Experimental Evaluation of Musca domestica (Diptera: Muscidae) as a Vector of Newcastle Disease Virus

Watson, D. Wes; Niño, Elina L.; Rochon, Kateryn; Denning, Steve; Smith, Lynda; Guy, James S.

ND Virus Culture. NDV (Roakin strain) was obtained from Dr. D. J. King, Southeast Poultry Research Laboratory, Athens, GA. The virus was propagated by inoculation of 10-d-old embryonated chicken eggs by the allantoic route, 0.1 ml per egg (SPAFAS, Charles River Laboratories Inc., Wilmington, MA). Allantoic ßuid was harvested from eggs that died 3Ð 4 d postinoculation. Titration of the virus was accomplished by preparation of 10-fold dilutions of allantoic ßuid in DulbeccoÕs minimal essential medium (DMEM) and inoculation of 0.2 ml of each dilution onto conßuent monolayers of chicken embryo Þbroblast (CEF) cells in 48-well tissue culture plates, four wells per dilution. Five days after inoculation, contents of wells were decanted into a container containing sodium hypochlorite to inactivate live virus, and cells were stained with 0.1% crystal violet. Titer was determined by calculation of the 50% infectious doses (ID 50 ) as described by Reed and Muench (1938) . An inoculum was prepared to contain Ϸ10 7 ID 50 /0.1 ml, and it was stored at Ϫ70ЊC. NDV Serology. Serum samples were assayed for presence of NDV-speciÞc antibody by using a hemagglutination inhibition test as described previously (Beard 1989) .