Experimental detection of rift valley fever virus by reverse transcription-polymerase chain reaction assay in large samples of mosquitoes

A reverse transcription-polymerase chain reaction (RT-PCR) was assessed in laboratory tests to detect the presence of single Aedes aegypti (L.) or Ere tmapodites quinquevittatus Theobald mosquitoes infected with Rift Valley fe ver virus in pools of mosquitoes, 50 - 600 in size, from laboratory colonie s or mixed field collections. The viral RNA was detected in all pools conta ining infected mosquitoes and was shown to be as sensitive as infant mice b ut more sensitive than Vero cell cultures for virus detection. Pools dilute d down to the equivalent of 1:16 000 mosquitoes were also positive by RT-PC R. RNAs from 4 other phlebovirus uses were negative, there were no false po sitives and the procedure followed, with the 2 particular primers chosen, g ave consistently clear Lands of the PCR products on agarose gels without ne sted PCR being necessary.