Study on West Nile virus persistence in monkeys

Abstract

Experiments in M. rhesus showed persistence to be a typical property of West Nile virus. This property was exhibited by strains belonging to different antigenic types, and varying in virulence and in the isolation area (U.S.S.R., Uganda, India). The duration of persistence was at least 5 1/2 months in asymptomatic infection and in convalescence after encephalitis or a febrile disease. The virus isolated within the first 2 weeks after inoculation of monkeys has the standard properties. The virus persisting for 2 months retains its cytopathic and antigenic activity, however, is non-pathogenic for white mice. After 5 1/2 months of persistence the virus has no neurovirulence or cytopathic properties but is capable of infecting the susceptible cells and induces in them the synthesis of virus-specific antigen detectable by immunofluorescence. The persisting virus has been isolated by cocultivation of trypsinized monkey organ cells and cells of the indicator culture. This virus was located mostly in the cerebellum, cerebral subcortical ganglia, lymph nodes, and kidneys. The monkeys experiencing encephalitis, febrile, or asymptomatic infection showed in morphological examinations a subacute inflammatory-degenerative process in the central nervous system. The results suggest that West Nile virus, one of the most widely spread arboviruses in Africa, Asia, and Europe, may be implicated in the etiology of subacute diseases of the CNS.

Detection of Persistent West Nile Virus RNA in Experimentally and Naturally Infected Avian Hosts

“…9 Viral antigen was detectable for up to 5.5 months in rhesus monkeys (Macca mulatta) experimentally infected with WNV. 10 Similar to the finding in hamsters, WNV RNA, but not infectious virus, was reported in 20% (n = 25) of urine samples, collected from human patients convalescing from WNV infection, 1.6-6.7 years pi.…”

Pathobiology of the Flaviviruses

“…No information is available regarding temperature markers or DI properties of these strains. Similar features have been described in intracerebrally and peripherally inoculated monkeys that developed asymptomatic or postencephalitic persistent infections with a variety of WN virus strains (Pogodina et al, 1983). Pathological changes in the CNS of persistently infected animals took the form of a subacute, progressive process with lesions at various stages of development indicating fresh, ongoing neuronal destruction as well as foci of reparation and scarring.…”

West Nile virus infection of horses

“…This phenomenon has been observed in vitro in neuroblastoma cell lines infected with JE and in vivo in many flavivirus related diseases [64] including WNV infections in monkeys where virus was recovered up to five months post-infection [77], and in hamsters with viruses being isolated up to day 53 post-challenge [103].…”

“…Persistent infections of flaviviruses, including WNV, have been documented in vitro and in vivo [26,50,77,95,103]. Persistent WNV infections have been associated with the generation of defective interfering particles, temperature sensitive mutants and non-plaquing mutants [15][16][17]19].…”