Researchers at Indian Institute of Science’s (IISc) Molecular Biophysics Unit have announced the development of effective vaccine strategies against the SARS-CoV-2 and HIV viruses that cause Covid-19 and AIDS, respectively.

The researchers reported the design of a ‘heat-tolerant’ vaccine candidate for Covid-19 which contains a part of the spike protein of the novel coronavirus called the receptor binding domain (RBD), with the help of which the virus adheres to the host’s cell.

Molecular Biophysics Unit professor Raghavan Varadarajan is developing the vaccine candidate in partnership with startup Mynvax and other institutes.

The candidate triggered a strong immune response when it was tested in guinea pig models and also remained stable for a month at 37°C, IISc reported.

The freeze-dried versions of the protein-based vaccine candidate were able to tolerate temperatures as high as 100°C.

These vaccines are warm and can be stored and transported to remote areas for mass vaccination.

Varadarajan said: “Now we have to get funds to take this forward to clinical development.”

As part of this, safety and toxicity studies will be carried out in rats along with development and GMP manufacture of a clinical trial batch, prior to their testing in human beings.

The vaccine candidate, which is being developed by Varadarajan’s team, only uses a specific part of the RBD, a string of 200 amino acids, instead of the complete spike protein.

The team used a carrier DNA molecule called a plasmid to insert genes coding for this part into mammalian cells, which then churned out copies of the RBD section.

It was found that the RBD formulation could trigger an immune response in guinea pigs just like the full spike protein. This response was much more stable at high temperatures for prolonged periods.

Additionally, the researchers reported the design of a rapid method for identifying specific regions targeted by antibodies, on the HIV envelope protein. These antibodies can help design effective vaccines.

The team comprising researchers from multiple institutes, sought to pinpoint the regions of the HIV’s envelope protein that are targeted by neutralising antibodies.

Vaccines based on these parts might induce a better immune response.

Researchers use methods such as X-ray crystallography and cryo-electron microscopy to map such areas which are time-consuming, complicated and expensive.

After exploring alternative approaches, Varadarajan and his team eventually arrived at a simpler, yet effective solution.