Prevalence and persistence of Chlamydia trachomatis-specific antibodies after occasional and recurrent infections.

OBJECTIVES: Population-based Chlamydia trachomatis seroepidemiological studies help to identify trends in chlamydia infection. However, an improved understanding of the antibody response to infection is required when using serology to estimate cumulative incidence. Thus, the objectives of this longitudinal, retrospective, biobank-based study were to assess the appearance and persistence of C. trachomatis major outer membrane protein (MOMP)-specific serum IgG antibodies after infection and to evaluate the role of antibodies in providing protective immunity against recurrent infection. METHODS: Data of notified C. trachomatis infections in Finland were obtained from the National Infectious Diseases Register. Serum samples were acquired from the Finnish Maternity Cohort. 411 women with single chlamydia infection and 62 women with recurrent infections, and for whom suitable paired serum samples were available, were included in the study. Antibody appearance, persistence after infection and the impact of recurrent infections were evaluated. IgG antibodies specific for MOMP were measured from serum using an ELISA method. RESULTS: Anti-C. trachomatis MOMP-specific IgG antibodies were detected in 65.5% (269/411) of women within 3 months of notification of infection. In the absence of recurrent infection, seroprevalence declined to 34.5% (142/411) 3-10 years after the initial infection. The serum antibody levels at baseline correlated positively with seroprevalence at follow-up. Reinfection boosted the humoral immune response by increasing seroprevalence and the serum antibody levels. Seroprevalence within 3 months after first notification of infection was 65.5% (19/29) in women who were later diagnosed with recurrent infection, comparable with women with single notification of infection (65.5%, 269/411). CONCLUSIONS: Approximately one-third of women with single notification of chlamydia infection remain seropositive 3-10 years after the initial infection. The concentration of antibodies remained stable during the follow-up. Recurrent infection boosted the humoral immune response, but reinfection occurred despite the presence of pre-existing antibodies.

Predictive Values of Serum Chlamydia trachomatis TroA and HtrA IgG Antibodies as Markers of Persistent Infection in the Detection of Pelvic Adhesions and Tubal Occlusion.

Chlamydia trachomatis IgG antibody testing (CAT) has been used as a screening test for tubal factor infertility (TFI), but as the CAT is only a marker of a past exposure to C. trachomatis and not of late sequelae, the positive predictive value (PPV) of the test is low. The persistence of C. trachomatis in the upper genital tract has been suggested as one of the key mechanisms in the development of TFI. Serum antibodies against C. trachomatis TroA and HtrA, proteins expressed specifically during persistent infection, have been suggested as novel biomarkers for TFI diagnostics. We studied serum IgG antibody responses against C. trachomatis TroA, HtrA and MOMP in 79 subfertile women, of whom 28 had laparoscopically proven TFI. We confirmed that the accuracy of CAT in diagnosing TFI is low, whereas TroA IgG and HtrA IgG are more accurate tests in detecting tubal occlusion and pelvic adhesions. However, the sensitivity and negative predictive value (NPV) of TroA IgG and HtrA IgG are still too low to justify their use as a screening test in clinical practice. Individual immunogenetic profiles combined with TroA and HtrA antibody responses might identify women with the highest risk for developing late complications after C. trachomatis infection.

Predicting tubal factor infertility by using markers of humoral and cell-mediated immune response against Chlamydia trachomatis.

PROBLEM: The accuracy of Chlamydia trachomatis antibody test in predicting tubal factor infertility (TFI) is limited, and more accurate methods are needed. Cell-mediated immune response (CMI) is crucial in the resolution of pathogen, but it may play an important role in the pathogenesis of C trachomatis-associated tubal damage. We studied whether combining the markers of C trachomatis-induced CMI to humoral immune response improves the accuracy of serology in TFI prediction. METHOD OF STUDY: Our prospective study consists of 258 subfertile women, of whom 22 (8.5%) had TFI. Women with other causes for subfertility served as a reference group. Serum C trachomatis major outer membrane protein (MOMP) and chlamydial heat-shock protein 60 (cHSP60) IgG antibodies were measured by ELISA. CMI was studied by lymphocyte proliferation assay in vitro. RESULTS: Serological markers were more prevalent in women with TFI than in other subfertile women (40.9% vs 12.3% for MOMP IgG and 27.3% vs 10.2% for cHSP60 IgG). The best test combination for TFI was C. trachomatis MOMP and cHSP60 antibody with an accuracy of 90.3%, sensitivity of 22.7% and specificity of 96.6%. Positive post-test probability of this combination was 54.2%, and negative post-test probability was 12.4%. Adding of the markers of CMI did not significantly improve the accuracy of serology in TFI prediction. CONCLUSION: The accuracy of TFI prediction increases when the combination of C trachomatis MOMP and cHSP60 antibody tests is used. C trachomatis-induced CMI was common in our study population, but the markers of CMI did not predict TFI.

Chlamydia trachomatis-induced cell-mediated and humoral immune response in women with unexplained infertility.

PROBLEM: What is the role of past Chlamydia trachomatis infection in unexplained infertility? METHOD OF STUDY: This is a prospective study of the impact of past C. trachomatis infection on pregnancy rates in 96 women with unexplained infertility. Both humoral and cell-mediated immune responses (CMI) against C. trachomatis were studied. Serum C. trachomatis IgG antibodies were analyzed using major outer membrane protein (MOMP) peptide-based ELISA. CMI was studied by lymphocyte proliferation (LP) assay in vitro. Data on given fertility treatment, time to pregnancy, and pregnancy outcome were collected. RESULTS: Altogether, 11.5% of the 96 women had C. trachomatis IgG antibodies. LP response to C. trachomatis was positive in 62.9% women. The overall pregnancy rate or live birth rate did not differ by the presence of antichlamydial antibodies or CMI against C. trachomatis. Time to spontaneous pregnancy was longer among C. trachomatis sero-positive women than among sero-negative women (2.9 years vs 2.0 years, P = .03). CONCLUSION: Past chlamydial infection does not play a major role in unexplained infertility. Women with unexplained infertility and positive immune response to C. trachomatis do not have reduced pregnancy rates, but time to spontaneous pregnancy is longer among C. trachomatis IgG sero-positive women than among sero-negative women.

