Increased frequency of Chlamydia pneumoniae antibodies in patients with asthma

The worldwide increase in asthma incidences and the impact of the disease on public health care have led to new investigations of the cause of the disease. Besides well-defined environmental causes, accumulating evidence suggests that respiratory tract infections play an important role in the pathogenesis of asthma. Among these microorganisms Chlamydia pneumoniae is an intracellular pathogen causing persistent infection. Chlamydia pneumoniae infection has been discussed as possibly inducing the development of asthma. This study was designed to investigate the presence of C. pneumoniae-specific IgG, IgA, and IgM antibodies in serum samples of 33 adults with a clinical history of asthma, positive methacholine test, and reduced FEV(1). Patients with asthma were compared with age-, sex-, and locality-matched control subjects (n = 33). We observed no acute infection either in patients with asthma or in control subjects, but 63% of all investigated individuals had signs of past infection. Chlamydia pneumoniae-specific IgA was detected in 52% of the patients with asthma and in 15% of the healthy control subjects (p < 0.01). Serological evidence of chronic infection with C. pneumoniae (high IgG [> pr = 1:512] and high IgA [> or = 1:40]) was more frequent in patients with asthma (18.2%) compared with control subjects (3.0%) (p < 0.01). Our results provide further evidence that chronic infection with C. pneumoniae is linked to asthma.     

Chlamydia pneumoniae infection in adults with chronic cough compared with healthy blood donors.

In a small uncontrolled study, persistent cough has recently been found to be associated with serological evidence of acute Chlamydia pneumoniae infection. In order to assess whether C. pneumoniae plays a role in chronic cough, the prevalence of C. pneumoniae infection in 201 adult patients with chronic cough was compared with the prevalence in 106 healthy blood donors without respiratory tract symptoms in the preceding 3 months. A microimmunofluorescence antibody test was used to determine C. pneumoniae antibodies in the immunoglobulin (Ig)M, IgG and IgA fractions. Further, nasopharyngeal aspirates from the 201 patients were examined for C. pneumoniae deoxyribonucleic acid by polymerase chain reaction (PCR). As judged by serology, nine patients (4%) and one control (1%) had acute C. pneumoniae infection, and 92 patients (46%) and 42 controls (40%) had previous or chronic C. pneumoniae infection. Of the nine patients with acute infection, three were C. pneumoniae PCR positive, and they all had an IgM antibody titre response. The remaining six patients had either an IgG antibody titre of > or =512 (five patients) or an IgA antibody titre of > or =512 (one patient). None of these six patients had detectable IgM antibodies. The mean cough period for the five IgG positive patients (10.8 weeks) was significantly longer than the mean cough period for the remaining patient population (6.4 weeks; p=0.004). It is concluded that Chlamydia pneumoniae infection was not statistically significantly more prevalent in patients with chronic cough than in healthy blood donors, and that Chlamydia pneumoniae appears to have a minor role in patients with chronic cough. Direct detection of Chlamydia pneumoniae by polymerase chain reaction on nasopharyngeal aspirates is highly correlated with detectable immunoglobulin M antibodies, but in the late stages of prolonged cough serological testing of immunoglobulin G and immunoglobulin A may be more beneficial for obtaining a microbiological diagnosis.     

Serological evidence of infection with Chlamydia pneumoniae is related to the severity of asthma.

There is evidence that infection with Chlamydia pneumoniae is associated with asthma of recent onset and that it can influence the severity of asthma. This has led to the suggestion that macrolide antibiotics may be useful in the treatment of asthma in subjects infected with C. pneumoniae. This study examined the association between immunoglobulin (Ig)G and IgA titres to C. pneumoniae and the severity of asthma. IgG and IgA antibodies to C. pneumoniae were measured in 619 subjects with asthma (18-60 yrs), using the microimmunofluoresence method. Subjects were asked about their use of asthma medicines, symptoms, previous hospitalization for asthma, smoking status and age of onset of asthma. In subjects with IgG titres of > or =1:64 and/or IgA titres > or =1:16 (n=212), spirometry was performed and peak expiratory flow rate (PEFR) and symptoms were recorded twice daily for 4 weeks on a diary card. The use of high dose inhaled steroids was associated with an increase of 74.1% in the titre of IgG antibodies (p=0.04) and an increase of 70.6% in the titre of IgA antibodies (p=0.0001) when compared with the use of low dose inhaled steroids. There was an inverse association between IgG antibodies and forced expiratory volume in one second (FEV1) as a percentage of predicted in those subjects with elevated IgG and/or IgA (p=0.04). In this group IgA antibodies were also associated with a higher daytime symptom score (p=0.04). Higher titres of antibodies to Chlamydia pneumoniae appears to be associated with markers of asthma severity. This raises the possibility that chronic infection with Chlamydia pneumoniae leads to an increase in the severity of asthma. Studies aimed at eradicating chronic infection with Chlamydia pneumoniae are necessary to determine whether or not this is the case.     

