The need for molecular tools for the differentiation of isolates of Mycobacterium leprae, the organism that causes leprosy, is urgent in view of the continuing high levels of new case detection, despite years of aggressive chemotherapy and the consequent reduction in the prevalence of leprosy. The slow onset of leprosy and the reliance on physical examination for detection of disease have restricted the epidemiological tracking necessary to understand and control transmission. Two genetic loci in several isolates of M. leprae have previously been demonstrated to contain variable-number tandem repeats (VNTRs). On the basis of these reports and the availability of the full genome sequence, multiple-locus VNTR analysis for strain typing has been undertaken. A panel of 11 short tandem repeat (STR) loci with repeat units of 1, 2, 3, 6, 12, 18, 21, and 27 bp from four clinical isolates of M. leprae propagated in armadillo hosts were screened by PCR. Fragment length polymorphisms were detected at 9 of the 11 loci by agarose gel electrophoresis. Sequencing of representative DNA products confirmed the presence of VNTRs between isolates. The application of nine new polymorphic STRs in conjunction with automated methods for electrophoresis and size determination allows greater discrimination between isolates of M. leprae and enhances the potential of this technique to track the transmission of leprosy.The World Health Organization and its partners created the Global Alliance for Leprosy Elimination in 1999 with the aim of achieving the elimination of leprosy by the end of the year 2005, a goal originally set for the year 2000 (http://www.who .int/inf-pr-1999/en/pr99-70.html). Leprosy is effectively controlled by a multidrug therapy (MDT) regimen composed of dapsone, rifampin, and clofazimine. However, continuing large numbers of new cases are being detected in areas of the world where the disease is highly endemic, despite the application of the MDT program since 1982 (36). In order to comprehend this rising incidence of leprosy, it is necessary to identify the natural reservoir of Mycobacterium leprae, the route of infection, and the mode of its transmission. It is commonly believed that the human is the host and reservoir of M. leprae and that successful MDT will eliminate leprosy. However, other modes of transmission involving nonhuman reservoirs, such as soil (6, 15), water (20), vegetation (16), animals (including armadillos and sooty mangabeys) (22, 33), and arthropods (fleas, ticks, mosquitoes, and flies), have been suggested, as reviewed by Blake et al. (3). The route of infection is also unknown, although the entry and the exit of the bacteria via the nasal passages have been proposed (9). Methods that specifically detect M. leprae DNA in nasal swabs are being developed with the aim of early detection in populations at the community and village levels and for the monitoring of leprosy transmission (13,23). Typing methods for distinguishing cases of relapse from new infections are also required. Molecular typing wi...

Mycobacterium leprae is the noncultivable pathogen of leprosy. Since the genome sequence of an isolate of M. leprae has become available, multiple-locus variable-number tandem-repeat (VNTR) analysis (MLVA) has been explored as a tool for strain typing and identification of chains of transmission of leprosy. In order to discover VNTRs and develop methods transferable to clinical samples, MLVA was applied to a global collection of M. leprae isolates derived from leprosy patients and propagated in armadillo hosts. PCR amplification, agarose gel electrophoresis, and sequencing methods were applied to DNA extracts from these infected armadillo tissues (n ‫؍‬ 21). We identified polymorphisms in 15 out of 25 short-tandem-repeat (STR) loci previously selected by in silico analyses of the M. leprae genome. We then developed multiplex PCR for amplification of these 15 loci in four separate PCRs suitable for fluorescent fragment length analysis and demonstrated STR profiles highly concordant with those from the sequencing methods. Subsequently, we extended this method to DNA extracts from human clinical specimens, such as skin biopsy specimens (n ‫؍‬ 30). With these techniques, mapping of multiple loci and differentiation of genotypes have been possible using total DNA extracts from limited amounts of clinical samples at a reduced cost and with less time. These practical methods are therefore available and applicable to answer focused epidemiological questions and to allow monitoring of the transmission of M. leprae in different countries where leprosy is endemic.The causative pathogen of leprosy is Mycobacterium leprae. A continued incidence, defying global campaigns to eliminate leprosy even after years of rigorous case finding and the availability of multidrug therapy regimens (28,29,30,31), is attributed to subclinical human and environmental reservoirs of the pathogen (1,8,13). In recent years, molecular strain-typing methodologies have complemented conventional infectious disease epidemiology. With the publication in 2001 of the complete genome sequence of an isolate from Tamil Nadu, India, called the TN strain (4), selection of potential polymorphic genomic markers for strain typing was feasible. The first genetic markers that showed polymorphism were short tandem repeats (STRs) in the M. leprae genome. One was a 6-bp intragenic sequence in the rpoT gene, and the second, a trinucleotide (TTC) repeat element upstream of a pseudogene (17, 23). These sequences exhibit variable numbers of tandem repeats (VNTRs) when sequenced in different isolates. Based on these observations, we short-listed 44 loci (including the rpoT and TTC loci) by in silico analyses of the M. leprae genome and accomplished the screening of 11 STR loci, of which 9 were polymorphic when tested in a small panel of four human isolates derived from passage through armadillos (6). Five were minisatellites (6-to 50-bp repeat units), and four were microsatellites (1-to 5-bp repeat units). Since then, others have also shown that VNTR loci exist in M. lepra...

