Saturday, March 6

‘Warm vaccine’ researchers are working on may be a game changer – Times of India

BENGALURU: In what could be a game changer in the immunisation drive against Covid-19, a group of scientists led by
IISc Prof Raghavan Varadarajan has found “good results” on a ‘
warm vaccine’ — one that would not require cold storage during transportation. This is extremely important in India where cold storage units are out of range of hundreds of villages.

Almost all SARS CoV-2 vaccines currently being clinically tested are stored in a refrigerated or frozen state and must be transported at cold temperatures prior to use since exposure to high temperatures affects their potency. Researchers say this is a major impediment to “deployment in resource-poor settings”.

Varadarajan collaborated with researchers from IISER Trivandrum, Translational Health Science and Technology Institute (THSTI) Faridabad, and the IISc-incubated startup Mynvax and the group’s paper has been accepted for publication in the Journal of Biological Chemistry, a peer-reviewed scientific journal published by the American Society for Biochemistry and Molecular Biology. TOI has accessed the preprint version.

The group was able to synthesise a fragment/sequence of
the S-Protein found on the surface of SARS CoV-2, and found it to be thermo-tolerant. However, instead of synthesising the whole S-Protein, the group synthesised only a sequence/fragment derived from the receptor binding domain (RBD). The RBD helps the virus attach itself to the host cell, leading to infection.

The researchers found that this fragment, when freeze-dried, is highly stable. It can be stored for more than a month at 37 degrees Celsius besides being able to withstand transient exposure to temperatures as high as 100 degrees Celsius, suggesting a cold-chain would not be required.

“We have got good results, but are still far away from a vaccine per se,” Varadarajan told TOI.

Antibodies are primarily directed against the virus’s RBD, the researchers said, adding that now that there is a thermo-tolerant RBD, further studies will test how it can it be tried as a vaccine candidate.

In their study, the authors used guinea pigs for initial immunisation. After two doses, their tests showed significant levels of RBD-blocking antibodies. Now, the researchers are testing if the formulation can protect animals from infectious virus. They will conduct safety and toxicity assessments prior to testing it on humans.

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