Indian virologists successfully culture coronavirus

Indian virologists successfully culture coronavirus

Hyderabad: The Centre for Cellular and Molecular Biology (CCMB) has successfully cultured the novel coronavirus (SARS-CoV-2) from samples of Covid-19 patients, enabling scientists to work towards vaccine development and testing of potential drugs to fight the virus infection.

A team of researchers led by Principal Scientist Dr Krishnan H Harshan has isolated infectious viruses from several isolates.

Novel coronavirus enters human cell when the spike protein on the surface of the SARS-CoV-2 binds to the host cell receptor ACE-2. The virus RNA is later released into the cytoplasm of the cells where it makes proteins before starting to replicate the genomic RNA. The virus uses resources from the cells to make more copies of itself.

Human epithelial cells in the respiratory tract copiously express ACE-2 receptors, causing respiratory disease in the infected patient.

“Currently, primary epithelial cells generated from human origins do not grow for many generations in labs, which is key to culturing viruses continuously. At the same time, the labs that are growing the virus need an ‘immortal’ cell line. They use Vero cells (kidney epithelial cell lines from green African monkey), which express ACE-2 proteins and carry a cell division that allows them to proliferate indefinitely,” Dr Harshan said.

But why cultivate a dreadful germ? Upon culturing a large amount of the virus and inactivating them, it can be used as inactivated virus vaccine. Once the inactivated virus is injected, the human immune system triggers production of germ-specific antibodies. One can inactivate the virus by heat or chemical means. The inactivated virus can trigger antibody response, but does not infect and make the receiver sick as they cannot reproduce.  

Virus cultures are important for the development of antibodies or antidots. Inactivated viruses can trigger antibody response in other mammalian hosts in addition to humans. Various such hosts are currently under test for their efficiency of antibody response. Such antibodies generated in these non-human hosts can be purified, processed and collected. The antibodies can be used as therapeutic intervention for patients suffering from the infection.  They can trigger antiviral response upon injection into humans and have the potential of limiting the infection. Administering antibodies does not provide immunity like a vaccine does, but can be considered as anti-dotes against the virus. 

These cultures may also be helpful in the process of drug screening. Potential drugs can be tested against the virus in a test-tube for their efficacy.

“Using the Vero cell lines to grow the coronavirus, CCMB is now in a position to isolate and maintain viral strains from different regions. We are working towards producing viruses in huge quantities that can be inactivated, and used in vaccine development and antibody production for therapeutic purposes”, says CCMB Director, Dr Rakesh Mishra.

CCMB has started testing potential drugs with other partners such as the Defence Research Development Organisation (DRDO) using the viral culture.

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