Severe acute respiratory syndrome (SARS), Middle East respiratory syndrome (MERS) and coronavirus disease – 2019 (COVID-19) are caused by closely related coronaviruses. SARS is due to the infection of SARS-CoV-1 and MERS is caused by MERS-CoV whereas COVID-19 is due to SARS-CoV-2. Coronaviruses are enveloped, spherical viruses with single stranded positive (ss+) RNA as genome. SARS, MERS and COVID-19 can lead to severe respiratory diseases leading to pneumonia. Human infections due to SARS-CoV-1, MERS-CoV and SARS-CoV-2 viral agents might have occurred after contact with reservoir animals. Reservoir animals for SARS and COVID-19 are bats, pangolins, snakes and other animals whereas for MERS the reservoir animal is camel. The genetic nature of coronaviruses is highly attributed to their drastic antigenic recombination. This antigenic change may result in the change of antigenic property of coronavirus ending in emergence of new type of coronavirus. Our phylogenetic analysis showed that SARS-CoV-1 and SARS-CoV-2 viruses are genetically related than MERS-CoV. This suggests that SARS-CoV-1 might be the genetic source for the evolution of SARS-CoV-2. There is no evidence that SARS-CoV-2 is manmade as an agent of bioweapon. Emergence of new coronaviruses can be contained by avoiding contact with wild animals. This can also be controlled by averting slaughter and eating of wild animals. There may be several undiscovered coronaviruses already existing in many animal reservoirs. These animal coronaviruses may have the capacity to cause human infection in the future. Due to the virion properties, genetic makeup and reservoir hosts, coronaviruses are continuously evolving over a period of time. We speculate that there may be another new human coronavirus that is entirely / partially different from the existing coronaviruses, may evolve in the future.
To cite this article
Emergence of Infectious Diseases – SARS, MERS, COVID-19: What is next?
Infectious Diseases & Tropical Medicine 2020;
Submission date: 30 Apr 2020
Revised on: 06 May 2020
Accepted on: 12 May 2020
Published online: 08 Jun 2020