Conrad E. Yunker

Growth of Colorado tick fever (CTF) virus in primary tissue cultures of its vector, Dermacentor andersoni Stiles (Acarina: Ixodidae), with notes on tick tissue culture.

Abstract Multiplication of two strains of CTF virus in primary tissue cultures of metamorphosing nymphal tick viscera was shown. A post inoculation latent period of 6–10 days was followed by a 4 1 2 logarithmic increase of extracellular virus at 4–5 weeks. Virus was recovered in diminishing quantities for as long as 159 days in medium and 166 days in triturated tissues. Certain characteristics of the Florio-2 strain remained unchanged after 98 and 124 days in vitro. Titers in whole nymphs fed on viremic hamsters remained relatively constant from drop-off to molting, but titers in cultures prepared from their tissues increased by approximately 5 logs 2 weeks after explantation. No differences were noted in appearance of virus-infected and uninfected cultures. Expiants of both produced cellular outgrowths within hours of explantation, initially probably from hemocytic migration. Within 4 days, mitotic activity was seen, which continued for at least 2 months. Expiants were viable for as long as 152 days, but peak activity occurred 4–6 weeks after explantation. Nymphs fed on hamsters produced larger and longer-lived outgrowths in vitro than those fed on rabbits; calf serum was superior to hamster or rabbit serum as a component of culture medium.

Isolation of a Soldado-like virus (Hughes group) fromOrnithodorus maritimus ticks in Ireland

Three isolations of a virus of the Hughes group were obtained from seabird ectoparasites,Ornithodoros (Alectorobius) maritimus, on Great Saltee Island, Ireland. The agent is closely related to Soldado virus, originally obtained from related ticks near Trinidad, West Indies, and represents the second recorded tickborne arbovirus in Ireland.