Cell-mediated immune responses in owl monkeys (Aotus trivirgatus) with trachoma to soluble antigens of Chlamydia trachomatis.
(1/94)
The first temporal study of the cell-mediated immune responses (CMI) following ocular infections with Chlamydia trachomatis is presented. We examined the CMI of owl monkeys infected with trachoma to soluble antigens of C. trachomatis by leucocyte migration inhibition (LIF) and delayed hypersensitivity skin testing. Delayed hypersensitivity of a systemic nature developed after a local eye infection in owl monkeys; clearance of inclusions from conjunctival cells coincided with the onset of this response. The association of eye secretion and circulating antibodies with recovery from primary infection was not so striking. Both cellular and humoral immune responses persisted for at least 2 months, at which time all test animals were completely resistant to re-infection. The elicitation of cell-mediated immune reactions with solubilized chlamydial antigens may permit the isolation of specific antigens involved in the generation of protective immunity in the owl monkey model. (+info)
Conjunctivitis caused by a swine Chlamydia trachomatis-like organism in gnotobiotic pigs.
(2/94)
The objective of this study was to determine whether a chlamydial strain recovered from growing and finishing swine with conjunctivitis or keratoconjunctivitis could cause the same infections in gnotobiotic pigs. The strain shares biological characteristics with Chlamydia trachomatis. After propagation in Vero cells and preparation of the inoculum (10(7) inclusion-forming units/ml), chlamydial strain H7 was instilled into the ventral conjunctival sac (0.15 ml/sac) of 12 anesthetized 3-day-old gnotobiotic piglets. Four age-matched gnotobiotic piglets were anesthetized and sham infected with uninfected cell culture lysates. None of the principal piglets developed clinical symptoms of conjunctivitis or keratoconjunctivitis. Principal piglets necropsied 7 days postinfection (DPI) had histologic lesions of mild or moderate conjunctivitis; immunohistochemical evaluation revealed chlamydial antigen in conjunctival epithelium. A majority of principal piglets necropsied at 14-28 DPI had histologic lesions of mild conjunctivitis, but chlamydial antigen was not detected by immunohistochemistry. The results indicated that chlamydial strain H7 can cause mild or occasionally moderate conjunctivitis in gnotobiotic pigs, but the conjunctival infection is asymptomatic. (+info)
Microvirus of chlamydia psittaci strain guinea pig inclusion conjunctivitis: isolation and molecular characterization.
(3/94)
The authors report the isolation and molecular characterization of a bacteriophage, φCPG1, which infects CHLAMYDIA: psittaci strain Guinea pig Inclusion Conjunctivitis. Purified virion preparations contained isometric particles of 25 nm diameter, superficially similar to spike-less members of the φX174 family of bacteriophages. The single-stranded circular DNA genome of φCPG1 included five large ORFs, which were similar to ORFs in the genome of a previously described CHLAMYDIA: bacteriophage (Chp1) that infects avian C. psittaci. Three of the ORFs encoded polypeptides that were similar to those in a phage infecting the mollicute Spiroplasma melliferum, a pathogen of honeybees. Lesser sequence similarities were seen between two ORF products and the major capsid protein of the φX174 coliphage family and proteins mediating rolling circle replication initiation in phages, phagemids and plasmids. Phage φCPG1 is the second member of the genus CHLAMYDIAMICROVIRUS:, the first to infect a member of a CHLAMYDIA: species infecting mammals. Similarity searches of the nucleotide sequence further revealed a highly conserved (75% identity) 375 base sequence integrated into the genome of the human pathogen Chlamydia pneumoniae. This genomic segment encodes a truncated 113 residue polypeptide, the sequence of which is 72% identical to the amino-terminal end of the putative replication initiation protein of φCPG1. This finding suggests that C. pneumoniae has been infected by a phage related to φCPG1 and that infection resulted in integration of some of the phage genome into the C. pneumoniae genome. (+info)
Chlamydiae as agents of sexually transmitted diseases.
(4/94)
Chlamydiae are being increasingly recognized as an important cause of human disease. The known geographical distribution of lymphogranuloma venereum and the role of chlamydiae as agents of sexually transmitted diseases are reviewed. The presence of chlamydiae in the urethra and the cervix, and their etiological relationship to genital infections, first recognized in connexion with ocular infections, have been proved in a number of studies in selected populations in a few countries. Chlamydiae appear to be the most important agent of nongonococcal urethritis, which in some cases appears now to be more frequent than gonococcal urethritis. In addition to their association with cervicitis, chlamydiae appear also to be fairly frequent in the cervix of apparently normal, asymptomatic, and sexually active women. The role of chlamydiae as agents of other human diseases still requires to be clarified. The organisms have been found in association with pelvic inflammatory disease, neonatal pneumonia, pharyngitis, and otitis. There is need for additional studies in view of the fact that effective chemotherapy is available. An outline is given of laboratory methods that may be useful for the diagnosis of chlamydial infections. (+info)
The effect of cyclophosphamide on the recovery from a local chlamydial infection. Guinea-pig inclusion conjunctivitis (GPIC).
