Analysis of antigens of Mycobacterium leprae by interaction to sera IgG, IgM, and IgA response to improve diagnosis of leprosy.

Till 2010, several countries have declared less than one leprosy patient among population of 10,000 and themselves feeling as eliminated from leprosy cases. However, new leprosy cases are still appearing from all these countries. In this situation one has to be confident to diagnose leprosy. This review paper highlighted already explored antigens for diagnosis purposes and finally suggested better combinations of protein antigens of M. leprae versus immunoglobulin as detector antibody to be useful for leprosy diagnosis.

Incidence of leprosy in Agra district.

This study presents estimates of incidence of leprosy among the familial contacts (FC) and non-familial contacts (NFC) of leprosy patients in Agra, a district endemic for leprosy. The study covers 42,113 persons followed up for 123,951.2 person years (PY) during which 77 individuals developed leprosy giving an incidence of 6.2/10,000 PY in the total leprosy-free population studied (TLPS). The incidence rate in NFCs was observed to be 4.6/10,000 PY while the FCs had a significantly higher incidence rate of 67.6/10,000 PY (P < 0.001). Incidence rate among the FC of paucibacillary leprosy (PB) patients was 41.0/10,000 PY while the corresponding figure for multibacillary leprosy (MB) contacts was 131.3/10,000 PY (P < 0.05). Applying methods of survival analysis, the incidence rate at the end of 1 year was observed to be 4-0 (per 10,000), increased to 12.0 by 2 years and 18.0 at the end of 3 years in TLPS. The incidence rate was almost similar in both the sexes and was found to increase significantly with age. The observations clearly indicate that leprosy is still endemic in the area and transmission continues.

Semi-quantitative detection of Mycobacterium leprae antigens in skin scrapings: suitability as a laboratory aid for field diagnosis of leprosy.

We describe here a method, potentially suitable for field applications, for semi-quantitative detection of Mycobacterium leprae antigens in skin scrapings, which are taken normally for smear microscopy. Thirty acid-fast bacilli-negative paucibacillary (PB) leprosy patients comprised the main study group; eight acid-fast bacilli-positive multibacillary (MB) patients and five healthy laboratory workers served as controls. Samples in saline were spotted on nitrocellulose paper and probed with mycobacterium-specific polyclonal or M. leprae-specific mAbs against 12, 35 and 65kDa protein antigens, using a dot-ELISA format. Spot densities were read through a densitometer and also graded visually. The polyclonal antibody produced the best sensitivity, resulting in densitometric detection of mycobacterial antigen in 100% MB, 76% multiple-lesion PB and 62% single-lesion PB patients. None of the healthy volunteers showed antigen positivity. A correlation was noted between the densitometric and visual estimates of the antigen. Determination of antigen in the lesion and an apparently uninvolved area of skin in a subset of PB patients provided clues to the state of the underlying infection. Serological positivity of PB patients for M. leprae-specific antibodies against the 35kDa and phenolic glycolipid-I antigens was too low (<20%) for any diagnostic significance.

Detection of antibodies against Mycobacterium leprae culture filtrate protein-10 in leprosy patients.

The prevalence of IgG antibodies against Mycobacterium leprae recombinant culture filtrate protein-10 (rCFP-10) was investigated in serum samples from 56 leprosy patients, 15 tuberculosis (TB) patients, 14 other skin-diseased patients and 20 healthy subjects. On classifying the patients into bacterial index (BI)-positive and BI-negative groups, the assay showed 83.3 % (15/18) sensitivity for detection of BI-positive leprosy patients. On the other hand, the sensitivity for detection of BI-negative patients was 18.4 % (7/38). None of the 15 TB patients and 14 other skin-diseased patients was positive; however, only one out of 20 healthy individuals was positive, indicating that antibody response to culture filtrate protein-10 (CFP-10) was highly specific (98.0 %; 48/49). Statistically, the performance of the CFP-10-based assay was found to be comparable (P>0.05) with that of an anti-phenolic glycolipid-I (PGL-I) antibody-detecting assay. Thus, M. leprae CFP-10 is potentially a specific antigen for measuring antibody response in BI-positive leprosy patients. Being a secreted antigen, CFP-10 may act as a marker for the viability of M. leprae inside the host, and hence its serological potential is worth exploring for application in monitoring the response of patients with BI-positive leprosy (a highly infectious form) during the course of chemotherapy. When comparing the bacteriological and serological results, an agreement of 82.1 % showed that seropositivity to M. leprae CFP-10 corresponded well with bacteriological criteria. Hence, CFP-10 seems to be a suitable antigen for classification of leprosy patients into BI-positive and BI-negative groups.

Detection of Mycobacterium leprae DNA for 36kDa protein in urine from leprosy patients: a preliminary report.