Trial of roxithromycin in subjects with asthma and serological evidence of infection with Chlamydia pneumoniae

An association has been reported between chronic infection with Chlamydia pneumoniae and the severity of asthma, and uncontrolled observations have suggested that treatment with antibiotics active against C. pneumoniae leads to an improvement in asthma control. We studied the effect of roxithromycin in subjects with asthma and immunoglobulin G (IgG) antibodies to C. pneumoniae > or = 1:64 and/or IgA antibodies > or = 1:16. A total of 232 subjects, from Australia, New Zealand, Italy, or Argentina, were randomized to 6 wk of treatment with roxithromycin 150 mg twice a day or placebo. At the end of 6 wk, the increase from baseline in evening peak expiratory flow (PEF) was 15 L/min with roxithromycin and 3 L/min with placebo (p = 0.02). With morning PEF, the increase was 14 L/min with roxithromycin and 8 L/min with placebo (NS). In the Australasian population, the increase in morning PEF was 18 L/min and 4 L/min, respectively (p = 0.04). At 3 mo and 6 mo after the end of treatment, differences between the two groups were smaller and not significant. Six weeks of treatment with roxithromycin led to improvements in asthma control but the benefit was not sustained. Further studies are necessary to determine whether the lack of sustained benefit is due to failure to eradicate C. pneumoniae.     

肺炎衣原体与中枢神经系统疾病相关性研究进展

肺炎衣原体(Chlamydia pneumoniae,Cpn)是一类具有独特双相发育周期的专性胞内寄生菌。Cpn感染过程复杂且致病类型广,除引起常见的呼吸道感染外,还可引起多个系统的慢性持续性感染。有文献报道,Cpn与中枢神经系统疾病的发生、发展密切相关。本文对Cpn与中枢神经系统疾病的相关性研究进展进行综述,为今后更合理地指导临床治疗提供重要信息。     

Short-term respiratory effects of cleaning exposures in female domestic cleaners.

Symptoms of obstructive lung disease in domestic cleaners have been related to the use of bleach and other irritant cleaning products. The short-term effects of cleaning exposures on respiratory symptoms and peak expiratory flow (PEF) were investigated in domestic cleaners with respiratory disorders. In a panel study, 43 female domestic cleaners with a recent history of asthma and/or chronic bronchitis completed a 2-week diary, collecting information on respiratory symptoms, PEF and cleaning exposures. Mixed regression models were used to assess daily changes in symptoms and PEF associated with specific cleaning exposures. The probability of having work-related asthma was individually assessed by a computerised diagnostic system and an occupational asthma expert. Lower respiratory tract symptoms were more common on working days and were predominantly associated with exposure to diluted bleach, degreasing sprays/atomisers and air fresheners. Associations with upper respiratory tract symptoms and PEF were less apparent. Eleven (30%) subjects scored positively for work-related asthma. It is concluded that exposure to certain irritant cleaning products aggravates lower respiratory tract symptoms in female domestic cleaners with asthma or chronic bronchitis.     

慢性阻塞性肺疾病患者肺炎衣原体感染的研究

目的 探讨肺炎衣原体感染与慢性阻塞性肺疾病（COPD）的相关性。方法 选择61例COPD急性加重期患者,35例COPD稳定期患者,26名正常对照者,采用微量免疫荧光法测定血清肺炎衣原体特异性抗体IgA,IgM,IgG,套式聚俣酶链反应检测痰中的肺炎衣原体DNA。结果 COPD急性加重期患者的急性肺炎衣原体的感染率为31．1％,明显高于COPD稳定期和且（P＜0．05）。COPD急性加重期组和稳定期组的慢性肺炎衣原体感染率分别为21．3％和31．4％,明显高于对照组（P均＜0．05）,同时IgA的几何平均滴度在COPD急性加重期中最高（20．5）,COPD稳定期组中次之（10．8）,对照组最低（3．6）,三组间差异有显著性（P＜0．05）。结论 急性肺炎衣原体感染为COPD急性加重的一个重要诊因,慢性肺炎衣原体感染可能参与COPD的发病机制。     

