The Biological Reasoning Behind the New Contagious COVID Variant

Kayla Berthoff

S&E Editor

 

By now, everyone has heard of the COVID Delta variant and the issues associated with it, but most people don’t know what exactly makes this variant more serious. The SARS-CoV-2 (COVID-19) virus is a cluster of single-stranded genetic information (RNA) inside of a membrane covered in spike proteins. These spike proteins are a chain of amino acids folded into a specific conformation that receptors on human body cells can recognize and bind to, with the tendency to increasingly bind when the protein is in an open conformation and specific amino acid residues are exposed. This binding action allows the COVID virus to be taken up into cells. Once the virus’ genetic information is taken up, whether through a vaccine or natural infection, the human cell will use its cellular machinery to copy the RNA and subsequently make more copies of the virus through replication. This also allows the immune system to respond and create antibodies that bind specifically to the spike proteins to prevent virus entry.

While the replication process in the cell is under tight control, mistakes happen, causing mutations that lead to variations in the final product. RNA viruses, such as COVID, are more likely to undergo mutation because they lack enzymes that typically have a “proofreading” ability, so changes in COVID’s genetic information are almost inevitable. Most mutations are harmless, having negative effects on the survivability of the virus, but some may make it more efficient. The Delta variant has a few changes to the amino acid sequence that affect the conformation and prevalence of the spike protein on the viral membrane surface, leading to more spike proteins that are a slightly different shape. Some of these mutations, specifically D614G and T478K, change the conformation of the spike protein so that it is always in the open conformation, making it easier for the COVID spike protein to bind to the receptors on human cells that take it in and simultaneously make it harder for antibodies to recognize and bind to the spike protein and prevent cellular uptake.

So, how worried should we be? The increased number of spike proteins on the Delta variant allows for a more rapid uptake of the virus in the cell and a shorter incubation time, meaning that individuals will become infected sooner and may be able to spread infections more rapidly, increasing the viral load. This is why the Delta variant appears to be more deadly despite not being any more lethal. However, the COVID vaccine is still effective in mounting antibodies against the Delta variant, and booster shots with more specificity to variants are more prevalent as the pandemic advances are in the works. In the meantime, masking and social distancing are still the most effective methods in preventing the spread of all COVID variants.