We have searched for Mycobacterium leprae DNA for 36kDa protein in urine using a M. leprae specific PCR technique. A limited number of 16 patients (of which 11 belonged to lepromatous leprosy and five to tuberculoid leprosy) and eight healthy individuals were included for the present study. The number of urine samples positive by PCR were 36.4% (4/11) in lepromatous patients and 40% (2/5) in tuberculoid patients. None of the samples from healthy individuals was positive. To our knowledge, the results indicate, for the first time, the presence of M. leprae DNA in urine from leprosy patients. Another important finding obtained out of the study is that amongst treated patients 66.6% (4/6) were positive whereas amongst untreated only 20% (2/10) were positive. From the present indicative data it appears that treatment improves the PCR results with urine as a sample. Thus, the approach could prove to be useful for monitoring the treatment response of individual patients and needs to be further evaluated with a large number of patients.

Detection of Mycobacterium leprae DNA for 36kDa protein in urine from leprosy patients: a preliminary report

Pesquisamos o DNA do Mycobacterium leprae para proteína 36 kDa na urina usando a técnica do PCR específica para M. leprae. Um número limitado de 16 pacientes (dos quais 11 tinham hanseníase multibacilar e cinco hanseníase paucibacilar) e oito indivíduos saudáveis foram incluídos neste estudo. O número de amostras de urina positivas pelo PCR foi de 36,4% (4/11) em pacientes com hanseníase multibacilar e 40% (2/5) em pacientes com hanseníase paucibacilar. Nenhuma das amostras de indivíduos saudáveis foi positiva. Até onde chega o nosso conhecimento, os resultados indicam, pela primeira vez, a presença de DNA do M. leprae na urina de pacientes com hanseníase. Outro fato importante obtido através do exame é que entre os pacientes tratados 66.6% (4/6) eram positivos enquanto entre os não tratados somente 20% (2/10) foram positivos. Pelos presentes dados indicativos parece que o tratamento melhora os resultados do PCR em amostra de urina. Assim, o acesso a estes dados prova ser útil no monitoramento da resposta ao tratamento de pacientes individuais e precisa ser melhor avaliado com um grande número de pacientes.

Immunological profile of treated lepromatous leprosy patients

The immune responses of 19 treated lepromatous patients who had remained smear negative for a long period were assessed for specific cell-mediated immunity (CMI), anti-Mycobacterium leprae antibodies and cytokine release in response to challenge with M. leprae soluble antigen (MLSA). All of these patients remained anergic to Mitsuda lepromin. Lymphoproliferation in response to M. leprae antigen was noted in only two patients. Significant reduction in the phenolic glycolipid I (PGL-I) antibody response in treated patients with no difference in the M. leprae 35-kDa antibody response was observed when these responses were compared with those of active lepromatous patients. More treated patients produced interleukin-2 (IL-2) and interferon gamma (IFN-gamma) than did active patients. On the other hand, fewer treated patients produced IL-10 than did active patients. These limited findings suggest that the host immune response makes an attempt toward upregulation of CMI in some treated LL/BL patients.

Identification fo Mycobacterium leprae antigens in tissues of leprosy patients using monoclonal antibodies

Five monoclonal antibodies (MAbs) directed against antigens of Mycobacterium leprae were tested for their ability to bind to components of tissue sections prepared from biopsies taken from patients with various forms of leprosy. Immunoperoxidase was the most successful marker system used, although immunofluorescence and alkaline phosphatase were also successful in certain cases. Positivity was high with all five antibodies successfully staining those sections containing a bacterial index of 3+ or more; sections with 0 bacterial counts also had areas staining positively with two of the MAbs. The positive staining in the tissues was confined to areas infiltrated by inflammatory cells; however it was not identifiable as being associated with individual bacteria. These findings suggest that immunostaining with specific monoclonal antibodies can help to identify leprosy in diagnostic samples in which acid-fast bacilli are not identifiable by standard histochemical means. Immunohistochemical techniques are likely to be valuable in studies of the distribution of M. leprae antigens and their association with individual tissue elements

Appraisal of two mycobacterium leprae specific serological assays for monitoring chemotherapy in lepromatous (LL/BL) leprosy patients

Two of the Mycobacterium leprae-specific assays--a serum antibody competition (for an epitope on 35-kDa protein) test (SACT) and an enzyme-linked immunosorbent assay (ELISA) for the disaccharide epitope of phenolic glycolipid-I (PGDS)--were comparatively evaluated as tools for monitoring chemotherapy in 125 lepromatous leprosy (LL/BL) patients. An adaptation of the SACT from a radioimmunoassay (RIA) to an ELISA procedure is also described. A moderate but statistically significant correlation was observed between the assays, although SACT appeared to be the more sensitive of the two. Levels of antibodies correlated better with the bacterial index (BI) than with the duration of treatment. However, wide individual variations in antibody levels (for a specific duration of treatment or BI) were seen in treated as well as untreated patients. Anti-PGDS antibody response of the IgG type was poorer than that of the IgM type and, apparently, it did not have a bearing on either treatment duration or the BI. Further studies will be needed to clarify whether the treated patients showing a negative (or low) BI and high antibody levels were harboring hidden foci of active infection, and whether treatment could safely be terminated in patients showing low values for both BI and antibody