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A pandemic strain of calicivirus threatens rabbit industries in the Americas.

McIntosh MT, Behan SC, Mohamed FM, Lu Z, Moran KE, Burrage TG, Neilan JG, Ward GB, Botti G, Capucci L, Metwally SA - Virol. J. (2007)

Bottom Line: Complete viral genome sequences of all USA outbreak isolates were determined and comparative genomics revealed that each outbreak was the result of a separate introduction of virus rather than from a single virus lineage.Rapid spread of the RHDVa pandemic suggests a selective advantage for this new subtype.Given its rapid spread, pathogenic nature, and potential to further evolve, possibly broadening its host range to include other genera native to the Americas, RHDVa should be regarded as a threat.

View Article: PubMed Central - HTML - PubMed

Affiliation: Foreign Animal Disease Diagnostic Laboratory, Animal and Plant Health Inspection Services, United States Department of Agriculture, Plum Island Animal Disease Center, P,O, Box 848, Greenport, NY 11944, USA. michael.t.mcintosh@aphis.usda.gov

ABSTRACT
Rabbit Hemorrhagic Disease (RHD) is a severe acute viral disease specifically affecting the European rabbit Oryctolagus cuniculus. As the European rabbit is the predominant species of domestic rabbit throughout the world, RHD contributes towards significant losses to rabbit farming industries and endangers wild populations of rabbits in Europe and other predatory animals in Europe that depend upon rabbits as a food source. Rabbit Hemorrhagic Disease virus (RHDV) - a Lagovirus belonging to the family Caliciviridae is the etiological agent of RHD. Typically, RHD presents with sudden death in 70% to 95% of infected animals. There have been four separate incursions of RHDV in the USA, the most recent of which occurred in the state of Indiana in June of 2005. Animal inoculation studies confirmed the pathogenicity of the Indiana 2005 isolate, which caused acute death and pathological changes characterized by acute diffuse severe liver necrosis and pulmonary hemorrhages. Complete viral genome sequences of all USA outbreak isolates were determined and comparative genomics revealed that each outbreak was the result of a separate introduction of virus rather than from a single virus lineage. All of the USA isolates clustered with RHDV genomes from China, and phylogenetic analysis of the major capsid protein (VP60) revealed that they were related to a pandemic antigenic variant strain known as RHDVa. Rapid spread of the RHDVa pandemic suggests a selective advantage for this new subtype. Given its rapid spread, pathogenic nature, and potential to further evolve, possibly broadening its host range to include other genera native to the Americas, RHDVa should be regarded as a threat.

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Relationship of VP60 capsid proteins among diverse isolates of RHDV. The predicted amino acid sequences of 45 RHDV isolates were aligned in CLUSTAL W. One thousand bootstrap replicates were subjected to protein distance and UPGMA methods and the consensus phylogenetic tree is shown. The VP60 region of a non-pathogenic rabbit calicivirus (RCV) was used as an outgroup. Two clades, one representing the original RHDV serotype and a second representing the new RHDVa subtype were identified. Bootstrap values greater than 50% are displayed above the tree branches.
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Figure 2: Relationship of VP60 capsid proteins among diverse isolates of RHDV. The predicted amino acid sequences of 45 RHDV isolates were aligned in CLUSTAL W. One thousand bootstrap replicates were subjected to protein distance and UPGMA methods and the consensus phylogenetic tree is shown. The VP60 region of a non-pathogenic rabbit calicivirus (RCV) was used as an outgroup. Two clades, one representing the original RHDV serotype and a second representing the new RHDVa subtype were identified. Bootstrap values greater than 50% are displayed above the tree branches.

Mentions: To determine whether the U.S. isolates were related to the pandemic RHDVa subtype currently spreading throughout Europe, we compared putative translations of the VP60 capsid regions for all US isolates (IA-00, NY-01, UT-01, and IN-05) to that of 41 other isolates of RHDV and RCV. All four U.S. isolates branched consistently with a group of 15 other isolates that included the typed RHDVa antigenic variants from France and Italy (Figure 2). Of note, RHDV isolates from New York and Utah in the same year, while both grouping within the RHDVa clade, did not branch together indicating separate origins for these outbreaks. Furthermore, another North American isolate, Mex-89, failed to cluster with the RHDVa clade distinguishing it from the other American isolates (Figure 2). Also consistent with the finding that this clade represented RHDVa subtypes, the IA-00 isolate was typed as RHDVa using an antigen capture ELISA and a panel of type-specific monoclonal antibodies (Figure 3). This further supports the inference that monoclonal antibody 3B12 recognizes an RHDVa type-specific epitope while monoclonal antibody 1H8 recognizes an original RHDV type-specific epitope (Figure 3) [34,35]. In contrast monoclonal antibody 2B4 recognizes a shared epitope between the two types of RHDV (Figure 3).


