The story so far: The Pune-based Gennova Biopharmaceuticals is expected to roll out India’s first home-grown mRNA (messenger ribonucleic acid) vaccine by April. The COVID-19 pandemic awakened the world to the power of RNA therapies — two of the first vaccines that emerged in late 2020, Pfizer-BioNtech and Moderna, used this technology. Now, an Indian company is developing an mRNA vaccine from scratch, signalling possibilities of the use of the molecule in a variety of diseases beyond COVID-19.
What is a mRNA vaccine?
Like other vaccines, the mRNA vaccine strives to activate the immune system to produce antibodies that help counter an infection from a live virus. While the traditional method to do this involves introducing a part or the whole virus in a way that it cannot replicate, there is always the risk of an adverse reaction in the case of the SARS-CoV-2 virus. Hence, a quest of vaccinology has been to tease out an immune response that is effective but also relatively safe. The theory goes that the less of a foreign body injected, the fewer the odds of an adverse response. A common approach by vaccine makers during the pandemic was to introduce a portion of the spike protein, the key part of the coronavirus, as part of a vaccine. Some makers, such as those that made the Oxford University vaccine (AstraZeneca) or Sputnik V, wrapped the gene that codes for the spike protein into an inactivated virus that affects chimpanzees, called the chimpanzee adenovirus. The aim is to have the body use its own machinery to make spike proteins from the given genetic code. The immune system, when it registers the spike protein, will create antibodies against it. Other vaccines use a piece of DNA to envelope the spike protein genes. An mRNA vaccine works in similar ways in that it too is a piece of genetic code inserted into the body to stimulate an immune response.
How are these vaccines different?
A piece of DNA must be converted into RNA for a cell to be able manufacture the spike protein. While an mRNA vaccine might look like a more direct approach to getting the cell to produce the necessary proteins, mRNA is very fragile and will be shred apart at room temperature or by the body’s enzymes when injected. To preserve its integrity, the mRNA needs to be wrapped in a layer of oily lipids, or fat cells. One way to think of this is that an mRNA-lipid unit most closely mimics how a virus presents itself to the body, except that it cannot replicate like one. DNA is much more stable and can be more flexibly integrated into a vaccine-vector. In terms of performance, both are expected to be as effective. While both the Pfizer-BioNTech and Moderna’s mRNA vaccines performed similarly in trials, the evidence over the last year shows that the latter generally elicited a more robust immune response and better protection against illness, though both vaccines were similar in their ability to stave off severe disease and death. A challenge with mRNA vaccines is that they need to be frozen from -90 degree Celsius to -50 degree Celsius. They can be stored for up to two weeks in commercial freezers and need to be thawed at 2 degree Celsius to 8 degree Celsius at which they can remain for a month. A major reason why mRNA vaccines never made it to India was the stringent freezer conditions that made them expensive. A major advantage of mRNA and DNA vaccines is that because they only need the genetic code, it is possible to quickly update vaccines to emerging variants and even use them for a variety of diseases. That said, none of the vaccines have been updated for the Delta or Omicron variant yet.
Is Gennova’s mRNA vaccine different?
Gennova has revealed little public information on its vaccine but Sanjay Singh, the head of the firm, has previously said that the prospective vaccine uses a concoction of lipids and enzymes that allows the vaccine to be stored at 2°C to 8°C. However, the bulk of the materials necessary to manufacture the vaccine rely on imports. Company officials also say that the Indian mRNA vaccine will be cheaper than their imported versions but probably costlier than Covishield or Covaxin.
What is the progress on the vaccine candidate so far?
The mRNA vaccine is currently in phase 2/3 trial to evaluate the safety, tolerability and immunogenicity of the candidate vaccine in healthy subjects. Around 4,000 volunteers have been recruited for the trial. Results from a phase-1 trial are expected to be published soon. Gennova has got ₹125 crore from the Department of Biotechnology. India has now fully vaccinated more than half its population and at least seven homegrown vaccines have been cleared by authorities. Vaccine makers are hoping to supply to those below 15 years as well as cater to demand for third doses. But there is a wide gap between readying vaccines and supplying them commercially because of the challenges of scaling up production.
Covaxin despite been approved in January 2021 and developed by Bharat Biotech, an experienced vaccine maker, has only contributed to 14% of India’s vaccination drive.
