesting hosts as they if had a understanding of their devastating consequences they might be ashamed and proud of their consequential affect on such large beings . Their devastation to humans is useless and pointless. If we had infinite life span that would be different especially if we became ill/sick in that case the virus would be a path to end pain and suffering and population control.
These lectures are just..fantastic. I followed all of them since the first one. The patience, the clarity, the material ...it is so inspiring to learn more. This professor is amazing.
You really make the topic come alive, Dr Racaniello; I've never enjoyed a lecture on such a technical subject as much. Thanks for making your course available to all.
Going through all of the lectures and taking notes; I can't thank you enough for making these available Dr. Racaniello. I study Trypanosoma cruzi so virology isn't directly pertinent, but everything in biology is essentially related, so these lectures will undoubtedly aid in my research!
Scientists tend to downplay the health of the host with their lab work. A healthy environment goes a long way, too. I wonder what might be improved in the hospital environment for a better outcome, and so there is less need for PPE with health care workers. People talk about effects of 5G, and I have even heard that fluorescent lighting can affect brain health in some people. Pasteur said on his death bed, "It is not the medium (germ, virus, pathogen) , but the milieu that determines whether there will be a healthy outcome from exposure." Look up terrain theory.
Absolutely amazing and fascinating. And only two episode in. Even someone who has only helped kids to a-level chem and bio and done pop sci reading can follow 90% of this with a couple of pauses to check things on Wiki. Thank you very much indeed.
Pedro Santos The professor is very good, isn’t he? I am glad that this successful scientist started teaching, and grateful that he posts these videos on RUclips. I would venture to add that your “pop science” reading must be rather wide and at least moderately deep for you to understand almost all of the lecture. As an old doctor (who spent about 4 years as a research assistant before medical school), part of this is a helpful review, but I am also picking up quite a bit of new information. It has been many years since I worked in a basic science laboratory!
Ad 44:09: "Why" is not a philosophical question. Actually this is a shortcut for "why this not that". I take this one as "why do viruses have to assembly, instead of creating virions at once?". Or, put another way, why it's not possible to produce a viroid all at once, without the assembly stage. (And one of the possible answers could be, because they are too complicated. By the way, do viroids also have the assembly stage? As far as I understand, these are just strands of RNA)
You have been extremely generous to share these videos with us....you are too good to listen to....I am also trying to learn and catch the way you teach...its amazing...
I' really grateful to you for making your lectures free. If you don't mind a bit of feedback, You very often assume knowledge that the listener does not have.
Thank you so much for passionately teaching the intricate details of the subject that too in such an easy to understand manner. There are very few who spend time and energy and make it viable for everyone. Everything is so structured and made so interesting! Would be always grateful for this amazing series!!
Vincent, great course! I like also the evolutionary aspect from the geological perspective. We owe our existence as humans and all life forms to a likely proto-cellular viral precurser.
@@be_rt Following what you have just mentioned, and in the case of COVID19, no one -- not even those scientist that published the genome sequence of SARS-CoV-2 -- have isolated & purified that virus causing this pandemic that we have to date.
@@be_rt if it was Facebook, I'd give you a 'haha reaction', it's not worth to debunk your awful thesis because it would be a waste of time. You want to sound like science is on your side, but it is not, you've literally commented on a lecture made by a professor that specializes in this field, who spent many years getting the knowledge and you have all the audacity to act like you know better. Peace n love
At about 20:51 the lecturer says that CPE has lost its significance due to the development of a more sensitive and specific test based on PCR. That sounds quite reasonable, on the other hand, the cost of PCR, in particular, the qPCR (as it is used currently) is rather high, and the demand for the screening tests has recently risen immensely. So here is my question: couldn't we take some cell cultures that would be even easier to grow than human epithelial cells, genetically transform them so they start producing a proper receptor protein (say human ACE2) and use them for a cheap and simple preliminary screening test for the presence of the new coronavirus? Some algae cells could be grown at a really low cost, besides they are green and often phototactic, so there is a chance their lysis could be visually detected without even the use of a microscope. Maybe only a little chlorophyllase or pheophytinase enzyme should be added to make the chlorophyll breakdown more rapid and more apparent as soon as it leaks out from the cells into the surrounding medium. The problem is, as I see from this lecture, that making algal cells susceptible does not mean they will also be permissive, and even in that case, the change in cell morphology, as caused by the coronavirus may be not lysis but rather the formation of syncitia. These are important problems but do they exclude the feasibility of the concept of using GM algae as really cheap detectors of specific viruses? Maybe not coronaviruses, but other similarly significant ones? I posted a similar question on the Quora forum but it was met with a very meagre interest www.quora.com/Is-it-possible-to-genetically-modify-common-algae-like-Chlorella-or-Dunaliella-so-that-they-could-be-readily-and-specifically-attacked-by-the-new-coronavirus . I know it is an experiment that can provide the most definitive answer to such a question but it would cost pretty much money, time and work. I suppose there are people out there whose experience allows them to comment here confidently and expertly. I would be grateful for such opinions.
I remain absolutely enthralled with very excellent educational opportunities and presentations here on RUclips. I am retired as a shop teacher. The EXCELLENT and great value education provided keeps my attention all day. College credit should be attached. Bless you RUclips.
David Robinson I just want to thank you for your service as a shop teacher. Our son’s shop teacher was the most influential teacher he had in high school.
