In 2010, a large outbreak of rotavirus gastroenteritis occurred in the Alice Springs region of the Northern Territory, Australia. The outbreak occurred 43 months after the introduction of the G1P rotavirus vaccine Rotarix(®). Forty-three infants were hospitalized during the outbreak and analysis of fecal samples from each infant revealed a G1P rotavirus strain. The outbreak strain was adapted to cell culture and neutralization assays were performed using VP7 and VP4 neutralizing monoclonal antibodies. The outbreak strain exhibited a distinct neutralization resistance pattern compared to the Rotarix(®) vaccine strain. Whole genome sequencing of the 2010 outbreak virus strain demonstrated numerous amino acid differences compared to the Rotarix(®) vaccine strain in the characterized neutralization epitopes of the VP7 and VP4 proteins. Phylogenetic analysis of the outbreak strain revealed a close genetic relationship to global strains, in particular RVA/Human-wt/BEL/BE0098/2009/G1P and RVA/Human-wt/BEL/BE00038/2008/G1P for numerous genes. The 2010 outbreak strain was likely introduced from a globally circulating population of strains rather than evolving from an endemic Australian strain. The outbreak strain possessed antigenic differences in the VP7 and VP4 proteins compared to the Rotarix(®) vaccine strain. The outbreak was associated with moderate vaccine coverage and possibly low vaccine take in the population.
Keywords: Australia; G1P; diarrheal outbreak; full-genome analysis; rotavirus, Rotarix®.