Antibodies may not work against the virus variant found in South Africa

Antibodies may not work against the virus variant found in South Africa

The variant referred to as 501 could also be immune to COVID-19 vaccines, scientists recently raised concerns as Live Science previously reported. Experts noted that the variant has accumulated a big number of mutations in its spike protein, which is a pointed structure that sticks off the virus's surface and binds to human cells to trigger infection. 

This spike protein is targeted by the authorized vaccines, so if it mutates substantially, the vaccines might not be as protective antibody drugs, and therefore the antibodies that folks naturally produce once they catch COVID-19 could even be less protective against such a mutant.

On January 4, a study posted to the preprint database bioRxiv suggests that this might be the case with 501.V2. The study which has not been peer-reviewed found that specific mutations within the spike protein make the variant less susceptible to antibodies of some people — but critically, these mutations don't make the new variant invincible, only less susceptible to attack.  


Antibodies against the coronavirus might not work.

"There is extensive person-to-person variation in how mutations affect serum antibody binding and neutralization", as an indicator of how well the antibodies prevent the virus from infecting cells, the authors stated. Mutations at one location on the spike protein — called E484 — stood out as a possible issue. For a few people, a mutation at E484 meant the antibodies' ability to dam the virus from entering cells fell quite 10-fold. Unfortunately, 501.V2 features a mutation at the E484 site, "as do other isolates from elsewhere", the authors noted during a tweet, meaning that the variant could also be less susceptible to some people's antibodies and antibody drugs, but more studies are needed to understand whether vaccine-generated antibodies are going to be similarly affected, the authors added.

These conclusions are achieved as the team zoomed in on the "receptor binding domain" (RBD), of the spike protein, a part of the spike that directly binds to the cell surface. Antibodies are available in different flavors, and people that focus on the RBD are the foremost critical for neutralizing the coronavirus consistent with a study published November 12 within the journal. Cells due to this mutation within the RBD could help new variants evade the system, the authors noted. 

The team mapped how different mutations within the RBD would affect its structure and thus the power of antibodies to bind to it; they then genetically modified yeast cells to grow the mutant RBD on their surfaces. In the experiments of "neutralization assays," their mutant yeast was exposed to serum, the liquid portion of blood that contains antibodies. They took these samples from individuals who had recovered from COVID-19 and developed antibodies against the virus. 

Assays with synthetic viruses called pseudoviruses were also conducted by the team which was made to resemble SARS-CoV-2 and were also equipped with mutant RBD a bit like the yeast. These pseudoviruses were incubated with human cells, and therefore the sampled antibodies to ascertain whether the antibodies stopped the cells from becoming infected. Mutations at the E484 site showed the most important effect on antibody binding and neutralization of the virus at the individual level "a few samples were essentially unaffected by E484 mutations" and other mutations stood out as a much bigger problem the team noted in their paper, for instance, a number of the samples from recovered patients didn't bind also to RBD with mutations within the so-called "443-450 loop" a structure that the Regeneron antibody cocktail called REGEN-COV2 also targets. As we learn more about the consequences of various mutations on SARS-CoV-2 immunity, it'll be important to run similar studies with vaccine-generated antibodies, the authors noted. The E484 mutations only mess with some blood samples, they didn't cancel out antibodies in any. That means the usefulness of available vaccines will be "for quite a while," they wrote. 


Covid-19 in South Africa.

As the 501.V2 variant is still being monitored, the priority now should be to vaccinate as many of us as possible, the authorities of many countries have stated. 

"The new variant has mutated a neighborhood of the spike protein that our antibodies bind to, to undertake to clear the virus itself, so this is often concerning," Gottlieb said. "Now, the vaccine can become a backstop against these variants getting more of an edge here within the US, but we'd like to quicken the pace of vaccination," he said. Furthermore, he believed that the spread of the new variant could be significantly contained with the use of medical items such as medical masks, disposable gloves, protective suits, especially products from the provider named MAZA.