Despite the success of multidrug therapy in reducing the number of registered leprosy cases worldwide, evidence suggests that Mycobacterium leprae continues to be transmitted. A serological diagnostic test capable of identifying and allowing treatment of early-stage disease could reduce transmission and prevent the onset of the disability, a common complication of the disease in later stages. Serological diagnosis based on antibody recognition of phenolic glycolipid I (PGL-I) cannot reliably identify individuals with lower bacterial indices (BI). One strategy that might improve this situation is the provision of highly specific serological antigens that may be combined with PGL-I to improve the sensitivity of diagnosis. Using serological expression cloning with a serum pool of untreated lepromatous leprosy (LL) patients, we identified 14 strongly reactive M. leprae proteins, 5 of which were previously unstudied. We present results suggesting that two of these proteins, ML0405 and ML2331, demonstrate the ability to specifically identify LL/borderline lepromatous (BL) patients on the basis of immunoglobulin G (IgG) reactivity. In a household contact study, LL index cases were identified on the basis of this reactivity, while household contacts of these patients demonstrated undetectable reactivity. At a serum dilution of 1:800, suitable to reduce background PGL-I IgM reactivity, two BL patients with a BI of <4 showed anti-human polyvalent immunoglobulin G, A, and M reactivity measured with a combination of ML0405, ML2331, and natural disaccharide O-linked human serum albumin (NDOHSA) (synthetic PGL-I) that was markedly higher than IgM reactivity to NDOHSA alone. We suggest that ML0405 and ML2331 may have utility in serological leprosy diagnosis.Leprosy is a devastating human disease caused by infection with Mycobacterium leprae bacilli. The disease predominantly affects the skin, although during infection, significant nerve destruction leads to deformities of the hand, foot, face, and, in some cases, eye (1). The disease is represented by a clinical spectrum. Lepromatous leprosy/borderline lepromatous (LL/ BL) patients represent one pole of the spectrum, demonstrating a high bacterial index (BI) and, as such, are classified as multibacillary (MB). LL/BL patients demonstrate high titers of M. leprae-specific antibodies and an absence of M. leprae-specific cell-mediated immunity. At the opposite pole, tuberculoid tuberculoid/borderline tuberculoid (TT/BT) patients demonstrate very low or absent BI and are designated paucibacillary. These individuals demonstrate significant M. leprae-specific cellmediated immunity and very low or absent titers of M. lepraespecific antibodies.Despite the success of multidrug therapy in reducing the number of registered leprosy cases worldwide, the annual rate of new case detection remains unchanged, at approximately 700,000 cases per year (33), with children representing 15% of new cases (18). This suggests that active transmission of M. leprae is still occurring, but the route and me...

In the virulent state (Bvg ؉ ), Bordetella bronchiseptica expresses adhesins and toxins that mediate adherence to the upper airway epithelium, an essential early step in pathogenesis. In this study, we used a rabbit tracheal epithelial cell binding assay to test how specific host or pathogen factors contribute to ciliary binding.

Although the global prevalence of leprosy has decreased over the last few decades due to an effective multidrug regimen, large numbers of new cases are still being reported, raising questions as to the ability to identify patients likely to spread disease and the effects of chemotherapy on the overall incidence of leprosy. This can partially be attributed to the lack of diagnostic markers for different clinical states of the disease and the consequent implementation of differential, optimal drug therapeutic strategies. Accordingly, comparative bioinformatics and Mycobacterium leprae protein microarrays were applied to investigate whether leprosy patients with different clinical forms of the disease can be categorized based on differential humoral immune response patterns. Evaluation of sera from 20 clinically diagnosed leprosy patients using native protein and recombinant protein microarrays revealed unique disease-specific, humoral reactivity patterns. Statistical analysis of the serological patterns yielded distinct groups that correlated with phenolic glycolipid I reactivity and clinical diagnosis, thus demonstrating that leprosy patients, including those diagnosed with the paucibacillary, tuberculoid form of disease, can be classified based on humoral reactivity to a subset of M. leprae protein antigens produced in recombinant form.