Absolutely wonderful...the super well presented information presented here with out charge give s a clear understanding of what these viruses are by a gifted professor! Thank you so much 🙏
1:00:54-1:01:00 That's odd because in another lecture 6 months prior to this one you repudiated the very idea of using PCR as a diagnostic, what changed? Also how can you talk about PCR and not mention the person who invented and won the Nobel prize for it?
Very informative and useful information. You have certainly spark an interest in virology. Very appreciative that these are available for free. I'm learning so much.
Excellent lecture #2 in the Virology course. The lecture is interesting, informative, and has many illustrations. Those highly motivated might consider referring to the two volume treatise entitled Principles of Virology, co-authored by Prof. Racaniello. I have the 4th edition (2015) of the two volume set which is comprised of over 1,000 pages, and provides more detailed information.
Is there a link to a one-step curve for SARS-CoV-2 available by any chance? (I've found some, mostly in the context of potential anti-virals, mostly with 24h sample intervals)
Thank you for your work and dedication. I have been fascinated myself about viruses and lack so much knowledge on these functions, the math, the jargon. You create such a brilliant clarity. I have obtained so much so far but I know I have so much to learn. Greatful I’ve stumbled upon you. Thank you thank you for sharing your life’s work/knowledge about these magnificent species of genetic material that seem to be a catalyst to evolution.
The plaque assey counting method seems to me to be sensitive to systematic errors. If you have a tendency to take 0.11 ml instead of 0.1, you get almost a factor 2 error by the time you reach 10^-6 and 10^-7 dilutions. Of course, if order of magnitud is what you really care about this is well within margin, but you need to have good skills/equipment to get confidence in even the first decimal (in my opinion). I am a mathematician with next to no lab experience so I don't know what magnitude of errors are actually reasonable.
It really a great job being done by you. I have no physical lectures for my virology course in this summer. sem due to coviD-19 but its good to learn here online. Highly interactive Slides and talk. kudos!
Prof. Racaniello: *Susceptible* - "has a functional receptor for a given virus" (3:06) - but what about macropinocytosis entry? "Most [viral entry] is receptor-mediated, but there also are some examples of macropinocycosis [entry]" (2019 #5 Attachment and Entry; 25:10) IIRC - once endocytosed, a virus has to have the ability to attach to the vesicle wall and that may be where the "receptor" exists (i.e., in macropinocytosis entry) in your definition of susceptible?
Are there any known cases of a virus being taken up by macropinocytosis and then exiting the macropinosome into the cytoplasm *without* using a receptor-mediated path to breach the macropinosome's plasma membrane? I guess they would have to do *something* to exit the vesicle before fusion with a lysosome - unless the virus was resistant to lysosome enzymes and could survive to enter the Golgi at the end of life of a lysosome.)
Fascinating. This lecture covers PCR in way that is very relevant in public health discussions and debate here 7 months later. And still no "lick strips." -Please let me know if there is a textbook associated with this class- TWiV #662 gives my answer: Principles of Virology, 5th Edition. Episode has a link to purchase.
Is there a relationship between the particle/pfu ratio and the tendency of a virus to cause mutations in the host cell? For example, would a virus with a high ratio, like papilloma virus, be more likely to cause mutations in the host cell due to defective particle formation (packaging wrong nucleic acids for example) vs another virus with a low ratio? I realize this sort of depends on what's being packaged and how it gets delivered to the host cell. But, I was just curious.
There does not appear to be a relationship between particle/pfu and mutation rate.. Packaging the wrong nucleic acid probably happens regularly, and we think such DNA can be incorporated into cells and affect them. We call it horizontal gene transfer and it has probably been a major driver of evolution. But I don't think defective particles are a major driver. On the other hand, there is increasing evidence that defective particles play a role in disease: they may stimulate the immune response, for example, helping to clear the infection. We'll hear more about that later in the course.
I'm disappointed that you didn't get an answer from somebody. These scientists with their lab work seem to overlook the effect of a healthy immune system which is why we are in this mess. A smart scientist can be wrong when it comes to what is really going on within different human bodies. On his death bed Pasteur said, : The Medium (virus, germ, pathogen), and the milieu/terrain is everything. That PCR test seems worthless. He says it can't be used for discovery, but isn't that what is being used to test for Covid ?
Thank you professor Racaniello for making these lectures available to the public. They are extremely in depth and informative and reminds me of being in the lecture hall (in great way. I’m an honour graduate and I love to learn). I’m living through this COVID-19 pandemic so why not educate myself on virology while this information is available. This has added structure to my day as I will attend to two classes a day as I self isolate. Thankful for this opportunity all the way from 🇨🇦
Hola Vincent. Una aclaración: creo que SARS-Cov-2 tiene arriba de 30k pares de base. Tú dijiste 15k. (No sé si esto ya se aclaró en los comentarios... con tanto comentario trol está difícil buscar). Mil gracias por tus clases. Son excelentes. Saludos desde Cuernavaca, Morelos, México.
A really interesting subject and field of study. A lot depends on the presenter and how they present the material. Vincent has done a great job at keeping my attention engaged with his impromptu questions thrown in to see if you're still awake.
