Genetic Reassortment of Rift Valley Fever Virus in Nature

Abstract

Rift Valley fever virus (RVFV), a phlebovirus of theBunyaviridae family, is an arthropod-borne virus which emerges periodically throughout Africa, emphasizing that it poses a major threat for animal and human populations. To assess the genetic variability of RVFV, several isolates from diverse localities of Africa were investigated by means of reverse transcription-PCR followed by direct sequencing of a region of the small (S), medium (M), and large (L) genomic segments. Phylogenetic analysis showed the existence of three major lineages corresponding to geographic variants from West Africa, Egypt, and Central-East Africa. However, incongruences detected between the L, M, and S phylogenies suggested that genetic exchange via reassortment occurred between strains from different lineages. This hypothesis, depicted by parallel phylogenies, was further confirmed by statistical tests. Our findings, which strongly suggest exchanges between strains from areas of endemicity in West and East Africa, strengthen the potential existence of a sylvatic cycle in the tropical rain forest. This also emphasizes the risk of generating uncontrolled chimeric viruses by using live attenuated vaccines in areas of endemicity.

Genetic characterization of hantaviruses isolated from Guizhou, China: Evidence for spillover and reassortment in nature

“…The genetic reassortment appeared to be nonrandom [Urquidi and Bishop, 1992;Rodriguez et al, 1998;Rizvanov et al, 2004]. Preferential reassortants with homologous L-M or L-S segments has been described for many viruses of the Bunyaviridae [Beaty et al, 1985;Urquidi and Bishop, 1992;Sall et al, 1999]. However, the frequency of the homologous L-M and L-S segments in virus progeny differs significantly for the closely related hantaviruses associated reassortment and the genetically distant hantaviruses associated reassortment.…”

“…Reassortment plays an important role in evolution, pathogenesis, and epidemiology of many segmented viruses [Li et al, 1995;Rizvanov et al, 2004]. A number of studies have shown that genetic reassortment can occur between the arthropod-borne members of the Bunaviridae naturally or experimentally [Beaty et al, 1985;Urquidi and Bishop, 1992;Sall et al, 1999;Nunes et al, 2005;Deyde et al, 2006]. Reassortment also occurred between different hantaviruses when they infected the same rodent host or the same cell.…”

Vaccination with virus-like particles protects mice from lethal infection of Rift Valley Fever Virus

“…Its use is also restricted in non-endemic areas and during outbreaks, due to the risk for revision to virulence and risk of reassortment. Reassortment events have been documented experimentally [222] as well as among natural RVFV isolates [223].…”

Bunyaviruses and climate change

“…For example, Ngari virus, which causes haemorrhagic disease in man, is a reassortment between Bunyamwera and Batai viruses, both of which cause nonhaemorrhagic febrile illness [43]. Reassortants of different strains of Rift Valley fever virus have been isolated during recent epidemics in East Africa [44]. Therefore, the capability of exchanging genome segments can have consequences for the virus influenced by climate change; new viruses could be created by reassortment between viruses, previously in separate geographical niches, brought together through changes in their vector distribution.…”