Ball Python Nidovirus: a Candidate Etiologic Agent for Severe Respiratory Disease in Python regius

Stenglein, Mark D.; Jacobson, Elliott R.; Wozniak, Edward J.; Wellehan, James F. X.; Kincaid, Anne; Gordon, Marcus; Porter, Brian F.; Baumgartner, Wes; Stahl, Scott; Kelley, Karen; Towner, Jonathan S.; DeRisi, Joseph L.

Nidovirus S proteins are involved in receptor binding and membrane fusion via their N-and C-terminal S1 and S2 subunits (1, 2, 51, 52) . The best alignment from a BLASTp search of the snake virus protein against the nr database was to thrush coronavirus HKU12-600 spike glycoprotein (YP_002308497 [53] ). This alignment had 18% pairwise identity over 333 aa in the C-terminal third of the protein, i.e., in the S2 membrane fusion domain (52) . The putative S1 receptor-binding domain of this protein possesses no clear similarity to other proteins by BLAST or HMMER analysis (residues 25 to 625 queried). Consistent with its putative identity as a spike glycoprotein, this protein is predicted to contain several transmembrane (TM) domains, including one characteristically near the C terminus, and is predicted to be glycosylated (see Fig. S4 in the supplemental material).