7/14/2020

Science Behind the Virus

James X. Hartmann, Ph.D., professor in the Charles E. Schmidt College of Science and immunologist in the Center for Molecular Biology, talks about the science behind the coronavirus that caused the recent global pandemic.

Q. What is coronavirus?

A. The coronaviruses are a group of viruses that primarily cause respiratory infections, but their infection may spread to other parts of the body. There are a variety of coronaviruses that infect animals and humans with a range of severity. They are single stranded RNA viruses surrounded by a protein coat that stabilizes the RNA and further enveloped in a membrane studded with the receptors (spike proteins) needed to bind and infect target cells. the membranous envelope with the spike proteins produces a halo or "corona" around the virus particles when viewed in an electron microscope. The current strain of the coronavirus is referred to as SARS COV-2, the abbreviation SARS referring to severe respiratory syndrome. There are seven strains of coronaviruses that can infect humans and when a human is infected with both human and animal strains, recombination of their genomes can occur – leading to new strains that may have increased virulence such as SARS COV-2, the causative agen in the current pandemic.

Q. How does it infect the body?

A. Typically the virus particles are expelled from the lungs of an infected, often asymptomatic, individual following a cough or forced exhalation during exercise etc. The virus particles are inhaled into the lungs where the spike proteins of the virus particles bind to a key receptor on the surface of a variety of cells. The receptor the spike proteins bind to is called angiotensin converting enzyme-2. That receptor is found on a wide variety of cells including the lung, brain, heart and muscles. Although the infection may begin in the lung, it may spread and multiple in a variety of tissues.

Q. Why is it so difficult to trace the virus and flatten the curve, or create a short vaccine for the virus?

A. The main difficulty in tracing the virus infection among the population and degree of herd immunity is the availability of test kits. A second major problem is that both the tests for presence of the virus or antibodies is the failure rate of the test. The tests can give either false positive or false negative readings so infections may be missed and we do not really know how many individuals, especially those asymtomatic, may have resistance through the production of antibodies.

Q. What evidence provided suggest truth that the virus is airborne and does the social distance or six-feet rule help reduce spreading?

A. Evidence that it is airborne comes from studies in Wuhan China where virus particles were detected in the air collected within hospitals, with highest concentrations of virus particles found in intensive care units administering to virus infected patients. Social distancing, six-foot rule and wearing a mask, all contribute to reducing the spread but obviously air movements may lessen their effectiveness.