Bats Possess Unique Variants of the Antiviral Restriction Factor Tetherin

Joshua A. Hayward; Mary Tachedjian; Adam Johnson; Tamsin B. Gordon; Jie Cui; Glenn A. Marsh; Michelle L. Baker; Lin-Fa Wang; Gilda Tachedjian

The analysis revealed that overall, bat tetherin genes have been subjected to positive selection, with an average ratio of non-synonymous (dN) to synonymous (dS) mutations, dN/dS, of 1.125 over the Chiropteran phylogeny, with numerous specific positions subjected to a large degree of positive selection, with dN/dS values of 2.626 -2.668 (Table 2 ). These sites are predominantly located in the transmembrane domain and the regions of the cytoplasmic and extracellular domains immediately adjacent to the transmembrane domain ( Figure 1A ). This analysis suggests the presence of evolutionary pressure exerted on tetherin, by viral antagonists or countermeasures that target residues in the tetherin, following the speciation of the Chiropteran family. The apparent ubiquity of tetherin among bats, in concert with significant sequence diversity and evidence of strong positive selection pressures operating on each species, supports the notion that tetherin plays a major role in the antiviral repertoire of bats.