Some evidence of mechanical transmission of reticuloendotheliosis virus by mosquitoes.

The possible role of mosquitoes in the mechanical transmission of reticuloendotheliosis virus (REV) in chickens was examined. A carbon-dioxide-baited trap was used to capture mosquitoes in poultry pens for one year to determine the seasonal occurrence and the species of mosquitoes prevalent in the area. Homogenates of captured mosquitoes were used for REV isolation in chicken embryo fibroblast cultures. Sera from sentinel chickens were also examined for REV antibodies. Population peaks of mosquitoes were seen in February, March, and April, and the dominant species, Culex quinqufasciatus, was present throughout the year. Of the 39 batches of mosquitoes examined, REV was isolated on seven occasions: once in summer and six times in autumn. Isolation of REV twice from unengorged mosquitoes from a pen with persistently viremic chickens and once from engorged mosquitoes in a pen with sentinel chickens implied that feeding on the viremic birds had been interrupted. Mechanical transmission of REV could have occurred when unengorged mosquitoes contaminated with REV completed their feeding on sentinel chickens. The birds developed REV antibodies following REV isolation from sentinel pens. REV was experimentally transmitted from persistently viremic donor chickens to a recipient chicken using Culex annulirostris.