I’m curious, how are new viruses discovered? So, let's say you have a patient sick with a flu and in hospital but all tests for anything remotely similar to that come back negative. Is it up to the doctor to be persistent? Would that doctor just treat the symptoms and if it still isn't resolved then look further into it? Would it have to be many cases of similar symptoms all with negative results and treating symptoms with no result before anyone even looked into it? Is it possible there are many different undiscovered and new viruses that just aren't yet detected but don't kill people in the same quantities but could at any time mutate to be as effective at propagating but we have no idea because they aren't life threatening? This is all very intriguing. I'm wondering because I and many others got sick in November/December. I never went to the doctor but now I’m reading articles about a mysterious upper respiratory infection that was going around. I’m making assumptions about what I’ve read in the news so this is likely wrong but how is it we never came up with what that sickness was as flu tests came back negative but China discovered Covid-19 and it had not yet come to the US (assuming it hadn’t come here).
I have subscribed. This is brilliant/explicit teaching. I wish all lecturers could be the same. I'm learning so much about this field that's incredible. Come to think humans (and all living creatures etc) and viruses must be sharing something or very closely related since life began millions/billions years ago. Fascinating and thanks to all relentless development and research to broaden/upgrade our scientific knowledge. Much appreciated.
thank you for sharing your information but as a layperson please could also give the different ways to stop spreading or getting infection ...like they say if we use soap or just wash this goes off ..is this true? how to avoid from a virologist opinion. thanks once again
@@markh7765 ..sure there are plenty but as the internet is so full of crap information too don't you think coming from a Virologist is more reliable than other sources? this is to help all of us too besides just knowing about the science of virus at the moment the most valuable information is to safeguard ourselves than just science of this..I am sorry I am more practical in the present life than just theoretical ...many thanks for your sharing this info :)
In the hemagglutination at, say, 52:53, to my eye it looks like the 1:4 dilution is the same between rows C and D, is there a reason it would be like that at that end?
I was wondering the same thing... so I checked out the Principles of Virology textbook that Dr. Racaniello co-edited (p. 43 of the 3rd edition), and seems that in addition to clumping the red cells by binding to sugars on different cells, the influenza virus can also enzymatically cut the sugars off, if the amount of virus is high enough. So in the 1:4 dilution with the virus, the highest concentration, a red cell lattice isn't seen because the sugars have been chopped off the red cells by the virus.
I ended up looking for a course on virology because of watching and reading some claims done by a german dr Stefan Lanka. He is claiming that virions in general have not been isolated, what is your position on the fact that there are no pictures of virions.
If a resistant cell simply means it doesn't have a receptor and it may or may not be supporting viral replication. Then does this mean a permissive cell may or may not be a resistant cell? Because as you said, we can bypass the need for receptor by using transfection agent, then if that resistant cell supporting viral replication, then it can still be a permissive cell. Do I understand this correctly?
The answer to all of that is yes. If a virus can enter, the cell is susceptible. If it cannot enter, it is resistant. If the virus can replicate, it is permissive. If the virus doesn't replicate, it is impermissive. A succesful virus (or viable host cell) enables both susceptibility and permissiveness. In a laboratory setting only permissive cells are also doable via transfection.
@@be_rt Maybe the problem is that scientists think that what they observe in the lab can translate to human s by making assumptions. I wonder about what we are really observing with Covid. I am skeptical that this is a contagious virus. Just because a virus is present doesn't always mean it is the cause of disease, and the prof. said the majority of virus is non-infectious, but the PCR test doesn't tell you that. That PCR test is misleading. He said that you can be infected for 14 days with a virus, but the PCR will register positive for 60 days!!!
When I worked at the Public Heath Lab in Newcastle, UK we used lots of HeLa culture in flat glass bottles. I'm not sure if this was where Newcastle disease was found. It was a long time ago. I'm finding your lectures most interesting bearing in mind the current Covid-19 pandemic.
at 7:50 "you can put viruses in different places in the egg, and different viruses will grow." Do you mean you can grow all these different kinds of virus strains from the one strain, or that only certain strains can be grown in certain areas of the egg? ie can u have a baseline virus strain, and grow influenza, herpes, mumps and avian Adeno from that baseline, in different parts of the egg?
Wow, watching these lectures have taught me so much. I had a question about what you said around 1:06:27 though. How do you know there's no infectivity and only pieces of the viral RNA in the PCR product? Do you have to compare the PCR product with something else simultaneously to know if the infectivity is still present?
This is also my question. I don't understand this study at all, I think is their fault because they don't explain properly what they mean by the red line, by what means they tested the ”infectious virus” www.sciencedirect.com/science/article/pii/S2211124717301134
They know what the length of cycle is for virus somehow, and they observe that PCR test produces a positive for 60 days even though the infection only lasts for 15 days or so...PCR test should not be used for discovery he said...
I really enjoyed the course! Is it possible to received some teaching materials like ppt or an open source book. Would really appreciate it. I plan to incorporate some of your work in my lectures. Thanks a mill
So a cell has to be susceptible and permissive to the virus, does that mean a cell is S and P to only a certain range of viruses? Are some cells not susceptible and permissive to rabies? CAN A CELL BE S AND P TO RABIES BUT NOT something else?
yes. a cell is only susceptible and permissive to a limited number of viruses. a bacteriophage will not enter a human cell because the cell has no receptor for the virus. in other cases a virus might enter a cell because there is a surface structure similar to the one of its natural host but can not replicate in the cell because the cells biochemistry does not support its replication.
What are your thoughts on Dr. Stefan Lanka's theory that viruses don't actually exist? Is there any credence to his work? Attempting to understand better...
