Immunoprophylactic effects of the anti-leprosy Mw vaccine in household contacts of leprosy patients: clinical field trials with a follow up of 8-10 years.

We report here a large scale, double blind immunoprophylactic trial of a leprosy vaccine based on Mycobacterium w (Mw) in an endemic area of Kanpur Dehat, Uttar Pradesh, India. A population of 420,823 spread over 272 villages was screened where 1226 multibacillary (MB) and 3757 paucibacillary (PB) cases of leprosy were detected. A total of 29,420 household contacts (HHC) of these patients were screened for evidence of active or inactive leprosy. After exclusion of 1622 contacts for any of the different exclusion criteria, a total of 24,060 HHC could be vaccinated for vaccine or placebo under coding (20,194 administered two doses and 3866 received single dose). The vaccine consisted of 1 x 10(9) heat killed bacilli (Mw) in normal saline for the first dose and half of the first dose, i.e. 5 x 10(8) bacilli for the second dose, given 6 months after the first dose. The placebo consisted of 1/8th dose of the normal dose of tetanous toxoid. Both placebo and vaccine were given under double-blind coding, The contacts were followed up during three surveys at 3, 6 and 9 years after the initial vaccination, for detection of post-vaccination cases (PVCs) and observing any side-effects caused as a result of vaccination. The codes were opened on 24th January 2001, after the analysis of the data following completion of the third and final follow-up survey. When only contacts received the vaccine, Mw vaccine showed a protective efficacy (PE) of 68-6% at the end of first, 59% at the end of the second and 39.3% at the end of the third follow-up survey. When both patients and contacts received the vaccine, the protective efficacy observed was 68%, 60% and 28% at the end of the first, second and third surveys, respectively. When patients, and not the contacts, received the vaccine, a PE of 42.9% in the first, 31% in the second and 3% in the third survey was shown. These results suggest that the vaccination of the contacts is more valuable in achieving the objective of immunoprophylaxis than that of patients, and the vaccine effects are noted maximally in children (as compared to adolescents and adults) who constitute the most responsive group The effect of vaccine is sustained for a period of about 7-8 years, following which there is a need to provide a booster vaccination for the sustained protection.

An immunotherapeutic vaccine for multibacillary leprosy.

On January 30, 1998, a vaccine for leprosy based on Mycobacterium w (the code word under which this species hitherto unspecified was investigated) was launched for public use for therapeutic purposes. The vaccine has completed phase III immunotherapeutic trials as an adjunct to chemotherapy in urban and rural leprosy control centres and has received the authorization from the Drugs Controller of India for industrial manufacture. It will be made available by M/s Cadila Pharmaceuticals, Ahmedabad. As an adjunct to chemotherapy, the vaccine expediates bacterial clearance and accelerates clinical regression of lesions. It shortens significantly the period for release from treatment (RFT) of patients. It is effective in inducing a fall of bacterial index (BI) in multibacillary patients who are either nonresponders or slow responders to the standard multidrug therapy and who have persistent BI over long periods. An additional benefit of immunization with this vaccine is the conversion of >60% of LL, 71% of BL and 100% of BB patients from lepromin negativity to lepromin positivity status. A significant number of vaccinated patients showed histopathological upgrading and eventually attainment of a state of nonspecific infiltration without dermal granulomas. The vaccine was well tolerated and the incidence of Type 2 reactions and their severity was less in combined immuno cum chemotherapy group than in the group receiving only chemotherapy. This review describes the nature of the vaccine and the way it was developed.

Molecular definition of unique species status of Mycobacterium w; a candidate leprosy vaccine strain.

Mycobacterium w, a candidate leprosy vaccine strain, is an atypical cultivable mycobacterium. Based on its growth and metabolic properties, M. w was listed in Runyon Group IV, along with other rapid growers such as M. fortuitum, M. smegmatis, M. chelonae and M. vaccae. However, M. w was not fully identical to any one of these. In the present study, a molecular biology approach was used to define the species identity of M. w in a manner that allows reliable comparison to be made with over 30 known mycobacterial species. A 383-bp region, present at the amino terminus of the conserved mycobacterial 65-kDa gene, has been polymerase chain reaction (PCR) amplified in M. w and DNA sequence was determined. A comparison of the M. w DNA sequence with those of M. tuberculosis, M. avium, M. paratuberculosis and M. fortuitum revealed a species-specific polymorphism, i.e., the presence of nucleotide substitutions unique to M. w. In an alternate approach, a 441-bp region, also a part of the 65-kDa gene, has been PCR amplified in M. w and a Hae III restriction pattern was generated.(ABSTRACT TRUNCATED AT 250 WORDS)

Localized lepromatous leprosy and its response to chemo-immunotherapy.

