Incidence of group C human rotavirus in central Australia and sequence variation of the VP7 and VP4 genes

Abstract

Human group C rotavirus was identified in central Australia in each of eight years over a 16-year period between 1982 and 1997. Cases occurred either sporadically but over a relatively short period of time or as clustered outbreaks. These are the only reports of human group C rotavirus in Australia other than that of a single case reported approximately 1,800 km away in 1982. The electrophoretic genome profiles of isolates were identical for all those identified within the same year but different between those identified in different years. The VP7 genes of four isolates identified in four different years over a 7-year period between 1987 and 1993, and the VP4 genes of two of these isolates showed relatively little variation in genome and deduced amino acid sequence upon comparison of the equivalent genes between isolates. The sequences were also very similar to those from the corresponding genes from most of the human group C rotavirus isolates from other countries. This continues the observation of a high degree of gene sequence conservation among human group C rotaviruses worldwide.

FIG. 1.

Alignment of the deduced VP7 amino acid sequences of the 4 Australian and 10 non-Australian human group C rotavirus isolates listed in Table 2. The sequences are numbered from the first methionine residue at the start codon, i.e., positions 49 to 51 of the VP7 gene. Identical amino acids are represented by a dot.

FIG. 2.

Phylogenetic tree of the VP7 genes of the 4 Australian (CHRV/A87J, CHRV/A88G, CHRV/A90L, CHRV/A93 M) and the 10 non-Australian (Preston, Belém, Solano, ad957, OK450, K9304, 208, KA4/949, Jajeri, and Moduganari) group C rotavirus isolates compared in Table 2.

FIG. 3.

Phylogenetic tree of the amino acid sequences deduced from the VP7 genes of the 4 Australian (CHRV/A87J, CHRV/A88G, CHRV/A90L, and CHRV/A93 M) and 10 non-Australian (Preston, Belém, Solano, ad957, OK450, K9304, 208, KA4/949, Jajeri, and Moduganari) group C rotavirus isolates compared in Table 2.

FIG. 4.

Alignment of the deduced VP4 amino acid sequences of the two Australian and five non-Australian human group C rotavirus isolates listed in Table 3. The sequences are numbered from the first methionine residue at the start codon, i.e., positions 21 to 23 of the VP4 gene. Identical amino acids are represented by a dot.

FIG. 5.

Phylogenetic tree of the VP4 genes of the two Australian (CHRV/A87J and CHRV/A93) and five non-Australian (Bristol, Belém, 208, Jajeri, and Moduganari) group C rotavirus isolates compared in Table 3.

FIG. 6.

Phylogenetic tree of the amino acid sequences deduced from the VP4 genes of the two Australian (CHRV/A87J and CHRV/A93 M) and five non-Australian (Bristol, Belém, 208, Jajeri, and Moduganari) group C rotavirus isolates compared in Table 3.