Chlamydia pneumoniae infection as a trigger for a Cogan's syndrome

Cogan's syndrome is often preceded by upper respiratory tract symptoms. The only reported specific agent possibly involved in pathogenesis of the Cogan's syndrome was Chlamydia pneumoniae. Positive IgA, IgM and IgG antibodies against C. pneumoniae in our patient suggest possibility of Chlamydia's role as a trigger for the vasculitis.     

Inverse association of Chlamydia pneumoniae infection with high blood pressure in Japanese adults

To determine whether Chlamydia pneumoniae (C. pneumoniae) infection is associated with hypertension in Japanese adults, we measured serum levels of IgA (a marker of reinfection) and of IgG (a marker of previous infection) antibodies to C. pneumoniae by enzyme-linked immunosorbent assay in 112 adults including normotensive and untreated hypertensive subjects and in 117 hypertensive subjects who had been receiving treatment for more than 3 years. In 112 adults, positivity rate for IgA was lower (P < .01) in hypertensive than in normotensive or borderline hypertensive subjects. Positivity rates for IgA and IgG together, which indicate persistent infection of C. pneumoniae, were lower (P < .01) in hypertensive than in normotensive subjects. IgA levels were inversely correlated with systolic blood pressure (SBP) (r = 0.530, P = .0001) and with diastolic blood pressure (DBP) (r = 0.398, P = .0001). In the 117 hypertensive subjects treated with medication, positivity rate for IgA was lower (P < .01) in subjects with poor control than in those with good control. Positivity rates for IgA and IgG together were lower (P < 0.01) in the poor control group than in the good or fair control groups. IgA levels were correlated inversely with SBP and DBP. In both 112 adults and 117 hypertensive patients, levels of SBP or DBP were inversely associated with positivity rates for IgA and IgG together in multiple logistic regression analysis. The results suggest an inverse relationship between high blood pressure and C. pneumoniae infection in Japanese adults.     

Chlamydia pneumoniae respiratory infections

Chlamydia pneumoniae is a significant cause of both upper and lower respiratory tract infections. The spectrum of diseases ranges from asymptomatic infection to serious disease, including severe pneumonia and exacerbations of chronic bronchitis requiring mechanical ventilation. There is increasing evidence of involvement of C. pneumoniae infection in bronchial asthma, and the role of this agent in immunocompromised patients has also begun to be appreciated.     

Helicobacter pylori and chronic bronchitis.

BACKGROUND: Chronic infections such as those caused by Helicobacter pylori, Chlamydia pneumoniae, and cytomegalovirus have been epidemiologically related to coronary heart disease (CHD). Other studies place H. pylori in relation to other extradigestive diseases. We carried out an epidemiologic pilot study to evaluate the prevalence of H. pylori in patients with chronic bronchitis, a respiratory disease characterized by persistent chronic inflammation, in comparison with a matched control group. METHODS: An enzyme-linked immunosorbent assay IgG test for H. pylori diagnosis was performed in 60 consecutive patients with chronic bronchitis (15 women and 45 men; age range, 50-89 years; mean age, 70.38 years) and in 69 control subjects, well matched for age and social status (19 women and 50 men: age range, 52-90 years; mean age, 71.3 years). RESULTS: Foty-nine of 60 patients with chronic bronchitis (81.6%) and 40 of 69 subjects in the control group (57.9%) were H. pylori-positive (P = 0.0079). The odds ratio, calculated by simple analysis (3.2) and confirmed by logistic regression analysis (3.399), indicated that H. pylori infection greatly increases the risk of chronic bronchitis. CONCLUSIONS: To date, CHD is the only convincing association between H. pylori infection and an extradigestive disease. The main conclusion of this pilot study is that H. pylori infection seems to increase the risk of developing of chronic bronchitis. An important step in this field will be to evaluate the possible change in the clinical conditions after successful eradication therapy in H. pylori-positive patients with chronic bronchitis.     

Chlamydia pneumoniae infection and atherosclerotic coronary disease.

