Search

The present study has revealed that, the temperature has a crucial role among the observed physiochemical parameters on the growth and survival of P. margaritifera spat. Instantaneous growth rates (IGRs) in DVM, APM and TWT were calculated and used to assess the variation in growth of spat reared with different feed mixtures (FM-1 - 8) of five diatoms and stocking densities (SD-10, 20 and 30). Among all treatments, FM-3, 4 and 5 gave better performance than that all other combinations of diatoms. Chaetoceros calcitrans, Nannochloropsis oculata and Chlorella marina was formed major shares (60%) respectively in combination with 10% each of rest of algae. FM-7 which had all diatoms in equal (20%) measure performed as the next best feed combination. Poor growth was observed in spat fed with FM-2 which was dominated by Isochrysis galbana (60%) and FM-6 which comprised of an equal measure (30%) of Pavlova salina, Isochrysis galbana, Chaetoceros calcitrans and Nannochloropsis oculata and Chlorella marina at 5% each. When the stocking density increases (SD–20 and 30) growth rates (IGRs) in all three variables decreased irrespective of feed combinations. Mortality rates varied in different treatments and also with stocking densities. Maximum mortality was observed in control (FM -8) in all the stocking densities. However, in all the feeding combinations and stocking densities, 100 % survival was observed upto the 9th DOC and mean cumulative mortalities showed a gradual increase. Comparatively very less cumulative mortality and better growth performance were recorded in stocking density, SD-10.

The global epidemic of tuberculosis (TB), fueled by the growing HIV pandemic, warrants the development of a safe and effective vaccine against TB. We report the construction and characterization of an unlinked double deletion mutant of Mycobacterium tuberculosis H37Rv that deletes both the primary attenuating mutation of BCG (DeltaRD1) and two genes required for the synthesis of pantothenate (DeltapanCD). The M. tuberculosis DeltaRD1 DeltapanCD (mc(2)6030) mutant undergoes limited replication in mice, and yet is both significantly safer than BCG in immunocompromised mice and also safe in guinea pigs. Additionally, the mc(2)6030 strain does not reactivate in a mouse chemo-immunosuppression model. Importantly, long-lived protective immune responses following immunization with the mc(2)6030 strain prolong the survival of wild type mice, and CD4-deficient mice against an aerosol challenge with virulent M. tuberculosis. Given its overall safety and effectiveness, the mc(2)6030 live attenuated strain should be considered as a human vaccine candidate for protecting both healthy and HIV-infected individuals against TB.

Tuberculous pleuritis is a good human model to understand the local and protective immune response against tuberculosis, due to the self-limitedness of the disease. Although the cellular immune response has been well characterised in tuberculous pleurisy, much less is known about the humoral immune response operating at the site of infection. To understand the humoral immune response, B cells were enumerated in peripheral blood mononuclear cells (PBMC) and pleural fluid mononuclear cells (PFMC) of tuberculous (TP) and non-tuberculous pleuritis patients (NTP). The levels of IgG, IgA and IgM antibodies for PPD, culture filtrate (CF) and sonicate antigens (Son Ag) were assessed in plasma (BL) and pleural fluid (PF) and a western blot was carried out with the CF antigen. The percentage of CD19+B-cells was similar in PBMC and PFMC of TP patients but was significantly lower in PFMCs of NTP patients. The IgG levels for PPD and CF antigens were higher in PF of TP than NTP patients. The antigen recognition patterns did not differ in plasma and pleural fluid of the same patient in both groups pointing out the passive diffusion of the plasma to the pleura. The antigens 25, 31, 33, 70, 110, 124 and 132 kDa were recognized exclusively by the TP patients. Thus our study showed that the local humoral response in TP did not differ from the systemic response. However, the humoral response differed in TP patients when compared to NTP patients.

The global epidemic of tuberculosis, fuelled by acquired immune-deficiency syndrome, necessitates the development of a safe and effective vaccine. We have constructed a DeltaRD1DeltapanCD mutant of Mycobacterium tuberculosis (mc(2)6030) that undergoes limited replication and is severely attenuated in immunocompromised mice, yet induces significant protection against tuberculosis in wild-type mice and even in mice that completely lack CD4(+) T cells as a result of targeted disruption of their CD4 genes (CD4(-/-) mice). Ex vivo studies of T cells from mc(2)6030-immunized mice showed that these immune cells responded to protein antigens of M. tuberculosis in a major histocompatibility complex (MHC) class II-restricted manner. Antibody depletion experiments showed that antituberculosis protective responses in the lung were not diminished by removal of CD8(+), T-cell receptor gammadelta (TCR-gammadelta(+)) and NK1.1(+) T cells from vaccinated CD4(-/-) mice before challenge, implying that the observed recall and immune effector functions resulting from vaccination of CD4(-/-) mice with mc(2)6030 were attributable to a population of CD4(-) CD8(-) (double-negative) TCR-alphabeta(+), TCR-gammadelta(-), NK1.1(-) T cells. Transfer of highly enriched double-negative TCR-alphabeta(+) T cells from mc(2)6030-immunized CD4(-/-) mice into naive CD4(-/-) mice resulted in significant protection against an aerosol tuberculosis challenge. Enriched pulmonary double-negative T cells transcribed significantly more interferon-gamma and interleukin-2 mRNA than double-negative T cells from naive mice after a tuberculous challenge. These results confirmed previous findings on the potential for a subset of MHC class II-restricted T cells to develop and function without expression of CD4 and suggest novel vaccination strategies to assist in the control of tuberculosis in human immunodeficiency virus-infected humans who have chronic depletion of their CD4(+) T cells.

We report the safety and immunogenicity of a double lysine and pantothenate auxotroph ofMycobacterium tuberculosisin mice. The ΔlysAΔpanCDmutant is completely attenuated in immunocompromised SCID and gamma interferon knockout mice yet induces short-term and long-term protection in immunocompetent and CD4-deficient mice following single-dose subcutaneous vaccination.

Tuberculous pleuritis (TB) provides a good model to study the correlates of protective immune response at the site of infection. To study the in vivo correlates of immunity, cell subset profile and cytokine assay in plasma (BL) and pleural fluid (PF) of 82 patients were done. Lymphocyte proliferation and cytokine response to mycobacterial antigens were measured in 32 subjects to understand the in vitro correlates. Increase in CD4(+) cells and CD4(+)/CD8(+) ratio with selective concentration of interferon (IFN)-gamma, tumour necrosis factor (TNF)-alpha and interleukin (IL)-12 in PF suggests that the CD4(+) population may be of TH1 type. We observed an accelerated lymphoproliferative response to purified protein derivative (PPD) and heat killed Mycobacterium tuberculosis (MTB) in PF cells of both TB and non-TB (NTB) subjects. Interestingly, in in vitro studies, IL-4 levels together with IFN-gamma were significantly increased in the supernatants of PF mononuclear cells (PFMC) of TB patients and showed a shift in immune response towards TH0/TH2 type. PPD and MTB antigens induced an enhanced proliferation of PFMC and also increased in vitro IL-4 response together with apoptosis, thus eliciting a dual response.