Bluetongue Virus Transmission with Culicoides Variipennis Via Embryonating Chicken Eggs

Embryonating chicken eggs were successfully used as infected donors and recipient hosts in bluetongue virus (strain 62-45S) transmission experiments with a colony population (Sonora Strain, 000 line) of the insect vector, Culicoides variipennis (Coquillett). Thirty-three % of all flies that took a blood meal on infected donor eggs at or near the period of peak viremia (geometric mean ELD50 titer = 106.5/0.1 ml) became infected and subsequently potential transmitters. This finding corroborates results from other systems in that the susceptibility rate with bluetongue virus (strain 62-45S) for this colony was about 30%. The period of maximum viremia in the infected donor eggs began within 4 to 7 hr before the time of death of the embryo. Sixty % of those flies infected via blood meal on donor eggs and incubated at 23° to 24°C for 14 days transmitted bluetongue virus when given a meal on normal recipient eggs of either blood or allantoic fluid or both.