Infection with the new coronavirus : from antigenic and serological screening and diagnosis to immunity and reinfection

Abstract

The new coronavirus or SARS-Cov2 responsible for the current global pandemic is an enveloped single RNA virus of the coronavirus family which shares several characteristics with other known coronaviruses responsible for respiratory infections, in particular those causing epidemics of 2002–2003 in China and 2012–2013 in the Middle East. The biological diagnosis of SARS-Cov-2 infection is essentially based on the
quantitative polymerase chain reaction with reverse transcription or RT-PCR which makes it possible to detect viral RNA and to identify virus-specific nucleotide sequences. However, antigenic and serological tests which allow to detect and/or measure the specific antigens of and/or antibodies for the virus are taking an increasingly important place both in the diagnosis of the disease and in the screening of subjects who have been infected and the identification of immunized individuals and those who have not been in contact with the virus. In this article we will present the different methods and techniques used in these antigenic and serological tests of which we will explain the interest and the limits. We will also discuss the notion of acquired immunity after infection with the virus, its duration and the often asked question of reinfection.