Background: Allergic reaction to guinea pig has been recognized as a problem in domestic settings and work environments for many years. Until recently, limited information was available on the properties of guinea pig allergen(s). In this study the major allergen Cav p 1 was characterized and the N-terminal amino-acid sequence was determined.
Methods and results: Sera from 40 patients with IgE-mediated allergy to guinea pigs were investigated by means of immunoblotting using extracts prepared from guinea pig hair and urine. Three major allergens were identified within both sources with molecular weights (MW) of 8 kDa, 17 kDa and 20 kDa, respectively. From aqueous hair extracts the 20 kDa allergen (Cav p 1) was purified to homogeneity by anion exchange chromatography and reverse-phase HPLC and the N-terminal amino-acid sequence was determined. On the basis of the 15 residues, 57% identity was obtained from computer search with a sub-sequence of MUP (major urinary protein), a member of the lipocalin superfamily. Allergenic relationships among guinea pig allergens derived from various sources (hair and urine) or different animal species (mouse, rat, cat) were studied by ELISA inhibition assays. Neither urine of mouse, rat and cat, nor hair extracts of rat and cat produced appreciable inhibitions in guinea pig ELISA.
Conclusion: Although the physicochemical characteristics of isolated Cav p 1 are very similar to those for other rodent allergens and furthermore partial sequence identity with Mus m 1 was found, it is clearly shown here to be an immunologically independent major allergen.