The vector competence of colonized Aedes (Stegomyia) katherinensis for dengue-2 virus

Colonized Aedes (Stegomyia) katherinensis mosquitoes from Australia were infected with the PR-159 strain of dengue-2 virus using a membrane feeding technique and by intrathoracic inoculation. Virus replication to low levels was detected when mosquitoes infected by both routes were assayed using the virus-sensitive Ae. pseudoscutellaris (LSTM-AP-61) mosquito cell line in a microculture system. Analysis by indirect immunofluorescence revealed the expected 100% infection rates in inoculated mosquitoes compared with only 45% in orally infected mosquitoes. Few of the orally infected mosquitoes showed any viral antigen associated with the head and no virus transmission was detected. Preliminary studies also demonstrated that Ae. (S.) katherinesis was refractory to oral infection with Japanese encephalitis virus but was readily infected by intrathoracic inoculation. On the basis of this data, it is concluded that there is a high threshold of infection in this mosquito and that it is unlikely that Ae. (S.) katherinensis could be important as a vector of dengue-2 virus in Australia.