Filoviruses

The viruses within the family Filoviridae are responsible for one of the most lethal viral hemorrhagic fever diseases in humans. The filamentous, negative-stranded RNA virus family is comprised of two genera: Marburgvirus and Ebolavirus. The latter is composed of four distinct species with varying degrees of lethality in man: Zaire ebolavirus (∼90% lethal), Sudan ebolavirus (∼50 % lethal), Reston ebolavirus (unknown lethality), and Ivory Coast ebolavirus (unknown lethality). In contrast, the genus Marburgvirus is composed of a single species, Lake Victoria marburgvirus, with individual isolates from different outbreaks having differing degrees of morbidity and mortality (20–90%). Early diagnosis of persons infected with filoviruses is complicated as patients often present with nonspecific clinical symptoms and the incubation period may vary between 2–21 days after exposure. Infections with these agents have gained recent notoriety for a number of factors including their dramatic clinical presentation, extreme lethality, the lack of available vaccines and therapeutics, the unresolved source of origin, and their potential for use as bioweapons. This article reviews the emergence of these viruses, the virion structure and composition, the genome organization and expression, the pathogenesis and host response to infection, and provides a summary on the current state of therapeutic interventions and vaccines.