Immunogenicity of Mycobacterium leprae unique antigens in leprosy endemic populations in Asia and Africa

Ongoing transmission of leprosy is evident from the stable disease incidence in high burden areas. Tools for early detection of Mycobacterium leprae (M. leprae) infection, particularly in sub-clinically infected individuals, are urgently required to reduce transmission. Following the sequencing of the M. leprae genome, many M. leprae-unique candidate proteins have been identified, several of which have been tested for induction of M. leprae specific T cell responses in different leprosy endemic areas. In this study, 21 M. leprae-unique proteins and 10 peptide pools covering the complete sequence of five M. leprae-unique proteins (ML0576, ML1989, ML1990, ML2283, and ML2567) were evaluated in 160 individuals in Nepal and Ethiopia. These included: tuberculoid and borderline tuberculoid (TT/BT), borderline borderline and borderline lepromatous (BB/BL) leprosy patients; healthy household contacts (HHC); tuberculosis (TB) patients and endemic controls (EC). Immunogenicity of the proteins was determined by IFN-gamma secretion via stimulation of PBMC in 6 days lymphocyte stimulation tests (LST) or in whole blood assays (WBA). In LST, BB/BL patients (40%) responded to ML0573 and ML1601 whereas ML1604 was most immunogenic in TT/BT (35%) and HHC (36%). Additionally, significant numbers of EC displayed IFN-gamma production in response to ML0573 (54%), ML1601 (50%) and ML1604 (54%). TB patients on the other hand, hardly responded to any of the proteins except for ML1989. Comparison of IFN-gamma responses to ML0121, ML0141 and ML0188 for TT/BT patients showed specific increase in diluted 6 days WBA compared to the undiluted 24 hours WBA, whereas EC showed a reduced response in the diluted WBA, which may indicate detection of disease-specific responses in the 6 days WBA. In summary, identification of multiple M. leprae proteins inducing M. leprae-specific T cell responses in groups at high risk of developing leprosy may contribute to improve early detection for M. leprae infection.     

Experiences with Mycobacterium leprae soluble antigens in a leprosy endemic population

Rees and Convit antigens prepared from armadillo-derived Mycobacterium leprae were used for skin testing in two leprosy endemic villages to understand their use in the epidemiology of leprosy. In all, 2602 individuals comprising 202 patients with leprosy detected in a prevalence survey, 476 household contacts and 1924 persons residing in non-case households were tested with two antigens. There was a strong and positive correlation (r = 0.85) between reactions to the Rees and Convit antigens. The distribution of reactions was bimodal and considering reactions of 12 mm or more as 'positive', the positivity rate steeply increased with the increase in age. However, the distributions of reactions to these antigens in patients with leprosy, their household contacts and persons living in non-case households were very similar. These results indicate that Rees and Convit antigens are not useful in the identification of M. leprae infection or in the confirmation of leprosy diagnosis in a leprosy endemic population with a high prevalence of nonspecific sensitivity.     

Anti-desmoglein 1 antibodies in healthy related and unrelated subjects and patients with pemphigus foliaceus in endemic and non-endemic areas from Tunisia

Background  Pemphigus foliaceus is an autoimmune blistering skin disease characterized by the production of pathogenic IgG autoantibodies directed against desmoglein 1.
Aim  To determine the prevalence of anti-desmoglein 1 antibodies in healthy subjects and their distribution in the different regions of Tunisia and to better identify endemic areas of pemphigus foliaceus.
Methods  We tested, by enzyme-linked immunoserbent assay, sera of 270 normal subjects recruited from different Tunisian areas and 203 related healthy relatives to 90 Tunisian pemphigus foliaceus patients.
Results  Seventy-six patients (84.4%), 20 healthy controls (7.4%), and 32 relatives (15.76%) had anti-desmoglein 1 antibodies. In southern regions where pemphigus foliaceus is associated with a significant sex ratio imbalance (9 female : 1 male in the south vs. 2.3 : 1 in the north) and a lower mean age of disease onset (33.5 in the south vs. 45 years in the north), a higher prevalence of anti-desmoglein 1 antibodies in healthy controls was observed (9.23% vs. 5.71% in the north). Interestingly, the highest prevalence of anti-desmoglein 1 antibodies in healthy relatives (up to 22%) was observed in the most rural southern localities. More than half anti-desmoglein 1–positive healthy controls were living in rural conditions with farming as occupation, which suggests that this activity may expose the subjects to particular environmental conditions.
Conclusion  These results show that the endemic features of Tunisian pemphigus foliaceus are focused in these southern areas more than in other areas and that both environmental and genetic factors contribute to the disease.

