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2012 Annual Report
1a.Objectives (from AD-416):
The objective of this project is to evaluate RVF Clone 13 vaccine viability as a possible U.S. veterinary vaccine and to assess the safety of the vaccine, and thus facilitate USDA, Center for Veterinary Biologics (CVB) to consider licensure in the U.S.
1b.Approach (from AD-416):
ABADRL will perform and coordinated exploratory research centered on: i) insect vector susceptibility, competency and transmissibility of Clone 13 vaccine strain, ii) reversion to virulence potential of Clone 13 vaccine strain, iii) ability of Clone 13 vaccine strain to prevent virulent RVF virus replication in young animals, and iv) onset of immunity studies.
3.Progress Report:
The Department of Homeland Security (DHS) is supporting an extension of ABADRU’s RVF research efforts to conduct evaluation of the efficacy and safety of potential commercial veterinary vaccines and complementary diagnostics that are currently unavailable in the U.S. This has resulted in additional studies through cooperative agreements with the U.S. Army Medical Research Institute for Infectious Diseases (USAMRIID), Colorado State University and Canadian Food Inspection Agency. A number of U.S. species were shown to be competent for RVFV including Culex tarsalis. In addition, two populations of Aedes vexans were examined and it was determined that one population was competent and the other not. In order to determine the most favorable conditions for reassortment (exchange of genome segments) to occur, eleven USAMRIID laboratory strains of RVFV were sequenced. The purpose was to find two genetically distinct strains, which genetic screening assays for each genome segment could be developed. These assays would allow the assessment of genetic reasortment rates providing insights into epidemiological impact of this phenomenon. Sheep MP-12 vaccine trials have been conducted that provided no evidence that mosquitoes could be efficiently infected by MP-12 vaccinates. CFIA performed young sheep RVFV challenge studies and a vaccine challenge study that demonstrated this model could be used to evaluate vaccine candidates. CSU conducted the small animal and immunological characterization studies and the data is currently being compiled. The multiplex real-time PCR has been further modified and has undergone additional laboratory and field validation. ELISAs have been developed and laboratory validated but the initial field evaluation failed due to delays associated with the shipment of the biological reagents. Cell-culture susceptibility studies using RVFV MP-12 vaccine strain as a model have suggested that RVFV is capable of replicating in not only North American livestock, but also North American wildlife including native deer species.
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