title: Randomized controlled field trial to assess the immunogenicity and safety of rift valley fever clone 13 vaccine in livestock.
abstract: BACKGROUND
  Although livestock vaccination is effective in preventing Rift Valley fever (RVF) epidemics, there are concerns about safety and effectiveness of the only commercially available RVF Smithburn vaccine. We conducted a randomized controlled field trial to evaluate the immunogenicity and safety of the new RVF Clone 13 vaccine, recently registered in South Africa.
  
  
  METHODS
  In a blinded randomized controlled field trial, 404 animals (85 cattle, 168 sheep, and 151 goats) in three farms in Kenya were divided into three groups. Group A included males and non-pregnant females that were randomized and assigned to two groups; one vaccinated with RVF Clone 13 and the other given placebo. Groups B included animals in 1st half of pregnancy, and group C animals in 2nd half of pregnancy, which were also randomized and either vaccinated and given placebo. Animals were monitored for one year and virus antibodies titers assessed on days 14, 28, 56, 183 and 365.
  
  
  RESULTS
  In vaccinated goats (N = 72), 72% developed anti-RVF virus IgM antibodies and 97% neutralizing IgG antibodies. In vaccinated sheep (N = 77), 84% developed IgM and 91% neutralizing IgG antibodies. Vaccinated cattle (N = 42) did not develop IgM antibodies but 67% developed neutralizing IgG antibodies. At day 14 post-vaccination, the odds of being seropositive for IgG in the vaccine group was 3.6 (95% CI, 1.5 - 9.2) in cattle, 90.0 (95% CI, 25.1 - 579.2) in goats, and 40.0 (95% CI, 16.5 - 110.5) in sheep. Abortion was observed in one vaccinated goat but histopathologic analysis did not indicate RVF virus infection. There was no evidence of teratogenicity in vaccinated or placebo animals.
  
  
  CONCLUSIONS
  The results suggest RVF Clone 13 vaccine is safe to use and has high (>90%) immunogenicity in sheep and goats but moderate (> 65%) immunogenicity in cattle.
authors.affiliation: Division of Global Health Protection, United States Centers for Disease Control and Prevention-Kenya, Nairobi, Kenya; Paul G. Allen School for Global Animal Health, Washington State University, Pullman, Washington, United States of America.
authors.forename: M Kariuki
authors.initials: MK
authors.lastname: Njenga
authors.affiliation: Kenya Ministry of Agriculture Livestock and Fisheries, Nairobi, Kenya.
authors.forename: Leonard
authors.initials: L
authors.lastname: Njagi
authors.affiliation: Paul G. Allen School for Global Animal Health, Washington State University, Pullman, Washington, United States of America.
authors.forename: S Mwangi
authors.initials: SM
authors.lastname: Thumbi
authors.affiliation: Kenya Ministry of Agriculture Livestock and Fisheries, Nairobi, Kenya.
authors.forename: Samuel
authors.initials: S
authors.lastname: Kahariri
authors.affiliation: Kenya Ministry of Agriculture Livestock and Fisheries, Nairobi, Kenya.
authors.forename: Jane
authors.initials: J
authors.lastname: Githinji
authors.affiliation: Kenya Ministry of Agriculture Livestock and Fisheries, Nairobi, Kenya.
authors.forename: Eunice
authors.initials: E
authors.lastname: Omondi
authors.affiliation: Division of Global Health Protection, United States Centers for Disease Control and Prevention-Kenya, Nairobi, Kenya.
authors.forename: Amy
authors.initials: A
authors.lastname: Baden
authors.affiliation: Kenya Ministry of Agriculture Livestock and Fisheries, Nairobi, Kenya.
authors.forename: Mbabu
authors.initials: M
authors.lastname: Murithi
authors.affiliation: National Institute for Communicable Diseases, Pretoria, South Africa.
authors.forename: Janusz
authors.initials: J
authors.lastname: Paweska
authors.affiliation: Kenya Ministry of Agriculture Livestock and Fisheries, Nairobi, Kenya.
authors.forename: Peter M
authors.initials: PM
authors.lastname: Ithondeka
authors.affiliation: Kenya Ministry of Agriculture Livestock and Fisheries, Nairobi, Kenya.
authors.forename: Kisa J
authors.initials: KJ
authors.lastname: Ngeiywa
authors.affiliation: Global Alliance for Livestock Veterinary Medicines, Edinburg, Scotland, United Kingdom.
authors.forename: Baptiste
authors.initials: B
authors.lastname: Dungu
authors.affiliation: Global Alliance for Livestock Veterinary Medicines, Edinburg, Scotland, United Kingdom.
authors.forename: Meritxell
authors.initials: M
authors.lastname: Donadeu
authors.affiliation: Division of Global Health Protection, United States Centers for Disease Control and Prevention-Kenya, Nairobi, Kenya.
authors.forename: Peninah M
authors.initials: PM
authors.lastname: Munyua
mesh_terms: D000818:Animals; D057134:Antibodies, Neutralizing / Q000097:blood; D000914:Antibodies, Viral / Q000097:blood; D002417:Cattle; D005260:Female; D006041:Goats; D007630:Kenya; D058751:Livestock; D008297:Male; D012296:Rift Valley fever virus / Q000276:immunology*; D012756:Sheep; D013019:South Africa; D014765:Viral Vaccines / Q000009:adverse effects / Q000276:immunology*
chemical_list: D057134:Antibodies, Neutralizing; D000914:Antibodies, Viral; D014765:Viral Vaccines