THE CROSS-REACTIVITY SPECTRUM OF A POLYCLONAL ANTISERUM RAISED AGAINST THE NATIVE AMPLIFIED A(2) ESTERASE INVOLVED IN INSECTICIDE RESISTANCE

Broad-spectrum insecticide resistance in the mosquito Culex quinquefasciatus is usually due to the overproduction of A- and B-type carboxylesterases (EC 3.1.1.1). Antiserum was raised against the carboxylesterase A(2) purified from an organophosphate-resistant Culex strain. This antiserum was used to show that, contrary to earlier reports, the A(2) esterase is immunologically related to other A- and B-type carboxylesterases from resistant and susceptible Culex strains. Dot-blot immunoassays revealed that the purified esterase B-2 is about 50-fold less reactive with the antiserum than the purified esterase A(2). A strong immunological relationship was observed between the A(2) antiserum and the organophosphate and carbamate target site acetylcholinesterase. A lower cross-reactivity with Anopheles stephensi esterases and no reactivity with resistance-associated esterases from grain beetles, planthoppers, and cockroaches were observed. The antiserum cross-reacted with some commercially available vertebrate esterases indicating its affinities with these enzymes. The observed cross-reactivity is not due to the antiserum cross-reacting with glycosylated residues, as the A(2) esterase to which the antiserum was raised is unglycosylated. The utility of this antiserum in future esterase cDNA cloning programs is discussed. (C) 1995 Academic Press, Inc.