Mycobacterium indicus pranii as stand-alone or adjunct immunotherapeutic in treatment of experimental animal tuberculosis.

Background & objectives: Mycobacterium w (M.w) is a saprophytic cultivable mycobacterium and shares several antigens with M. tuberculosis. It has shown good immunomodulation in leprosy patients. Hence in the present study, the efficacy of M.w immunotherapy, alone or in combination with multi drug chemotherapeutic regimens was investigated against drug sensitive M. tuberculosis H37Rv and three clinical isolates with variable degree of drug resistance in mice. Methods: BALB/c mice were infected with M. tuberculosis H37Rv (susceptible to all first and second line drugs) and three clinical isolates taken from the epository of the Institute. The dose of 200 bacilli was used for infection via respiratory route in an aerosol chamber. Chemotherapy (5 days/wk) was given one month after infection and the vaccinated group was given a dose of 1×107 bacilli by subcutaneous route. Bacterial load was measured at 4 and 6 wk after initiation of chemotherapy. Results: M.w when given along with chemotherapy (4 and 6 wk) led to a greater reduction in the bacterial load in lungs and other organs of TB infected animals compared to. However, the reduction was significantly (P<0.05) more in terms of colony forming units (cfu) in both organs (lungs and spleen). Conclusion: M.w (as immunomodulator) has beneficial therapeutic effect as an adjunct to chemotherapy.

Mycobacteria and innate cells: critical encounter for immunogenicity.

Protective immunity against mycobacterial infections such as Mycobacterium tuberculosis is mediated by interactions between specific T cells and activated macrophages.To date,many aspects of mycobacterial immunity have shown that innate cells are the key elements that substantially influence the subsequent adaptive host response.During the early phases of infection,phagocytic cells and innate lymphocyte subsets play a pivotal role.Here we summarize the findings of recent investigations on macrophages,dendritic cells and gammadelta T lymphocytes in the response to mycobacteria.

Effectivity of crude versus purified mycobacterial secretory proteins as immunogen for optimum antibody production.

Monospecific antibodies have been successfully utilized in antigen detection, which is better indicator of active infection. Mycobacterium tuberculosis excretory secretory (M tb ES) antigens such as ES 31, ES 41 and ES 43 (31 kDa, 41 kDa and 43 kDa protein, respectively) have been shown to be present in Mycobacterium tuberculosis H37Ra culture filtrate and are of diagnostic interest. To study the immunogenic potential of crude versus purified antigen, goat was immunized with M tb detergent soluble sonicate (DSS) antigen as well as purified antigen fraction (ESAS 7) containing ES 31 antigen. Both anti-DSS IgG antibody and anti ESAS 7 IgG antibody were found to be reactive with ES 31 antigen upto 1 ng concentration of antibody by ELISA. Crude DSS antigen was found to be quite effective in producing high titre antibodies and showed further high reactivity with other ES antigens (ES 41 and ES 43) of diagnostic interest.

Identification of a 75 kDa highly immunodominant antigen from Mycobacterium smegmatis and cross-reactivity with other species.

Three monospecific antibodies MSAb 1, MSAb 2 and MSAb 3 were raised in BALB/C mice against respective antigens. M. smegmatis whole cell lysate was first separated on SDS-PAGE and randomly chosen bands were cut and then used for immunization. Antibodies were collected as ascites by injecting mice with myeloma cell line P3X63 Ag 658.4. All the three antibodies showed high reactivity with denatured antigens compared to native. Different extent of cross-reactivity was observed as evident from ELISA. MSAb1 recognized a 75 kDa immunodominant antigen from M. smegmatis and 66 kDa from M. tuberculosis (H37Ra), respectively. An apparently similar molecular weight antigen shown to be present in M. tuberculosis (H37Ra) an avirulent strain and BCG, but not recognized by MSAb1. The 75 kDa antigen has a stimulatory effect on T-cell proliferation.

Mycobacterial proteins--immune targets for antituberculous subunit vaccine.

Cellular and humoral immunity induced by Mycobacterium tuberculosis has led to identification of newer vaccine candidates, but despite this, many questions concerning the protection against tuberculosis remain unanswered. Recent progress in this field has centered on T cell subset responses and cytokines that these cells secrete. There has been a steady progress in identification and characterization of several classes of major mycobacterial proteins which includes secretory/export proteins, cell wall associated proteins, heat shock proteins and cytoplasmic proteins. The protein antigens are now believed to represent the key protective immunity inducing antigens in the bacillus. In this review, various mycobacterial protein antigens of vaccination potential are compared for their efficacy in light of current immunological knowledge.