Population-Based Study of Prediagnostic Antibodies to Chlamydia trachomatis in Relation to Adverse Pregnancy Outcome.

BACKGROUND: Chlamydia trachomatis infection is one of the most common sexually transmitted reported bacterial infections worldwide. The well-known sequelae of chlamydial infection include pelvic inflammatory disease and tubal factor infertility, but the evidence linking C. trachomatis infection and adverse pregnancy outcome is inconsistent and has been largely based on case-control studies with limited study populations. We evaluated this link in a population-based longitudinal biobank health registry setting. METHODS: The association between C. trachomatis major outer membrane protein (MOMP) peptide-specific IgG antibodies and ectopic pregnancy, miscarriage, and preterm delivery was examined in a prospective case-control study nested in the Finnish Maternity Cohort. Ectopic pregnancy and miscarriage cases were identified through the Hospital Discharge Register 1998-2005; cases with preterm deliveries were identified through the Finnish Medical Birth register 1988-2005. Control samples were retrieved from the Finnish Maternity Cohort serum bank. A total of 800 cases of ectopic pregnancy, 800 cases of miscarriage, and 1350 cases of preterm birth were included. Equal number of pregnant women without the outcome diagnosis served as controls. The cases and controls were matched by sampling time, at the serum sampling and postal code district. RESULTS: Antichlamydial IgG antibodies were associated with ectopic pregnancy. Positive antibody levels were found in 21.0% of cases and 14.6% of controls (P = 0.001; odds ratio, 1.56; 95% confidence interval, 1.20-2.03). Previous exposure to C. trachomatis, as indicated by serum antibodies, doubled the risk of ectopic pregnancy within age and was highest among women 35 years or older. Antichlamydial IgG antibody rates between the cases with miscarriage (16.3% in cases vs. 16.8% in controls) or preterm delivery (18.1% vs. 18.1%) and controls did not differ. CONCLUSIONS: Our findings confirm the association between previous exposure to C. trachomatis and ectopic pregnancy. We found no association between C. trachomatis seropositivity and miscarriage or preterm birth.

The role of Chlamydia trachomatis infection in male infertility.

To study the association between plasma antibodies to Chlamydia trachomatis and male infertility, 90 men from infertile couples attending a University Hospital IVF clinic for IVF/intracytoplasmic sperm injection, and 190 healthy blood donors as control subjects were studied for IgG and IgA antibodies to C. trachomatis, and for the men from infertile couples seminal fluid analysis was performed according to the World Health Organization criteria. The prevalence of plasma IgG antibodies to C. trachomatis was higher among men from infertile couples than control men, and men with chlamydial antibodies had lower sperm counts than those without.

Detection of human picornaviruses by multiplex reverse transcription-PCR and liquid hybridization.

A qualitative multiplex reverse transcription (RT)-PCR and liquid hybridization assay for the detection of human enteroviruses, rhinoviruses, parechoviruses, and Aichi virus was developed. Furthermore, a separate assay for the recognition of hepatitis A virus was established to complement the test pattern so that all human picornaviruses were covered. The amplicons, which represented the 5' untranslated regions of the viral RNA genomes, were identified in liquid hybridization reactions with genus-specific digoxigenin-labeled oligonucleotide probes. The sensitivity of the multiplex RT-PCR and liquid hybridization assay was 10 to 100 picornavirus genome equivalents for representatives of each picornavirus genus. The hepatitis A virus assay exhibited a sensitivity of 10 genome copies. Both the uniplex and the multiplex tests were highly specific for the target viruses. Twenty-three clinical samples, including cerebrospinal fluid, serum, and nasopharyngeal swab specimens, were used for clinical evaluation of the multiplex RT-PCR assay. The results obtained were consistent with the results of routine virus diagnostic assays. Furthermore, the assay was used to screen 68 stool specimens for the presence of parechoviruses and Aichi virus. One sample was found to contain parechovirus RNA, whereas no Aichi virus was detected. The assay described here can be applied for the efficient identification of human enteroviruses and rhinoviruses in clinical specimens and simultaneously enables the collection of information on the epidemiology and clinical outcomes of infections caused by the currently poorly known human parechoviruses and Aichi virus.

Antigenic sites of coxsackie A9 virus inducing neutralizing monoclonal antibodies protective in mice.

A panel of murine IgG monoclonal antibodies (MAbs) was produced against coxsackievirus A9 (CAV9). Fifty-nine MAbs reactive in ELISA with purified CAV9 were identified. Eighteen of them could efficiently inhibit infection by CAV9 but not coxsackieviruses B. Neutralization-resistant CAV9 variants to four different MAbs were isolated and tested for resistance to neutralization by other MAbs of the panel. Three groups of reactivity including 10, 7, and 1 MAbs were thus identified. Sequencing of neutralization-escape virus mutants showed that neutralization by one MAb group was affected by change of VP3 amino acids 62 or 69. For the second group of reactivity, mutations included amino acids 154 or 165 of VP2. The only MAb of the third group selected for a change at residue 70 of VP2. Protection studies in a newborn mouse model of myositis suggested that either epitopes in VP2 or in VP3 mediate protection from CAV9 infection in vivo.