Distribution of an antigenically related iron-regulated protein among the Neisseria spp

Abstract

Several iron-regulated proteins of Neisseria gonorrhoeae have been reported. One of these, a 37,000molecular-weight protein (37K protein), appears to be common to all gonococcal isolates. Recently, the occurrence of a similar protein has also been noted in N. meningitidis. The gonococcal 37K protein has been purified and used to produce both rabbit monospecific antiserum and murine monoclonal antibodies. Using these antibody reagents, we analyzed 57 strains from nine species of Neisseria and the closely related organism Branhamella catarrhalis for the presence of proteins antigenically related to the gonococcal 37K protein. Strains grown on medium with low iron content were probed for antigenic reactivity by Western blot techniques and an enzyme-linked immunosorbent assay. Proteins which cross-reacted with the rabbit monospecific antiserum were designated as AgR-37K proteins. The data indicated that the AgR-37K proteins were conserved among the 40 strains of N. gonorrhoeae, N. meningitidis, N. lactamica, and N. cinerea tested. Seventeen strains from other species of Neisseria and Branhamella did not express AgR-37K proteins with the exception of one N. subflava isolate. All AgR-37K proteins appeared to be regulated by the amount of available iron in the growth medium. Murine monoclonal antibodies were used to probe the antigenic heterogeneity of the AgR-37K proteins from different Neisseria spp. Two of seven monoclonal antibodies were broadly cross-reactive, recognizing the AgR-37K proteins from all species examined. The remaining five monoclonal antibodies were more discriminating, recognizing the AgR-37K proteins from certain species. The antigenic conservation of these AgR-37K proteins, particularly among the pathogenic members of the genus Neisseria, may imply that these proteins serve a common function in pathogenicity.

Antigenic cross-reactivity between outer membrane proteins of Neisseria meningitidis and commensal Neisseria species

“…Horseradish peroxidase (HRP)-conjugated rabbit antimouse or anti-human immunoglobulins (Sigma Chemical Co., USA) were used to detect the mouse or human Ig bound to the membranes. Total antibody titres in the sera were determined by ELISA essentially as described previously [20,21] using microtitre plates coated with OMV suspensions containing 10 Wg of total protein in 50 mM carbonate bu¡er, pH 9.6. The antibody titre was determined as the highest dilution for which the ratio between the absorbance of the immune serum and that of nonimmune serum was v 3.…”

The ferric iron‐binding protein of pathogenic Neisseria spp. functions as a periplasmic transport protein in iron acquisition from human transferrin

“…Fbp is conserved in all pathogenic Neisseria spp. examined to date (Mietzner et al, 1986) and probably has homoiogues in distantly related organisms such as Haemophilus /nf/uenzae (Berish etal., 1992;Harkness etal,, 1992) and Serratia marcescens (Angerer etal., 1990;Berish etal.,, 1992). Recently, evidence has been presented for the periplasmic localization of this protein (Berish et al, 1992).…”

In vivo human immune response to transferrin-binding protein 2 and other iron-regulated proteins of Neisseria meningitidis

“…A number of meningococcal IROMPs have been shown to be important antigens in animal models. Examples include 37 kDa and-70 kDa proteins, the first one presumably implicated in iron transport [6][7][8], and human-transferrin-binding protein 2 (TBP2), which is probably necessary for meningococcal growth in the human body [9][10][11]. The stress imposed by iron restriction also induces the synthesis of other important antigens ('stress proteins'), such as the 56 kDa protein found in most strains studied by us [9].…”