Evaluation of lamb and calf responses to Rift Valley fever MP-12 vaccination

Authors: Wilson, William; BAWA, BHUPINDER - Kansas State University; Drolet, Barbara; Lehiy, Christopher; FABURAY, BONTO - Kansas State University; Jasperson, Dane; Reister-Hendricks, Lindsey; Gaudreault, Natasha; CARLSON, JOLENE - Kansas State University; MA, WENJUN - Kansas State University; MOROZOV, IGOR - Kansas State University; McVey, David; RICHT, JUERGEN - Kansas State University

Submitted to: Veterinary Microbiology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 4/8/2014
Publication Date: 4/18/2014
Publication URL: http://handle.nal.usda.gov/10113/62668
Citation: Wilson, W.C., Bawa, B., Drolet, B.S., Lehiy, C.J., Faburay, B., Jasperson, D.C., Reister, L.M., Gaudreault, N.N., Carlson, J., Ma, W., Morozov, I., Mcvey, D.S., Richt, J. 2014. Evaluation of lamb and calf responses to Rift Valley fever MP-12 vaccination. Veterinary Microbiology. 172(1-2):44-50. DOI: org/10.1016/j.vetmic.2014.04.007.

Interpretive Summary: An important viral disease of animals and humans in Africa and the Middle East is a mosquito-transmitted disease called Rift Valley fever. The disease is of concern to international agricultural and public health communities. The RVF MP-12 strain has been the most safety tested attenuated vaccine strain; thus it is being considered as a potential vaccine for the US national veterinary stockpile. Although a lot of research has been done with RVF MP-12, especially in small animal models, the developers of the vaccine have conducted a majority of the studies involving target livestock species. This study was designed to establish safety protocols for large animal research with virulent RVF viruses, establish a target host immune response baseline using RVF MP-12 strain and independently evaluate this strain as a potential US emergency response vaccine. No clinical or febrile response was observed in this study. There was no significant pathology in the lambs; however, some pathology was observed in the calves. Whether this pathology is due to the attenuated vaccine or another cause is not known at the time of abstract submission. This study has provided confirmation of our biosafety procedures and provides independent and baseline information on RVF attenuated vaccination in vaccine-age target species.

Technical Abstract: Rift Valley fever (RVF) is an important viral disease of animals and humans in Africa and the Middle East that is transmitted by mosquitoes. The disease is of concern to international agricultural and public health communities. The RVF MP-12 strain has been the most safety tested attenuated vaccine strain; thus it is being considered as a potential vaccine for the US national veterinary stockpile. This study was designed to establish safety protocols for large animal research with virulent RVF viruses, establish a target host immune response baseline using RVF MP-12 strain and independently evaluate this strain as a potential US emergency response vaccine. Ten, four month-old lambs and calves were vaccinated with RVF MP-12 strain; two additional animals per species provided negative control specimens. The animals were monitored for clinical and immune response, fever, and viremia. Two animals per species were sacrificed on 2, 3, 4, 10 and 28 days post infection and full necropsies were performed for histopathological examination. No clinical or febrile response was observed in this study. The onset and titer of the immune response will be discussed. There was no significant histopathology in the lambs; however, 5 out of 10 vaccinated calves had multifocal, random areas of hepatocellular degeneration and necrosis. RVF MP12 antigen was detected in these areas of necrosis by immunohistochemistry in one calf. This study provides independent and baseline information on the RVF MP-12 attenuated vaccination in vaccine-age target species and indicates the importance of performing safety testing on vaccine aged target animals.