Development of chronic conjunctivitis with scarring and pannus, resembling trachoma, in guinea-pigs

A Review on Chlamydial Diseases in Animals: Still a Challenge for Pathologists?

Chlamydiae have a worldwide distribution causing a wide range of diseases in human hosts, livestock, and companion animals as well as in wildlife and exotic species. Moreover, they can persist in their hosts as asymptomatic infections for extended periods of time. The introduction of molecular techniques has revolutionized the Chlamydia field by expanding the host range of known chlamydial species but also by discovering new species and even new families of bacteria in the broader order Chlamydiales. The wide range of hosts, diseases, and tissues affected by chlamydiae complicate the diagnosis such that standard diagnostic approaches for these bacteria are rare. Bacteria of the Chlamydiales order are small and their inclusions are difficult to detect by standard microscopy. With the exception of avian and ovine chlamydiosis, macroscopic and/or histologic changes might not be pathognomic or indicative for a chlamydial infection or even not present at all. Moreover, detection of chlamydial DNA in specimens in the absence of other methods or related pathological lesions questions the significance of such findings. The pathogenic potential of the majority of recently identified Chlamydia-related bacteria remains largely unknown and awaits investigation through experimental or natural infection models including histomorphological characterization of associated lesions. This review aims to summarize the historical background and the most important developments in the field of animal chlamydial research in the past 5 years with a special focus on pathology. It will summarize the current nomenclature, present critical thoughts about diagnostics, and give an update on chlamydial infections in domesticated animals such as livestock, companion animals and birds, as well as free-ranging and captive wild animals such as reptiles, fish, and marsupials.

The effect of infectious dose on humoral and cellular immune responses in Chlamydophila caviae primary ocular infection

Following infection, the balance between protective immunity and immunopathology often depends on the initial infectious load. Several studies have investigated the effect of infectious dose; however, the mechanism by which infectious dose affects disease outcomes and the development of a protective immune response is not known. The aim of this study was to investigate how the infectious dose modulates the local and systemic humoral and the cellular immune responses during primary ocular chlamydial infection in the guinea pig animal model. Guinea pigs were infected by ocular instillation of a Chlamydophila caviae-containing eye solution in the conjunctival sac in three different doses: 1×10², 1×10⁴, and 1×10⁶ inclusion forming units (IFUs). Ocular pathology, chlamydial clearance, local and systemic C. caviae-specific humoral and cellular immune responses were assessed. All inocula of C. caviae significantly enhanced the local production of C. caviae-specific IgA in tears, but only guinea pigs infected with the higher doses showed significant changes in C. caviae-specific IgA levels in vaginal washes and serum. On complete resolution of infection, the low dose of C. caviae did not alter the ratio of CD4⁺ and CD8⁺ cells within guinea pigs’ submandibular lymph node (SMLN) lymphocytes while the higher doses increased the percentages of CD4⁺ and CD8⁺ cells within the SMLN lymphocytes. A significant negative correlation between pathology intensity and the percentage of CD4⁺ and CD8⁺ cells within SMLN lymphocyte pool at selected time points post-infection was recorded for both 1×10⁴, and 1×10⁶ IFU infected guinea pigs. The relevance of the observed dose-dependent differences on the immune response should be further investigated in repeated ocular chlamydial infections.

Infectious dose and repeated infections are key factors influencing immune response characteristics in guinea pig ocular chlamydial infection

The aim of this study was to determine whether infectious dose of Chlamydia caviae after repeated infections influences the immunological responses and subsequent clearance of pathogen at the ocular surface of guinea pigs. Animals were infected three times via the conjunctiva at six- and twelve-week intervals by applying either 1 × 10(4) or 1 × 10(6) inclusion-forming units (IFUs) of C. caviae. Ocular pathology, infection course, C. caviae-specific serum IgG levels and their capacity to bind and neutralize infection ex vivo were assessed. Animals infected with 1 × 10(4) IFUs had completely diminished ocular infection and pathology after the 2nd infection with increased levels of C. caviae-specific serum IgG and their effective capacity to bind and neutralize C. caviae. Only partial protection was observed in animals infected with 1 × 10(6) IFUs after the 2nd and 3rd infections. Our findings show that full protection was observed in animals repeatedly infected with the lower dose. The lower dose appeared not to compromise the host immune system, thereby enabling fast clearance of the pathogen and the establishment of competent neutralizing antibodies.

