new ammunition in the fight against the leak of viral antibodies

new ammunition in the fight against the leak of viral antibodies

The viral evasion concept of antibody neutralization seems intimately familiar in our post-COVID world – it’s why we wait online for new iterations of vaccines while dreading the inevitable arrival of new viral variants that may escape these vaccines. It’s a stark reminder that when our immune systems, scientists and governments fight this virus, the virus fights back. In a recent preprint published on bioRxivTimothy Yu, graduate student in the laboratory of Dr. Jesse Bloom, and colleagues report efforts to predict viral escape from complex mixtures of neutralizing antibodies. In doing so, they hope to leverage state-of-the-art experimental and computational techniques to stay ahead in the arms race between the virus and humans, while potentially gaining new insights into how antibody mixtures interact with viral antigens at a fundamental level.

First, some vocabulary: antibody are small proteins produced by our immune system whose role is to bind viral proteins called antigens (for example, the spike protein on the surface of SARS-CoV-2) and neutralize or prevent them from invading our cells. To be more precise, any given antibody binds only a specific part of its corresponding antigen – this region is called a epitope. We would like to imagine a simple scenario, in which a viral infection causes your body to produce a single type of antibody targeting a specific epitope, which the virus will slowly mutate to disrupt antibody binding and evade neutralization. However, as is usually the case in biology, the reality is more complicated. A viral infection or immunization causes your body to produce a mixture of antibodies that recognize many different epitopes. Although this is thought to increase the durability of antiviral responses, we know from experience that viruses are still able to escape these “polyclonal” mixtures of antibodies by accumulating mutations in multiple antigenic regions (multiple epitopes ). Understanding how viruses manage this escape – and developing tools to predict when they will – is of paramount importance to public health and basic science.

Methods exist to experimentally test whether a viral variant can lead to escape from mixtures of antibodies, but these are relatively slow and laborious, as each variant must be tested individually – a daunting challenge in situations where adaptation viral is rapid, and many different variants appear in the population. Fundamentally, these methods also rely on prior knowledge of the mutations to be produced, which constantly leaves us “one step back” on the virus we are trying to combat.

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