Human host cell entry restriction of Lassa and other arenaviruses

Arenaviruses are the largest family of viral haemorrhagic fever causing viruses. They have worldwide distribution and are divided into Old World (OW) and New World (NW) viruses based on their phylogeny, geographical distribution and serological cross-reactivity. Endemic to West Africa and South America, these emerging RNA viruses jump the species barrier from their natural rodent hosts to humans, resulting in illnesses ranging from mild flu-like syndromes to severe and highly fatal haemorrhagic zoonoses. Recent increased frequency of outbreaks and associated high fatality rates of the most common arenavirus, Lassa, in Nigeria has emphasised that these viruses should no longer be treated as causes of sporadic epidemics. The immense impact of these outbreaks on human health is further exacerbated by the lack of vaccines and effective treatments and makes it imperative to understand the molecular basis of viral pathogenesis and immune evasion.

Virus entry is a key determinant of viral host range, cellular tropism and disease outcome, hence, targeting this step of the arenavirus lifecycle could have significant impact on the control of viral infection. Our data demonstrate for the first time a synergistic restriction activity against arenavirus entry by two cellular host factors known for their control of enveloped virus infections. This co-operative restriction activity appears to conserved and we have evidence that arenaviruses may have evolved strategies to escape inhibition, through entry receptor switching, thus alluding to an understanding of the dynamics of arenavirus infection and adaptations that the viruses have made to escape host restriction pressures.