Essential role for neutrophils in pathogenesis and adaptive immunity in Chlamydia caviae ocular infections

Trachoma, the world's leading cause of preventable blindness, is produced by chronic ocular infection with Chlamydia trachomatis, an obligate intracellular bacterium. While many studies have focused on immune mechanisms for trachoma during chronic stages of infection, less research has targeted immune mechanisms in primary ocular infections, events that could impact chronic responses. The goal of this study was to investigate the function of neutrophils during primary chlamydial ocular infection by using the guinea pig model of Chlamydia caviae inclusion conjunctivitis. We hypothesized that neutrophils help modulate the adaptive response and promote host tissue damage. To test these hypotheses, guinea pigs with primary C. caviae ocular infections were depleted of neutrophils by using rabbit antineutrophil antiserum, and immune responses and immunopathology were evaluated during the first 7 days of infection. Results showed that neutrophil depletion dramatically decreased ocular pathology, both clinically and histologically. The adaptive response was also altered, with increased C. caviae-specific IgA titers in tears and serum and decreased numbers of CD4(+) and CD8(+) T cells in infected conjunctivae. Additionally, there were changes in conjunctival chemokines and cytokines, such as increased expression of IgA-promoting interleukin-5 and anti-inflammatory transforming growth factor β, along with decreased expression of T cell-recruiting CCL5 (RANTES). This study, the first to investigate the role of neutrophils in primary chlamydial ocular infection, indicates a previously unappreciated role for neutrophils in modulating the adaptive response and suggests a prominent role for neutrophils in chlamydia-associated ocular pathology.

Trachoma

Trachoma is a keratoconjunctivitis caused by ocular infection with Chlamydia trachomatis. Repeated or persistent episodes lead to increasingly severe inflammation that can progress to scarring of the upper tarsal conjunctiva. Trichiasis develops when scarring distorts the upper eyelid sufficiently to cause one or more lashes to abrade the cornea, scarring it in turn and causing blindness. Active trachoma affects an estimated 84 million people; another 7.6 million have end-stage disease, of which about 1.3 million are blind. Trachoma should stand on the brink of extinction thanks to a 1998 initiative launched by WHO--the Global Elimination of Trachoma by 2020. This programme advocates control of trachoma at the community level with four inter-related population-health initiatives that form the SAFE strategy: surgery for trichiasis, antibiotics for active trachoma, facial cleanliness, and environmental improvement. Evidence supports the effectiveness of this approach, and if current world efforts continue, blinding trachoma will indeed be eliminated by 2020.

Clinical examination and laboratory tests for estimation of trachoma prevalence in a remote setting: what are they really telling us?

Worldwide, an estimated 84 million people have active trachoma and 7.6 million people have trachomatous trichiasis. WHO's SAFE strategy is an effective tool in the worldwide effort to eliminate blinding trachoma, but its institution and monitoring requires a simple, reliable, and cost-effective method to detect disease. To date, clinical examination has provided the main method of diagnosis. Detection of Chlamydia trachomatis with nucleic acid amplification tests does not always correlate well with clinical findings, which has prompted the suggestion that these methods should replace clinical examination. However, a review of the research carried out in animals and human beings suggests the relation between laboratory tests and clinical examination is due to the kinetics of trachoma and not to an inherent problem in either detection system. Given the increased difficulties of using laboratory tests in parts of the world where trachoma is endemic, we should not abandon clinical grading as a tool to assess the need for, and the effectiveness of, trachoma intervention programmes.

