The Indian government-run Centre for Cellular and Molecular Biology (CCMB) has succeeded in establishing stable cultures of coronavirus from patients' samples, in a development virologists say could help develop a vaccine against the contagion.
Virologists at CCMB have isolated the infectious viruses from several isolates, reports our New Delhi correspondent, quoting CCMB Director Rakesh Mishra.
The ability to cultivate the virus in a lab has enabled CCMB to work towards vaccine development and testing of potential drugs to fight Covid-19, he said.
Novel coronavirus enters the human cell by binding with the ACE-2 receptor on the cell surface. Not all cells have ACE-2 receptors. Human epithelial cells in the respiratory tract copiously express ACE-2 receptors, causing respiratory disease in the infected patient.
"However, we cannot grow human epithelial cells in lab. 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," said Krishnan H Harshan, Principal Scientist at CCMB.
If a large amount of the virus is cultured and inactivated, then it can be used as inactivated virus vaccine.
"Once we inject the inactivated virus, the human immune system triggers the production of germ-specific antibodies or antidote. One can inactivate the virus by heat or chemical means. The inactivated virus can trigger antibody response but does not infect and make us sick as they cannot reproduce," Harshan also said.
Various mammal hosts are currently under test for the efficiency of antibody response, he said, adding such antibodies generated in non-human hosts can be purified, processed and collected.
"The antibodies can be used as therapeutic intervention for patients suffering from the infection," according to Harshan.
The Principal Scientist said such antibodies "can trigger antiviral response upon injection into humans and have the potential of limiting the infection".
Harshan said, while administering antibodies does not provide immunity like a vaccine does, they 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," he said.
"CCMB is working towards producing viruses in huge quantities that can be inactivated and used in vaccine development and antibody production for therapeutic purposes," said Mishra.
He said CCMB has also started testing potential drugs with other partners such as the Defence Research Development Organisation (DRDO) using the viral culture.
Mishra's remarks came a day after Principal Scientific Adviser to the Indian government K Vijayaraghavan said that the country has identified six local Covid-19 vaccine candidates with 30 groups trying to develop the drug.