Allergenicity of native/recombinant tropomyosin, per a 7, of American cockroach (CR), periplaneta Americana, among CR allergic Thais.

ABSTRACT

In this study, native tropomyosin (Per a 7) of American cockroach (CR), Periplaneta americana, caught in Thailand was purified. Also, gene sequence encoding full length tropomyosin of the CR was PCR ampli-fied by using degenerate primers designed from gene sequences coding for P. americana tropomyosin of the data-base (Per a 7.0101 and Per a 7.0102; accession no.Y14854 and AF106961, respectively). Amino acid sequence deduced from the nucleotide sequence encoding P. americana tropomyosin of this study (GenBank accession no. FJ976895) had 98.59% identity with the sequences of Per a 7.0101 and Per a 7.0102 and was 97.18% identical to the Bla g 7 sequence of German cockroach, Blatella germanica (accession no. AF260897). The native and recom-binant tropomyosins (~34 kDa) were used as antigens in sandwich ELISA for detecting specific IgE in serum sam-ples of 14 consented allergic patients who were positive by skin test to crude CR extract in comparison to 5 indi-viduals who were skin test negative. It was found that 8 (57%) and 6 (43%) of the CR allergic patients gave positive IgE binding results to the native and the recombinant proteins, respectively, while none of the non-allergic counter-parts was positive. Results of immunoblotting conformed to the ELISA results. Tropomyosin extracted from the P. americana caught in Thailand has potential as standard P. americana allergen in clinical monitoring of the allergic Thai patients.