Thank you for comparing and contrasting Ebola and the COVID-19, I shared what you said ... people on social media are acting like all the viruses are the same and that COVID-19 is not worse than the flu. ( 45:09 )
@@Flatleava Fear mongering. He says viruses don't have extraordinary abilities. No evidence that a virus can cause a specific disease. Look up HIV/AIDS: Fact or Fiction. He says viruses mutate all the time, so there is nothing special about any virus. Just because there may be an exponential rise in an epidemic doesn't mean the virus is mutating or doing anything tricky. Look to the host, and the environment to see what factors are causing disease increase. A healthy immune system is the most important factor. They will use the "mutation" to explain why there are different effects in different areas, when there are other regional factors such as air pollution, 5G radiation, medication use (nursing homes),etc..
First thank you sir for spending time and creating this lecture for RUclips it has given me further knowledge and understanding about this facinating organism. Second is a question of can a sperm be considered as a virus?
Good analogy. Machines are man made. Living creatures/organisms preceeded man made machines. Their purpose and functionality are coded through biological and other processes some still unknown and many unreplicatble. Viruses are biological code structures, navigating various biological kingdoms realms, "infecting" organisms exchanging instructions and genetic material to maintain the infrastructure of lifes ordering. The Creators knowledge is beyond understanding, but we are instilled with the capacity to know and be known by him. Most importantly to Love which is the ability to choose what to accept as truth, aka believe in.
I have a feeling that the story/narrative that we have learned about viruses makes them out to be our adversaries that have an intelligence, and the only way to defeat them is to get vaccinated, but only against a few rogue ones. LOL It's a scam.
If you come back here from the third lecture where he explains that some viruses have segmented genomes there dna is separated into segments then when he explains 30:30 one hit vs two hit you have an aha moment
I can't thank you enough for making your lectures available for free. It really warms my heart to see people that love to share knowledge. Many blessings to you!!
A very sincere thank you from me as well!
These lectures are a valuable contribution. You are enlarging our world and making something dangerous and mysterious more understandable. That which is understandable is less frightening. Knowledge is power and it also reduces fear. Thank you.
@@be_rt Good God. Isn't there a conspiracy theory phoning you right now? I'm not even going to ask you WTF you mean because, frankly, you don't know.
@@markh7765 Who would win: random youtube QAnon commenter vs PhD virologist who helped eliminate polio
Mark H ikr these conspiracy idiots think that everyone is out to get them when they have physical proof in front of them
This man is phenomenal and his lectures are great! I’m a retired physician and know a lot of research but I have learned so much from these talks! It is amazing that these are free to view. I applaud the professor.
@@be_rt your ignorance is on another level
@@be_rt whoosh! In one ear, out the other.
The only dogma is here is your ignorance and appeal to Koch's postulates which even Koch had to admit there were limitations and not all 4 postulates could be met. Introduce virual diseases and it's even more oblivious especially because the criterion was established before viruses was discovered.
I've taken over 70+ college courses and Professor Racaniello, you've given some of the best lectures I've seen. I'm giddy with knowledge! Wonderful information! Thank you!
Giddy with propaganda.
Why has this only got 12k odd views! - All of humanity should be educating themselves on this stuff! - I'm just some random bank worker, but i have to say virus's are fascinating "things"
Bell Curve and curiosity by non-medical people!
Perhaps an algorithm
I think the viruses find us interesting hosts as they if had a understanding of their devastating consequences they might be ashamed and proud of their consequential affect on such large beings . Their devastation to humans is useless and pointless. If we had infinite life span that would be different especially if we became ill/sick in that case the virus would be a path to end pain and suffering and population control.
You have to make this lecture into a Fortnite program. Then you'll get millions of views.
Most people don't have the basic biology background to understand this.
These lectures are just..fantastic. I followed all of them since the first one. The patience, the clarity, the material ...it is so inspiring to learn more. This professor is amazing.
Got to say, I'm loving this series, please keep doing them!
You really make the topic come alive, Dr Racaniello; I've never enjoyed a lecture on such a technical subject as much. Thanks for making your course available to all.
Going through all of the lectures and taking notes; I can't thank you enough for making these available Dr. Racaniello. I study Trypanosoma cruzi so virology isn't directly pertinent, but everything in biology is essentially related, so these lectures will undoubtedly aid in my research!
Thank you for showing where you are referring to on the visual aid.
I found every year you have been incorporating new information. Thanks for doing this. Love itI have been listening these lectures for a couple year.
I worked as a front line health worker with a high respect for PPE. You are amazing to freely share your knowledge.
Scientists tend to downplay the health of the host with their lab work. A healthy environment goes a long way, too. I wonder what might be improved in the hospital environment for a better outcome, and so there is less need for PPE with health care workers. People talk about effects of 5G, and I have even heard that fluorescent lighting can affect brain health in some people. Pasteur said on his death bed, "It is not the medium (germ, virus, pathogen) , but the milieu that determines whether there will be a healthy outcome from exposure." Look up terrain theory.
Thanks Prof. Dr. Vincent for all your great effort to what you teach us all about virology
Thank you for making these lecture available to public. I realized how much I learn from your lecture than my previous class.
This series is really interesting because it follows allong with the outbreak of coronavirus 19 and the emerging information about it
Yeah, that PCR test seems to be misleading according to what he said...