Secretion of proinflammatory cytokines by epithelial cells in response to Chlamydia infection suggests a central role for epithelial cells in chlamydial pathogenesis

Chlamydia species infect epithelial cells at mucosal surfaces, and are major causes of sexually transmitted diseases. Infection is characterized by inflammation which is exacerbated upon reinfection, ultimately leading to tissue damage and scarring. Although central for the development of disease manifestations, little is known about the mechanisms that initiate and sustain the inflammatory response to Chlamydia. Infection of cervical and colonic epithelial cells with Chlamydia trachomatis and Chlamydia psittaci is shown in the present studies to upregulate mRNA expression and secretion of the proinflammatory cytokines IL-8, GRO alpha, GM-CSF, and IL-6. In contrast to the rapid, but transient, cytokine induction following infection with other invasive bacteria, the epithelial cytokine response to Chlamydia was delayed until 20-24 h after infection, persisted throughout the chlamydial growth cycle (2-4 d), and required bacterial protein synthesis. Moreover, epithelial cell lines and primary endocervical epithelial cells released IL-1alpha after Chlamydia infection, and increased secretion of the proinflammatory cytokines could be inhibited by anti-IL-1alpha. This suggests that IL-1alpha, released following lysis of infected epithelial cells, may amplify the inflammatory response by stimulating additional cytokine production by noninfected neighboring cells. These findings suggest a novel pathophysiologic concept wherein the acute host response to Chlamydia at mucosal surfaces is primarily initiated and sustained by epithelial cells, the first and major targets of chlamydial infection.

Recurrent chlamydial infections increase the risks of hospitalization for ectopic pregnancy and pelvic inflammatory disease

OBJECTIVE

We examined whether the risks of hospitalization for ectopic pregnancy and pelvic inflammatory disease increase with increasing numbers of chlamydial infections.

STUDY DESIGN

A retrospective cohort design was used to evaluate the risks of hospitalization for ectopic pregnancy or pelvic inflammatory among 11,000 Wisconsin women who had one or more chlamydial infections between 1985 and 1992. Logistic regression was used to evaluate the strength of association between recurrent infection and sequelae.

RESULTS

After adjustment in multivariate analyses, we observed elevated risks of ectopic pregnancy among women who had two (odds ratio 2.1, 95% confidence interval 1.3 to 3.4) and three or more chlamydial infections (odds ratio 4.5, 95% confidence interval 1.8 to 5.3). These groups were also at increased risk for pelvic inflammatory (two infections: odds ratio 4.0, 95% confidence interval 1.6 to 9.9; three or more infections: odds ratio 6.4, 95% confidence interval 2.2 to 18.4).

CONCLUSIONS

A unique prevention opportunity occurs at the diagnosis of any chlamydial infection because women with subsequent recurrences are at increased risk for reproductive sequelae.

Cytotoxic-T-lymphocyte-mediated cytolysis of L cells persistently infected with Chlamydia spp

Persistent chlamydial infections have been proposed as a means whereby chlamydiae evade immune resolution of infection. Such a mechanism would require evasion not only of the humoral immune responses but also of cell-mediated immune responses. We hypothesized that if such a mechanism is important, persistently infected cells should not be recognized by cytotoxic T cells. Persistent infections were simulated in vitro by treatment of Chlamydia trachomatis- or Chlamydia psittaci-infected cells with gamma interferon (IFN-gamma), penicillin, or tryptophan depletion. Cultures were examined for induction of a chlamydial stress response (measured by transcription of groesl RNA) and for the effects on viability, infectivity, morphology, and immune recognition. Although both IFN-gamma and penicillin induced aberrant chlamydial morphology and growth, we did not find evidence that these treatments elicited a classical stress response. In addition, T-cell-mediated lysis of Chlamydia-infected target cells treated with IFN-gamma or penicillin or grown in tryptophan-deficient media was examined. The immune cell-mediated lysis of these treated infected cells demonstrated that despite the effects of these compounds on chlamydial growth and development, the infected cells continued to be efficiently recognized and killed by cytotoxic T cells. Thus, it seems unlikely that these in vitro models of persistence represent functional mechanisms to evade immune clearance.

