Microbial community diversity dynamics in a dual-stage membrane bioreactor (MBR) treating petrochemical wastewater (original) (raw)
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Infection and Immunity, 2001
Virulence variability was investigated by analyzing the experimental pathogenicity of 19 Leishmania major strains in susceptible BALB/c mice. Twelve strains were isolated from Tunisian patients with zoonotic cutaneous leishmaniasis; seven strains were isolated in Syria (n ؍ 1), Saudi Arabia (n ؍ 2), Jordan (n ؍ 2), or Israel (n ؍ 2). BALB/c mice were injected in the hind footpad with 2 ؋ 10 6 amastigotes of the various isolates, and lesion progression was recorded weekly for 9 weeks. Interleukin-4 (IL-4) and gamma interferon (IFN-␥) production of lymph node mononuclear cells activated in vitro with parasite antigens were evaluated 5 weeks after infection. We show that disease progression induced by different L. major isolates was largely heterogeneous although reproducible results were obtained when using the same isolate. Interestingly, isolates from the Middle East induced a more severe disease than did the majority of Tunisian isolates. Strains with the highest virulence tend to generate more IL-4 and less IFN-␥ in vitro at week 5 postinfection as well as higher levels of early IL-4 mRNA in the lymph node draining the inoculation site at 16 h postinfection. These results suggest that L. major isolates from the field may differ in virulence, which influences the course of the disease induced in mice and the type of immune response elicited by the infected host.
Parasite Immunology, 2013
Four genotypically distinct strains of L. major collected from persons residing in different endemic areas of cutaneous leishmaniasis in Iran were evaluated in BALB/c mice. Parasite virulence was evaluated by measuring the parasite burden in the lymph nodes. Immunogenicity of the strains was assessed by analysis of cytokines mRNA expression levels in popliteal lymph nodes of the mice in early (3, 16, 40 h) and late (week 1, W3, W5 and W8) time periods after infection. The expression of cytokines mRNA, namely Ifng, Il2, Il4, Il10 and Il12, was quantitated by real-time PCR. The lowest and the highest parasite loads were induced by Damghan (2Á15 9 10 7) and Shiraz (9Á59 9 10 9) strains, respectively. Moreover, Damghan strain elicited higher expression levels of Ifng and Il2 mRNA and the highest ratio of Ifng/Il4 mRNA expression compared with the other strains at 40 h and 8 weeks post-infection. The results indicate that the inoculation of BALB/c mice with different strains induced high diversity in parasite burden and cytokines gene expression. Amongst the four strains, Damghan strain showed the lowest parasite load and the highest tendency to induce expression of Th1 cytokines gene and might be considered as a safe and immunogenic strain.
A Laboratory Strain of Leishmania major: Protective Effects on Experimental Leishmaniasis
Acta Parasitologica
Purpose Leishmaniasis, as one of the most important vector-borne and zoonotic diseases, can be seen in different forms and is more prevalent in developing countries worldwide. Due to the absence of effective strategies in its prevention, treatment, and control, investigation of effective control strategies against the disease is necessary. In this research, we evaluated the immunogenicity of a cold-adapted laboratory strain of Leishmania major (LMC) in the mouse model. Methods Twenty BALB/c mice were divided into two groups. LMC group received 4 × 10 6 of LMC strain in 0.5 ml DMEM, and VLM group, as the control group, received 0.5 ml Dulbecco's modified Eagle's medium. Both groups were challenged with virulent L. major 3 weeks after inoculation. Results The data obtained from the analysis of immune responses and histopathological changes interestingly revealed protection against L. major in immunized mice. Compared with the VLM group, the mice immunized with LMC strain of L. major in the LMC group showed a significant increase in IFN-γ and IgG2a levels (P < 0.05) which are important indexes for Th1-related immune responses. Additionally, significant differences in concentration of IgG1 and IgG total before and after the challenge was observed in LMC group (P < 0.05). Furthermore, the immunized mice showed a significant reduction in mean sizes of skin lesion and liver damage compared to the VLM group. Conclusion Based on the present findings on immunogenicity of LMC strain, it seems this strain is able to induce both humoral and cellular immunity and a significant protection against L. major in the mouse model.
Animal Models for the Study of Leishmaniasis Immunology
Revista do Instituto de Medicina Tropical de São Paulo, 2014
Leishmaniasis remains a major public health problem worldwide and is classified as Category I by the TDR/WHO, mainly due to the absence of control. Many experimental models like rodents, dogs and monkeys have been developed, each with specific features, in order to characterize the immune response to Leishmania species, but none reproduces the pathology observed in human disease. Conflicting data may arise in part because different parasite strains or species are being examined, different tissue targets (mice footpad, ear, or base of tail) are being infected, and different numbers ("low" 1x10 2 and "high" 1x10 6 ) of metacyclic promastigotes have been inoculated. Recently, new approaches have been proposed to provide more meaningful data regarding the host response and pathogenesis that parallels human disease. The use of sand fly saliva and low numbers of parasites in experimental infections has led to mimic natural transmission and find new molecules and immune mechanisms which should be considered when designing vaccines and control strategies. Moreover, the use of wild rodents as experimental models has been proposed as a good alternative for studying the host-pathogen relationships and for testing candidate vaccines. To date, using natural reservoirs to study Leishmania infection has been challenging because immunologic reagents for use in wild rodents are lacking. This review discusses the principal immunological findings against Leishmania infection in different animal models highlighting the importance of using experimental conditions similar to natural transmission and reservoir species as experimental models to study the immunopathology of the disease.
