Sapoviruses

Abstract

Sapovirus particles are typically 41-46 nm in diameter and have a cup-shaped depression and/or 10 spikes on the outline. The sapovirus genome is a single-stranded, positive sense RNA molecule of approximately 7.5 kb that is polyadenylated at the 3′ end. Sapovirus can be divided into ve genogroups (GI-GV; Figure 11.1), among which GI, GII, GIV, and GV are known to infect humans, whereas sapovirus GIII infects porcine species. The sapovirus GI, GIV, and GV genomes are each predicted to contain three main open reading frames (ORFs), whereas sapovirus GII and GIII have two ORFs. Sapovirus ORF1 encodes for nonstructural proteins, including the VPg, protease and RNA dependent RNA polymerase (RdRp), and a major capsid protein (VP1). Human sapovirus ORF2 and ORF3 encode proteins of yet unknown functions. Previously, sapoviruses have been classied based on either their partial RdRp and/or capsid sequences, but since the discovery of recombinant sapovirus strains [16,17] classication numbering schemes have conicted between the different research groups. Ideally,