ILHEUS VIRUS (FLAVIVIVIDAE, FLAVIVIRUS) IS CLOSELY-RELATED TO JAPANESE ENCEPHALITIS-VIRUS COMPLEX

The Ilheus (ILH) virus has long been known to belong to group B of the arboviruses. Previous attempts to relate it to existing serogroups wi thin the Flavivirus genus using conventional serological techniques su ch as hemagglutination inhibition, neutralization and complement fixat ion tests have been inconclusive. We have first used denaturing gel el ectrophoresis to estimate the molecular weight of immunoprecipitated r adiolabeled viral proteins and the crossreactivity among ILH proteins and hyperimmune sera to several flaviviruses only from the mosquito-bo rne encephalitis virus serogroups. The estimated molecular weight for the three proteins was in the same order of magnitude, as previously e stablished, for mosquito-borne flaviviruses. Cross-immunoprecipitation tests showed that NS3 protein is the most cross-reactive. Partial nuc leotide sequence analyses of the NS3 gene, corresponding to an area li nking the helicase and the RNA triphosphatase domains, revealed that I LH virus is very closely related to the Japanese encephalitis virus co mplex confirming earlier serological data.