Comparison of in vitro and in vivo systems for propagation of Rift Valley fever virus from clinical specimens.

Several cell cultures and animals were compared for their relative sensitivity as primary isolation systems for Rift Valley fever virus (RVFV) and to determine if virulence characteristics of the isolates were altered in these systems. Eleven human sera from known cases of Rift Valley fever (RVF) were obtained from the 1987 epidemic in Mauritania and served as the source of virus for these studies. Sera were inoculated directly into cell cultures (Vero, C6/36 and DBS-FRhL-2) and animals (ICR suckling mice, Lak:LVG(SYR) hamsters and WF rats) concurrently. The cell lines provided a quick method to propagate, quantitate and identify these specimens without prior adaption. The isolates were highly virulent for suckling mice and hamsters, but not for WF rats, even after cell culture passage, which indicated that the Mauritanian isolates more closely resembled those strains from sub-Saharan Africa than those from the 1977-78 Egyptian epidemic.