New answers tagged immunology
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The CD4 receptor is a protein complex that harbors very specific chemistry. A virus is able to bind with the receptor if it harbors a particular protein/set of proteins that are able to interact with the receptor. The virus is basically disguised as something the CD4 receptor recognizes, and from there it is internalized within the cell via a process called ...
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is it 100% effective in 95% of the population, or 95% effective in 100% of the population
If every person takes the vaccine once, these situations are experimentally equivalent. They're only different if people who the vaccine fails for take it a second time.
It is possible for a vaccine to fail the first time a person takes it but succeed the second time -...
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Vaccine efficacy
Pfizer's target measures for efficacy (see the study on clinicaltrials.gov) seem to be:
Confirmed COVID-19 in Phase 2/3 participants without evidence of infection before vaccination
Confirmed COVID-19 in Phase 2/3 participants with and without evidence of infection before vaccination
From Pfizer's study plan (VE = vaccine efficacy):
VE ...
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It means protection against the virus brought to you by the vaccination.
In the trial, around 45.000 people participate. Among them, 50% are vaccinated with the trial vaccine, the other half receives a placebo. Additionally you exclude people from the trial which had COVID-19 before. Since infecting people with a potentially deadly disease is ethically not ...
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Vaccine efficacy is the percent change in the percent of individuals who test positive in the vaccinated group versus the placebo group in a trial. The CDC website explains it here
So a 95% efficacy means the vaccinated group had 95% less percentage of people test positive than in the placebo group. So if the placebo group had a 20% positive rate, the ...
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According to the person who made this video's response to my comment asking this question, the transfected cells are killed by cytotoxic T cells, but the amount of transfected cells dying is not enough to cause irreparable harm since the cells regenerate themselves fairly quickly through division. Plus, the acquired cell-mediated in addition to humoral ...
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"On MHC II, do cells present only antigen they have receptors for?"
Thank you for boiling your question down to its essence. The answer is no. Professional antigen-presenting cells (APCs) such as macrophages, dendritic cells, B cells, etc., which present peptides in the context of the major histocompatibility complex (MHC) Class II to CD4+ Thelper ...
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We cannot say if the virus in ferrets gets less or more dangerous than the one which actually circulates in humans. There are two problems with this infection:
The ferrets can build a reservoir for the virus making it possible for circulation to occur among these animals and re-introduce it into the human population. It may also be possible that the virus ...
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You can test for antibody titers (and also connected memory) for the persons who got the vaccine and then decide, if these antibody levels are protective or not. Problem with this method is, that it is not clear, what levels are protective. There is still no experience with it for SARS-CoV-2, this is routinely done for other diseases.
According to ...
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CRISPR/cas is used for exactly this purpose in bacteria.
The CRISPR array contains sequences from bacteriophages, which will prime various cas-nucleases to cleave either the DNA or the RNA of the virus.
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The human body basically does this on its own. We express various RNAses, some of which appear to have specific antiviral or bactericidal roles.
(This appears to be due to both RNAse activity and to biochemical properties of the proteins independent of RNA digestion)
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In Janeway it's been said without further explanation (I will edit and add reference) that B-cells and macrophages "become targets" of cytotoxic t-cell after these killer cells have become activated, have been primed. According to basic knowledge that indeed calls for questions, as B-cells have a job to to, they do not present - like dendritic ...
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Here is some exciting textbook reference (Janeway 5th ed.):
https://www.ncbi.nlm.nih.gov/books/NBK27118/
Try to read Figure 8.14 and compare with text. Whereas the figure shows some presentation of antigen at the site of infection, the text elaborates on this actually happening only after (or during) movement of APCs to lymph nodes. It seems to be only there ...
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