Absolutely amazing and fascinating. And only two episode in. Even someone who has only helped kids to a-level chem and bio and done pop sci reading can follow 90% of this with a couple of pauses to check things on Wiki. Thank you very much indeed.
Pedro Santos The professor is very good, isn’t he? I am glad that this successful scientist started teaching, and grateful that he posts these videos on RUclips.
I would venture to add that your “pop science” reading must be rather wide and at least moderately deep for you to understand almost all of the lecture. As an old doctor (who spent about 4 years as a research assistant before medical school), part of this is a helpful review, but I am also picking up quite a bit of new information. It has been many years since I worked in a basic science laboratory!
Ad 44:09: "Why" is not a philosophical question. Actually this is a shortcut for "why this not that". I take this one as "why do viruses have to assembly, instead of creating virions at once?". Or, put another way, why it's not possible to produce a viroid all at once, without the assembly stage.
(And one of the possible answers could be, because they are too complicated. By the way, do viroids also have the assembly stage? As far as I understand, these are just strands of RNA)
You have been extremely generous to share these videos with us....you are too good to listen to....I am also trying to learn and catch the way you teach...its amazing...
Thank you Professor. Fascinating, Educational and is removing false ideas I got from the MSM and other places in the murk of the internet.
I' really grateful to you for making your lectures free. If you don't mind a bit of feedback, You very often assume knowledge that the listener does not have.
Thank you so much for passionately teaching the intricate details of the subject that too in such an easy to understand manner. There are very few who spend time and energy and make it viable for everyone. Everything is so structured and made so interesting! Would be always grateful for this amazing series!!
Vincent, great course! I like also the evolutionary aspect from the geological perspective. We owe our existence as humans and all life forms to a likely proto-cellular viral precurser.
he mentioned that in the first lecture
Thanks for lecture number two... Politicians should take this lectures so they know what is going on too.
thanks dr
I am from Libya
I am very happy to listen your interesting lecture
thank you very much
@@be_rt Can you please demonstrate 10 proofs that this lecture is non-sense. Thank you!
@@be_rt Following what you have just mentioned, and in the case of COVID19, no one -- not even those scientist that published the genome sequence of SARS-CoV-2 -- have isolated & purified that virus causing this pandemic that we have to date.
@@be_rt if it was Facebook, I'd give you a 'haha reaction', it's not worth to debunk your awful thesis because it would be a waste of time. You want to sound like science is on your side, but it is not, you've literally commented on a lecture made by a professor that specializes in this field, who spent many years getting the knowledge and you have all the audacity to act like you know better. Peace n love
At about 20:51 the lecturer says that CPE has lost its significance due to the development of a more sensitive and specific test based on PCR. That sounds quite reasonable, on the other hand, the cost of PCR, in particular, the qPCR (as it is used currently) is rather high, and the demand for the screening tests has recently risen immensely. So here is my question: couldn't we take some cell cultures that would be even easier to grow than human epithelial cells, genetically transform them so they start producing a proper receptor protein (say human ACE2) and use them for a cheap and simple preliminary screening test for the presence of the new coronavirus? Some algae cells could be grown at a really low cost, besides they are green and often phototactic, so there is a chance their lysis could be visually detected without even the use of a microscope. Maybe only a little chlorophyllase or pheophytinase enzyme should be added to make the chlorophyll breakdown more rapid and more apparent as soon as it leaks out from the cells into the surrounding medium. The problem is, as I see from this lecture, that making algal cells susceptible does not mean they will also be permissive, and even in that case, the change in cell morphology, as caused by the coronavirus may be not lysis but rather the formation of syncitia. These are important problems but do they exclude the feasibility of the concept of using GM algae as really cheap detectors of specific viruses? Maybe not coronaviruses, but other similarly significant ones? I posted a similar question on the Quora forum but it was met with a very meagre interest www.quora.com/Is-it-possible-to-genetically-modify-common-algae-like-Chlorella-or-Dunaliella-so-that-they-could-be-readily-and-specifically-attacked-by-the-new-coronavirus . I know it is an experiment that can provide the most definitive answer to such a question but it would cost pretty much money, time and work. I suppose there are people out there whose experience allows them to comment here confidently and expertly. I would be grateful for such opinions.
I remain absolutely enthralled with very excellent educational opportunities and presentations here on RUclips. I am retired as a shop teacher. The EXCELLENT and great value education provided keeps my attention all day. College credit should be attached. Bless you RUclips.
David Robinson I just want to thank you for your service as a shop teacher. Our son’s shop teacher was the most influential teacher he had in high school.
Thanks for the wonderful lectures! Got the virology virus now! :)
Doing my Virology course in veterinary, and your lectures are very helpful , thank you for sharing them
Your lectures are mesmerizing. S. P. Athan, Ph.D.
Absolutely wonderful...the super well presented information presented here with out charge give s a clear understanding of what these viruses are by a gifted professor!
Thank you so much 🙏
1:00:54-1:01:00 That's odd because in another lecture 6 months prior to this one you repudiated the very idea of using PCR as a diagnostic, what changed? Also how can you talk about PCR and not mention the person who invented and won the Nobel prize for it?
Very informative and useful information. You have certainly spark an interest in virology. Very appreciative that these are available for free. I'm learning so much.
Excellent lecture #2 in the Virology course. The lecture is interesting, informative, and has many illustrations. Those highly motivated might consider referring to the two volume treatise entitled Principles of Virology, co-authored by Prof. Racaniello. I have the 4th edition (2015) of the two volume set which is comprised of over 1,000 pages, and provides more detailed information.
