Sequence analysis of the gene encoding the capsid protein of the Snow Mountain human calicivirus

Snow Mountain virus (SMV) is the reference strain for serotype 3 as determined by immune electron microscopy of the human caliciviruses that are associated with epidemic gastroenteritis. In order to establish the genetic relationship of its capsid protein with those from other human caliciviriuses, the sequence of the open reading frame 2 (ORF2) encoding the SMV capsid protein was determined. The SMV ORF2 sequence was 1626 nucleotides in length and the deduced protein of 542 amino acids had a calculated molecular weight of 59.2 kD. The SMV capsid sequence showed approximately 48 and 77% amino acid sequence identity with the capsid proteins of the Norwalk (serotype 1) and Hawaii (serotype 2) human calicivirus reference strains, respectively, a finding consistent with its serotypic distinctiveness. Furthermore, the predicted amino acid sequence of the SMV capsid was found to share highest sequence identity (98%) with the Melksham human calicivirus in database searches.