Molecular characterization of Camberwell virus and sequence variation in ORF3 of small round-structured (Norwalk-like) viruses.

Five small round-structured viruses (SRSVs) associated with gastroenteritis in Victoria, Australia, from January to November 1994 were examined by sequencing cDNA prepared from faecal samples using RT-PCR. The sequence of the 3' half (3.8 kb) of the genome of one of these viruses, Camberwell, was determined. Camberwell virus was related most closely to Bristol and Lordsdale viruses, and belonged to the genetic group of SRSVs containing Bristol, Lordsdale, Toronto, OTH-25, Mexico, and Hawaii viruses. The amino acid identities between Camberwell and Bristol viruses for proteins encoded by ORF1 (partial), ORF2, and ORF3 were 99%, 98%, and 90%, respectively. A highly variable region in ORF3 corresponding to amino acid residues 123 to 169 (Bristol and Camberwell numbering) were identified. Short segments of ORF1 (polymerase region) and the highly variable ORF3 region was analysed for the other four viruses. The results obtained indicated the potential usefulness of the variable region in distinguishing between closely related viruses.