Researchers have recently created a virus in the lab that infects cells and interacts with antibodies just like the COVID-19 virus. But this virus lacks the ability to cause severe disease. This is good news for scientists across the world working on a vaccine because everybody does not have access to high-level biosafety facilities. Airborne and potentially deadly, the virus that causes COVID-19 can only be studied safely under high-level biosafety conditions. Scientists handling the infectious virus must wear full-body biohazard suits with pressurized respirators, and work inside laboratories with multiple containment levels and specialized ventilation systems. While necessary to protect laboratory workers, these safety precautions slow down efforts to find drugs and vaccines for COVID-19 since many scientists lack access to the required biosafety facilities. Also Read – You’re are more likely to contract COVID-19 at home, says study
A hybrid virus that is safer to handle
To help remedy that, researchers at Washington University School of Medicine in St. Louis have developed a hybrid virus that will enable more scientists to enter the fight against the pandemic. The researchers genetically modified a mild virus by swapping one of its genes for one from SARS-CoV-2, the virus that causes COVID-19. The resulting hybrid virus infects cells and is recognized by antibodies just like SARS-CoV-2, but can be handled under ordinary laboratory safety conditions. The study is available online in Cell Host & Microbe. According to researchers, the virus has been distributed to researchers in Argentina, Brazil, Mexico, Canada and, of course, all over the U.S. Requests pending from the U.K. and Germany. Also Read – COVID-19 Live Updates: Cases in India surge to12,87,945 as death toll reaches 30,601
Antibodies recognise this new virus
To create a model of SARS-CoV-2 that would be safer to handle, researchers started with vesicular stomatitis virus (VSV). This virus is a workhorse of virology labs because it is fairly innocuous and easy to manipulate genetically. Primarily a virus of cattle, horses and pigs, VSV occasionally infects people, causing a mild flu-like illness that lasts three to five days. Viruses have proteins on their surfaces that they use to latch onto and infect cells. The researchers removed VSV’s surface-protein gene and replaced it with the one from SARS-CoV-2, known as spike. The switch created a new virus that targets cells like SARS-CoV-2 but lacks the other genes needed to cause severe disease. They dubbed the hybrid virus VSV-SARS-CoV-2. Also Read – Nitric oxide treatment may slow progression of COVID-19
Using serum from COVID-19 survivors and purified antibodies, the researchers showed that the hybrid virus was recognized by antibodies very much like a real SARS-CoV-2 virus that came from a COVID-19 patient. Antibodies or sera that prevented the hybrid virus from infecting cells also blocked the real SARS-CoV-2 virus from doing so; antibodies or sera that failed to stop the hybrid virus also failed to deter the real SARS-CoV-2. In addition, a decoy molecule was equally effective at misdirecting both viruses and preventing them from infecting cells.
Developments hold promise for vaccine development
Humans develop antibodies against other SARS-CoV-2 proteins, but it’s the antibodies against spike that seem to be most important for protection. Researchers say that as long as a virus has the spike protein, it looks to the human immune system like SARS-CoV-2, for all intents and purposes. The hybrid virus could help scientists evaluate a range of antibody-based preventives and treatments for COVID-19. The virus could be used to assess whether an experimental vaccine elicits neutralizing antibodies, to measure whether a COVID-19 survivor carries enough neutralizing antibodies to donate plasma to COVID-19 patients, or to identify antibodies with the potential to be developed into antiviral drugs. One of the problems in evaluating neutralizing antibodies is that a lot of these tests require a BSL-3 facility, and most clinical labs and companies don’t have BSL-3 facilities. With this surrogate virus, scientists can use serum, plasma or antibodies and do high-throughput analyses at BSL-2 levels, which every lab has, without a risk of getting infected.
A potential vaccine candidate
According to researchers, since the hybrid virus looks like SARS-CoV-2 to the immune system but does not cause severe disease, it is a potential vaccine candidate. They are currently conducting animal studies to evaluate the possibility.
(With inputs from Agencies)