A 28 kDa major immunogen of Chlamydia psittaci shares identity with Mip proteins of Legionella spp. and Chlamydia trachomatis-cloning and characterization of the C. psittaci mip-like gene

Chlamydia psittaci strain guinea-pig inclusion conjunctivitis (GPIC) produces a self-limiting ocular infection of guinea-pigs, and this condition is a representative animal model of ocular chlamydial disease. Convalescent guinea-pigs, which are resistant to reinfection, produce antibodies to several elementary-body proteins, including an uncharacterized antigen of 28 kDa. Convalescent guinea-pig sera were used to identify, from a lambda expression library, two overlapping GPIC genomic clones that produced the 28 kDa antigenic protein. Nucleotide sequence analysis revealed that the gene coding for the 28 kDa protein was similar to the mip (macrophage infectivity potentiator) genes from Legionella pneumophila and Chlamydia trachomatis. The GPIC gene and its product were accordingly designated mip and Mip, respectively. Analysis of the regions flanking mip identified three tightly linked open reading frames coding for predicted products with sequence similarity to asparagine tRNA ligase (AspS), rRNA methylase (SpoU), and thioredoxin (TrxA). The arrangement of these genes in GPIC was aspS-mip-spoU-trxA. Sequence analysis of PCR products produced using genomic DNA from an ovine abortion strain of C. psittaci and from C. trachomatis strain LGV-434 demonstrated that the arrangement of mip, spoU and trxA is common among these chlamydiae.

Repeated and persistent infection with Chlamydia and the development of chronic inflammation and disease

Chlamydia trachomatis is an important human pathogen that mediates disease processes capable of inflicting permanent damage. Aggressive inflammatory responses to repeated infections, and to a persistent form of this intracellular bacterium, are thought to initiate the pathogenic events that lead to the debilitating sequelae of blinding trachoma and infertility.

Risk factors for recurrent Chlamydia trachomatis infections in women

OBJECTIVE

We evaluated risk factors for recurrent Chlamydia trachomatis infections in women.

STUDY DESIGN

We used a retrospective cohort design to examine predictors of recurrent infection in the 38,866 female residents of Wisconsin whose first reported C. trachomatis infection occurred between 1985 and 1989.

RESULTS

Young age at first reported infection was the strongest predictor of recurrent C. trachomatis infection, after adjustment for covariates. Adolescents < 15 years old had an eightfold increased risk, those 15 to 19 years old had a fivefold increased risk, and women 20 to 29 years old had a twofold increased risk of recurrent C. trachomatis infection, compared with that among women 30 to 44 years old. In 54% of those aged < 15 at initial infection and 30% of those aged 15 to 19, recurrence developed. Other characteristics associated with recurrence included black race, residence in Milwaukee County, coinfection with gonorrhea, and past sexually transmitted diseases; receiving care in a family-planning clinic appeared protective.

CONCLUSIONS

Implementation of strategies to reduce the markedly elevated risk of recurrent chlamydia infections is urgently needed in female adolescents.

Protein antigens of Chlamydia psittaci present in infected cells but not detected in the infectious elementary body