Conflicts of interest

None declared.     

Serologic abnormalities in patients with endemic pemphigus foliaceus (Fogo selvagem), their relatives, and normal donors from endemic and non-endemic areas of Brazil

Based on epidemiologic data, a current hypothesis states that Fogo selvagem (FS) may be triggered by environmental factors present in endemic areas of Brazil. Because the appearance of new cases is limited to those areas, we wanted to ascertain if the presence of the pemphigus autoantibodies was restricted to the patients. To further delineate the restriction of the autoantibody response in these patients we also investigated the presence of lupus-associated autoantibodies. Using indirect immunofluorescence (IF) we tested the sera of patients with FS (n = 196), their relatives (n = 138), their cohabitants (n = 13), and normal donors from endemic (n = 38) and non-endemic areas (n = 44) for pemphigus autoantibodies. Antinuclear antibodies (ANA) and anti-nDNA antibodies were determined by indirect IF against Hep-2 cells and Crithidia lucilliae, respectively. Autoantibodies against nRNP, Ro/SSA, La/SSB, and Sm were assayed by double immune diffusion in agarose gels. FS autoantibodies were present in the sera of all patients with active disease (n = 196, 100%, titers greater than 40 to 2560), but were not found in any sera from normal individuals in endemic or non-endemic areas. The titer of the FS autoantibody showed a rough correlation with the extent and activity of the disease. Furthermore, lupus-associated autoantibodies were not present in any of the tested samples. We conclude the FS antiepidermal autoantibodies are specific serologic markers of the disease and are not present in unaffected individual from the endemic areas. As such, they provide an important marker that should be useful in ongoing epidemiologic studies aimed at identifying putative etiologic agent(s).     

Postgenomic Mycobacterium leprae antigens for cellular and serological diagnosis of M. leprae exposure, infection and leprosy disease

Due to changes in leprosy control programs and the special expertise required for diagnosis, the need for simple rapid diagnostic tests that could be applied in non-expert settings may now be greater than ever before. Since the sequencing of the M. leprae genome, many research groups have investigated the potential of M. leprae antigens in either serologic or cell mediated assays. Here we provide an overview of the nearly 200 recombinant single proteins that were investigated during the last decade for their potential to be applied in field-friendly tests for the early diagnosis of leprosy.     

Demonstration of Mycobacterium leprae specific antigens in leprosy lesions using monoclonal antibodies

Cryostat sections of dermal lesions from 13 untreated patients of leprosy were studied by indirect immunoperoxidase using monoclonal antibodies (MLO4 & MLO6), defining M. leprae specific antigens. The lymphocytes and macrophages in both the tuberculoid and lepromatous granulomas showed membranous staining with the above antibodies. M. leprae organisms in the lepromatous granulomas and the cells in the section of lymph nodes of patients with tuberculosis, or sections of normal skin or psoriatic lesions did not show any staining with these antibodies. These observations suggest that M. leprae specific antigens are present and expressed on the cells infiltrating the granulomas of leprosy lesions.     

麻风流行区饮用水中麻风杆菌的分子生物学检测

目的:检测麻风病流行区饮用水中麻风杆菌DNA,以探讨其对麻风流行区麻风持续流行的影响.方法:分别从云南丘北县有、无患者村和北京非流行区乡村采集70份水样,提取DNA、PCR扩增后测序检测样品中麻风杆菌DNA.结果:流行区36.7％(22/60)的水样含麻风杆菌DNA,而非流行区水样中未检出麻风杆菌.流行区有患者的村庄中,患者和健康者家庭内饮水中麻风杆菌的检出率有统计学差异.结论:麻风流行区患者家庭饮用水中麻风菌的存在可能与持续性流行有关,但须进一步研究.     

