‘Virus mutations won’t mar vaccines’

In what could be good news for firms that have pumped in billions of dollars for developing Covid-19 vaccines, a team of Australian researchers, led by an India-born scientist, has shown that the recent mutations in the SARS-CoV2 virus will not adversely affect these potential vaccines.

The finding reported in the journal NPJ Vaccine on Thursday by the team led by SS Vasan, Professor at the Australian Centre for Disease Preparedness of the Commonwealth Scientific and Industrial Research Organisation (CSIRO), is significant because the virus has mutated significantly since it was first reported in Wuhan last year.

G-strain

More importantly, most vaccines that are currently under development are modelled on the original ‘D-strain’ of the virus, which was more common among sequences published early in the pandemic. Since then, the virus has evolved to the globally dominant ‘G-strain’, which accounts for nearly 85 per cent of the published SARS-CoV2 genomes. In India, 81.2 per cent of the virus samples sequenced belong to the G-strain.

Since the mutation has occurred in the spike protein, which the virus uses to get latched on to angiotensin-converting enzyme (ACE2), found on the surface of the lung cells, many in the scientific community feared that the mutation could confer an advantage to the virus, making it capable of transmitting more vigorously, apart from being more virulent. As a result, the efficacy of the potential candidate vaccines that are currently under development may be less on the mutated strains, they feared.

However, the research by Vasan and his team at CSIRO found no evidence the change would adversely impact the efficacy of vaccine candidates. Their study tested blood samples from ferrets (which they had successfully demonstrated as a good animal model for testing candidate Covid vaccines), given a candidate vaccine against virus strains that either possessed or lacked this mutation, known as “D614G”.

“This is very reassuring,” Vasan told BusinessLine from Geelong, the Australian harbour city where his institute is located. Vasan, who heads the Dangerous Pathogens Team at CSIRO, is also an honorary chair in Health Sciences at the University of York in the UK.

“This is good news for the hundreds of vaccines in development around the world, with the majority targeting the spike protein as this binds to the ACE2 receptors in our lungs and airways, which are the entry point to infect cells. Despite this D614G mutation to the spike protein, we confirmed through experiments and modelling that vaccine candidates are still effective,” he said.

Vaccine matching

This would save vaccine developers from what they call ‘vaccine matching’, the process of developing new vaccines to combat the virus strains that are in circulation in each season. “At least till this point,” Vasan said.

Already seasonal influenza vaccines, which are currently in use, suffer from this problem, forcing vaccine companies to modify their flu vaccines frequently.

“This brings the world one step closer to a safe and effective vaccine to protect people and save lives,” said CSIRO Chief Executive Larry Marshall, commenting on the work.

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