2013
Resolution of leishmanial infection is dependent on the coordinated interactions between components of cell mediated immune response, central to which is the activation of targeted T-cell populations for appropriate cytokine production and activation of infected cells. In human as well as murine leishmaniasis, cure is associated with predominant Th1 response, good cell-mediated immunity (CMI), production of interferon gamma (IFN-γ) and macrophage activation. On the other hand, cytokine analysis in visceral leishmaniasis reveals enhanced induction of IL-10 and⁄or IL-4 mRNA in tissues, poor CMI, hypergammaglobulinaemia and enhanced presence of IL-4 in circulation of patients with progressive disease. The Th1/Th2 paradigm of resistance/susceptibility is an oversimplication of a far more complicated network of regulatory/counterregulatory interactions and thus a deficit in the understanding of the exact mechanisms involved in resolution vs severity of leishmaniasis. This review, in addition to giving a general overview of basic immunology of Leishmania infection, consolidates findings on immune responses in experimental and human leishmaniasis. Such information is important in giving a feasible direction in designing prophylactic and therapeutic strategies against leishmaniasis.
Scandinavian Journal of Immunology, 2008
T-cell mediated immune responses are key determinants to the natural course of infection caused by intracellular parasites such as Leishmania. Thus, T-cell activating proteins of these microbes continue to generate active interest particularly in view of their possible role in the design and development of newer and more effective vaccines. We have recently reported the presence of T-cell immunostimulatory antigens with the high-molecular-weight (MW) fractions (134–64.2 kDa) of whole Leishmania donovani antigen (strain 2001), which stimulated variable amounts of IFN-γ, IL-12 and IL-10 in exposed immune individuals. The present study was undertaken to further evaluate these high-MW antigenic fractions (MW range >100–60 kDa) for potential protective efficacy. The high-MW region of the parasite was resolved into five antigenic fractions (Prep A–E) using continuous elution gel electrophoresis. Prior to in vivo protection studies in hamsters, these fractions were used to evaluate in vitro cellular responses in eight Leishmania-exposed individuals and treated cured hamsters. The protective efficacy of prep (A + B), C, D and E in combination with BCG was evaluated in inbred hamsters using standard immunization protocol. Proliferative responses were seen in all eight of eight exposed individuals to prep D [median stimulation index (SI): 5.2 (range 3.9–7.1)] and E [median SI: 5.6 (range 4.4–8.2)], five of eight individuals to prep B and prep C and three of eight to prep A [median SI: 0.2 (range 0.1–7.2)]. The median proliferative responses to prep D and prep E were significantly higher than to fraction prep A; (P < 0.05) but not to prep B and prep C. However, prep A–E induced equivalent levels of IFN-γ, IL-10 and IL-12 cytokines. Fractions D and E also exhibited marked parasite inhibition in spleen (52.5% and 73.7%) and liver (65% and 80.2%) as compared with prep (A + B) (23% in spleen and 24% in liver) and prep C (38% in spleen and 24% in liver). Prep D and prep E vaccinated animals showed higher in vitro stimulatory responses (mean SI: 6.6 and 8.8) and nitric oxide (NO) induction (mean NO levels: 6.4 and 10.7 μg/ml) against whole cell extract as compared with other groups. The protection also correlated with presence of suppressed Leishmania-specific IgG levels in prep D and prep E immunized hamsters. These studies indicate the presence of immunostimulatory and protective molecules in 60–80 kDa region of L. donovani, which may be further exploited for developing a subunit vaccine.
Clinical and Experimental Immunology, 2006
Summary Human visceral leishmaniasis (VL), also known as kala azar (KA) in India, is a systemic progressive disease caused by Leishmania donovani. In VL, Th1 responses correlate with recovery from and resistance to disease and resolution of infection results in lifelong immunity against the disease. However, recent data suggest an important role for interleukin (IL)-10 in maintaining the resistant state. We evaluated whole cell extract (WE) and 11 antigenic fractions [F1–F11, molecular weight (MW) range of 139–24·2 kDa] from L. donovani (2001 strain, a fresh field isolate from Bihar), for their ability to induce in vitro T cell proliferation and production of interferon (IFN)-γ, interleukin (IL)-12, IL-10 and IL-4 by peripheral blood mononuclear cells (PBMCs) of exposed immune individuals (14 patients with history of VL, 10 household endemic contacts) and 20 non-endemic healthy controls. Twenty-one of 24 exposed individuals and no healthy controls showed proliferative response to WE...