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.
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.
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.
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.
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.
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.