Rotaviruses

Rotaviruses are icosahedral, nonenveloped viruses with a genome consisting of 11 segments of double-stranded RNA. They are the leading cause of severe diarrhea in young children worldwide and important pathogens of many animal species. Approximately 1600 children die daily due to rotavirus (RV) diarrhea, primarily in developing countries. Viral prevalence is similar in developed and developing countries and cost-effectiveness studies justify the use of RV vaccines in both settings. Rotaviruses are very well adapted to their host: they replicate very efficiently, sterilizing immunity is not developed and, despite an important host range restriction, there are many animal hosts. These characteristics help explain the high viral prevalence and, as viral eradication does not seem feasible, suggest that a reasonable goal of vaccination is to prevent severe disease. RV replication principally occurs in enterocytes but recent studies indicate that some replication is also likely to occur systemically. Pathogenic mechanisms include an osmotic malabsorptive diarrhea, stimulation of the enteric nervous system by the virus, and the enterotoxic effect of the viral nonstructural protein NSP4. Two new RV vaccines have been recently approved for use in a variety of countries and may help reduce the disease burden due to this pathogen.