BACKGROUND: Previous works have suggested an association between Chlamydia pneumoniae infection and coronary heart disease. We evaluated the prevalence of C. pneumoniae infection in patients with acute myocardial infarction (AMI) and coronary heart disease (CHD). METHODS AND RESULTS: Ninety-eight patients with AMI, 80 patients with CHD, and 50 control subjects matched for age and sex were investigated. Immunoglobulin (Ig)M, IgG, and IgA antibodies to C pneumoniae were measured by the microimmunofluorescence test. IgM antibodies were not found; IgG positivity was found in 58.2% of the AMI group, 60.0% of the CHD group, and 38% of the control group, whereas for IgA, positivity was found in 33.7%, 43.7%, and 22% of cases in AMI, CHD, and control groups, respectively. Titers indicating reinfection were found in AMI and CHD groups in 6.1% and 10%, respectively, whereas titers indicating chronic infection were found in 14% of the AMI group and 25% of the CHD group. A significant correlation was found between chronic C pneumoniae infection and dyslipidemias in the AMI and CHD groups (P =.003; P =. 0006). CONCLUSIONS: The results suggest that chronic C pneumoniae infection may be associated with the development of atherosclerotic coronary disease. In our next step, we will test whether antichlamydial antibiotics may help to reduce the risk of atherosclerotic disease.     

Persistent infection with Chlamydia pneumoniae following acute respiratory illness.

Chlamydia pneumoniae is emerging as a significant cause of respiratory disease, including pneumonia and bronchitis, in humans. In this recently completed study of infection due to C. pneumoniae in patients presenting with pneumonia to SUNY Health Science Center at Brooklyn, we identified two individuals for whom cultures were positive on multiple occasions over a 1-year period. To determine the frequency of persistent respiratory infection with C. pneumoniae, follow-up specimens were obtained from nine individuals with culture-documented C. pneumoniae infection. Five of these individuals had persistent infection: four had a flulike illness characterized by pharyngitis, and one had bronchitis with prominent bronchospasm. All five individuals appeared to have acute C. pneumoniae infection as determined by results of serologic tests (titers of IgM antibody for all individuals were greater than or equal to 1:16). For three patients, cultures remained positive for 11 months despite therapy with 10- to 21-day courses of tetracycline or doxycycline. These observations suggest that persistent infection with C. pneumoniae may follow acute infection and may persist for many months. Infection with C. pneumoniae may be very difficult to eradicate with use of currently available antibiotics even if there is a clinical response to therapy.     

Host immune response to Chlamydia pneumoniae heat shock protein 60 is associated with asthma.

Chlamydia pneumoniae infection has been associated with asthma. It has also been suggested that heat shock protein 60 (Hsp60) belonging to a class of highly conserved proteins may play a role in the pathogenesis of chlamydial infections. The purpose was to study whether the host immune response to C. pneumoniae Hsp60 is associated with asthma and decreased pulmonary function. An enzyme immunoassay was used to measure immunoglobulin-(Ig)A and IgG antibodies against recombinant C. pneumoniae Hsp60 and human Hsp60 in a study group consisting of 24 cases of recently symptomatic asthma and 62 nonasthmatic controls. A strong (r=0.50) and significant (p<0.001) correlation was observed between C. pneumoniae and human Hsp60 IgA antibodies, but only C. pneumoniae Hsp60 IgA antibodies were significantly associated with asthma (p = 0.02). Pulmonary function, as measured by forced expiratory volume in one second, also inversely correlated (r = -0.23, p = 0.04) with the quantity of C. pneumoniae Hsp60 IgA antibodies, suggesting an association with the severity of pulmonary obstruction. By showing an association of Chlamydia pneumoniae heat shock protein 60 immunoglobulin A antibodies with asthma, the results support the hypothesis of an association between Chlamydia pneumoniae infection and asthma and support the need for further investigations on the role of heat shock protein 60 in the pathogenesis of asthma.     

