4.1.2.1  Hypothesis: whole-genome sequencing and phylogenetic analysis shed light on the origin of the 2019-nCoV virus – It has been probably introduced from bats to men
Genome sequencing of a fecal bat sample, Rp3, could detect an isolate of coronaviruses, which was almost identical to the causative agent of the SARS-CoV outbreak of 2002–2003. Hence, it attained the name SARS-like coronavirus isolate Rp3 (SL-CoV Rp3) [12]. The bronchoalveolar lavage fluid (BALF) of a patient with SARS contained the 2019-nCoV. RNA sequencing could reveal about 90% similarity in nucleotides of the novel coronavirus and of SARS-like coronavirus that had previously related to bats [13], [14]. In particular, the S protein of the 2019-nCoV has a high sequence identity of 80–98% with the S protein of bat SARS-like CoVs, such as SARSr-CoV ZXC21 S, ZC45 S, and RaTG13 [3]. Moreover, in phylogenomic trees, branches for the 2019-nCoV are of greater length than those for the 2003 SARS-CoV, and therefore more favorable to bats.