BACKGROUND: This is an unusual presentation of lepromatous leprosy (LL) in a young boy, 12 years of age. The study forms part of a large scale immunotherapeutic trial with Mycobacterium w (M.w) antileprosy vaccine. The trial is being conducted in two major hospitals in New Delhi, India. MATERIALS AND METHODS: This patient presented with three lesions: one on each forearm and the third on the left leg. He was classified initially as borderline tuberculoid leprosy. Slit-skin smears and histopathology from the lesions proved the diagnosis to be lepromatous leprosy with a bacterial index (BI) 6+. The initial lepromin test was negative. The patient was treated with chemo-immunotherapy (standard multidrug therapy and immunotherapy with Mycobacterium w vaccine). RESULTS: Investigations after 1 year (15 months) of multi-drug therapy and three doses of vaccine, showed a remarkable fall in the BI from 6 to 0 in the lesions, a lepromin positivity of 5 mm, and a histological upgrading from lepromatous leprosy to borderline tuberculoid. Immunologic studies at 15 months revealed a good LTT response and high levels of cytokines, specifically IL-2 and IFN-gamma. CONCLUSIONS: This report presents an LL patient with disease limited to a few sites. It stresses the importance of slit-smear and biopsy in all patients of leprosy, and it highlights the upgrading observed on administration of chemo-immunotherapy.

Field trials on the use of Mycobacterium w vaccine in conjunction with multidrug therapy in leprosy patients for immunotherapeutic and immunoprophylactic purposes.

A double blind field trial was started with a candidate anti-leprosy vaccine, Mycobacterium w as an immunotherapeutic and immunoprophylactic agent against leprosy in a highly endemic region with a prevalence rate of over 18 per 1000 population. By 31 August 1992, 224 villages have been surveyed, covering a population of 307,981 (1981 census). A total of 979 MB patients and 2801 PB patients have been registered. A total of 19,453 household contacts of leprosy patients have been examined for clinical signs of disease, of which 16,519 have received the initial dose while 10,434 have also received the booster dose of vaccine/placebo. The aims and objectives, study design of the trial, present status as well as the socio-cultural aspect involved are highlighted in this paper.

Molecular cloning and characterization of contiguously located repetitive and single copy DNA sequences of Mycobacterium tuberculosis: development of PCR-based diagnostic assay.

Screening of a lambda gt11 genomic library has been used as an approach for molecular cloning of the Mycobacterium tuberculosis repetitive DNA shown to be present on a previously described 5.6-kb Alu I genomic fragment. The recombinant clone R18.8.2, which strongly hybridized with the radiolabeled 5.7-kb Alu fragment, carried two Eco RI inserts of 2 kb and 1.4 kb in size. Southern hybridization of each of these fragments to restriction endonuclease-cleaved M. tuberculosis DNA clearly demonstrated the 2 kb to contain the repetitive DNA sequence, while the 1.4 kb is represented in a single copy. When replica plaque lifts from the genomic library were probed, the 5.6-kb genomic fragment and the cloned 2-kb repetitive insert hybridized to an identical number of plaques, indicating the similarity and the high copy number of the repeating unit shared by the two fragments. Restriction mapping and Southern hybridization patterns indicated that the 2-kb repetitive and the 1.4-kb single-copy DNA sequences originated from a contiguous piece of genomic DNA. Both fragments were found to be unique to members of the M. tuberculosis complex, except that the 2-kb insert exhibited a weak hybridization with M. kansasii DNA. Finally, a 169-bp region from one end of the single-copy sequence has been amplified by polymerase chain reaction (PCR) in a manner specific to members of the M. tuberculosis complex. The sensitivity of the PCR was such that as few as 9-10 bacilli could be detected.

Immunotherapy with Mycobacterium w vaccine decreases the incidence and severity of type 2 (ENL) reactions.

Immunotherapy with Mycobacterium w (M.w) vaccine was given to 45 patients with multibacillary (MB) leprosy; 41 similarly classified patients served as controls. All patients received standard multidrug therapy (MDT). Incidence, severity and frequency of type 2 (ENL) reactional episodes were monitored in both groups in a follow-up extending up to 4 years. Reactions were seen in fewer vaccinated (10/37) BL and LL patients than in the control group (12/34). A total of 20 episodes were recorded in the vaccine group as against 29 in the controls, 75% of reactions were mild in vaccinated and 51.72% were mild in the control group patients, and 3 patients in the control group had more than 3 reactional episodes. None of the vaccinated patients showed this. No additional incidence of neuritis were seen among vaccinated individuals during reactional episodes.

Combined multidrug and Mycobacterium w vaccine therapy in patients with multibacillary leprosy.

Immunotherapy with Mycobacterium w vaccine was attempted in patients with borderline-borderline, borderline lepromatous (BL), or lepromatous leprosy (LL) to determine whether immunization can hasten recovery and reduce treatment time by invigorating cell-mediated immunity. Mycobacterium w, a nonpathogenic, rapidly growing, atypical mycobacterium, shares a number of common B and T cell determinants with Mycobacterium leprae and Mycobacterium tuberculosis. Patients receiving the vaccine had rapid clinical improvement and accelerated bacteriologic clearance. After treatment with vaccine for 2 years, 13 of 31 BL and LL patients were bacteriologically negative as were 5 of 25 controls. Vaccinated patients had one of two distinct histologic features, either an upgrading in the disease spectrum or complete clearance of granuloma. Some 80% of lepromin conversions were in BL and LL patients who received vaccine versus none and 14.3% of BL and LL controls, respectively. Thirteen of 17 vaccinated LL patients were released from treatment after 2 years in contrast to 2 of 15 controls.

