Sequencing Analysis of cDNA Clones Encoding the American Cockroach Cr-PI Allergens

Abstract

A previous article described the isolation of several gt22A cDNA clones expressing the American cockroach (Periplaneta americana) Cr-PI allergens recognized by both human atopic IgE antibodies and anti-Cr-PI monoclonal antibodies (Wu, C. H., Lee, M. F., and Liao, S. C. (1995) J. Allergy Clin. Immunol. 96, 352-359). This article presents the nucleotide and deduced amino acid sequences of two cDNA clones encoding major allergens of P. americana. Clones C12 and C20 encode proteins of 685 and 631 amino acids with two potential N-glycosylation sites each. The predicted molecular weights for C12 and C20 cloned proteins are 79,300 and 75,500 with isoelectric point values of 6.26 and 6.63, which are compatible with the determined sizes (M r 78,000 and 72,000) and isoelectric point value (6.2) of the Cr-PI allergens of P. americana. A high degree of identity (69.1%), including several overlapped predicted central antigenic determinant residues, was found between two allergens. The anti-fusion protein antibody-based enzyme-linked immunosorbent assay was able to detect crude American cockroach extract, Cr-PI, recombinant proteins, and commercial cockroach extracts, which provides further evidence that two allergens share common antigen determinants. Recombinant allergens of clones C12 and C20 both showed 47.4% skin reactivities on 19 cockroach-sensitive asthmatic patients. Unexpectedly, although no sequence similarity was found to other known allergens, two aromatic amino acid-rich allergens were found to have a striking sequence identity to insect storage proteins (20.1-33.9%), insect juvenile hormone-suppressible proteins (30.9 -36.4%), and arthropod hemocyanins (29.7-34.6%). Results suggested that two prominent allergens of P. americana are ancestrally related to these insect hemolymph proteins and represent a new group of proteins in the hemocyanin superfamily. These data will now facilitate epitope-mapping studies, and the recombinant allergens may be valuable for diagnostic and therapeutic purposes.

Allergenic Characterization of Tropomyosin from the Dusky Brown Cockroach,Periplaneta fuliginosa

“…Only three allergens from the American cockroach have been cloned: Per a 1, a protein of unknown function which is cross-reactive with Bla g 1 (24); Per a 3, an insect storage protein related to arylphorin (36); and Per a 7, tropomyosin (8). No detailed studies have been performed on other cockroach species, which may also represent sources of indoor allergens.…”

Induction of IgE Antibody Responses by GlutathioneS-Transferase from the German Cockroach (Blattella germanica)

“…Thus if P. americana produces a GST allergen, it is a different isoform or GST class to B. germanica GST. We have recently cloned the cross-reactive Bla g 1 homologue from P. americana (Per a 1) and this allergen, in addition to Per a 3, could be used for diagnosis of sensitization to Periplaneta species (14).…”

“…B. germanica allergen Bla g 2 shows sequence homology to aspartic proteases, whereas Bla g 4 is a ligand-binding protein or calycin (12,13). In Taiwan, P. americana is an important cause of asthma, and a 72-kDa allergen, Per a 3, has recently been cloned, which shows homology to insect hemolymph proteins (arylphorins) (14).…”

“…Although cockroach may carry viral and bacterial pathogens, asthma is the only disease for which an unequivocal causal relationship with cockroach exposure has been established (9 -11). Over the last few years, several allergens from the principal domiciliary cockroach species, Blattella germanica (German cockroach) and Periplaneta americana (American cockroach), have been cloned and insights into their biological function have been obtained (12)(13)(14)(15). B. germanica allergen Bla g 2 shows sequence homology to aspartic proteases, whereas Bla g 4 is a ligand-binding protein or calycin (12,13).…”

Expressed sequence tags analysis of Blattella germanica

“…The generation and analysis of expressed sequence tags (ESTs) provides useful information on development, metabolism, virulence factors, drug targets, and pathogenesis in various organisms (el-Sayed et al, 1995;Wu et al, 1996;Manger et al, 1998;Bahl et al, 2003).…”