ABSTRACT
The number of registered leprosy patients world-wide has decreased dramatically after extensive application of WHO recommended Multiple Drug Therapy (MDT). The annual number of new cases has, however, been almost unchanged in several populations, indicating that the infection is still present at community level. Nasal carriage of Mycobacterium leprae DNA was studied in Lega Robi village in Ethiopia. MDT had been applied for more than ten years, and 718 residents over 5 years old were eligible for the study. During the first survey nasal swab samples were collected from 664 (92.5%) individuals. The results of a Peptide Nucleic Acid-ELISA test for M. leprae DNA interpreted by stringent statistical criteria were available for 589 (88.7%) subjects. Thirty-five (5.9%) individuals without clinical signs of leprosy were positive for M. leprae DNA. Seven PCR positive individuals lived in a household where one or two other members were also positive for M. leprae DNA. During a second survey 8 (46%) of 175 interpretable PNA-ELISA tests were positive. Of 137 individuals tested twice, only two were positive on both occasions whereas 10 were PCR positive only once. The study confirms the widespread distribution of M. leprae DNA in healthy individuals. The feasibility of curbing possible transmission of subclinical infection needs further consideration.
Subject(s)
Female , Male , Adolescent , Adult , Aged , Child , Humans , Middle Aged , DNA, Bacterial , Enzyme-Linked Immunosorbent Assay , Ethiopia , Leprosy , Mycobacterium leprae , Nose , Polymerase Chain ReactionABSTRACT
BACKGROUND: A third of the world's population has latent infection with Mycobacterium tuberculosis, and in areas of low endemicity, most cases of active tuberculosis arise as a result of reactivation of latent bacilli. We sought to establish the cellular location of these latent organisms to facilitate their elimination. METHODS: We applied in-situ PCR to sections of macroscopically normal lung tissue from 13 individuals from Ethiopia and 34 from Mexico who had died from causes other than tuberculosis. Sections of lung tissue from six Norwegian individuals (ie, individuals from a non-endemic population) acted as negative controls, and six Ethiopian tuberculosis cases acted as positive controls. FINDINGS: Control necropsy samples from the Norwegian individuals were all negative by in-situ PCR and conventional PCR, whereas all samples from known Ethiopian tuberculosis cases were positive by both methods. However, in macroscopically normal lung tissue from Ethiopian and Mexican individuals without tuberculous lesions, the in-situ PCR revealed five of 13 and ten of 34 positive individuals, respectively. These results were confirmed by conventional PCR with extracted DNA. Positive cells included alveolar and interstitial macrophages, type II pneumocytes, endothelial cells, and fibroblasts. INTERPRETATION: M. tuberculosis can persist intracellularly in lung tissue without histological evidence of tuberculous lesions. M. tuberculosis DNA is situated not only in macrophages but also in other non-professional phagocytic cells. These findings contradict the dominant view that latent organisms exist in old classic tuberculous lesions, and have important implications for strategies aimed at the elimination of latent and persistent bacilli.
Subject(s)
DNA, Bacterial/isolation & purification , Lung/microbiology , Mycobacterium tuberculosis/isolation & purification , Tuberculosis, Pulmonary/microbiology , Adolescent , Adult , Case-Control Studies , Child , Endothelium, Vascular/microbiology , Female , Fibroblasts/microbiology , Humans , Lung/pathology , Macrophages/microbiology , Macrophages, Alveolar/microbiology , Male , Middle Aged , Polymerase Chain Reaction/methods , Primed In Situ Labeling , Pulmonary Alveoli/microbiologyABSTRACT
For the detection of the synthesis in vitro of anti-Mycobacterium leprae antibodies in various tissues of leprosy patients, biopsy specimens of skin lesions, nasal mucosa, larynx, lymph nodes, and bone marrow were cultured in a medium containing 14C-labeled lysine and isoleucine. The culture fluids were analyzed by crossed immunoelectrophoresis with intermediate gel and autoradiography. The results show that synthesis of anti-M. leprae antibodies occurs at the investigated sites of leprosy patients and that the specificities of the synthesized antibodies differ between sites in individual patients. It is conceivable that these antibodies play a role in the local defense against M. leprae.
Subject(s)
Antibodies, Bacterial/biosynthesis , Antibody Specificity , Mycobacterium leprae/immunology , Antigens, Bacterial/immunology , Autoradiography , Bone Marrow/immunology , Culture Techniques , Humans , Immunoelectrophoresis, Two-Dimensional , Immunoglobulins/biosynthesis , Larynx/immunology , Lymph Nodes/immunology , Nasal Mucosa/immunology , Skin/immunologyABSTRACT
About twenty distinct antigenic components have been demonstrated in Mycobacterium leprae (M. leprae) by crossed immunoelectrophoresis against a rabbit antiserum produced by immunization with concentrated M. leprae antigen. This system allows a more detailed analysis of the antigenic relationship between M. leprae and other mycobacteria and a better characterization of the antigenic content of various M leprae preparations than with previously available anstisera of the antigenic content of various M. leprae preparations than with previously available antisera which reacted with far fewer components. The antibody activity in sera of patients with lepromatous leprosy was studied by incorporating the sera into the intermediate gel of the M. leprae reference system. Antibodies were found against only seven of the components. Since those compared are all known to be cross-reacting widely with antigens of other mycobacteria, it is speculated that cross-immunization may influence the antibody response in lepromatous leprosy.