Ocular infection of guinea pigs with the guinea pig inclusion conjunctivitis (GPIC) strain of Chlamydia psittaci produces a clinical condition representative of acute chlamydial conjunctivitis in humans. Guinea pigs which had recovered from two challenges with GPIC were used as a source of sera for the identification of antigens present in GPIC-infected tissue culture cells but absent in the infectious elementary body (EB). Immunoblots of lysates of infected HeLa cells probed with the convalescent-phase sera identified protein antigens of 22, 34, and 52 kDa (p22, p34, and p52, respectively) that were not detected in lysates of purified EB or in uninfected HeLa cells. Protein p22 was also not detected in lysates of purified reticulate bodies. Immunoblotting of lysates of HeLa cells infected with other chlamydiae demonstrated that the antigenicity of p22 and p34 was subspecies specific. Immunoblotting was also used to detect p22 and p34 in lysates of the conjunctivae of infected guinea pigs. Adsorption of convalescent-phase sera with GPIC EB produced a reagent with dominant reactivity toward p22, p34, and a 28-kDa EB protein. Immunofluorescent staining of GPIC-infected HeLa cells demonstrated that these adsorbed sera labeled the inclusion and inclusion membrane, with no apparent reactivity toward EB or reticulate bodies. Collectively, these data identify non-EB chlamydial components which may be released into the inclusion during intracellular growth.

Chlamydia trachomatis pneumonia induces in vivo production of interleukin-1 and -6

Cytokine induction during Chlamydia trachomatis pneumonia may alter the pathogenesis or course of disease. We examined interleukin-1 (IL-1) and IL-6 production by measuring mRNA and bioactivity in murine lungs. mRNA and bioactivity for IL-1 alpha, IL-1 beta, and IL-6 increased after Chlamydia infection. These cytokines may be important in regulating host defenses against C. trachomatis.

The antigenic specificity of the humoral immune response to primary and repeated ocular infections of the guinea pig with the GPIC agent (Chlamydia psittaci)

The antigenic specificity of the humoral immune response in guinea pigs to primary and repeated ocular infections with the guinea pig inclusion conjunctivitis (GPIC) chlamydial agent was analysed using microbiological, serological and Western blotting techniques. The results indicate that although there was a response to many minor polypeptide antigens, there was a marked lack of reactivity to the major outer membrane protein (MOMP), particularly following reinfection of guinea pigs. It is suggested that, lack of a good antibody response to the MOMP, may be one of the reasons why guinea pigs are susceptible to repeated ocular infections with this chlamydial agent.

Chlamydial disease pathogenesis. The 57-kD chlamydial hypersensitivity antigen is a stress response protein

Chlamydia trachomatis infection of humans is commonly a localized inflammation that can result in infertility, blindness, and perhaps arthritis. The pathogenic process(es) that cause these sequelae are thought to be immunological. A 57-kD protein that is common among Chlamydia elicits ocular inflammation when introduced onto the conjunctivae of guinea pigs or nonhuman primates previously sensitized by chlamydial infection. This protein is thought to mediate the immunopathology that follows chlamydial infection. To more thoroughly characterize this chlamydial component, we cloned its gene from a C. psittaci strain and identified a particular recombinant that produced the 57-kD polypeptide. The recombinant gene product was immunoreactive with a monospecific anti-57-kD serum, and elicited an ocular inflammation similar to that produced by the 57-kD antigen isolated from chlamydiae. Sequencing identified two ORFs that encode polypeptides of 11.2 and 58.1 kD and are co-transcribed. These two polypeptides show homology with Escherichia coli groE and Coxiella burnetii htp heat-shock proteins. Striking homology (greater than 50%) was found between the 57-kD protein and the HtpB, GroEL, 65-k Mycobacterium tuberculosis and Hsp60 proteins. Thus, the 57-kD chlamydial protein, previously implicated as mediating a deleterious immunologic response to chlamydial infections, is a stress-induced protein similar to those that occur universally in both prokaryotic and eukaryotic organisms.