An epidemiological study on Mycobacterium leprae infection and prevalence of leprosy in endemic villages by molecular biological technique.

One of the most important unsolved questions in epidemiology of leprosy is the highly uneven geographic distribution of the disease. There are many hyperendemic "pockets" in endemic countries. Little is known about the reasons why leprosy is hyperendemic in these areas. We conducted, therefore, a series of epidemiological studies on Mycobacterium leprae infection and prevalence of leprosy in North Maluku district, Maluku Province, Indonesia where leprosy is highly endemic. It was found that considerable number of general inhabitants are seropositive to various mycobacterial antigens and 27% of the villagers were carrying leprosy bacilli on their surface of nasal cavity. These results suggested the importance of M. leprae in the residential environment in infection of the leprosy bacillus and the resulting transmission of the disease. Based on these observations, we conclude that new preventive measures are essential for global elimination of leprosy in addition to early diagnosis and multidrug therapy (MDT).     

Evaluation of Mycobacterium leprae antigens in the monitoring of a dapsone-based chemotherapy of previously untreated lepromatous patients in Cebu, Philippines

Thirty-five previously untreated lepromatous patients receiving dapsone-based therapy were monitored throughout their 5-year period of treatment by serology and by pathology. Sequentially collected sera were used to evaluate the usefulness of four Mycobacterium leprae antigens as used in ELISA to monitor the progress of their therapy. ELISA results were compared with each other and with bacterial load over the treatment period and with duration of treatment. The ELISAs, based on the measurement of IgM antibody reactivity to the two neoglycoproteins (NDO and NTO) representing the phenolic glycolipid antigen of M. leprae, were found to be the most effective in monitoring treatment. A whole M. leprae based ELISA was less efficient in monitoring treatment because it failed to measure antibodies in 8 out of 35 patients and because it provided consistently lower values than either NTO or NDO. The ELISA-inhibition test based on the detection of antibodies to a species-specific epitope on the 36 K antigen of M. leprae was less suitable because of persistent reactivity during therapy, consequently resulting in no significant correlation with ELISA reactivities to NTO or NDO.     

Identification of Mycobacterium leprae and Mycobacterium lepromatosis in Formalin-Fixed and Paraffin-Embedded Skin Samples from Mexico

BackgroundThe causative agents of leprosy are the well-known Mycobacterium leprae and the newly discovered Mycobacterium lepromatosis. This agent was found in 2008, and it was found to be the cause of diffuse lepromatous leprosy in two Mexican patients.ObjectiveThe objective of this work was to determine if M. leprae and M. lepromatosis were present in formalin-fixed and paraffin-embedded skin samples from cases from different regions in Mexico.MethodsA total of 41 skin samples were obtained from 11 states of Mexico. All patients'' samples were diagnosed by clinical and histopathological analyses. Total DNA was isolated using a Qiagen-DNeasy blood and tissue kit and molecular identification was achieved by two semi-nested polymerase chain reactions.ResultsThe 41 patient included 33 samples from men and 8 samples from women; 29 samples were polymerase chain reaction (PCR)-positive to Mycobacterium and 12 samples were PCR-negative. From those 29 samples, 13 were PCR-positive to M. leprae, 8 to M. lepromatosis and 8 were positive to both species. The histopathological diagnosis included; Nodular lepromatous leprosy (NLL); Diffuse lepromatous leprosy (DLL); and Borderline leprosy (BL). The 29 PCR-positive samples were classified as follow: 14 NLL, 4 DLL, and 11 BL. In the 12 samples negative to Mycobacterium, 7 showed the NLL, 2 DLL and 3 BL.ConclusionThese findings add evidence to the M. leprae and M. lepromatous distribution, clinical forms and participation of dual infections in Mexico.