Differences in susceptibilities of the lymphogranuloma venereum and trachoma biovars of Chlamydia trachomatis to neutralization by immune sera

Abstract

Sera from seven patients from whom a C. trachomatis serovar L2 strain was isolated were tested in vitro for their ability to neutralize the infectivity of this organism. In one patient an inguinal lymph node was culture positive, whereas the remaining six patients had positive rectal biopsies. Sera from four of the patients, including the patient with the lymph node isolate, failed to neutralize serovar L2(434). In addition, the homologous strain recovered from the inguinal lymph node was available and was resistant to neutralization by the homologous sera. However, the same sera effectively neutralized a trachoma serovar, E(Bour). All four sera had inclusion immunofluorescent-antibody titers to C. trachomatis serovar L2 of 2,048 to 16,384 and microimmunofluorescent-antibody titers to the lymphogranuloma venereum biovar were equal or higher in all cases than to the 12 serovars of the trachoma biovar. The three remaining sera, while neutralizing the infectivity of the L2 strains tested, neutralized serovar E to a greater extent. These sera had the same inclusion immunofluorescent antibody titers as the sera that failed to neutralize serovar L2. To see whether this difference in the sensitivity of the biovars toward neutralization could be characterized, sera were obtained from mice immunized with different doses of both serovars L2 and E. Sera obtained from mice immunized with serovar E were able to effectively neutralize the homologous strain. In contrast, neutralization of the immunizing strain, L2(UCI-20), was not seen with sera obtained on days 7, 14, and 21 after immunization from animals receiving 8 x 105 and 8 x 104 inclusion-forming units of L2(UCI-20); however, these same sera neutralized serovar E. However, with a higher immunizing dose of L2 (107 IFUs), both E and L2 were neutralized with sera obtained 7 and 14 days after immunization. Therefore, the relative resistance to neutralization by serovar L2 compared with that of serovar E in the mouse model was inoculum dependent. All stock strains were raised in either HeLa 229 cells or McCoy cells and frozen in a sucrose-phosphate glutamic acid buffer (2-SPG) at -70°C (6). Clinical isolates were collected, placed in 2-SPG, and cultured on McCoy or HeLa 229 cells. To obtain high titers, strains were passed at least four times on HeLa 229 or McCoy cells before being frozen in 2-SPG at -70°C. Clinical isolates were serotyped by microimmunofluorescence (MIF) with monoclonal antibodies (11).Chlamydia serology. Sera obtained from patients were assayed by two different indirect immunofluorescent assays. The MIF assay used elementary bodies of the 15 serovars of C. trachomatis as the antigens as previously described (5). In the other method, which will be referred to as the inclusion indirect immunofluorescence assay (IFA), acetone-fixed McCoy cells infected with serovar L2(434) were used (5). Dilutions of sera in phosphate-buffered saline (0.01 M, pH 7.4) were placed on the antigen-containing slides and allowed to incubate at 37°C for 30 min, followed by washing...

Characterization of kinetics and target proteins for binding of human complement component C3 to the surface-exposed outer membrane of Chlamydia trachomatis serovar L2

“…The cell surface of C. trachomatis EBs has been studied extensively with monoclonal antibodies (MAb) to map and catalog the antigenic profiles of the outer membrane proteins (OMPs). Studies of these membrane antigens have revealed that the major OMP (MOMP) binds specific antibody and plays an important role both structurally and immunologically (20,21). It is surface exposed at its four immunochemically variable domains (1), which bear the species and subspecies determinants for C. trachomatis serovars.…”

Some aspects of the immune response of koalas (Phascolarctos cinereus) and in vitro neutralization of chlamydia psittaci (koala strains)

“…Various studies demonstrated that antisera, against either EBs or secretions from chlamydiainfected tissues, neutralized chlamydial infection [13,20,33]. Previously antibody directed against the 31 kDa and 18 kDa proteins inhibited chlamydial infection to the same extent as antibody raised against the whole organism [8].…”

“…The report of Hugall [35] suggests it is rare for both strains to be found in the same swab material. Peterson et al [20] described differences in the susceptibilities of different biovars of C. trachomatis to neutralization by immune sera, reporting the relative resistance of the L2 serovar compared to the E serovar to be inoculum dependent. The results presented here do not suggest such a dependence to exist for the koala strains over a five-fold dilution range ( Table 2).…”

“…Polyclonal antibodies raised against elementary bodies (EBs) prevented attachment and ingestion of the LGV biovar in HeLa cells [8,18], and C. psittaci 6BC strain in L cells [19]. Monoclonal antibodies against epitopes in variable domains 1 and 4 of the MOMP gene were shown to block the attachment of C. trachomatis LGV and trachoma biovars to HeLa cells [17,20]. Despite considerable examination of the diseases affecting koalas, the immune response to their predominant pathogen, C. psittaci, is poorly understood [21].…”

Antibody-neutralizing activity against all urogenital Chlamydia trachomatis serovars in Chlamydia suis-infected pigs

“…It is known that neutralizing species‐specific or serovar‐specific antibodies are produced in response to chlamydial infection in humans and in some animal species (Banks et al , 1970; Peterson et al , 1990; Girjes et al , 1993; Donati et al , 1996, 2006, 2009). The detection of these antibodies could be useful in the diagnosis of mixed infections or in the detection of immunogenic antigens as vaccine candidates.…”