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Development of a sheep challenge model for Rift Valley fever

Bonto Faburay, Natasha N. Gaudreault, Qinfang Liu, A. Sally Davis, Vinay Shivanna, Sun Young Sunwoo, Yuekun Lang, Igor Morozov, Mark Ruder, Barbara Drolet, D. Scott McVey, Wenjun Ma, William Wilson, Juergen A. Richt
Virology 2016 v.489 no. pp. 128-140
Rift Valley fever, abortion (animals), animal models, epizootic diseases, liver, mortality, nucleotide sequences, pathogenesis, phenotype, sequence analysis, sheep, sheep diseases, temperature, vaccines, viremia, virulence, viruses, zoonoses, United States
Rift Valley fever (RVF) is a zoonotic disease that causes severe epizootic disease in ruminants, characterized by mass abortion and high mortality rates in younger animals. The development of a reliable challenge model is an important prerequisite for evaluation of existing and novel vaccines. A study aimed at understanding the pathogenesis of RVF virus infection in US sheep using two genetically different wild type strains of the virus (SA01-1322 and Kenya-128B-15) was performed. A group of sheep was inoculated with both strains and all infected sheep manifested early-onset viremia accompanied by a transient increase in temperatures. The Kenya-128B-15 strain manifested higher virulence compared to SA01-1322 by inducing more severe liver damage, and longer and higher viremia. Genome sequence analysis revealed sequence variations between the two isolates, which potentially could account for the observed phenotypic differences. We conclude that Kenya-128B-15 sheep infection represents a good and virulent challenge model for RVF.