Thanks for having these lectures for free i really enjoy them
Thank you Doc. You are sharing your knowledge for free, that is incredible!
Excellent. Well done for sharing.
Thank you Vincent... I'm simply amazed that I have access to these incredible lectures...
Shouldn't the optic cup have been made from an ectodermal cell? (Optic cups in vertebrate embryos are derived from ectoderm.)
Is there a link to a one-step curve for SARS-CoV-2 available by any chance? (I've found some, mostly in the context of potential anti-virals, mostly with 24h sample intervals)
Thank you for your work and dedication. I have been fascinated myself about viruses and lack so much knowledge on these functions, the math, the jargon. You create such a brilliant clarity. I have obtained so much so far but I know I have so much to learn. Greatful I’ve stumbled upon you. Thank you thank you for sharing your life’s work/knowledge about these magnificent species of genetic material that seem to be a catalyst to evolution.
Thank you prof can you please recomended abook about cell and Genetics and microbial immunity
The plaque assey counting method seems to me to be sensitive to systematic errors. If you have a tendency to take 0.11 ml instead of 0.1, you get almost a factor 2 error by the time you reach 10^-6 and 10^-7 dilutions. Of course, if order of magnitud is what you really care about this is well within margin, but you need to have good skills/equipment to get confidence in even the first decimal (in my opinion). I am a mathematician with next to no lab experience so I don't know what magnitude of errors are actually reasonable.
It really a great job being done by you. I have no physical lectures for my virology course in this summer. sem due to coviD-19 but its good to learn here online. Highly interactive Slides and talk. kudos!
Love the lectures :) I couldn't find that video of the plaque forming in cell culture anywhere. Could someone link it?
Prof. Racaniello: *Susceptible* - "has a functional receptor for a given virus" (3:06) - but what about macropinocytosis entry? "Most [viral entry] is receptor-mediated, but there also are some examples of macropinocycosis [entry]" (2019 #5 Attachment and Entry; 25:10) IIRC - once endocytosed, a virus has to have the ability to attach to the vesicle wall and that may be where the "receptor" exists (i.e., in macropinocytosis entry) in your definition of susceptible?
I would say, it doesn't matter where the receptor is, if it is absent, the cell is not susceptible.
Are there any known cases of a virus being taken up by macropinocytosis and then exiting the macropinosome into the cytoplasm *without* using a receptor-mediated path to breach the macropinosome's plasma membrane? I guess they would have to do *something* to exit the vesicle before fusion with a lysosome - unless the virus was resistant to lysosome enzymes and could survive to enter the Golgi at the end of life of a lysosome.)
Fascinating. This lecture covers PCR in way that is very relevant in public health discussions and debate here 7 months later. And still no "lick strips."
-Please let me know if there is a textbook associated with this class- TWiV #662 gives my answer: Principles of Virology, 5th Edition. Episode has a link to purchase.
Dr. Racaniello, I'm curious, did Ms. Skloot pay you for working with her to get the science in her book correct or is standard practice to help out?
Is there a relationship between the particle/pfu ratio and the tendency of a virus to cause mutations in the host cell? For example, would a virus with a high ratio, like papilloma virus, be more likely to cause mutations in the host cell due to defective particle formation (packaging wrong nucleic acids for example) vs another virus with a low ratio? I realize this sort of depends on what's being packaged and how it gets delivered to the host cell. But, I was just curious.
There does not appear to be a relationship between particle/pfu and mutation rate.. Packaging the wrong nucleic acid probably happens regularly, and we think such DNA can be incorporated into cells and affect them. We call it horizontal gene transfer and it has probably been a major driver of evolution. But I don't think defective particles are a major driver. On the other hand, there is increasing evidence that defective particles play a role in disease: they may stimulate the immune response, for example, helping to clear the infection. We'll hear more about that later in the course.
@profvrr Hi Vincent, at 35:56 would innate immunity of the host cell also partially account for the >1 particle-to-PFU ratio? Thanks.
I'm disappointed that you didn't get an answer from somebody. These scientists with their lab work seem to overlook the effect of a healthy immune system which is why we are in this mess. A smart scientist can be wrong when it comes to what is really going on within different human bodies. On his death bed Pasteur said, : The Medium (virus, germ, pathogen), and the milieu/terrain is everything. That PCR test seems worthless. He says it can't be used for discovery, but isn't that what is being used to test for Covid ?
A privilege to view.. So well done and communicative. Thank you.
Thank you professor Racaniello for making these lectures available to the public. They are extremely in depth and informative and reminds me of being in the lecture hall (in great way. I’m an honour graduate and I love to learn). I’m living through this COVID-19 pandemic so why not educate myself on virology while this information is available. This has added structure to my day as I will attend to two classes a day as I self isolate. Thankful for this opportunity all the way from 🇨🇦
Hola Vincent.
Una aclaración: creo que SARS-Cov-2 tiene arriba de 30k pares de base. Tú dijiste 15k. (No sé si esto ya se aclaró en los comentarios... con tanto comentario trol está difícil buscar).
Mil gracias por tus clases. Son excelentes.
Saludos desde Cuernavaca, Morelos, México.
Is there a bibliography on this subject (the whole playlist)?
