Enzyme-linked immunosorbent assay to detect antigens of Dirofilaria immitis (Spirunida: Filariidae) larvae in Aedes albopictus and Culex tritaeniorhynchus (Diptera: Culicidae).

An enzyme-linked immunosorbent assay (ELISA) method was developed for detecting the larval antigens of Dirofilaria immitis (Leidy) in Aedes albopictus (Skuse) and Culex tritaeniorhynchus Giles to replace the conventional dissection method. The assay was sensitive enough to detect 21.3 ng/ml (2.13 ng per microplate well) or more of the soluble antigen obtained from adult worms and an antigen amount corresponding to at least one larva at any developing stage. No inhibitory effect of host tissues was observed on the ELISA reaction even when the homogenate of 20 mosquitoes was included in the 1-ml ELISA diluent. Moreover, third-stage larval antigen could be detected readily when mixed with up to 100 mosquito heads. The ELISA method has been effective in field surveys of mosquito populations with low filarial infection rates.