Comparison of the neuropathology induced by two West Nile virus strains

PLoS One. 2013 Dec 18;8(12):e84473. doi: 10.1371/journal.pone.0084473. eCollection 2013.

Abstract

Some strains of West Nile virus (WNV) are neuroinvasive and may induce fatal encephalitis/meningitis in a variety of animal species including humans. Whether, however, there is a strain-specific signature in the brain is as yet unknown. Here we investigated the neuropathogenesis induced by two phylogenetically distant WNV strains of lineage 1, WNV(IS98) and WNV(KUN35 911). While four-week old C57Bl/6J mice were susceptible to both strains and succumbed rapidly after intraperitoneal inoculation, differences were observed in virulence and clinical disease. WNV(KUN35 911), the less virulent strain as judged by determination of LD50, induced typical signs of encephalitis. Such signs were not observed in WNV(IS98)-infected mice, although they died more rapidly. Histological examination of brain sections also revealed differences, as the level of apoptosis and inflammation was higher in WNV(KUN35 911)- than WNV(IS98)-infected mice. Moreover, staining for cleaved caspase 3 showed that the two WNV strains induced apoptotic death through different molecular mechanisms in one particular brain area. Finally, the two strains showed similar tropism in cortex, striatum, brainstem, and cerebellum but a different one in hippocampus. In summary, our data show that, upon peripheral administration, WNV(IS98) and WNV(KUN35 911) strains induce partially distinct lesions and tissue tropism in the brain. They suggest that the virulence of a WNV strain is not necessarily correlated with the severity of apoptotic and inflammatory lesions in the brain.

Publication types

  • Comparative Study
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Apoptosis
  • Brain / pathology*
  • Brain / virology*
  • Inflammation / virology
  • Mice
  • Mice, Inbred C57BL
  • Species Specificity
  • West Nile virus / pathogenicity*
  • West Nile virus / physiology

Grants and funding

This work was financially supported by the European Commission (EUROWESTNILE - HEALTH-F3-2011-261391). ED received financial support from ANSES (French Agency for food, environmental and occupational Health § Safety) and INRA (French National Institute for Agricultural Research). The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.