Chlamydia trachomatis-induced production of interleukin-1 by human monocytes

Human diseases caused by the intracellular bacterium Chlamydia trachomatis include genital tract infections and blinding trachoma. Chlamydial infections are characterized by chronic inflammation and scarring, and development of such complications is thought to be immunologically mediated. In this study, we show that coculture of C. trachomatis (serovar L2) with human blood monocytes induced the production of interleukin-1 (IL-1), an important mediator of inflammation, tissue remodeling, and scarring. IL-1 was produced in response to UV-inactivated elementary bodies containing from 0.1 to 50 micrograms of protein per ml, with a maximal response at 5 to 10 micrograms/ml. IL-1 activity was detected by 6 h of incubation and was maximal by 24 h. Peak levels were maintained throughout 96 h of incubation. Rabbit antibody to human IL-1(alpha + beta) effectively neutralized the thymocyte-stimulating activity of the supernatants. The apparent molecular weight of chlamydia-induced IL-1 was 16,000, as determined by gel filtration on a Bio-Gel P-60 column. Isoelectric focusing yielded two peaks of activity, with pIs of 5.5 and 6.9. Neutralization studies with antisera against human IL-1 alpha and IL-1 beta showed that the acidic and neutral peaks corresponded to IL-1 alpha and IL-1 beta, respectively, with IL-1 beta predominating. Heat-killed chlamydiae, which are not internalized by monocytes, were effective IL-1 inducers, indicating that phagocytosis was not required for IL-1 induction. Purified C. trachomatis lipopolysaccharide was also an effective IL-1 inducer, suggesting that the response to intact organisms may be largely a response to chlamydial lipopolysaccharide. Finally, purified chlamydial major outer membrane protein induced low but detectable IL-1 activity.

Chlamydial disease pathogenesis. Ocular hypersensitivity elicited by a genus-specific 57-kD protein

Recurrent or persistent infections with Chlamydia trachomatis are thought to provide the antigenic stimulus for the chronic inflammation associated with blinding trachoma. We used the guinea pig model of inclusion conjunctivitis to identify chlamydial antigens that may be involved in this deleterious immune response. We purified from chlamydial elementary bodies a genus-specific 57-kD protein that elicited an ocular hypersensitivity response when placed topically onto the conjunctiva of ocular immune guinea pigs. This response was characterized by a predominantly mononuclear macrophage and lymphocyte cellular infiltrate of the submucosal epithelium. The clinical and histological findings were consistent with those of a delayed hypersensitivity response. These data demonstrated that the 57-kD chlamydial protein was a potent stimulator of ocular delayed hypersensitivity. Our findings may be critical to understanding the pathogenesis of the debilitating chlamydial diseases associated with chronic inflammation, such as trachoma and many urogenital syndromes.

Management and prevention of ocular viral and chlamydial infections

A majority of cases of preventable and/or curable ocular morbidity and blindness are caused by ocular infections. They may account for 70 to 90% of all ocular morbidity seen by family doctors, general practitioners, health centers, and local ophthalmologists in both developed and developing countries. Unfortunately, most health authorities and doctors, including ophthalmologists, consider these diseases to be of little or no importance because they are not fully aware of the high prevalence of these infections and the blinding sequelae which may occur following incorrect diagnosis and treatment. Also, they are not aware of the social and economic impact of these infections in the absence of proper management and implementation of preventive measures. In this review, we examine present knowledge of chlamydial and common viral ocular infections. We discuss the problems of diagnosis, management, and prevention and propose solutions relevant to developed and developing countries.

Susceptibility to reinfection after a primary chlamydial genital infection

Female guinea pigs which had been infected genitally with the agent of guinea pig inclusion conjunctivitis were challenged at various times after infection with fresh inocula to determine the duration of immunity resulting from the primary infection. At 30 days after infection, most guinea pigs were resistant to reinfection, as indicated by the inability to isolate chlamydiae from cervical swabs. However, at 77, 155, and 294 days, all animals became reinfected, although the course of the infection was abbreviated and of lower intensity. When various immune parameters were examined, a decrease in antibodies in both serum (immunoglobulin G [( IgG]) and genital secretions (IgA, IgG) was observed after 30 days. A decrease in antibodies to the major outer membrane protein and an 84K component was noted in serum. In genital secretions, IgA antibodies to all major chlamydial components declined markedly after 30 days. Cell-mediated immunity as measured by proliferation of peripheral blood lymphocytes to guinea pig inclusion conjunctivitis antigen also was at a peak response 30 days after infection and decreased thereafter. Thus, loss of complete immunity could not be associated with a particular immune parameter. When genital secretions were examined 14 days after the challenge infection, IgA antibody levels to the lipopolysaccharide and 61K protein components had increased in intensity, whereas other antibodies were relatively low. In addition, complete immunity to a third infection was not increased in duration when animals had recovered from two previous genital infections.

