CCMB's COVID-19 virus culture has potential use in vaccine development

A team of researchers at the Centre for Cellular and Molecular Biology, Hyderabad have isolated infectious COVID-19 viruses from several patients.

CSIR-CCMB has established stable cultures of COVID-19 causing coronavirus - SARS-CoV-2 - from patients’ samples, over the last few weeks. This ability to culture the virus in the lab, CCMB says, will enable it to work towards vaccine development and testing potential drugs to fight COVID-19.

“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. We have also started testing potential drugs with other partners such as DRDO using this viral culture. We hope that such systems are replicated at multiple research institutes and private companies to become a useful resource in the fight against this pandemic as well as for future preparedness”, says CCMB director Dr Rakesh Mishra.

Potential uses of cultured SARS-CoV-2 can be in developing vaccines, antibodies or anti-dotes, testing of antibodies, drug screening, testing of various disinfectants and also testing of UV ray instruments, CCMB said in a press release.

The SARS-CoV-2 virus is known to infect epithelial cells in the human respiratory tract. The viruses infect these cells by interacting with receptor proteins called the ACE-2 following which the virus is internalised by a process called endocytosis. Virus RNA is later released into the cytoplasm of the cells where it makes viral proteins first and then starts to replicate the genomic RNA. Thus, the virus uses resources from these cells to make more copies of itself.

Which means the virus needs a set of host factors that allow it to replicate. “Currently, primary epithelial cells generated from human origins do not grow for many generations in labs, which is key to culturing viruses continuously. Hence, CCMB and other labs who are growing the virus need an ‘immortal’ cell line”, says Dr. Krishnan H Harshan, the virologist under whom the CCMB team isolated infectious COVID-19 viruses. So, they use Vero cells – kidney epithelial cell lines from green African monkeys, which express ACE-2 proteins and carry a mutation that allows them to proliferate indefinitely.