A pandemic strain of calicivirus threatens rabbit industries in the Americas.

McIntosh MT, Behan SC, Mohamed FM, Lu Z, Moran KE, Burrage TG, Neilan JG, Ward GB, Botti G, Capucci L, Metwally SA - Virol. J. (2007)

Relationship of VP60 capsid proteins among diverse isolates of RHDV. The predicted amino acid sequences of 45 RHDV isolates were aligned in CLUSTAL W. One thousand bootstrap replicates were subjected to protein distance and UPGMA methods and the consensus phylogenetic tree is shown. The VP60 region of a non-pathogenic rabbit calicivirus (RCV) was used as an outgroup. Two clades, one representing the original RHDV serotype and a second representing the new RHDVa subtype were identified. Bootstrap values greater than 50% are displayed above the tree branches.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC2147015&req=5

Figure 2: Relationship of VP60 capsid proteins among diverse isolates of RHDV. The predicted amino acid sequences of 45 RHDV isolates were aligned in CLUSTAL W. One thousand bootstrap replicates were subjected to protein distance and UPGMA methods and the consensus phylogenetic tree is shown. The VP60 region of a non-pathogenic rabbit calicivirus (RCV) was used as an outgroup. Two clades, one representing the original RHDV serotype and a second representing the new RHDVa subtype were identified. Bootstrap values greater than 50% are displayed above the tree branches.
Mentions: To determine whether the U.S. isolates were related to the pandemic RHDVa subtype currently spreading throughout Europe, we compared putative translations of the VP60 capsid regions for all US isolates (IA-00, NY-01, UT-01, and IN-05) to that of 41 other isolates of RHDV and RCV. All four U.S. isolates branched consistently with a group of 15 other isolates that included the typed RHDVa antigenic variants from France and Italy (Figure 2). Of note, RHDV isolates from New York and Utah in the same year, while both grouping within the RHDVa clade, did not branch together indicating separate origins for these outbreaks. Furthermore, another North American isolate, Mex-89, failed to cluster with the RHDVa clade distinguishing it from the other American isolates (Figure 2). Also consistent with the finding that this clade represented RHDVa subtypes, the IA-00 isolate was typed as RHDVa using an antigen capture ELISA and a panel of type-specific monoclonal antibodies (Figure 3). This further supports the inference that monoclonal antibody 3B12 recognizes an RHDVa type-specific epitope while monoclonal antibody 1H8 recognizes an original RHDV type-specific epitope (Figure 3) [34,35]. In contrast monoclonal antibody 2B4 recognizes a shared epitope between the two types of RHDV (Figure 3).

Bottom Line: Complete viral genome sequences of all USA outbreak isolates were determined and comparative genomics revealed that each outbreak was the result of a separate introduction of virus rather than from a single virus lineage.Rapid spread of the RHDVa pandemic suggests a selective advantage for this new subtype.Given its rapid spread, pathogenic nature, and potential to further evolve, possibly broadening its host range to include other genera native to the Americas, RHDVa should be regarded as a threat.

View Article: PubMed Central - HTML - PubMed

Affiliation: Foreign Animal Disease Diagnostic Laboratory, Animal and Plant Health Inspection Services, United States Department of Agriculture, Plum Island Animal Disease Center, P,O, Box 848, Greenport, NY 11944, USA. michael.t.mcintosh@aphis.usda.gov

ABSTRACT
Rabbit Hemorrhagic Disease (RHD) is a severe acute viral disease specifically affecting the European rabbit Oryctolagus cuniculus. As the European rabbit is the predominant species of domestic rabbit throughout the world, RHD contributes towards significant losses to rabbit farming industries and endangers wild populations of rabbits in Europe and other predatory animals in Europe that depend upon rabbits as a food source. Rabbit Hemorrhagic Disease virus (RHDV) - a Lagovirus belonging to the family Caliciviridae is the etiological agent of RHD. Typically, RHD presents with sudden death in 70% to 95% of infected animals. There have been four separate incursions of RHDV in the USA, the most recent of which occurred in the state of Indiana in June of 2005. Animal inoculation studies confirmed the pathogenicity of the Indiana 2005 isolate, which caused acute death and pathological changes characterized by acute diffuse severe liver necrosis and pulmonary hemorrhages. Complete viral genome sequences of all USA outbreak isolates were determined and comparative genomics revealed that each outbreak was the result of a separate introduction of virus rather than from a single virus lineage. All of the USA isolates clustered with RHDV genomes from China, and phylogenetic analysis of the major capsid protein (VP60) revealed that they were related to a pandemic antigenic variant strain known as RHDVa. Rapid spread of the RHDVa pandemic suggests a selective advantage for this new subtype. Given its rapid spread, pathogenic nature, and potential to further evolve, possibly broadening its host range to include other genera native to the Americas, RHDVa should be regarded as a threat.

Show MeSH
Related in: MedlinePlus