Experimental chlamydial keratitis in rabbits. Correlation with chlamydia infected McCoy tissue culture cells

Rabbit corneas were inoculated three times at weekly intervals with the agent of chlamydia trachomatis using the scratch method. Specimens of the corneal epithelium were obtained using the replica technique on the 1st, 2nd, 3rd and 4th day after each inoculation and at two weeks after the last inoculation. The development of chlamydial inclusions and the inflammatory cell response were monitored using Giemsa stain, acridine orange stain and direct immunofluorescent technique. Primary inoculation produced mild clinical disease associated cytologically with polymorphonuclear leucocytic cellular inflammatory response. Repeated inoculations produced more severe disease associated clinically with pannus formation and cytologically with the presence of lymphocytes and Leber cells in addition to polymorphonuclear leucocytes. Halberstaedter Prowazek inclusion bodies were detected in all the specimens. Additional intracytoplasmic and intranuclear inclusions of different morphological appearances were present. The cytological findings detected in the corneal epithelium of rabbits were correlated with the findings in McCoy tissue culture cells inoculated with chlamydia trachomatis.

The microbial epidemiology of trachoma

Detailed longitudinal studies of the microbiology of endemic trachoma in field situations have provided useful information concerning the epidemiology of this blinding disease. This knowledge should be of particular value for the further development of diagnostic techniques, and for the design of future trachoma control programs.

Responses to tuberculin in the guinea-pig eye as a model of cell mediated immune responses in the external eye

The clinical and histological findings in an animal model of ocular cell mediated immune responses are described. These were evoked in sensitised guinea-pigs by dropping tuberculin into the conjunctival sac or injecting it under the palpebral conjunctiva. When tuberculin was dropped into the conjunctival sac, higher doses were required to evoke a strong response than when it was injected subconjunctivally. When high doses of antigen were used for challenge, a mild response was observed in unchallenged contralateral eyes. The cellular response at low doses of tuberculin consisted predominantly of mononuclear cells. At higher doses the cellular infiltrate was more pronounced, and polymorphonuclear cells tended to predominate 24 hours after challenge, while at 48 hours mononuclear cells predominated.

Chlamydial pelvic infection in cats: a model for the study of human pelvic inflammatory disease

The inoculation of feline keratoconjunctivitis agent (Chlamydia psittaci) directly into the oviducts of eight cats produced an acute disease that was characterised by hyperaemia of the tissue and pronounced polymorphonuclear leucocyte infiltration of the epithelium and subepithelial stroma. The lumens of the tubes contained exudates of desquamated epithelial cells and polymorphonuclear leucocytes. After about 30 days the disease subsided leaving chronic inflammation with the tissue infiltrated with both polymorphonuclear and mononuclear cells. Fimbrial scarring and formation of adhesions were apparent by 40 to 50 days after inoculation. Chlamydiae were isolated in McCoy cell cultures from most cats, in one for as long as 51 days after inoculation. Inclusions were seen in histological sections or smears of cells from the fimbriae of four of the eight cats. Six of the eight cats developed antibodies to feline keratoconjunctivitis agent, which were detectable as early as 12 days after inoculation. To facilitate repeated examinations of the cats' fallopian tubes, techniques for laparoscopy in cats and for the collection of specimens while under laparoscopic examination were developed. The latter technique has since been applied successfully in man.

