Rift valley fever: recent insights into pathogenesis and prevention

Abstract

Rift Valley fever virus (RVFV) is a zoonotic pathogen that primarily affects ruminants but can also be lethal in humans. A negative-stranded RNA virus of the family Bunyaviridae, this pathogen is transmitted mainly via mosquito vectors. RVFV has shown the ability to inflict significant damage to livestock and is also a threat to public health. While outbreaks have traditionally occurred in sub-Saharan Africa, recent outbreaks in the Middle East have raised awareness of the potential of this virus to spread to Europe, Asia, and the Americas. Although the virus was initially characterized almost 80 years ago, the only vaccine approved for widespread veterinary use is an attenuated strain that has been associated with significant pathogenic side effects. However, increased understanding of the molecular biology of the virus over the last few years has led to recent advances in vaccine design and has enabled the development of more-potent prophylactic measures to combat infection. In this review, we discuss several aspects of RVFV, with particular emphasis on the molecular components of the virus and their respective roles in pathogenesis and an overview of current vaccine candidates. Progress in understanding the epidemiology of Rift Valley fever has also enabled prediction of potential outbreaks well in advance, thus providing another tool to combat the physical and economic impact of this disease.

Fig. 1.

Countries with confirmed cases of Rift Valley fever from July 2009 to November 2010 (indicated in red). Data were obtained from ProMed-mail (International Society For Infectious Diseases [http://www.promedmail.org]).

Fig. 2.

Structural and genomic organization of RVFV. (A) A single-particle cryo-electron microscopy reconstruction of RVFV MP-12 is shown. The black arrowheads point to connecting densities protruding through the lipid envelope, most likely representing glycoprotein cytoplasmic tails. (B) Genomic organization of RVFV. Asterisks over the M segment indicate possible hydrophobic domains of Gn and Gc. Reprinted from reference with permission of the publisher.