Non-specific interstitial pneumonia and Chlamydia pneumoniae infection

Recently, the clinical features of non-specific interstitial pneumonia (NSIP) have been described. We hypothesize that recurrent infection caused by Chlamydia pneumoniae may play a role in the pathogenesis of NSIP. To prove this, we quantified serum IgA and IgG antibodies against C. pneumoniae using the enzyme linked-immunosorbent assay kit. The study included 15 patients diagnosed with NSIP, 20 patients with chronic obstructive pulmonary diseases (COPD) as disease group, and 27 control subjects. IgA antibody against C. pneumoniae was positive in 12 of 15 patients with NSIP, in 16 of 20 patients with COPD, and in 14 of 27 control subjects. IgG antibody against C. pneumoniae was positive in 14 of 15 patients with NSIP, in 17 of 20 patients with COPD, and in 16 of 27 control subjects. If the cut off value (mean +/- 2SD, index more than 3.0) was introduced, IgA and/or IgG antibodies against C. pneumoniae were positive in 8 of 15 patients with NSIP (53.3%), in 9 of 20 patients with COPD (45%), and in 2 of 27 control subjects (7.4%). These results suggest that infection of C. pneumoniae might play a role in the pathogenesis of NSIP.     

A prospective study of Chlamydia pneumoniae antibodies in children between 7 months and 8 years of age

To provide insight into the appearance and longitudinal course of Chlamydia pneumoniae antibodies in childhood, C. pneumoniae immunoglobulin G (IgG), IgA and, in selected children, IgM antibodies were measured annually in 199 healthy children, followed prospectively from age 7 months to age 8 y (number of samples 1225) using a commercial enzyme immunoassay kit. IgG antibodies to C. pneumoniae were common throughout the follow-up, and the values declined rapidly after apparent infections during early childhood. Of the 128 identified seroconversions, 94 were probably primary infections and 34 reinfections. IgM antibodies were detected in 28% of the samples that showed a clear increase in IgG. IgA antibodies were scarce before 2 y of age, but their proportion then increased gradually. At the ages of 7 and 8 y, 10% of the children had clearly positive IgG and IgA antibody values. Increases in IgG were not associated with clinical respiratory symptoms. This study shows that C. pneumoniae infections probably occur commonly already at an early age, and that the infections are often asymptomatic. Consecutive high IgG and IgA antibody concentrations at the ages of 7 and 8 y indicate that persistent seropositivity for both antibodies may already develop in young children.     

Influence of Chlamydia pneumoniae infection on aortic stiffness in healthy young men

Though Chlamydia pneumoniae infection has been implicated in the pathogenesis of atherosclerosis, its role in early atherogenesis has not been well elucidated. To clarify whether C. pneumoniae infection was related to early atherogenesis, we evaluated the association between serological detection of C. pneumoniae antibodies and aortic stiffness in 102 healthy young male volunteers (mean age 27.1+/-0.4 years). Serum C. pneumoniae IgA and IgG antibodies were measured by the enzyme-linked immunosorbent assay (ELISA). Aortic stiffness was estimated using the brachial-ankle pulse wave velocity (PWV). No significant differences were observed between IgA seropositive and seronegative groups with regard to conventional cardiovascular risk factors. However, the mean PWV value was significantly higher in the IgA seropositive group than the seronegative group. Analyses of subgroups according to C-reactive protein (CRP) level showed that those subjects with IgA seropositivity and a high CRP level (>0.17 mg/l) had the highest PWV values. Multivariate logistic regression analysis revealed that a combination of C. pneumoniae IgA seropositivity and a high CRP level was an independent predictor of high values of PWV. These results suggest that C. pneumoniae infection might contribute to early atherogenesis, which might be associated with chronic inflammation.     

Chlamydia pneumoniae infection and inflammation in adults with asthma

BACKGROUND: Chlamydia pneumoniae infection and immune response to the C. pneumoniae heat shock protein 60 (CpHsp60) have been suggested to be associated with asthma. OBJECTIVES: To study whether a slightly elevated C-reactive protein (CRP) level as a marker of low-grade systemic inflammation has a role in this association, we collected serum and sputum samples from 103 asthma patients with disease severity ranging from mild to moderate and from 30 healthy volunteers. METHODS: IgA and IgG antibodies to C. pneumoniae elementary bodies (CpEB) and CpHsp60 were measured by enzyme immunoassay. Serum CRP levels were measured with a rapid two-site ultra-sensitive assay based on time-resolved immunofluorometry. RESULTS: The asthma patients, especially those with moderate asthma, had higher serum IgA antibody levels to CpHsp60 than the healthy controls (test for trend, p = 0.05), whereas antibody levels to CpEB antigen did not differ between the study groups. CRP levels were higher in both asthma groups compared to the control group and moreover, the patients with moderate asthma had higher CRP levels than those with mild asthma (test for trend, p < 0.01). The subjects with a slightly elevated CRP level, defined as > or =1.8 mg/l, had higher CpEB IgA (p = 0.001), CpEB IgG (p = 0.008) and CpHsp60 IgA (p = 0.023) antibody levels in serum compared to the subjects with lower CRP levels. CONCLUSIONS: Slightly elevated CRP levels as a marker of low-grade systemic inflammation may be associated with C. pneumoniae infection in asthma patients.     

