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 quinquefas ciatus is usually due to the overproduction of A- and B-type carboxyle sterases (EC 3.1.1.1). Antiserum was raised against the carboxylestera se 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 carboxyles terases from resistant and susceptible Culex strains. Dot-blot immunoa ssays revealed that the purified esterase B-2 is about 50-fold less re active with the antiserum than the purified esterase A(2). A strong im munological relationship was observed between the A(2) antiserum and t he organophosphate and carbamate target site acetylcholinesterase. A l ower cross-reactivity with Anopheles stephensi esterases and no reacti vity with resistance-associated esterases from grain beetles, planthop pers, and cockroaches were observed. The antiserum cross-reacted with some commercially available vertebrate esterases indicating its affini ties with these enzymes. The observed cross-reactivity is not due to t he antiserum cross-reacting with glycosylated residues, as the A(2) es terase to which the antiserum was raised is unglycosylated. The utilit y of this antiserum in future esterase cDNA cloning programs is discus sed. (C) 1995 Academic Press, Inc.