Maintenance and transmission of keystone virus by Aedes atlanticus (Diptera: Culicidae) and the gray squirrel in the pocomoke cypress swamp, Maryland

Among 43 seronegative squirrels, 65% were infected with KEY virus during July, August, and September 1975, coincident with the emergence and activity of KEY virus-infected Ae. atlanticus . Although Ae. atlanticus was infected readily following per os exposure to KEY virus, only 1 of 83 infected mosquitoes transmitted virus to a suckling mouse. In contrast, 33 of 46 (72%) parenterally infected Ae. atlanticus transmitted virus to mice. KEY virus also was transmitted vertically be Ae. atlanticus to F sub(1) progeny, and one of two vertically infected females transmitted virus to suckling mice by bite.