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 lipid bilayers of nidoviruses contain one or more proteins in addition to S, including the membrane (M) protein present in some nidoviruses (1, 2) . The protein encoded by ORF4 is likely to be a homolog of the M protein of other large nidoviruses. This prediction is based on several attributes of the deduced protein sequence. First, the size of the snake virus protein (215 aa) is just under the range for other Coronaviridae M proteins (216 to 268). Second, the protein contains 3 predicted TM domains in the N-terminal half, a characteristic feature (see Fig. S4 in the supplemental material). Third, the protein possesses sequence similarity to the putative M protein of the white bream virus nidovirus that is detectable by BLASTp analysis of the nr database. The sequences are 21% identical over 116 aa, and the E value of this alignment is slightly lower than those of alignments to various bacterial protein sequences. Whether this putative M protein performs the same functional role as its distant relatives remains to be validated experimentally.