Liver tissue from animals that died of rabbit hemorrhagic disease (RHD) was used to identify the causative agent. After extraction of liver homogenates and sucrose density gradient ultracentrifugation, distinct bands were obtained. The respective gradient fractions reacted positively in an enzyme-linked immunosorbent assay as well as in hemagglutination assays and were infective for rabbits. These fractions contained virions which had a diameter of 40 nm and resembled morphologically those of the family Caliciviridae. By immunoblotting, a major structural protein with a molecular weight of 60,000 was identified. Highly pure RNA of about 8 kilobases was isolated from virions. Labeled cDNA synthesized from virion RNA detected two RNAs of 8 and 2 kilobases in Northern (RNA) blots of liver RNA from animals infected with RHD virus. Finally, isolated virion RNA injected into the liver of rabbits produced a disease with clinical symptoms and pathological findings typical of RHD. We conclude that a calicivirus represents the causative agent of RHD.
Viruses from the recent epidemic of swine vesicular disease (SVD) in Europe have been isolated and characterized by antigenic and genetic methods to examine the likely epidemiological origins of the disease. Antigenic analysis was performed on 77 SVD viruses (SVDV) isolated in Europe between 1966 and 1994 using two panels of monoclonal antibodies (MAb) in a trapping ELISA. Genetic analysis of 33 of the SVD viruses by reverse transcription-polymerase chain-reaction (RT-PCR) amplification and nucleotide sequencing of the ID (VP1) coding region was also performed. Comparison of the nucleotide sequences with each other and with three other previously published SVDV sequences revealed four distinct groups which correlated exactly with the results of the pattern of reactivity with MAbs. The first group consisted solely of the earliest SVD virus isolated (ITL/1/66) while the second group comprised viruses present in Europe and Japan between 1972 and 1981. The third group consisted of viruses isolated from outbreaks of SVD in Italy between December 1988 and June 1992. Viruses isolated between 1987 and 1994 from Romania, the Netherlands, Italy and Spain formed a fourth group. The genetic and antigenic similarity of the most recent virus isolates from Western Europe to a virus isolated in Romania 5 years previously suggests that the possible origin of the recent epidemic of swine vesicular disease in Western Europe was in Eastern Europe.
Monoclonal antibodies directed against the capsid protein of rabbit hemorrhagic disease virus (RHDV) were used to identify field cases of European brown hare syndrome (EBHS) and to distinguish between RHDV and the virus responsible for EBHS. Western blot (immunoblot) analysis of liver extract of an EBHS virus (EBHSV)-infected hare revealed a single major capsid protein species of approximately 60 kDa that shared epitopes with the capsid protein of RHDV. RNA isolated from the liver of an EBHSV-infected hare contained two viral RNA species of 7.5 and 2.2 kb that comigrated with the genomic and subgenomic RNAs of RHDV and were recognized by labeled RHDV cDNA in Northern (RNA) hybridizations. The nucleotide sequence of the 3' 2.8 kb of the EBHSV genome was determined from four overlapping cDNA clones. Sequence analysis revealed an open reading frame that contains part of the putative RNA polymerase gene and the complete capsid protein gene. This particular genome organization is shared by RHDV but not by other known caliciviruses. The deduced amino acid sequence of the capsid protein of EBHSV was compared with the capsid protein sequences of RHDV and other caliciviruses. The amino acid sequence comparisons revealed that EBHSV is closely related to RHDV and distantly related to other caliciviruses. On the basis of their genome organization, it is suggested that caliciviruses be divided into three groups.
Torque teno virus: Determination of viral genomic loads by genogroup-specific multiplex rt-PCR, detection of frequent multiple infections with genogroups 1 or 2, and establishment of viral full-length sequences. Veterinary Microbiology, Elsevier, 2009, 143 (2-4) This is a PDF file of an unedited manuscript that has been accepted for publication. As a service to our customers we are providing this early version of the manuscript. The manuscript will undergo copyediting, typesetting, and review of the resulting proof before it is published in its final form. Please note that during the production process errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain.Page 1
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