The International Committee on Taxonomy of Viruses (ICTV) has recently approved several proposals submitted by the present Caliciviridae Study Group. These proposals include the division of the family into 4 new genera designated Lagovirus, Vesivirus, "Norwalk-like viruses (NLVs), and "Sapporo-like viruses (SLVs); the latter 2 genera were assigned temporary names until acceptable names can be determined by the scientific community. The genera have been further divided into the following species: Feline calicivirus and Vesicular exanthema of swine virus (genus Vesivirus), Rabbit hemorrhagic disease virus and European brown hare syndrome virus (genus Lagovirus), Norwalk virus (genus NLV), and Sapporo virus (genus SLV). In addition, the ICTV approved a proposal to remove the hepatitis E virus from the Caliciviridae into an "unassigned classification status.

The need for rapid, highly sensitive, and versatile diagnostic tests for viral pathogens spans from human and veterinary medicine to bioterrorism prevention. As an approach to meet these demands, a diagnostic test employing monoclonal antibodies (mAbs) for the selective extraction of viral pathogens from a sample in a chip-scale, sandwich immunoassay format has been developed using surface-enhanced Raman scattering (SERS) as a readout method. The strengths of SERS-based detection include its inherent high sensitivity and facility for multiplexing. The capability of this approach is demonstrated by the capture of feline calicivirus (FCV) from cell culture media that is exposed to a gold substrate modified with a covalently immobilized layer of anti-FCV mAbs. The surface-bound FCVs are subsequently coupled with an extrinsic Raman label (ERL) for identification and quantification. The ERLs consist of 60-nm gold nanoparticles coated first with a layer of Raman reporter molecules and then a layer of mAbs. The Raman reporter molecule is strategically designed to chemisorb as a thiolate adlayer on the gold nanoparticle, to provide a strong and unique spectral signature, and to covalently link a layer of mAbs to the gold nanoparticle. The last feature provides a means to selectively tag substrate-bound FCV. This paper describes the development of the assay, which uses cell culture media as a sample matrix and has a linear dynamic range of 1 x 10(6)-2.5 x 10(8) viruses/mL and a limit of detection of 1 x 10(6) viruses/mL. These results reflect the findings from a detailed series of investigations on the effects of several experimental parameters (e.g., salt concentration, ERL binding buffer, and sample agitation), all of which were aimed at minimizing nonspecific binding and maximizing FCV binding efficiency. The performance of the assay is correlated with the number of captured FCV, determined by atomic force microscopy, as a means of method validation.

Caliciviruses, grouped into four genera, are important human and veterinary pathogens with a potential for zoonosis. In these viruses, capsid-related functions such as assembly, antigenicity, and receptor interactions are predominantly encoded in a single protein that forms an icosahedral capsid. Understanding of the immunologic functions and pathogenesis of human caliciviruses in the Norovirus and Sapovirus genera is hampered by the lack of a cell culture system or animal models. Much of our understanding of these viruses, including the structure, has depended on recombinant capsids. Here we report the atomic structure of a native calicivirus from the Vesivirus genus that exhibits a broad host range possibly including humans and map immunological function onto a calicivirus structure. The vesivirus structure, despite a similar architectural design as seen in the recombinant norovirus capsid, exhibits novel features and indicates how the unique modular organization of the capsid protein with interdomain flexibility, similar to an antibody structure with a hinge and an elbow, integrates capsid-related functions and facilitates strain diversity in caliciviruses. The internally located N-terminal arm participates in a novel network of interactions through domain swapping to assist the assembly of the shell domain into an icosahedral scaffold, from which the protruding domain emanates. Neutralization epitopes localize to three hypervariable loops in the distal portion of the protruding domain surrounding a region that exhibits host-specific conservation. These observations suggest a mechanism for antigenic diversity and host specificity in caliciviruses and provide a structural framework for vaccine development.neutralization epitopes ͉ norovirus ͉ vesivirus

Bovine viral diarrhea virus (BVDV) is divided into 2 different species within the Pestivirus genus, BVDV type 1 (BVDV-1) and BVDV type 2 (BVDV-2). Further phylogenetic analysis has revealed subgenotype groupings within the 2 types. Thus far, 12 BVDV-1 subgenotypes (a-l) and 2 BVDV-2 subgenotypes (a and b) have been identified. The purpose of the current study was to determine the prevalence of BVDV subgenotypes in the United States and Australia and to determine if there are detectable antigenic differences between the prevalent subgenotypes. To determine prevalence, phylogenetic analysis was performed on 2 blinded panels of isolates consisting of 351 viral isolates provided by the Elizabeth Macarthur Laboratory, New South Wales, and 514 viral isolates provided by Oklahoma State University. Differences were observed in the prevalence of BVDV subgenotypes between the United States (BVDV-1b most prevalent subgenotype) and Australia (BVDV-1c most prevalent subgenotype). To examine antigenic differences between the subgenotypes identified in samples from the United States and Australia, polyclonal antisera was produced in goats by exposing them at 3-week intervals to 2 noncytopathic and 1 cytopathic strain of either BVDV-1a, BVDV-1b, BVDV-1c, BVDV-2a, or Border disease virus (BDV). Virus neutralization (VN) assays were then performed against 3 viruses from each of the 5 subgenotypes. Comparison of VN results suggests that there are antigenic differences between BVDV strains belonging to different subgenotypes. The present study establishes a foundation for further studies examining whether vaccine protection can be improved by basing vaccines on the BVDV subgenotypes prevalent in the region in which the vaccine is to be used.