Caliciviruses in and around us.

Caliciviruses (Cvs) are a family of viruses whose molecular biology, replic ation and genome organisation are just beginning to be understood. Based on their genetic relatedness and genomic organisation, they have recently bee n classified into four genera: 1. Norwalk-like viruses, 2. Sapporo-like vir uses, 3. Vesiviruses 4. Lagoviruses. The virions consist of a single polype ptide and possess a posotive-sense polyadenylate RNA genome of approximatel y 7.5 kb Even though FCV, SMSV and other Cvs of animal origin can be readil y propagated in tissue culture, progress on the molecular characterisation of human Cvs has been slow because of the lack of appropriate cell culture systems. The application of modem molecular biological techniques has recen tly led to the recognition of the genetic diversity of Cvs and changed the assessment of their epidemiological importance. Moreover, the discovery of movement of SMSV from ocean reservoirs to terrestrial hosts led to the conc lusion that fish and perhaps other forms of marine life may serve as a vehi cle for transmission. The etiological role of Cvs in a number of veterinary and human diseases in by now well established. Human cases are associated mainly with food-bome and water-borne outbreaks of gastro-enteritis in peop le of all ages on all continents. In Hungary, the observation of caliciviru s-like particles in animal feacal samples, limited unpublished investigatio ns on RHDV and EBHSV, and results of serological surveys for Norwalk and MX viruses in human sera collected from different geographic areas demonstrat ed the circulation of these viral pathogens in the country.