SAN DIEGO (KGTV) – Scientists detected the first cases of the South African variant in California this week, a version of the coronavirus that appears to be more elusive for current vaccines and the natural immunity produced by previous infections.
The South African variant shares a mutation with the UK variant that scientists believe makes the virus more adherent to cells and more transmissible. The South African variant, officially known as B.1.351, also has two other mutations in its peak proteins that scientists find worrying.
Researchers pay close attention to the peak proteins in the virus because they allow the pathogen to stick to cells. Spike is also the target protein of the current generation of COVID-19 vaccines.
All current vaccines train the immune system to build antibodies by introducing fake spike proteins. These harmless impostors are designed to look like the pointed buttons on the surface of the real coronavirus.
But the South African variant has small mutations at its peaks that make blocking some antibodies more difficult, based on previous research.
“The whole peak doesn’t change shape. What happens is a small button or piece – we call it an epitope – to which specific antibodies bind is changed so that they no longer bind, ”said UC San Diego virologist Dr. Doug Richman.
A Moderna study using blood samples found that antibodies produced by its vaccine were six times less effective against the South African variant.
There have also been several confirmed cases of COVID survivors being reinfected with the variant. A vaccine study in South Africa found new infections in 2 percent of people who had been infected with an earlier version of the virus.
Second infections usually tend to be milder than the first, Richman noted.
He also pointed out that vaccines have shown promising results in their ability to prevent serious illnesses caused by the variant, even if they fail to fully prevent symptoms.
“What will happen is that someone with a potentially fatal infection or requiring hospitalization will have a milder infection,” he said.
The South Africa variant is different from the United Kingdom variant, which was detected in about 1,000 people in the United States.
The UK variant, B.1.1.7, currently accounts for about 1 to 2 percent of infections in the United States, but is spreading rapidly. A study by Scripps Research estimates that it is doubling in cases every 10 days and will become the dominant strain in the country in late March.
The two variants share a mutation that makes the virus more adherent, known as N501Y. This scientific abbreviation means at the 501st amino acid position in the viral sequence, an “N” (the abbreviation for asparagine) has been replaced by an “Y” (the abbreviation for tyrosine).
But the South Africa variant contains two other mutations, E484K and K417N, which appear to help it escape, said Scripps researcher Karthik Gangavarapu.
“Together with these mutations, the end result is that he is able to escape immunity,” he said.
Gangavarapu is part of the laboratory that detected the United Kingdom variant in San Diego. He said that so far, they have not detected the South Africa variant in their samples.