**4. Most likely ecological pool and source of coronavirus**

It is important to be acquainted with its origin and transmission to develop preventive measures and to inhibit the spread of infection. As far as the occurrence of SARS-CoV, surveyors primarily concentrate on palm civets and raccoon dogs as the main storehouse of infection. Only the specimens excluded from the civets demonstrated positive outcomes for viral RNA identification in the food market, suggesting that the secondary host might be the civet palm [19]. In 2001, the samples obtained from sound people of Hong Kong were isolated, and the molecular analyses were conducted; the result showed 2.5 percent of antibodies developed against SARScoronavirus. This implied that SARS-coronavirus might have circulated in humans before giving rise to the outbreak in 2003 [20]. Subsequently, Rhinolophus bats were also discovered to develop antibodies against SARS-CoV, suggesting that bats were a source for viral reproduction [21]. For the first time, MERS-coronavirus evolved in the Kingdom of Saudi Arabia in 2012 [22]. MERS-coronavirus, known as beta-coronavirus, had camels as a primary host for the zoonotic disease [23]. In a recent study, MERS-coronavirus is believed to be spotted in Perimyotisbats and Pipistrellus [24], implying that bats are the virus' primary source and transmission mode [25, 26]. At the outset, a group of researchers believed that snakes were the probable origin; however, genomic analysis for similarity measures explains that novel coronaviruses and SARS viruses support the assertion that snakes were not the central storehouse, however, bats were [27, 28]. Further analyses of homologous rearrangement showed that SARS-CoV (CoVZXC21) generated receptor binding and the prim of the spike glycoprotein of novel coronaviruses (as shown in **Figure 1**). The construction of respiratory syndrome generating human coronavirus CoVZC45 is an unknown Beta-CoV [29].
