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 bat tetherins that we assessed for function which were most similar to human l-tetherin, P. alecto tetherin isoforms A and B, and M. macropus tetherin A, were all found to predominantly form dimers. This was shown by non-reducing SDS-PAGE size separation and subsequent Western blot analysis in which a detectable signal was observed almost exclusively at the expected size of tetherin dimers (Figure 7 ). In contrast, P. alecto tetherin isoform C was present in similar amounts in both the dimeric and monomeric forms ( Figure 7A ). This observation is surprising because P. alecto tetherin isoform C contains all of the conserved cysteine residues and the same extracellular coiled-coil domain as isoforms A and B. The distinct C-terminal region in isoform C is the result of an alternative splicing event that also causes the loss of the final three amino acid residues of the coiledcoil region possessed by isoforms A and B. Additionally, the inserted HA tag is located in the position immediately following then coiled-coil domain. It is possible that the absence of the three terminal amino acid residues in the coiled-coil domain of isoform C relative to isoform A and B accounts for the difference in relative extents of dimerisation.