A study of inclusion conjunctivitis in newborn and young adults. Clinical picture, culture, conjunctival scrapings and cytology of the tear fluid in 12 cases

Chlamydia trachomatis were cultured from the conjunctiva of 8 newborn babies and 4 young adults' (age 20-30 years) affected with acute or therapy-resistant chronic conjunctivitis. The newborn had acute purulent conjunctivitis noticed 4 to 12 days after birth. Five of them had been treated with topical chloramphenicol without effect before the diagnosis was made. They responded well to topical tetracycline ointment, but 3 relapsed. Two developed chronic conjunctivitis and respiratory tract infection, one under long time topical chloramphenicol treatment. The adults had a chronic, in 3 unilateral, conjunctivitis with pronounced follicularly (3) or papillary (1) conjunctival hypertrophy. Different degrees of pseudoptosis, micropannus and corneal infiltrates (in 3) were noticed. In the tear fluid, the quantitative pipette method revealed inflammation shown by neutrophilic granulocytes and lymphocytes with an appreciable predominance of the former in the newborn, while less so in the adults. In the newborn the diagnosis was easily made by culture and by demonstrating inclusions bodies in Giemsa-stained conjunctival scrapings. In the adults the methods were less sensitive. A negative response to one culture does not preclude chlamydial infection.

Chlamydial genital infection in prostitutes in Iran

The prevalence of chlamydial genital infection was studied in 177 prostitutes in Iran; 100 in Teheran and 77 in the port of Bandar Abbas. Chlamydia trachomatis was isolated in eight (6.9%) of 116 patients with valid cultures. Type-specific antibodies were found against C trachomatis serotypes D to K (genital serotypes) in 94.2% and against serotypes A to C (trachoma serotypes) in 2% of the prostitutes. Type-specific IgM at a titre of greater than or equal to 8, indicating current infection, was found in 29.2%, whereas type-specific IgG at a titre greater than or equal to 64, suggesting a current or recent infection, was present in 71.5%. The lower chlamydial isolation rate in these women may have been due to previous treatment with antichlamydial drugs and because of immune responses resulting from repeated reinfection with chlamydiae. The results indicate that in Iran prostitutes are commonly infected with C trachomatis and are probably a major reservoir of chlamydial genital infection.

Ocular and dermal delayed hypersensitivity reactions in guinea-pigs following infection with guinea-pig inclusion conjunctivitis agent (Chlamydia psittaci)

Guinea-pigs which had been sensitized to guinea-pig inclusion conjunctivitis agent by ocular infection, were given ocular and dermal challenges with a range of doses of agent. Ocular delayed-type hypersensitivity responses were elicited by a wide range of doses. Such responses were associated with the presence of chlamydial inclusions and inflammatory cells. The EID50 for ocular reinfection was only slightly higher than that for primary ocular infection. Dermal delayed-type hypersensitivity reactions were produced only when high doses of agent were used. The relevance of these observations to human chlamydial eye disease is discussed.

Guinea-pig inclusion conjunctivitis as a model for the study of trachoma: clinical, microbiological, serological, and cytological studies of primary infection

The course of primary ocular infection with guinea-pig inclusion conjunctivitis agent was followed in 2 groups of animals. One group of fully grown animals was repeatedly scraped; the other of small animals was used on 1 occasion only and scraped after clinical examination. The intensity of conjunctival inflammation was measured, conjunctival scrapings were taken, and the numbers of polymorphonuclear cells, mononuclear cells, and epithelial cells containing chlamydial inclusions were counted, and the level of antibodies in serum was measured. It was found that inflammation of the conjunctiva lasted for about 30 to 40 days, and the clinical features (oedema, hyperaemia, papillary reaction) were very similar in the 2 groups. Inclusions and polymorphonuclear cells were found for up to 21 days, and mononuclear cells were found on days 7 to 25. Serum antibodies were first detected on day 10 and reached a peak on day 21. The intensity of inflammation was significantly higher on day 2 in the animals which had been scraped. After this the severity of the inflammation and the course of disease were similar in the 2 groups.