DNA encoding individual mycobacterial antigens protects mice against tuberculosis

Over the last few years, some of our experiments in which mycobacterial antigens were presented to the immune system as if they were viral antigens have had a significant impact on our understanding of protective immunity against tuberculosis. They have also markedly enhanced the prospects for new vaccines. We now know that individual mycobacterial protein antigens can confer protection equal to that from live BCG vaccine in mice. A critical determinant of the outcome of immunization appears to be the degree to which antigen-specific cytotoxic T cells are generated by the immune response. Our most recent studies indicate that DNA vaccination is an effective way to establish long-lasting cytotoxic T cell memory and protection against tuberculosis

IgG response to some mycobacterial antigens in selected leprosy patients.

Serum samples from selected leprosy patients with putative tuberculosis were tested by indirect ELISA to determine the level of IgG antibody against six mycobacterial antigen preparations. PCR-positive leprosy patients were confirmed with PGL-I ELISA. A ratio of antibodies to antigens of tuberculosis and leprosy was found to be a valuable serological marker for tuberculosis in long-treated leprosy patients.

Standardization of a dot blot immunoassay for antigen detection in cases of pulmonary tuberculosis & its evaluation with respect to the conventional techniques.

A simple dot (blot) ELISA test for detecting tubercular antigen in sputum samples of patients of pulmonary tuberculosis has been standardized using nitrocellulose paper. The sensitivity of the assay is 20 ng/ml. The cut-off value was 80 ng/ml. Of the 1042 patients in the study group, the percentage positivity by smear and culture was 54.51 and 57.93 per cent respectively; 68.7 per cent of the ELISA positives were confirmed by smear. The dot blot ELISA could be used as a rapid and specific test as it not only picked up 88.88 per cent of the smear positive, culture positive cases but also 81.89 per cent of the smear negative, culture positive cases. If the results of smear and dot blot ELISA are combined, 91.08 per cent of the culture positive cases were picked up as positive. If such a noninvasive test is commercialized and used in conjunction with smear, the pick up rate of tuberculosis cases will improve considerably.

Usefulness of ELISA using antigen A60 in serodiagnosis of neurotuberculosis.

Anti-mycobacterial antibody to A60 antigen were quantified in the sera and cerebrospinal fluid (csf) samples of one hundred patients of neurotuberculosis and twenty non-tubercular controls by immunoenzymatic (ELISA) assay. Sixty three patients (63%) had "significant" antibody titres in serum and/or CSF samples. In contrast, none of the samples from the control group showed this level of antibody concentration. The evaluation of this assay in tuberculoma (group A, 79 cases) vis-a-vis tubercular meningitis or TBM (group B, 21 patients) revealed significant antibody levels in the former 46 (58.2%) in comparison to 17 (77.3%) in the latter group. A positive relationship was observed in the titres of anti-mycobacterial antibodies in serum and in CSF both in cases of tuberculoma and TBM. This study indicates the utility of A60 antigen ELISA assay in categorising these patients into tubercular aetiology specially in the absence of bacteriological isolation from CSF which still remains the gold standard diagnostic criterion.

The hamster cheek pouch: an immunologically privileged site suitable to the study of granulomatous infections

A bolsa jugal do hamster (BJH) e uma invaginacao da mucosa oral, caracterizada histologicamente como semelhante a pele. Nesse estudo nos descrevemos algumas de suas caracteristicas anatomicas, histologicas e embriologicas e comentamos sobre sua propriedade como local imunologicamente privilegiado, considerando a ausencia de drenagem linfatica e o reduzido numero de celulas de Langerhans ...

Mycobacterium vaccae immunotherapy in the treatment of multi-drug-resistant tuberculosis: a preliminary report

Multiple drug resistance [MDR] of tubercle bacilli to chemotherapy is becoming a problem of major concern. In this study 41 patients infected with resistant strains of tubercle bacilli received immunotherapy with killed Mycobacterium vaccae as an adjunct to continuing chemotherapy. Eleven of the 41 patients were cured and became sputum negative. The combined therapy was particularly effective in male patients with short histories of previous chemotherapy. We conclude that immunotherapy with M. vaccae may be helpful in the treatment of multiple drug resistant tuberculosis

Liposomes as a carrier for mannophosphoinositide antigens of mycobacteria.

Phosphatidylcholine liposomes have been used as carriers of mannophosphoinositides (PIMs) of mycobacteria to examine their immunological properties. PIMs incorporated in egg phosphatidylcholine (EPC) liposomes elicited both humoral and cell-mediated immune responses in mice. Addition of cholesterol at 43 mole% to PC enhanced the immune responses while the reverse was observed with EPC liposomes bearing negative or positive charge. Liposomes made of dioleoylphosphatidylcholine (DOPC) with cholesterol (43 mole%) proved to be a better immunoadjuvant with this antigen as compared to those made of EPC or dipalmitoylphosphatidylcholine (DPPC). Our results suggest that DOPC liposomes containing cholesterol are better carriers for PIMs-antigen as compared to Freund's incomplete adjuvant.