The new coronavirus is a stupid virus comparing with HIV
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The new coronavirus is a stupid virus comparing with HIV
The new coronavirus is a stupid virus comparing with HIV. This is a key indicator of vaccine protection against infection and an important basis for choosing enhanced vaccination.
With COVID-19 vaccine animal experiment results: one for neutralizing antibodies and one for T cell response.
Compared to HIV, SARS-CoV-2 seems really a stupid virus.
1. The new coronavirus has only one immunodominant epitope, the RBD on Spike, and it is this epitope for both T and B cells. And it has been 40 years since HIV appeared, and we still don’t know what its dominant immune epitope is.
(Figure: On the left, the new coronavirus binds to the ACE2 protein of the host cell through the RBD of its S protein, thereby entering the cell; on the right, the neutralizing antibody binds to the RBD region of the virus to block the virus from binding to ACE2 and Further into the host cell. Source: genengnews.com [UNC School of Medicine])
2. In theory, blocking RBD with antibodies can prevent infection with the new coronavirus.
Just like the schematic diagram of UNC in the above figure:
The figure on the left shows the key mechanism by which the new coronavirus enters the host cell.
The new coronavirus can enter the cell by binding to the ACE2 protein of the host cell through the receptor binding domain (RBD) of its spike protein (S protein);
The right shows how the neutralizing antibody protects the host.
The neutralizing antibody blocks the binding of the virus to ACE2 by binding to the RBD region of the virus, thereby blocking the virus from entering the host cell.
It is precisely because of this single immunodominant epitope that the level of neutralizing antibodies against S protein RBD has become a key indicator of vaccine protection against COVID-19 infection.
3. Clinical trials have verified that the level of neutralizing antibodies is a key indicator of the level of protection against COVID-19.
That is, the level of neutralizing antibodies induced in the phase 1 clinical trial is positively correlated with the protection against infection in the phase 3 clinical trial.
The phase 1 clinical trial results show that the neutralizing antibodies induced by the mRNA vaccine of Pfizer/BioNTech of Germany, the mRNA vaccine of Moderna of the United States and the recombinant protein vaccine of Novavax of the United States are about 4 times that of the recovered patients’ serum; The protection against infection of these three vaccines in phase 3 clinical trials also reached about 95%.
4. It can also be used as an indicator to judge the protection of enhanced vaccination against COVID-19.
As countries are considering re-vaccinations for high-risk populations before winter, some vaccine companies have also announced their neutralizing antibody levels after booster immunization in their quarterly reports.
American Pfizer’s mRNA vaccine, after the third dose of intensification, the middle-aged group induced neutralizing antibody titers that were 4.99 times (wild strain) and 5.48 times (Delta strain) after the second dose.
(Source: Pfizer 2Q quarterly report)
The American Moderna company’s mRNA vaccine induces a neutralizing antibody titer that is 3.79 times that of the second dose (wild strain) after the third dose intensification with half a dose.
(Source: Moderna 2Q quarterly report)
The recombinant protein vaccine of Novavax in the United States, after the third dose of intensification, the neutralizing antibody titers induced by all age groups are 4.3 times that of the second dose (wild strain).
(Source: Novavax 2Q quarterly report)
As mentioned earlier, these three vaccines can induce 4 times the level of neutralizing antibodies in the survivors’ serum after the second dose, and the third dose of booster induces 4 times higher drops than after the second dose. Highly neutralizing antibodies are expected to be able to form sufficient containment of Delta virus.
The reduction of neutralizing antibodies significantly reduces the prevention of infection with COVID-19, but does not significantly reduce the prevention of critical illness or death after infection with COVID-19.
It should be noted that the most positive correlation with neutralizing antibody titer is the prevention of infection with COVID-19; that is, when the antibody titer is particularly low, it is difficult to suppress infection with COVID-19.
However, when the vaccine is exposed to the virus, the memory lymphocyte immune response that is established after vaccination will be activated by infection with the new coronavirus; therefore, even if the COVID-19 infection progresses to serious illness or death, it is also related to the neutralizing antibody titer. The reduction has some relationship, but it is not particularly obvious. Even if the neutralizing antibody is significantly reduced, vaccination can still effectively prevent critical illness or death after infection with COVID-19 due to the activation of memory immunity.
Compared with HIV, the new coronavirus is indeed a stupid virus.
Only one epitope can play. Therefore, humans have developed a high-quality COVID-19 vaccine in less than a year.
However, the new coronavirus is also a vicious virus, constantly mutating; the Delta mutant strain is highly contagious and ranks among the top three of all viruses.
The only way to deal with this highly contagious vicious virus is to attack it: vaccinate yourself to contain the only epitope it can attack.
(source:internet, reference only)
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