Here: ruclips.net/p/PLGhmZX2NKiNldpyRUBBEzNoWL0Cso1jip
A really interesting subject and field of study. A lot depends on the presenter and how they present the material. Vincent has done a great job at keeping my attention engaged with his impromptu questions thrown in to see if you're still awake.
Please link to this video anyone who doesn't know how covid-19 works.
You know that someone is a born teacher when you come across one.
Excellent information and presented in a very clear manner. Ta.
Does the Corona (COVID-19) virus use STAT3 in replication?
What is the protein made of?
Thanks for shareing your knowledge .
May Allah bless you sir we really appreciate that you make your valuable information free for us
Anyone know if the course is postponed because of the corona virus?
Thank you for sharing this with us! Very interesting. A valuable reminder of what I learned at high school!
I’m curious, how are new viruses discovered? So, let's say you have a patient sick with a flu and in hospital but all tests for anything remotely similar to that come back negative. Is it up to the doctor to be persistent? Would that doctor just treat the symptoms and if it still isn't resolved then look further into it? Would it have to be many cases of similar symptoms all with negative results and treating symptoms with no result before anyone even looked into it? Is it possible there are many different undiscovered and new viruses that just aren't yet detected but don't kill people in the same quantities but could at any time mutate to be as effective at propagating but we have no idea because they aren't life threatening? This is all very intriguing. I'm wondering because I and many others got sick in November/December. I never went to the doctor but now I’m reading articles about a mysterious upper respiratory infection that was going around. I’m making assumptions about what I’ve read in the news so this is likely wrong but how is it we never came up with what that sickness was as flu tests came back negative but China discovered Covid-19 and it had not yet come to the US (assuming it hadn’t come here).
Oh, I wrote this before I watched your videos. I didn’t even know about our viome before this.
You probably got sick from the flu shot, or some other toxic exposure like air pollution, or tap water.
I believe there are around 29,800 base pairs, not 15,000 bases.
Important...
Is it possible to create a functioning version of the furin enzyme with xeno nucleic acids?
what do you call it when a person gets on plane travels abroad ? Getting infected...
Fear mongering. I don't think there is any rationale for cancelling flights. Personalized medicine!!!
Thanks a lot professor this lecture is very helpful for me 🌹🌹❤️
I have subscribed. This is brilliant/explicit teaching. I wish all lecturers could be the same. I'm learning so much about this field that's incredible. Come to think humans (and all living creatures etc) and viruses must be sharing something or very closely related since life began millions/billions years ago. Fascinating and thanks to all relentless development and research to broaden/upgrade our scientific knowledge. Much appreciated.
thank you for sharing your information but as a layperson please could also give the different ways to stop spreading or getting infection ...like they say if we use soap or just wash this goes off ..is this true? how to avoid from a virologist opinion. thanks once again
This is a college course in Virology. Plenty of information can be found using Google.
@@markh7765 ..sure there are plenty but as the internet is so full of crap information too don't you think coming from a Virologist is more reliable than other sources? this is to help all of us too besides just knowing about the science of virus at the moment the most valuable information is to safeguard ourselves than just science of this..I am sorry I am more practical in the present life than just theoretical ...many thanks for your sharing this info :)
In the hemagglutination at, say, 52:53, to my eye it looks like the 1:4 dilution is the same between rows C and D, is there a reason it would be like that at that end?
I was wondering the same thing... so I checked out the Principles of Virology textbook that Dr. Racaniello co-edited (p. 43 of the 3rd edition), and seems that in addition to clumping the red cells by binding to sugars on different cells, the influenza virus can also enzymatically cut the sugars off, if the amount of virus is high enough. So in the 1:4 dilution with the virus, the highest concentration, a red cell lattice isn't seen because the sugars have been chopped off the red cells by the virus.
I ended up looking for a course on virology because of watching and reading some claims done by a german dr Stefan Lanka. He is claiming that virions in general have not been isolated, what is your position on the fact that there are no pictures of virions.
wissenschafftplus.de/uploads/article/Dismantling-the-Virus-Theory.pdf
Thanks for sharing this
How do we stop viruses?
Great lecture, love the plaque part
Sir make one vido in the topic methods to invastigating a viruse structure pleas sir
Polarity, very interesting. Quantum theory application to Biological science. I'm hooked and thank you for your on line presentation.
this is an amazing public education ...thank you
If a resistant cell simply means it doesn't have a receptor and it may or may not be supporting viral replication. Then does this mean a permissive cell may or may not be a resistant cell? Because as you said, we can bypass the need for receptor by using transfection agent, then if that resistant cell supporting viral replication, then it can still be a permissive cell. Do I understand this correctly?
The answer to all of that is yes.
If a virus can enter, the cell is susceptible. If it cannot enter, it is resistant. If the virus can replicate, it is permissive. If the virus doesn't replicate, it is impermissive. A succesful virus (or viable host cell) enables both susceptibility and permissiveness. In a laboratory setting only permissive cells are also doable via transfection.
Enjoying this lecture.
Thanks a lot for making your courses available to everyone, I highly appreciate. I really look forward to reading your book I just ordered
@@be_rt Maybe the problem is that scientists think that what they observe in the lab can translate to human s by making assumptions. I wonder about what we are really observing with Covid. I am skeptical that this is a contagious virus. Just because a virus is present doesn't always mean it is the cause of disease, and the prof. said the majority of virus is non-infectious, but the PCR test doesn't tell you that. That PCR test is misleading. He said that you can be infected for 14 days with a virus, but the PCR will register positive for 60 days!!!
