Host range specificity of flaviviruses: correlation with in vitro replication.

Vector-borne flaviviruses have been traditionally grouped into either mosquito-borne or tick-borne group. However, this vector range specificity has sometimes been questioned because of the puzzling records of occasional isolation of mosquito-borne viruses from ticks and of tick-borne viruses from mosquitoes. In this study, host range of the flaviviruses representing not only the two vector-borne groups but also insect flaviviruses and vertebrate viruses that are not arboviruses was comprehensively reexamined by a serial passage experiment in vitro by using cell cultures derived from mosquitoes, ticks, and vertebrates. The results showed that the host range specificity in the four groups of viruses, based on replication for five consecutive passages as a criterion to evaluate the ability of viruses to replicate in three different cell cultures, agreed with the conventional grouping as well as phylogenetic clustering. Thus, this assay provides useful, supplementary information regarding host range for those flaviviruses when their natural host range is unknown, ambiguous, or questionable.