Could you link the actual study from this statement: 'Ogando et al. (2020) in Nature Communications claim to have purified SARS-CoV-2 directly from patient samples using ultracentrifugation'?
As I read through this study, I can't seem to find where ultracentrifugation was done directly from the patient sample without first being passed through the cell culture technique using Vero E6 cells. They even called them 'cell culture supernatants.' This is a critical step in that it is not just the patient sample being centrifuged to separate out the particles. Am I misunderstanding the method?
ChatGPT answered your question: You are correct in your observation. In the study by Ogando et al. (2020), the researchers did not purify SARS-CoV-2 directly from patient samples using ultracentrifugation. Instead, they first inoculated Vero E6 cell cultures with samples containing the virus. After allowing the virus to replicate within these cells, they collected the resulting 'cell culture supernatants'—the fluid above the cell layer containing the virus particles—and then subjected these supernatants to ultracentrifugation to concentrate and purify the virus. This methodology means that the virus was amplified in Vero E6 cells before purification, rather than being isolated directly from patient specimens.
This approach is common in virology to obtain sufficient quantities of the virus for study, as direct isolation from patient samples often yields insufficient viral material. However, it's important to note that propagating viruses in cell cultures can sometimes lead to mutations or adaptations specific to the cell line used, which may not fully represent the virus's properties in its natural human host.
--Just want to point out one detail concerning what you wrote -- "Koch’s Postulates—has never been fully satisfied for SARS-CoV-2 or many other viruses."
--You should really change that to simply, "Koch's Postulates have never been satisfied for SARS-CoV-2 or ANY other virus."
This is an interesting stack that implicitly rejects the widespread consensus that Koch's postulates are obsolete and have been debunked. Consensus is of course not science. Nonetheless, it would be interesting to read a defense of the postulates that attempts to refute claims that they are obsolete and debunked and that even Koch himself was at least partially aware of and acknowledged limitations of his postulates.
All EM images show artifacts, not representations of specific organisms. For two reasons: 1) the very process of preparing EM samples meticulously destroys everything live; 2) EM images are scientifically unreliable.
The second issue is not being discussed, ever. Let us assume that the EM sample contains some “organism”. It is already perfectly dead, killed by several methods in the sample preparation. Therefore: a) it cannot be “observed” over time, or b) re-examined by a different lab, or c) compared to anything else, or d) put on a time map - we don’t know at what stage of life (infectivity?) this “organism” is.
The sample is minuscule. You cannot EM-examine a reliable-size sample, like 5 by 5 inches.
You cannot repeat EM observation of a sample left for some time to see if anything changed because the sample is perfectly dead.
Why don’t scientists send the same sample (split into lots) to 20 different EM labs to check whether their observations are meaningful?
Could you link the actual study from this statement: 'Ogando et al. (2020) in Nature Communications claim to have purified SARS-CoV-2 directly from patient samples using ultracentrifugation'?
https://www.microbiologyresearch.org/content/journal/jgv/10.1099/jgv.0.001453?utm_source=chatgpt.com
As I read through this study, I can't seem to find where ultracentrifugation was done directly from the patient sample without first being passed through the cell culture technique using Vero E6 cells. They even called them 'cell culture supernatants.' This is a critical step in that it is not just the patient sample being centrifuged to separate out the particles. Am I misunderstanding the method?
ChatGPT answered your question: You are correct in your observation. In the study by Ogando et al. (2020), the researchers did not purify SARS-CoV-2 directly from patient samples using ultracentrifugation. Instead, they first inoculated Vero E6 cell cultures with samples containing the virus. After allowing the virus to replicate within these cells, they collected the resulting 'cell culture supernatants'—the fluid above the cell layer containing the virus particles—and then subjected these supernatants to ultracentrifugation to concentrate and purify the virus. This methodology means that the virus was amplified in Vero E6 cells before purification, rather than being isolated directly from patient specimens.
This approach is common in virology to obtain sufficient quantities of the virus for study, as direct isolation from patient samples often yields insufficient viral material. However, it's important to note that propagating viruses in cell cultures can sometimes lead to mutations or adaptations specific to the cell line used, which may not fully represent the virus's properties in its natural human host.
Thanks for the info.
Very nice, thank you.
--Just want to point out one detail concerning what you wrote -- "Koch’s Postulates—has never been fully satisfied for SARS-CoV-2 or many other viruses."
--You should really change that to simply, "Koch's Postulates have never been satisfied for SARS-CoV-2 or ANY other virus."
This is an interesting stack that implicitly rejects the widespread consensus that Koch's postulates are obsolete and have been debunked. Consensus is of course not science. Nonetheless, it would be interesting to read a defense of the postulates that attempts to refute claims that they are obsolete and debunked and that even Koch himself was at least partially aware of and acknowledged limitations of his postulates.
All EM images show artifacts, not representations of specific organisms. For two reasons: 1) the very process of preparing EM samples meticulously destroys everything live; 2) EM images are scientifically unreliable.
The second issue is not being discussed, ever. Let us assume that the EM sample contains some “organism”. It is already perfectly dead, killed by several methods in the sample preparation. Therefore: a) it cannot be “observed” over time, or b) re-examined by a different lab, or c) compared to anything else, or d) put on a time map - we don’t know at what stage of life (infectivity?) this “organism” is.
The sample is minuscule. You cannot EM-examine a reliable-size sample, like 5 by 5 inches.
You cannot repeat EM observation of a sample left for some time to see if anything changed because the sample is perfectly dead.
Why don’t scientists send the same sample (split into lots) to 20 different EM labs to check whether their observations are meaningful?
It has never been done.