Induction of lepromin positivity by a candidate anti-leprosy vaccine Mycobacterium w in lepromin negative healthy contacts of multibacillary leprosy patients.

In a hospital based study, 362 household contacts of multibacillary leprosy patients were screened for evidence of leprosy and 54 (14.9%) were found to be having leprosy. The remaining 308 apparently healthy contacts were lepromin tested and 109 (35.4%) were observed to be negative to Mitsuda lepromin. M.w vaccine was administered intradermally to 95 of these 109 lepromin negative contacts. Sixty eight of them could be retested for lepromin A reactivity. Fifty six (82.35%) manifested lepromin conversion. The twelve subjects who did not show lepromin conversion, received a second dose of the vaccine, and eleven subsequently became lepromin positive. The overall lepromin conversion rate was thus 98.5% (67 out of 68). Follow-up of these contacts upto a period of 30 months did not demonstrate reversion of lepromin positivity back to negativity status. No untoward effects of vaccination were observed except for local ulceration at the site of vaccine administration.

Histopathological monitoring of an immunotherapeutic trial with Mycobacterium w.

Immunotherapeutic trials with Mycobacterium w (M. w.) on multibacillary patients are in progress at two large hospitals in New Delhi. A total of 380 patients so far have been inducted into the trial. The histopathological profile of the initial 87 patients (52 in the vaccine group, 35 in the control group) who have now completed 2 years of treatment are presented in this report. The vaccine group received multidrug therapy (MDT) and eight intradermal injections of M. w. every 3 months; the control group had MDT with starch injections as a placebo. Skin biopsies were taken at induction and thereafter at every 6 months. The results show a significantly higher proportion of biopsies with histopathological upgrading and/or clearance of dermal granuloma among the vaccinated cases. The number of patients becoming bacteriologically negative was higher in the vaccine group. There was no increase in the degree of neural inflammation in the biopsies showing upgrading. The lepromin site biopsy in patients who converted to positivity after vaccination showed epithelioid cell granulomas as did the biopsies from the nodules developing at the vaccination sites. The histopathological observations confirm the additional immunotherapeutic effect of M. w. used along with standard MDT therapy.

Association of HLA antigens with differential responsiveness to Mycobacterium w vaccine in multibacillary leprosy patients.

Leprosy patients undergoing phase II trials in two hospitals of New Delhi, India, were HLA typed to see the association of HLA with differential responsiveness to Mycobacterium w vaccine. The vaccine comprises an atypical, nonpathogenic mycobacterium, Mycobacterium w, which has cross-reactive antigens with M. leprae. Multibacillary patients who are lepromin negative are vaccinated at an interval of 3 months. Considerable improvement is evident in the patients in terms of a decline in bacterial indices and histopathological and immunological upgrading. But all the patients do not respond to the vaccine in the same manner; some are slow responders, while others are good responders. HLA-A28 and DQw3 (DQw8 + 9) were found to be associated with slow responsiveness, while DQw1 and DQw7 were found to be associated with a more rapid responsiveness to the M. w vaccine. However, these associations were not significant after P correction for the number of antigens tested for each locus except for HLA-DQw3 (DQw8 and DQw9) and DQw7. DQw7, a new defined split of HLA-DQw3, seems to be associated with the responsiveness to M. w vaccine.

Immunological upgrading with combined immunotherapy and chemotherapy in a lepromatous leprosy patient: a case report.

Immunotherapy with Mycobacterium w was given, in addition to standard multidrug therapy (MDT) to a lepromatous leprosy (LL) patient with a bacteriological index (BI) of 6. After 15 months of treatment this patient attained bacteriological negativity and clinical inactivity. Histopathologically the patient upgraded to borderline-tuberculoid at 12 months, and at 15 months showed features of nonspecific infiltration in the dermis. The rapid immunological upgrading seen in the patient is highlighted in this paper.

T-cell responses to fractionated antigens of Mycobacterium w, a candidate anti-leprosy vaccine, in leprosy patients.

Mycobacterium w, an atypical cultivable mycobacterium, is undergoing phase III clinical trials as a vaccine against leprosy in India. It has brought about lepromin conversion and histopathological upgradation in a significant number of patients studied so far. It is important to identify antigens of M. w that trigger T-cell responses in leprosy patients vaccinated with this organism. In the present study the peripheral T-cell repertoire of 12 M. w-vaccinated leprosy patients, 10 unimmunized leprosy patients, 8 tuberculoid and 5 healthy contacts was analysed with fractionated antigens of M. w. The lepromatous leprosy patients who are in general anergic to antigens of M. leprae did not respond to antigens of M. w. However, peripheral blood mononuclear cells obtained from leprosy patients who had been vaccinated with M. w responded to many antigens. These responses were frequently directed against low molecular weight entities of 14-45 kDa. T cells from tuberculoid leprosy patients and healthy contacts also responded predominantly to a number of low molecular weight antigens of M. w. The study also identified an immunodominant 28-31 kDa antigenic fraction carrying T- as well as B-cell activating determinants.