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.

The 152-aa protein predicted to be encoded by ORF5a is similar to nucleocapsids (N) from other nidoviruses. This similarity is detectable by BLASTp, with the best such alignments from a search of the NCBI nr database being to porcine reproductive and respiratory syndrome virus (PRRSV) N proteins (22% pairwise identity over 125 aa) and by HMMER3 analysis, which identifies the Arteri_nucleo PFam domain in this sequence (E value, 5.6 ϫ 10 Ϫ9 ). Although the best local alignments from a BLASTp search of nr are to arterivirus N sequences, by pairwise global alignments the ORF5a-encoded N sequence is more similar to bafinivirus and torovirus N sequences (e.g., 24% pairwise identity to white bream virus N) than to arterivirus N sequences (e.g., 18% pairwise identity to PRRSV N). This protein is predicted to be basic, with an isoelectric point of 10.6, and to contain no transmembrane do-mains, consistent with a putative function as an RNA-binding nucleocapsid protein.