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The complete RNA genome of the avian nephritis virus (ANV) associated with acute nephritis in chickens has been molecularly cloned and sequenced. Excluding the poly(A) tail, the genome comprises 6,927 nucleotides and contains three sequential open reading frames (ORFs). The first ORF (ORF 1a) contains a sequence encoding a serine protease motif, and the second ORF (ORF 1b) has a sequence encoding an RNA-dependent RNA polymerase. ORF 1a may be linked to the second ORF by a ribosomal frameshifting mechanism. The third ORF (ORF 2) may encode the virion structural proteins as a polyprotein precursor. Two RNAs, probably genonic and subgenonic RNA (7.5 and 3.0 kb), were detected in the cytoplasm of ANV-infected cells. ANV and human astroviruses have the same genonic organization, and both are characterized by the presence of two RNA bands. The amino acid homologies of the products of ORF 1a, 1b, and 2 were 20.3, 41.9, and 25.8% to products of the corresponding ORFs of human astrovirus serotype 1 (A/88 Newcastle strain). We have constructed a genonic-length cDNA clone of ANV to test whether the in vitro transcript is infectious. When a chicken kidney cell culture was transfected with RNA transcribed in vitro and the cDNA clone, infectious virus was produced with cytopathic effects in the absence of trypsin. These observations suggested that the ANV (G-4260 strain) is a new genus of the family Astroviridae.

The central event in prion disease is thought to be conformational conversion of the cellular isoform of prion protein (PrP C ) to the insoluble isoform PrP Sc . We generated polyclonal and monoclonal antibodies by immunizing PrP C

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The expression of porcine endogenous retroviruses (PERV) was investigated in primary porcine peripheral blood leukocytes (PBL) of ten different pig breeds. The data suggest that PERV exists in all porcine PBL. A new retroviral element, a foamy-like pol-related sequence, was also detected in PBL. Three types of PERV were detected in almost every animal. The breeding of PERV-free pigs is likely to be difficult. Further studies are required to assess the infectious disease risks associated with xenotransplantation.