When I worked at the Public Heath Lab in Newcastle, UK we used lots of HeLa culture in flat glass bottles. I'm not sure if this was where Newcastle disease was found. It was a long time ago. I'm finding your lectures most interesting bearing in mind the current Covid-19 pandemic.
at 7:50 "you can put viruses in different places in the egg, and different viruses will grow." Do you mean you can grow all these different kinds of virus strains from the one strain, or that only certain strains can be grown in certain areas of the egg? ie can u have a baseline virus strain, and grow influenza, herpes, mumps and avian Adeno from that baseline, in different parts of the egg?
Wow, watching these lectures have taught me so much. I had a question about what you said around 1:06:27 though. How do you know there's no infectivity and only pieces of the viral RNA in the PCR product? Do you have to compare the PCR product with something else simultaneously to know if the infectivity is still present?
It (the red curve) was probably done in parallel using a plaque test or CPE.
This is also my question. I don't understand this study at all, I think is their fault because they don't explain properly what they mean by the red line, by what means they tested the ”infectious virus” www.sciencedirect.com/science/article/pii/S2211124717301134
They know what the length of cycle is for virus somehow, and they observe that PCR test produces a positive for 60 days even though the infection only lasts for 15 days or so...PCR test should not be used for discovery he said...
I really enjoyed the course! Is it possible to received some teaching materials like ppt or an open source book. Would really appreciate it. I plan to incorporate some of your work in my lectures. Thanks a mill
So a cell has to be susceptible and permissive to the virus, does that mean a cell is S and P to only a certain range of viruses? Are some cells not susceptible and permissive to rabies? CAN A CELL BE S AND P TO RABIES BUT NOT something else?
1:05:20 it look like wuhan is and older strain than SARS?
yes. a cell is only susceptible and permissive to a limited number of viruses. a bacteriophage will not enter a human cell because the cell has no receptor for the virus. in other cases a virus might enter a cell because there is a surface structure similar to the one of its natural host but can not replicate in the cell because the cells biochemistry does not support its replication.
what a great lecture series!
Hi teacher. I think the farm chemistry..... can solve covid.
Thank you for your information! Are you going to speak about prevention of covoid-20, who we can protect yourself, masks???
52:23 couldn't this be why they are finding blood clots in the body now in recent studies for the current sars-covid2?
What are your thoughts on Dr. Stefan Lanka's theory that viruses don't actually exist? Is there any credence to his work? Attempting to understand better...
It goes against 130 years of science.
Thank you for comparing and contrasting Ebola and the COVID-19, I shared what you said ... people on social media are acting like all the viruses are the same and that COVID-19 is not worse than the flu. ( 45:09 )
This one copy itself once it enters you in grate speed
That depends on what you mean by "worse than"
@@Pdrum2 it spreads faster and has a higher mortality rate
@@dlgang Vinncent has said nothing about mortality rate. in fact he said there are many he believes that have it but don't get any symptoms at all
@@Flatleava Fear mongering. He says viruses don't have extraordinary abilities. No evidence that a virus can cause a specific disease. Look up HIV/AIDS: Fact or Fiction. He says viruses mutate all the time, so there is nothing special about any virus. Just because there may be an exponential rise in an epidemic doesn't mean the virus is mutating or doing anything tricky. Look to the host, and the environment to see what factors are causing disease increase. A healthy immune system is the most important factor. They will use the "mutation" to explain why there are different effects in different areas, when there are other regional factors such as air pollution, 5G radiation, medication use (nursing homes),etc..
Out of curiosity, about how long does the infectious cycle take?
I think it is 15 days max., but he was saying the bogus PCR test will show a positive for 60 days, and isn't that the test they are using?
What about laser Dynamic Light Scattering for concentration/size of virus particles?
Very possible but expensive beyond the reach of most labs, hence not mainstream (yet?)
Thank you professor for your lectures.
First thank you sir for spending time and creating this lecture for RUclips it has given me further knowledge and understanding about this facinating organism. Second is a question of can a sperm be considered as a virus?
Viruses are like tiny machines. Like little tiny programmers sending code to a cell to manufacture more of the virus. Like computers. 🤔🧐
Good analogy. Machines are man made. Living creatures/organisms preceeded man made machines. Their purpose and functionality are coded through biological and other processes some still unknown and many unreplicatble.
Viruses are biological code structures, navigating various biological kingdoms realms, "infecting" organisms exchanging instructions and genetic material to maintain the infrastructure of lifes ordering.
The Creators knowledge is beyond understanding, but we are instilled with the capacity to know and be known by him.
Most importantly to Love which is the ability to choose what to accept as truth, aka believe in.
What is the COVID-19 multiplicity of infection? ( 48:00 )
Damon Lee Gang It depends on the viral load you are exposed to. MOI is a parameter during in
vitro-experiments
Virology is going to be more important than self driving cars! Too bad we don't have as many virologists as computer game designers.
I have a feeling that the story/narrative that we have learned about viruses makes them out to be our adversaries that have an intelligence, and the only way to defeat them is to get vaccinated, but only against a few rogue ones. LOL It's a scam.
Should I understand how DNA works before watching these?
another fantastic session. thank you so much.
If you come back here from the third lecture where he explains that some viruses have segmented genomes there dna is separated into segments then when he explains 30:30 one hit vs two hit you have an aha moment