Coronaviruses and how to fight against it

A fiew monts after the first confirmate case of coronaviruses, we need remember the virus was named severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) by the International Committee on Taxonomy of Viruses. Human infection with SARS-CoV-2 leads to a wide range of clinical manifestations ranging from asymptomatic, mild, moderate to severe. The severe cases present with pneumonia, which can progress to acute respiratory distress syndrome.

The outbreak provides an opportunity for real-time tracking of an animal coronavirus that has just crossed species barrier to infect humans. The outcome of SARS-CoV-2 infection is largely determined by virus-host interaction. A new study suspects that we need remember old lessons from a big enemy.

Here, we review the discovery, zoonotic origin, animal hosts, transmissibility and pathogenicity of SARS-CoV-2 in relation to its interplay with host antiviral defense.

HIVs are the most studied viruses in history and the best model to understand the interplay between virus and host antiviral defence. Tracing the origins of HIVs would provide a framework for us to understand cross-species transmission and pathogenicity of SARS-CoV-2. The comparison of SARS-CoV-2 and HIVs would reveal a common theme and the requirements for their successful species jumping. In particular, lessons learnt from HIVs are highly relevant and instructive to SARS-CoV-2 for the following reasons. First, both HIVs and SARS-CoV-2 are of zoonotic origin. Second, infection of their reservoir hosts with parental viruses of HIVs and SARS-CoV-2 results in no or mild symptoms, third, the similarities and differences between HIV-1 and HIV-2 resemble those between SARS-CoV and SARS-CoV-2. Finally, both HIVs and SARS-CoV-2 are plausibly derived from discrete cross-species transmission events from animals to humans.

HIVs and SARS-CoVs bear many similarities in terms of cross-species transmission. It is difficult to predict how the ongoing outbreak of SARS-CoV-2 might develop in the coming weeks and months.

The outbreak of SARS-CoV-2 provides an unprecedented opportunity for us to keep track of a zoonotic CoV that has just crossed the species barrier to infect humans. Whether the transmission of SARS-CoV-2 within humans will come to a dead end depends primarily on whether the virus has acquired the ability to transmit from person-to-person efficiently and sustainably. 

The interplay between SARS-CoV-2 and host antiviral defence is at the core of viral pathogenesis. It also determines the infection outcome and might explain the existence and risk of asymptomatic carriers. SARS-CoV-2 is very similar to SARS-CoV in many aspects. Particularly, comparative analyses of SARS-CoV-2 and SARS-CoV will advance the understanding of SARS-CoV-2 pathogenesis. The new knowledge gained will guide the development of vaccines and anti-SARS-CoV-2 therapeutics.

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