[Isolation of Tahyna virus from mosquitoes in 2 different European natural foci].

Collecting during two periods, from September 4, 1979, to September 12, 1980, and from August 17 to September 10, 1981, a total of 45,705 mosquitoes was caught for virus isolation studies in 6 different regions in Germany and the Netherlands (Lower Rhine area, Upper Rhine area near Germersheim, Upper Main area near Baunach, Amper Moos), in Austria (eastern shore of Lake Neusiedl), and in Italy (Isonzo river delta). 25 mosquito species were identified belonging to the genera Aedes, Culex, Culiseta, Mansonia, and Uranotaenia. The relative mosquito species composition was determined for the different collecting sites. By intracerebral inoculation of 2 to 4 days old suckling mice with extracts of each mosquito pool 6 virus strains were isolated which were identified as Tahyna (TAH) virus strains using the indirect immunofluorescence technique in cell culture and the baby mouse neutralization test. The origin of these strains were the following regions: one TAH virus strain was isolated from Aedes caspius mosquitoes (1 of 158 pools) collected from 17. 8 to 30. 8. 81 at the eastern shore of Lake Neusiedl. 5 additional isolates were obtained from 6,066 mosquitoes (62 pools) collected on 9. and 10. 9. 81 in the Upper Rhine area near Germersheim (Isle Grün). Two of these virus strains were isolated from Aedes vexans and three from unidentified mosquitoes. This is the first TAH virus isolation from mosquitoes in the Upper Rhine area, which had been regarded by Ackermann and coworkers (1970) and Spieckermann and Ackermann (1974) as a potential natural TAH virus focus on the basis of serological studies in humans and sentinel rabbits during 1969. The isolation of TAH virus in the Lake Neusiedl area essentially confirms the results obtained by Aspöck and Kunz (1967) for this region. The possible influence of some ecological factors on the geographical distribution of TAH virus is discussed.