CHARACTERIZATION OF A RHESUS CALICIVIRUS REPRESENTS A NEW GENUS OF CALICIVIRIDAE

Tulane University Of Louisiana, New Orleans LA

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Abstract

This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. The subproject and investigator (PI) may have received primary funding from another NIH source, and thus could be represented in other CRISP entries. The institution listed is for the Center, which is not necessarily the institution for the investigator. We reported the characterization of a novel calicivirus (CV) that was isolated from stool samples of captive juvenile rhesus macaques (Macaca mulatta) of the Tulane National Primate Research Center (TNPRC). The complete genome of the Tulane virus (TV) contains 6714 nucleotides (nt) plus a poly-A tail and is organized into 3 open reading frames (ORF) which encode the nonstructural (NS) polyprotein (ORF1), the capsid protein (ORF2) with an estimated molecular mass (Mr) of 57.9 kDa, and a possible minor structural protein (ORF3) with a isoelectric point (pI) of 10.0 and calculated Mr of 22.8 kDa. The NS- polyprotein revealed all typical CV amino acid motifs, including GXXGXGKT (NTPase), EYXEX (Vpg), GDCG (protease), GLPSG and YGDD (polymerase). Phylogenetic trees constructed for the NS-polyprotein, NTPase, protease, polymerase, and capsid protein sequences consistently placed the TV on a branch rooted with Norovirus but with distances equal to those between other genera. The TV can be cultured in a monkey kidney cell line (LLC-MK2) with the appearance of typical cytopathic effect (CPE). TV exhibits a typical CV morphology with a diameter of 36 nm and has a buoyant density of 1.37 g/ml. According to these physicochemical and genetic characteristics, TV represents a new CV genus for which we propose the name "Recovirus" (Rhesus Enteric CV). Although the pathogenicity of TV in rhesus macaques remains to be elucidated, the likelihood of TV causing intestinal infection and the availability of a tissue culture system makes this virus a valuable surrogate to human CVs.