COVID-19 and immunity-THE HINDU-12-04-2020

Details:

A cascade of viral particles enters the body through the nose, eyes or mouth. Breathing carries some of these particles to the lower respiratory tract where the spike proteins of the coronavirus, acting like a key, lock into epithelial cells that line the respiratory tract as well as those in the the airsacs in the lungs. SARS-CoV-2 is able to stay undetected longer than many flu or coronaviruses and its spike proteins are able to gain entry by unlocking the ACE2 protein on the lung cells. Once in, they hijack the cell’s machinery, replicate and multiply and infect adjoining cells.

Like the defining ACE2 proteins on the epithelial cells, viruses too have a tell-tale signature on their surface called antigens and spotting these is what kicks the immune system into action by producing antibodies. The inflammation triggers a fluid build-up in the lungs.

Why are some infections mild and others life-threatening?

If the infection is acute, it can also lead to a depletion of the frontline white blood corpuscles tasked with fighting the infection and making the body vulnerable to other secondary infections, which may lead to death.

How have the elderly reacted to the virus?

The elderly, especially those with existing conditions such as diabetes and cardiovascular disease, already have an inherent malfunctioning in the immune system. The different kinds of drugs, whether it is hydroxycholoroquine or anti-HIV drugs, deployed to treat serious COVID-19 infection, also work in some way to moderate the immune-system’s aggressive defence. Mortality statistics globally suggest that men are twice more likely than women to succumb to a COVID-19 infection.

The bulk are aimed at developing a molecular construct, in some cases a weakened version of the coronavirus, that mimics the antigens of the virus and triggers an appropriate antibody response.