Association of seropositivity for antibody to Chlamydia-specific lipopolysaccharide and coronary artery disease in Japanese men

Recent studies suggest an association between Chlamydia pneumoniae infection and coronary artery disease (CAD). To examine this relationship in Japanese men, serum IgA and IgG antibodies to Chlamydia-specific lipopolysaccharide were measured by enzyme-linked immunosorbent assay in 507 patients with CAD and 200 age-matched controls. CAD patients were divided into (1) 269 patients with myocardial infarction (MI) and (2) 238 patients with chronic coronary heart disease (CCHD). Compared with the control group, the CAD group did not differ in the prevalences of both antibodies (IgA: 23.7 vs 18.0%, p=0.10; IgG: 52.7 vs 51.0%, p=0.6). The index of IgG antibody was not significantly different between CAD and control groups (median 1.19 vs 1.18, p=0.3), whereas the index of IgA antibody was significantly higher in CAD than control group (median 0.60 vs 0.46, p<0.0001). Compared with the control group, the MI group had a significantly higher prevalence of IgA antibody (28.6 vs 18.0%, p=0.007); however, there was no difference in the prevalence of IgG antibody (58.0 vs 51.0%, p=0.13). The CCHD group did not differ in the prevalences of both antibodies (IgA: 18.1 vs 18.0%, p=0.9; IgG: 45.6 vs 51.0%, p=0.2). After the adjustment for coronary risk factors, odds ratios (ORs) of seropositive antibodies for CAD were 1.59 [95% confidence interval (CI): 0.88-2.87, p=0.12] for IgA seropositivity and 0.92 (95%CI: 0.58-1.47, p=0.7) for IgG seropositivity in all cases. In the MI and control groups, ORs of seropositive antibodies for MI were 2.67 (95%CI: 1.32-5.38, p=0.007) for IgA seropositivity, and 1.36 (95%CI: 0.79-2.36, p=0.2) for IgG seropositivity. This study discovered that IgA antibody to Chlamydia was significantly associated with CAD, especially with MI, in Japanese Men and the findings suggest that chronic infection of Chlamydia may be linked to the pathogenesis of MI.     

Chlamydia pneumoniae infections

Chlamydia pneumoniae, an obligate intracellular human pathogen, causes infections of the respiratory tract. It is a significant cause of both lower and upper acute respiratory illnesses, including pneumonia, bronchitis, pharyngitis and sinusitis. Most respiratory infections caused by C. pneumoniae are mild or asymptomatic. Some studies have suggested a possible association of C. pneumoniae infection and acute exacerbations of asthma and chronic obstructive pulmonary disease (COPD). Seroepidemiological studies showing antibody prevalence rates in a range of 50 to 70% suggest that C. pneumoniae is widely distributed and that nearly everybody is infected with the agent at some time. C. pneumoniae can cause prolonged or chronic infections which may be due to persistence for months or years. These persistent infections have been implicated in the development of a number of chronic diseases including atherosclerosis, asthma and COPD. These persistent chlamydial infections can be established in vitro using several methods including cytokines, antibiotics and deprivation of certain nutrients. Despite differences in treatment, chlamydiae respond to form inclusions containing atypical reticulate bodies (RBs), which occasionally have been shown to be pleomorphic forms, termed aberrant form (AF). The AF is generally larger in diameter than typical RBs, and display a sparse densinometric appearance. In general, it is likely that this aberrant developmental step leads to the persistence of viable but nonculturable chlamydiae within infected cells over long periods. Removal of several stress factors described above results in the condensation of nuclei, the appearance of late proteins, and the production of viable, infectious elementary bodies (EBs). Most of the major sequelae of chlamydial disease are thought to arise from either repeated or persistent chlamydial infection of an individual. The persistence would allow constant presentation to the individual immune response of these potentially deleterious immune targets. Since repeated infection can certainly be documented in many clinical settings, persistence is thought to also play a role.