Coronavirus strain mutation no cause for alarm, scientists say

The D614G mutation in SARS-CoV-2, which has become the dominant strain of the virus worldwide, was recently reported to have been detected in the Philippines, causing alarm to the general public.

This handout illustration image obtained February 27, 2020 courtesy of the National Institutes of Health taken with a transmission electron microscope shows SARS-CoV-2, the virus that causes COVID-19, isolated from a patient in the US. (AFP/Handout / National Institutes of Health / MANILA BULLETIN)

As more questions follow about its real-life implications, scientists at the Philippine Genome Center (PGC), which reported the detection of this virus strain in randomly selected COVID-19 positive samples in Quezon City, said there's no need to be alarmed.

The G614 variant in PH

The G614 variant, known to be widely circulating in Europe in March and has been reported to be the dominant strain of SARS-CoV-2 in circulation worldwide, contains a mutation that results to a single amino acid change at position 614, changing the D or aspartic acid to a G or glycine, thus the D614 wild type genotype of the original strain has become the G614 variant.

In its bulletin posted on August 13 that was previously submitted to the DOH, the PGC said that it has detected the G614 variant in all of the nine (9) randomly selected COVID-19 positive samples collected in Quezon City in July.

"We were a little bit skeptical about the G614 variant in the beginning because we thought that its dominance in the GISAID (Global Initiative for Sharing All Influenza Data) database might not necessarily reflect the situation on the ground. We know that the G614 variant predominates in Europe and in the US and since submissions to the genome databases largely come from researchers in these countries, we reckon that a large number of G614 variants might reflect this source bias," Dr. Cynthia Saloma, PGC Executive Director, told Manila Bulletin.

"We did not also expect that nine out of nine in QC are all G614. We were still expecting to see some D614 among the small samples we randomly tested," she added.

While the G614 variant of SARS-CoV-2 has been reported to have become the dominant strain of the virus in circulation around the world, Saloma said they are still unsure if this is also the prevalent strain in the Philippines as their sampling is localized and the size is still small.

Is it highly infectious?

According to Dr. Saloma, many scientists around the world speculated that the G variant is highly infectious due to its rising dominance across the globe.

However, she said that there is still no "direct evidence" that it is more infectious than the original strain and a lot of the speculation about its infectiousness or transmissibility comes from in vitro or cell culture data.

"Based on the in vitro data, it seems to be more infectious. Molecular modeling suggests that it is more stable in structure than the wild type, but in terms of in vivo or person-to-person data, we don't have direct evidence that it is so," Dr. Saloma explained.

This means that while the G614 variant seems to be more infectious in laboratory settings, its increased infectivity in humans is still unconfirmed.

Dr. Saloma emphasized that based on available clinical data published by several research groups in other countries, the G614 variant has no significant association with disease severity.

"Even if the G614 variant has reached the country, it does not necessarily mean that the disease trajectory will be more severe," she said.

Is it more challenging for vaccine development?

Dr. Saloma mentioned that the D614G mutation "created a lot of interest" in the science community as many scientists have designed their vaccines based on the sequences of the spike region of the virus.

But Dr. Saloma said, so far, with this mutation, it seems not to compromise those vaccine designs.

"Fortunately, with this G614 variant that seems to have dominated around the world, hindi naman doon sa region binding the receptor ng cell nag-occur ang mutation so yung mga na-design na vaccine, okay pa rin kasi hindi naman nag occur ang mutation sa most likely region of contact," she pointed out.

(Fortunately, with this G614 variant that seems to have dominated around the world, the mutation did not occur in the region of the spike protein that directly binds to the receptor, so the vaccines that have been designed are still okay as the mutation is not in the region of contact with the receptor on the cell surface).

'Don't be alarmed'

While we are facing a global shift of the SARS-CoV 2 variant, from D614 to G614, Dr. Saloma reminded the public to not be scared and alarmed.

"We just want to clarify that we don't have to be very, very alarmed about this. This is not a new mutation. We just reported that it has been detected in the Philippines, but it has been in circulation in Europe as well as in the US," Dr. Saloma emphasized.

Instead, the UP professor reminded the public to be more vigilant and strictly follow the health and safety protocols as recommended by the DOH.

"It is very important that all of us will continue to be vigilant, we follow the advice of the health department while at the same time we should also protect the more vulnerable population, particularly those with co-morbidities," she said.