Laboratory tests for evaluating the level of attenuation of bluetongue virus

Istituto Zooprofilattico Sperimentale dell'Abruzzo e del Molise G. Caporale, Via Campo Boario, 64100 Teramo, Italy.
Journal of Virological Methods (Impact Factor: 1.78). 10/2008; 153(2):263-5. DOI: 10.1016/j.jviromet.2008.07.007
Source: PubMed


One of the most important steps when preparing a live attenuated vaccine is the assessment of the level of attenuation in target animals. It is costly and time consuming as it requires, on each occasion, a large number of susceptible animals and contained accommodation. This study assessed the consistency of the bovine foetal aorta endothelial (BFA) cell line and newborn mice for evaluating the attenuation level of BTV4, BTV9 and BTV16 Italian field isolates. Following serial passages in BHK(21c13) or Vero cell cultures, BTV attenuated clones demonstrated a reduced replication capability in the BFA cells compared to the homologous virulent strains. Similarly, following intracerebral inoculation, the attenuated clones were completely innocuous to newborn mice contrary to the homologous virulent strains which killed all animals within 10 days. Vaccines produced with the BTV9 or BTV4 attenuated clones were safe, immunogenic and capable of preventing clinical symptoms and viraemia in sheep following challenge with homologous virulent virus. The two assays may be valuable indicators of the gradual changes occurring in the BTV population leading to virus attenuation, they can predict the safety of a BTV attenuated vaccine and, in turn, reduce the number of sheep and cattle required to assess the level of attenuation attained.

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Available from: Umberto Molini, May 14, 2014
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    • "The possibility of evaluating in vivo properties in ruminants was considered, but would have led to a lack of statistical power due to low animal numbers. Another animal model was therefore required and intracranial inoculation of suckling mice therefore conducted (Caporale et al., 2011; Franchi et al., 2008).In an effort to find a better statistical method than a standard parallel design, a " Response Surface Pathway Design " was chosen. The model was developed to reduce the number of animals included in LD 50 studies, without loss of information. "
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    ABSTRACT: Experimental infection studies with bluetongue virus (BTV) in the mammalian host have a history that stretches back to the late 18(th) century. Studies in a wide range of ruminant and camelid species as well as mice have been instrumental in understanding BTV transmission, bluetongue (BT) pathogenicity/pathogenesis, viral virulence, the induced immune response, as well as reproductive failures associated with BTV infection. These studies have in many cases been complemented by in vitro studies with BTV in different cell types in tissue culture. Together these studies have formed the basis for the understanding of BTV-host interaction and have contributed to the design of successful control strategies, including the development of effective vaccines. This review describes some of the fundamental and contemporary infection studies that have been conducted with BTV in the mammalian host and provides an overview of the principal animal welfare issues that should be considered when designing experimental infection studies with BTV in in vivo infection models. Examples are provided from the authors' own laboratory where the three Rs (replacement, reduction and refinement) have been implemented in the design of experimental infection studies with BTV in mice and goats. The use of the ARRIVE guidelines for the reporting of data from animal infection studies is emphasised.
    Full-text · Article · Jan 2014 · Virus Research
    • "Bluetongue (BT), an OIE-listed, vector borne disease, is caused by dsRNA virus belonging to genus Orbivirus and family Reoviridae. BT is characterized by fever, facial (Bonneau et al., 2002; MacLachlan et al., 2008; Franchi et al., 2008). Given differential cell tropism of BTV in natural host, in addition to virus strain, species and breed differences, the route of administration could dramatically affect outcome of the disease (Hemati et al., 2009; MacLachlan et al., 2009; Schwartz-Cornil et al., 2008). "
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    ABSTRACT: The pathogenesis of bluetongue (BT) could vary with route of inoculation. Using laboratory-passaged moderately virulent bluetongue virus serotype 23 (BTV-23), one of the most prevalent Indian serotype, we investigated the pathogenesis of BT in intradermally (ID) and intravenously (IV) inoculated native sheep. The ID inoculation resulted in relatively increased clinical signs and lesions in many organs as compared to IV inoculation. BTV-23 detection by real-time RT-PCR and isolation studies revealed that ID inoculation can be more efficient than IV ones in disseminating and spreading virus to systemic organs, including pre-scapular draining lymph node, spleen, lungs and pulmonary artery. Furthermore, the ID inoculation resulted in early onset and increased humoral response with significant increase (P<0.01) in antibody titre at various intervals. Taken together, these data suggest that ID inoculation can be more potent in reproducing many aspects of natural infection, including clinical disease, viral and immune responses, and may be useful route in setting up experimental infections for challenge or pathogenesis studies using laboratory passaged BTVs.
    No preview · Article · Jun 2011 · Veterinary Immunology and Immunopathology
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