WEST NILE VIRUS (FLAVIVIRIDAE, FLAVIVIRUS) IN EXPERIMENTALLY INFECTEDARGAS TICKS (ACARI, ARGASIDAE)

To better define the possible role of argasid ticks in the epidemiolog y of West Nile virus, adult Argas arboreus, A. persicus, and A. herman ni were fed through a membrane on fetal bovine serum containing 10(5.5 ) 50% tissue culture infective doses (TCID50)/ml of West Nile virus. T he virus was detected for three and four days after feeding in A. pers icus and A. hermanni, respectively. The virus titers then decreased to undetectable levels in both species. When the infective dose was incr eased to 10(6.2), virus was detected until days 6 and 8, respectively. In A. arboreus, virus titers in whole tick homogenates reached a peak of 10(4.0) on day 4 postfeeding and remained constant at 10(3.0) afte r day 6 throughout the 20- or 50-day observation periods. Virus was de tected by isolation, indirect fluorescent antibody, and histochemical techniques in the salivary glands, ovaries, synganglia, and coxal flui ds. Infected ticks successfully transmitted virus to clean chickens on day 20 postfeeding. No evidence of transstadial transmission from nym ph to adult was detected. Larvae from experimentally infected females successfully transmitted virus to clean chicks and virus was recovered from F1 larvae. Venereal transmission was not detected. Virus was pre sent in coxal fluids secreted by infected females after infective meal s. This study demonstrates West Nile virus infection in experimentally infected A. arboreus ticks and documents horizontal and vertical tran smission in this species.