(5/94)
The immune mechanism involved in the recovery from and resistance to guinea-pig inclusion conjunctivitis (GPIC) was studied. Guinea-pigs were injected with a dose of cyclophosphamide (CY) (300 mg/kg wt) that inhibits antibody synthesis. Such treatment was shown to produce a cellular depletion in the B-cell area without producing an appreciable change in the T-cell area of the spleen and lymph nodes. CY treatment markedly delayed the appearance of secretory immunoglobulin A antibody to GPIC in the tears, and other classes of antibodies to GPIC and sheep erythrocyte in the serum. Furthermore, recovery from infection was impaired and a subsequent injection of CY prolonged the duration of infection. The results indicate that B cells may play an important role in the control of this infection. (+info)
Role of Bcl-2 family members in caspase-independent apoptosis during Chlamydia infection.
(6/94)
Infection with an obligate intracellular bacterium, the Chlamydia trachomatis lymphogranuloma venereum (LGV/L2) strain or the guinea pig inclusion conjunctivitis serovar of Chlamydia psittaci, leads to apoptosis of host cells. The apoptosis is not affected by a broad-spectrum caspase inhibitor, and caspase-3 is not activated in infected cells, suggesting that apoptosis mediated by these two strains of Chlamydia is independent of known caspases. Overexpression of the proapoptotic Bcl-2 family member, Bax, was previously shown to induce caspase-independent apoptosis, and we find that Bax is activated and translocates from the cytosol to the mitochondria in C. psittaci-infected cells. C. psittaci-induced apoptosis is inhibited in host cells overexpressing Bax inhibitor-1 and is inhibited through overexpression of Bcl-2, which blocks both caspase-dependent and -independent apoptosis. As Bax and mitochondria are ideally located to sense stress-related metabolic changes emanating from the interior of an infected cell, it is likely that Bax-dependent apoptosis may also be observed in cells infected with other intracellular pathogens. (+info)
Trachoma and ocular Chlamydia trachomatis were not eliminated three years after two rounds of mass treatment in a trachoma hyperendemic village.
(7/94)
PURPOSE: The World Health Organization recommends mass treatment of trachoma-hyperendemic communities, but there are scant empiric data on the number of rounds of treatment that are necessary for sustainable reductions. The rates of active trachoma and infection with C. trachomatis were determined in a community 3.5 years after two rounds of mass treatment with azithromycin. METHODS: Maindi village in Tanzania received a first round of mass treatment with azithromycin after a baseline survey for trachoma and infection. All residents aged 6 months and older were offered single-dose treatment with azithromycin (excluding pregnant women with no clinical trachoma, who were offered topical tetracycline). The residents were followed over an 18-month period, and, according to similar treatment criteria, were offered retreatment at 18 months. Five years after baseline (3.5 years after the second round of mass treatment), a new census and survey of current residents for trachoma and infection was conducted. Children are the sentinel markers of infection and trachoma in communities, so data are presented specifically for ages 0 to 7 years (preschool age) and 8 to 16 years. RESULTS: Treatment coverage was above 80% for all ages in the first round, and highest (90%) in preschool-aged children. Second-round coverage was lower, <70%, and 70% in preschool-aged children. At 5 years, trachoma rates were still lower than baseline, ranging from 45% in those aged 0 to 3 years to 8% in those aged 11 to 15 years (compared with 81% and 39% at baseline, respectively). Infection rates at baseline ranged from 71% to 57%, but were 27% to 17% at 5 years after two rounds of mass treatment. At 5 years, there were no differences in trachoma or infection rates, when comparing new residents who came after the second mass treatment with those who had been resident in the village during both rounds (P > 0.05). Infection rates were lower in those who had been treated twice or at 18 months than in those treated only at baseline or never treated. CONCLUSIONS: Although mass treatment appears to be associated with lower disease and infection rates in the long term, trachoma and C. trachomatis infection were not eliminated in this trachoma hyperendemic village 3.5 years after two rounds of mass treatment. Continued implementation of the SAFE strategy in this environment is needed. (+info)
Immunofluorescent detection of adenovirus antigen in epidemic keratoconjunctivitis.
(8/94)
An immunofluorescent technique was used to demonstrate soluble adenoviral antigens in epithelial cells on conjunctival scrapings of patients with epidemic keratoconjunctivitis (EKC). Conjunctival scrapings for immunofluorescence and viral isolation studies were performed on 79 patients suspected of having EKC or other acute follicular or papillary conjunctivitides. Of 41 patients with clinical findings consistent with a diagnosis of EKC and three patients with pharyngoconjunctional fever, 43 were positive by immunofluorescence. All 39 patients with adenovirus isolation had positive immunofluorescence studies. The five remaining cases had other documented evidence of EKC. No false-positive responses were encountered in relation to the clinical diagnoses. The fluorescent staining was predominantly found in the cytoplasm. Speckled nuclear fluorescence was also noted. The cytoplasmic fluorescence is compatible with the adenovirus cellular replication cycle. The immunofluorescent technique was found to be a reliable, sensitive, specific, and rapid diagnostic technique for detection of group-reaction adenoviral antigens in conjunctival scrapings. (+info)