XBB – BioQuakes

Did you know that different variants of COVID-19 can have SUB variants as well? Because the Omicron variant is now the world’s most prevalent strain, it has been able to mutate into different sub variants. The XBB sub variants stood out because they contain a high number of genetic mutations compared to other variants. These mutations or changes help the virus avoid the body’s immune response even if one has been vaccinated for COVID-19 already. Specifically the XBB. 1.5 sub variant (also known as Kraken) has a mutation that helps the virus bind to cells making it more contagious. Scientists believe that XBB. 1.5 binds “more tightly to cells in the human body that the predecessors” (Andrea Garcia). This was the dominant strain in June 2023.

The updated COVID-19 vaccine is now being recommended by the CDC and has been approved by the FDA as of this September. It is a monovalent or single component version that specifically targets this sub variant of Omicron (XBB. 1.5). This vaccine is meant to broaden vaccine-induced immunity and provide protection from other XBB sub variants as well. This is similar to how the flu shot works in that the formula changes every year depending on which strain is spreading the most at the time. The vaccine will not prevent every version of COVID-19, however, unless there is a great change in the genetics of the virus, it should provide at least partial protection from other strains as well. The treatments for COVID-19 such as antivirals will still work against this new XBB. 1.5 sub variant.

In AP Biology, we learned about the immune system and how memory T cells and B cells are made to fight the same virus in the future. A virus enters the body through a macrophage or dendritic cell. Viral antigens are then presented on the surface of the dendritic cells or macrophages and infected cells. The viral antigen then binds to the Helper T cell and causes cytokines to be released to stimulate B cells and cytotoxic T cells. This creates a memory helper T cell. B cells divide to create plasma cells and memory B cells. The plasma cells secrete antibodies for this virus.

This process is why it is important to receive this vaccine even if one has already been infected by COVID before or if one has received the vaccine before because of the new variants such as XBB. 1.5 that are emerging. The previous COVID-19 vaccine does not necessarily protect against the XBB subvariants and having COVID-19 previously and getting those antibodies through the process described above does not mean you have the antibodies for the new strains.

I still got COVID after having the vaccine because it was a different strain of the virus than the one being targeted in the vaccine. This is very common but hopefully this vaccine means that there will be one less sub variant to worry about!

Winter is Coming

“The U.S. is going to see a winter surge in COVID infections,” predicts William Hanage, an epidemiologist at the Harvard T.H. Chan School of Public Health. “And I think that if nothing else changes BQ.1 and BQ.1.1 are likely to be very significant players”.

Two new omicron subvariants – BQ.1 and BQ.1.1 – are becoming dominant in the United States, causing fear of another COVID-19 surge as people prepare to gather for the winter holidays. These subvariants appear to be the most adept yet at evading immunity from vaccination and previous infection.

Mutations in Spike Proteins

New mutations in the virus’s spike protein appear to make BQ.1 and BQ.1.1 as much as seven times more ‘immune evasive’ than past variants. Spike proteins are the antigens on the surface of the COVID-19 virus. A mutation in the spike protein is an issue because the body’s immune system creates antibodies to fend off foreign invaders specific to that antigen. Memory helper T and B cells then keep these antibodies within the body in the case of a secondary exposure, which would then cause a faster, stronger, and longer immune response. Because the spike proteins are mutated, the body needs to reenact the process of producing antibodies, which could take a long time to have a noticeable effect on the body’s immune system, therefore increasing concern for the individual’s overall health.

A Closer Look at the Mutation (RBD)

The specific site of the mutation in the BQ.1 and BQ.1.1 variants is the receptor binding domain (RBD) which allows [the virus] to dock to body receptors to gain entry into cells and lead to infection; in other words, the RBD is the target of antibodies that deliver a potent immune response. Researcher Cao and his team believe that the RBD mutations allow the variant to evade infection-blocking ‘neutralizing’ antibodies that were a response to previous COVID-19 vaccines and exposure to earlier Omicron variants, such as BA.2 and BA.5. There seems to be a direct correlation between the RBD changes and the faster it spreads both within the body and the population. This is where BQ.1 and BQ.1.1 differ; variants, such as BQ.1, with five key RBD changes (relative to BA.2) seem to be growing in number at a slower rate than variants with six changes. A descendant of BQ.1 called BQ.1.1 has six such changes, and is rising rapidly across Europe, North America and other places.

Double Immunity?

Another variant of COVID-19, XBB, is predicted to “gain an edge” against BQ.1.1 because it has seven changes in its RBD, allowing it to grow at an even faster rate. Although there is currently no data to back up the theory that double immunity could be at play, researcher Cao and his team have a feeling that if you’re infected with BQ.1, you might have some protection against XBB.

How to Stay Safe

Although there is never a 100% guarantee that you won’t catch BQ.1, BQ.1.1, or XBB, there are preventative measures you can take to decrease your chances. As we have been advised since the start of COVID, one should continue to stay sanitary, wear a mask if in a susceptible/crowded place, and be updated on new vaccines. Winter is coming, and it is time to fortify and protect yourself against what lurks beyond your body’s walls.

BioQuakes

AP Biology class blog for discussing current research in Biology

Tag: XBB

New COVID-19 Vaccine

Winter is Coming, and so is BQ.1 and BQ.1.1

Winter is Coming

Mutations in Spike Proteins

A Closer Look at the Mutation (RBD)

Double Immunity?

How to Stay Safe

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