Rift Valley fever virus (RVFV) is a mosquito-borne zoonotic pathogen that causes periodic outbreaks of abortion in ruminant species and hemorrhagic disease in humans in sub-Saharan Africa. These outbreaks have a significant impact on veterinary and public health. Its introduction to the Arabian Peninsula in 2003 raised concerns of further spread of this transboundary pathogen to non-endemic areas. These concerns are supported by the presence of competent vectors in many non-endemic countries. There is no licensed RVF
vaccine available for humans and only a conditionally licensed veterinary
vaccine available in the United States. Currently employed modified live attenuated virus
vaccines in endemic countries lack the ability for differentiating infected from vaccinated animals (DIVA). Previously, the efficacy of a recombinant
subunit vaccine based on the RVFV Gn and Gc
glycoproteins, derived from the 1977 human RVFV isolate ZH548, was demonstrated in sheep. In the current study, cattle were vaccinated subcutaneously with the Gn only, or Gn and Gc combined, with either one or two doses of the
vaccine and then subjected to heterologous virus challenge with the virulent Kenya-128B-15 RVFV strain, isolated from Aedes mosquitoes in 2006. The elicited immune responses by some
vaccine formulations (one or two vaccinations) conferred complete protection from RVF within 35 days after the first vaccination.
Vaccines given 35 days prior to RVFV challenge prevented
viremia,
fever and RVFV-associated histopathological lesions. This study indicates that a recombinant RVFV
glycoprotein-based
subunit vaccine platform is able to prevent and control RVFV
infections in target animals.