Evaluation of Rift Valley Fever Diagnostic Tests for Use in a Diva Control Strategy
Arthropod-Borne Animal Diseases Research
2013 Annual Report
1a.Objectives (from AD-416):
The goal of this project is the laboratory evaluation of rapid, reliable, and sensitive diagnostic assays for Rift Valley fever that are suitable for use in Differentiate Infected from Vaccinated Animal control strategies.
1b.Approach (from AD-416):
The National Veterinary Stockpile Recommendations list Rift Valley Fever (RVF) as the third most important agricultural threat to U.S. livestock. There are new diagnostic assays available that have not been evaluated as to their effective timeframe for use post-infection and sensitivity. The main objectives of this proposal are: 1. To determine the optimal time points post infection and diagnostic samples (blood, saliva etc.) for detection of RVFV with these assays, and 2.) To evaluate the compatibility of these assays with a DIVA control strategy which will be determined by comparing the diagnostic results of vaccinated sheep with wild-type infected sheep. These studies may include evaluating the ability of diagnostic assays to detect infectious virus, viral antigen(s) and virus-specific nucleic acids in insects.
RVFV MP-12 vaccine infection of lambs and calves has been conducted at BSL-3+ condition to practice and demonstrate the safety protocol necessary for conduction of animal research with virulent RVFV. Biological samples collected during these time course infections studies were evaluated to determine the effective time frame for various newly developed diagnostic assays. This included microscopic and macroscopic pathology of animals exposed to the vaccine strain of RVFV. Stocks of virulent challenge virus have been produced in both mammalian and mosquito cell-lines. Final authorization for large animal research is still pending.