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.

One distinguishing feature of the snake virus replicase polyprotein is the apparent lack of an ADP-ribose binding "macro" domain that is present in nidoviruses in the family Coronaviridae ( Fig. 4E and Table 2 ) (46) (47) (48) . The activity of this domain is not essential for replication in vitro but may help counteract the innate immune response in vivo (49, 50) . At approximately the same position of snake virus pp1a is a predicted protein kinase (PFam PKinase domain) that is not present in any other nidovirus as determined by HMMER analysis (HMMER3 E value, 1.5 ϫ 10 Ϫ6 ) ( Fig. 4B and Table 2 ). This prediction is also supported by BLASTp analysis, with the best alignments from a search of the NCBI nr database with pp1ab residues 2300 to 2500 being to cellular serine/threonine protein kinases (lowest E value, 3 ϫ 10 Ϫ5 ).