The use of ELISA demonstrates the absence of Culex organophosphorus-resistance-associated esterases in Anopheles species

Abstract The esterase enzymes Est A′ and Est B are both quantitatively increased in organophosphorus-resistant Culex quinquefasciatus from Monrovia. An enzyme fraction containing Est B and traces of another unidentified esterase, but no Est A′, was produced by centrifugation and size exclusion chromatography. SDS-electrophoresis revealed five protein bands in this fraction. Antibodies raised in Balb-C mice to this fraction gave high levels of cross reactivity, in a peroxidase-linked ELISA test, to both organophosphorus-resistant and susceptible C. quinquefasciatus in fractions containing either Est B or Est A′. Only low levels of reactivity were obtained to a number of organophosphorus-resistant and susceptible Anopheles strains. This suggests that the family of esterases quantitatively changed in Culex are not present in the anophelines tested.