Indigenous Indian Covid 19 vaccines in the global race

by Dr TV Venkateswaran

New Delhi, July 5, 2020: With the announcement of COVAX-IN by Bharat Biotech and ZyCov-D Vaccine by Zydus Cadila the proverbial silver line in the dark clouds of COVID19 appears at the horizon.

Now the nod given by the Drug Controller General of India CDSCO (The Central Drugs Standard Control Organisation) for the con-duct of human trial for the vaccines, marks the begin-ning of the end.

In the past years, India has emerged as one of the sig-nificant vaccine manufactur-ing hubs.

Indian manufacturers account for 60% of vaccine supplies made to UNICEF.

The vaccine for novel coronavirus may be devel-oped anywhere in the world, but without Indian manufac-turers involved the produc-tion of required quantity is not going to be feasible.

Vaccine race More than 140 candidate vaccines are under various stages of development.

One of the leading candi-dates is AZD1222 devel-oped Jenner Institute of Uni-versity of Oxford and licenced to AstraZeneca British-Swedish multina-tional pharmaceutical and biopharmaceutical company headquartered in Cam-bridge, England.

The MRNA-1273 vaccine developed by Kaiser Perma-nente Washington Health Research Institute, Washing-ton and taken up for production by the US-based Mod-erna pharmaceutical is just a step behind.

Both these firms have already inked an agreement with Indian manufacturers for production of the COVID vaccines.

Parallelly Indian institu-tions have also engaged in R&D for the development of vaccines in India.

With the primary scientific inputs coming from institu-tions like Pune based ICMR institution National Institute of Virology and Hyderabad based CSIR institution Cen-ter for Cellular and Molecu-lar Biology, six Indian com-panies are working on a vaccine for COVID-19.

Along with the two Indian vaccines, COVAXIN and ZyCov-D, the world over, 11 out of 140 vaccine candi-dates have entered human trials.

Immune system Antigen from the pathogen and antibodies produced by the human immune cells can be thought of as matching the compati-ble pair.

Every pathogen has spe-cific molecular structures called as antigen.

They are like the surface with a particular hue and design.

Once infected by the germ, the human immune system develops antibodies that match the antigen.

Just as the retailer of design matching material stockpile hundreds of design pieces of riots of colours and hues, our immune system has ten thousand types of antibodies.

If the pathogen is a known enemy, the immune system can pull the matching design piece from the stock.

Once the match is made the pathogen is inactivated. No longer it can infect. However, if the microor-ganism is unfamiliar, and mainly when it has evolved for the first time, there is no matching colour and hue in the repertoire.

Nonetheless, unlike the textile, the antibody can evolve.

At first, near matches are tried. After various cycles of antibody development, the best fit matures. The time lag between the identifica-tion of the main surface colour that is an antigen and finding a pairing design piece, that is antibodies, is what makes the infection mild or severe.

If only the immune system can neutralise the germ instantly, the infection can be prevented.

Immune System memory and vaccine Like a new hue of design piece once acquired is stocked for future, once the new antibody matching the antigen evolves, it is retained in the immunological memory.

Next time the same pathogen invades, immuno-logical memory getsactivat-ed, and twinned antibody is released.

The infection is nipped in the bud. We acquire immu-nity.

A vaccine is a method to artificially inducing the immunological memory.

Once the antigens of the nasty pathogen are intro-duced, the immune system is triggered into developing pairing antibodies and immunological memory.

There are many ways in which one can artificially stroke the immune system to develop antibodies and memory.

The bottom-line is pre-senting the antigens of the novel coronavirus to the human immune system. From adenovirus-based live-attenuated virus to recombinant genetic tech-nology is used to develop several types of vaccines.

Two among the various possibilities produced in India are inactivated virus vaccine and DNA plasmid vaccine.

How do these vaccines work We can inactivate a whole virus with heat or formalde-hyde (that is ‘killed’), yet keep the antigen molecular structures still intact.

However, the inactivated virus will not be able to infect or cause disease, as it is no longer functional.

The Bharat Biotech’s COVAXIN uses the virus isolated from an Indian patient by the National Insti-tute of Virology to develop the inactivated virus vaccine.

Novel coronavirus infects the human cells with the help of its spike proteins.

The spike protein of the virus binds with the ACE2 receptors on the surface of the human respiratory tract cells.

Once the virus fuse, the viral genome is slipped into the human cell where around a thousand copies of the virus are made in just ten hours.

These baby viruses emi-grate to nearby cells.

Infection can be arrested if only we can deactivate the spike protein of the novel coronavirus.

Thus the antigen on the spike protein is a crucial vaccine target. If the anti-body blocks the spike pro-tein, then the virus cannot bind the cell and multiply.

The genomic code of the spike protein is spliced into a harmless DNA plasmid.

This modified plasmid DNA with the genetic code of viral spike protein is introduced into the host cells.

The cellular machinery translates the DNA and pro-duces the viral protein encoded in the genome. The human immune system recognises the alien protein and develops a matching antibody.

After this vaccination, if at any time, we are infected by the novel coronavirus, then sensing the spike protein antibodies are released instantly.

The immune killer cells seize deactivated viruses.

Contagion is arrested even before infection sets in.

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