Table 1.

Phenotypic reversion of SP variant of WNV recovered from infected Culex pipiens^a

Incubation temperature	No. virus-positive mosquitoesb	No. mosquitoes with virus that displayed a mixed-plaque phenotypec (% of virus-positive mosquitoes)
15°C	62	9 (14.5%)
27°C	105	14 (13.3%)
32°C	92	18 (19.5%)

^aMosquitoes were inoculated intrathoracically with Vero cell amplified SP virus at 21 pfu per mosquito, and maintained at the indicated temperatures

^bNumber of SP-infected mosquitoes with detectable virus, evaluated by plaque assay on Vero cells (includes mosquitoes harvested at various times post inoculation)

^cSP virus recovered from mosquitoes had a mixed-plaque phenotype when 10 to 70% of its plaques were greater than 1.0 mm in diameter, measured at 72 hpi on Vero cells