A SYBR green I-based quantitative RT-PCR assay for bovine ephemeral fever virus and its utility for evaluating viral kinetics in cattle.

We developed a SYBR green I-based reverse-transcription quantitative PCR (RT-qPCR) assay for bovine ephemeral fever virus (BEFV). Analytical sensitivity of the assay was ~ 100 times higher than conventional RT-PCR. The precision of the RT-qPCR established for RNA standards was high, with intra-assay and inter-assay coefficients of variation of 0.23-0.89% and 0.23-1.02%, respectively. The test was highly specific for BEFV strains, with no cross-reactivity with other viruses of veterinary significance. The assay detected BEFV RNA as early as 1 d post-infection (dpi) and up to 7-8 dpi in the blood samples of experimentally infected cattle. The most stable reference gene, peptidylprolyl isomerase A (PPIA), was selected for the quantification of BEFV. Viral RNA loads reached peak level at 3-5 dpi and then decreased rapidly through 7-8 dpi. Our assay provides a reliable approach for the detection of BEFV in the early infection stage and for use in the profiling of BEFV kinetics in vivo.