El. Roggen et al., ANTIGEN-DETECTION AND IMMUNOLOGICAL TYPING OF HAEMOPHILUS-DUCREYI WITH A SPECIFIC RABBIT POLYCLONAL SERUM, Journal of clinical microbiology, 31(7), 1993, pp. 1820-1825
A rabbit polyclonal serum was raised against the 29-kDa species-specif
ic marker, as well as the 30- to 34-kDa immunotype-specific markers of
Haemophilus ducreyi described elsewhere (E. Roggen, S. De Breucker, E
. Van Dyck, and P. Piot, Infect. Immun. 60:590-595, 1992). These antig
ens were purified from a cocktail of H. ducreyi isolates by sodium dod
ecyl sulfate-polyacrylamide gel electrophoresis. The immune serum reac
ted in enzyme-linked immunosorbent assay (ELISA) preferentially with H
. ducreyi, at a titer as high as 50,000. To make it specific to H. duc
reyi, nonspecific antibodies were removed by adsorption on a mixture o
f Haemophilus spp., Escherichia coli, Candida albicans, and Corynebact
erium spp. In the 29- to 34-kDa region of immunoblot profiles from H.
ducreyi isolates (n = 450), the adsorbed serum revealed essentially th
e same antigens as did a pool of well-characterized human sera. Yet, e
ight different immunotypes were observed. With this rabbit polyclonal
serum, an ELISA-based antigen detection test was developed. The adsorb
ed serum reacted specifically with all H. ducreyi isolates tested (n =
450), but not with other bacterial species (n = 15). This test was ev
aluated with a limited number of clinical specimens from African patie
nts with culture-proven chancroid and no evidence for any other ulcera
ting etiology (n = 10) and a number of chancroid-negative control pati
ents from Belgium (n = 20). Within this context, the test yielded a se
nsitivity and specificity of 100%.