title: A single vaccination with an improved nonspreading Rift Valley fever virus vaccine provides sterile immunity in lambs.
abstract: Rift Valley fever virus (RVFV) is an important pathogen that affects ruminants and humans. Recently we developed a vaccine based on nonspreading RVFV (NSR) and showed that a single vaccination with this vaccine protects lambs from viremia and clinical signs. However, low levels of viral RNA were detected in the blood of vaccinated lambs shortly after challenge infection. These low levels of virus, when present in a pregnant ewe, could potentially infect the highly susceptible fetus. We therefore aimed to further improve the efficacy of the NSR vaccine. Here we report the expression of Gn, the major immunogenic protein of the virus, from the NSR genome. The resulting NSR-Gn vaccine was shown to elicit superior CD8 and CD4-restricted memory responses and improved virus neutralization titers in mice. A dose titration study in lambs revealed that the highest vaccination dose of 10(6.3) TCID50/ml protected all lambs from clinical signs and viremia. The lambs developed neutralizing antibodies within three weeks after vaccination and no anamnestic responses were observed following challenge. The combined results suggest that sterile immunity was achieved by a single vaccination with the NSR-Gn vaccine.
authors.affiliation: Department of Virology, Central Veterinary Institute, part of Wageningen University and Research Centre, Lelystad, The Netherlands ; Department of Infectious Diseases and Immunology, Virology Division, Faculty of Veterinary Medicine, Utrecht University, Utrecht, The Netherlands.
authors.forename: Nadia
authors.initials: N
authors.lastname: Oreshkova
authors.forename: Lucien
authors.initials: L
authors.lastname: van Keulen
authors.forename: Jet
authors.initials: J
authors.lastname: Kant
authors.forename: Rob J M
authors.initials: RJ
authors.lastname: Moormann
authors.forename: Jeroen
authors.initials: J
authors.lastname: Kortekaas
mesh_terms: D000818:Animals; D015496:CD4-Positive T-Lymphocytes / Q000276:immunology*; D002460:Cell Line; D006224:Cricetinae; D005260:Female; D016679:Genome, Viral; D006801:Humans; D007111:Immunity, Cellular; D007156:Immunologic Memory; D051379:Mice; D008807:Mice, Inbred BALB C; D011247:Pregnancy; D012295:Rift Valley Fever / Q000276:immunology / Q000517:prevention & control; D012296:Rift Valley fever virus / Q000276:immunology*; D012756:Sheep; D014611:Vaccination; D014765:Viral Vaccines / Q000276:immunology / Q000494:pharmacology*
chemical_list: D014765:Viral Vaccines