The battle against SARS and MERS coronaviruses: Reservoirs and Animal Models

Gong, Shu-ran; Bao, Lin-lin

Recently, a five year study provided futher evidence that bats in the Yunnan province of China are more likely to be the prime reservoir than those detected elsewhere. The study compared the nonstructural protein genes ORF1a and 1b of the virus and concluded that SARSr-CoV strains from a cave in Yunnan village were more closely related to human SARS-CoV and cell entry studies demonstrated that three newly identified SARSr-CoVs with different S protein sequences are all able to use human ACE2 as the receptor. 4 Just as horseshoe bats were postulated to be the primary SARS host, van Boheeman et al. 5 indicated that two kinds of bats carry similar MERS coronaviruses. Then, Susanna K. P. Lau et al. 6 used sequences of RNA polymerase (RdRp), spike (S), and nucleocapsid (N) genes to determine that human MERS-CoV RdRp is more closely related to the pipistrelle bat CoV HKU5 (92.1%-92.3% amino acid identity) and the S and N genes are more closely related to the Tylonycteris bat CoV HKU4 (respectively, 66.8%-67.4% and 71.9%-72.3% amino acid identity), indicating that these three viruses may share the same ancestor. However, these results did not definitively prove bat CoV to be the ancestor of the human CoV.