Emerging novel coronavirus (2019-nCoV)-current scenario, evolutionary perspective based on genome analysis and recent developments

Abstract

Coronaviruses are the well-known cause of severe respiratory, enteric and systemic infections in a wide range of hosts including man, mammals, fish, and avian. The scientific interest on coronaviruses increased after the emergence of Severe Acute Respiratory Syndrome coronavirus (SARS-CoV) outbreaks in 2002-2003 followed by Middle East Respiratory Syndrome CoV (MERS-CoV). This decade's first CoV, named 2019-nCoV, emerged from Wuhan, China, and declared as 'Public Health Emergency of International Concern' on January 30^th, 2020 by the World Health Organization (WHO). As on February 4, 2020, 425 deaths reported in China only and one death outside China (Philippines). In a short span of time, the virus spread has been noted in 24 countries. The zoonotic transmission (animal-to-human) is suspected as the route of disease origin. The genetic analyses predict bats as the most probable source of 2019-nCoV though further investigations needed to confirm the origin of the novel virus. The ongoing nCoV outbreak highlights the hidden wild animal reservoir of the deadly viruses and possible threat of spillover zoonoses as well. The successful virus isolation attempts have made doors open for developing better diagnostics and effective vaccines helping in combating the spread of the virus to newer areas.

Keywords: 2019-nCoV; Coronavirus; Middle East Respiratory Syndrome CoV; Public Health Emergency; Severe Acute Respiratory Syndrome CoV; genetic analyses; reservoir host; therapeutics; vaccines; zoonoses.

Figure 1.

World-map depicting countries with SARS-CoV and MERS-CoV outbreaks. Red and yellow colors represent the global distribution of only MERS-CoV and SARS-CoV, respectively. The yellow-red dotted pattern shows the incidence of both viruses in the countries.

Figure 2.

Countries, territories or regions with reported confirmed cases of 2019-nCoV, February 4^th, 2020. Different colors indicate different geographical regions with the number of confirmed cases. In the table, region-wise total number of confirmed cases are depicted.

Figure 3.

Phylogenetic analysis of 2019-nCoV isolates using complete genomes. The 2019-nCoV isolates analyzed with related CoVs from past human outbreaks and of animal origin. The solid-black circles are for nCoV isolates from China and solid-black squares are for the isolates from the USA.

Figure 4.

Spike (S) glycoprotein gene-based phylogenetic analysis of 2019-nCoV isolates (10 Chinese and 5 USA isolates). The 2019-nCoV isolates analyzed with related CoVs from past human outbreaks and of animal-origin including MERSV (camel), bovine coronavirus, canine coronavirus, bat_coronaviruses. The solid-black circles are for nCoV isolates from China and the USA.

Figure 5.

Genome organization of novel coronavirus. Comparative spike (S) protein sequence length of different Betacoronaviruses is depicted.