Kinetics of Rift Valley Fever Virus in experimentally infected mice using quantitative real-time RT-PCR.

Rift Valley Fever (RVF) is an important viral zoonosis in Africa affecting animals and humans. Since no protective vaccines or effective treatments are available for human use, accurate and reliable diagnostic methods are essential for surveillance of the disease in order to implement adequate public health actions. To study the kinetics of the RVF Virus (RVFV) infection, a SYBR Green-based quantitative real-time RT-PCR assay was developed. By using primers targeting the S-segment of RVFV, the detection limit of this assay was estimated to 30 RNA templates. Blood and organs of experimentally infected mice were sampled at different time points and RVFV RNA was quantified. High amounts of RVFV RNA were found in blood, brain, and liver samples shortly after infection with a 1-4 days post infection window for viral RNA detection. Mice developed symptoms after the appearance of serum antibodies, indicating that the host response plays an important role in the outcome of the disease. The RVFV quantitative RT-PCR proved to be a valuable diagnostic tool during the first days of infection, before detectable antibody levels and visual symptoms of RVF were observed.