Flow cytometric analysis of cellular immune responses in dogs experimentally infected with a North American isolate of Leishmania infantum (original) (raw)
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Veterinary Immunology and Immunopathology, 2005
Cellular immune response to Leishmania plays a key role in canine leishmaniosis. However, there are few assays to evaluate this response in the dog. Here, we evaluated and compared three assays of specific cellular immune response to Leishmania infantum in dogs: the leishmanin skin test (LST), lymphocyte proliferation assay (LPA) and IFN-g cytopathic effect inhibition bioassay (IFNB). Fifty-six healthy dogs from an endemic area for leishmaniosis on the island of Mallorca were studied. In all, 37 dogs showed a positive LST and 32 a positive IFNB, 24 were positive for both assays. The 17 dogs positive for LPA also gave positive results for either LST or IFNB, or both. These findings indicate that although LST is the method of choice, IFNB is a complementary test. Therefore, both assays should be performed and analyzed jointly. In comparison with LST and IFNB, LPA is much less sensitive, and yields many false negative results. #
Veterinary parasitology, 2014
Visceral leishmaniasis has a great impact on public health, and dogs are considered the main domestic reservoir of Leishmania infantum, the causal parasite. In this study, 159 animals naturally infected by L. infantum from an endemic area of Brazil were evaluated through an analysis of cellular responses, using flow cytometry, and of the hematological parameters. The results confirmed that disease progression is associated with anemia and reductions in eosinophils, monocytes and lymphocytes. The investigation of the immune response, based on the immunophenotypic profile of peripheral blood, showed declines in the absolute numbers of T lymphocytes CD5(+) and their subsets (CD4(+) and CD8(+)) and a drop of B lymphocytes in asymptomatic seropositive (AD-II) and symptomatic seropositive (SD) dogs. Neutrophils, when stimulated with soluble antigen of L. infantum, showed higher synthesis of interferon (IFN)-γ(+) in AD-II and SD groups, with decreased production of interleukin (IL)-4(+) in...
Infection and Immunity, 1994
In this paper we describe a number of immunological parameters for dogs with a chronic Leishmania infantum infection which exhibit patterns of progressive disease or apparent resistance. The outcome of infection was assessed by isolation of parasites, serum antibody titers to Leishmania antigen, and development of clinical signs of leishmaniasis. Our studies show that 3 years after experimental infection, asymptomatic or resistant dogs responded to L. infantum antigen both in lymphocyte proliferation assays in vitro and in delayed-type hypersensitivity reaction, whereas no serum antibodies to parasite antigen were shown. In
Humoral and cellular immune responses in dogs with inapparent natural Leishmania infantum infection
The Veterinary Journal, 2011
Molecular analysis, serology and immunophenotyping for T lymphocytes and their subsets, B lymphocytes and monocytes were performed on dogs naturally infected with Leishmania infantum. Animals were categorised as asymptomatic dogs I (AD-I), with negative serology and positive molecular results, and asymptomatic dogs II (AD-II), with positive serology and positive molecular results, and these were compared to symptomatic dogs (SD) and control dogs (CD). AD-I exhibited immunophenotypic features similar to those of CD, including isotype profiles and concentrations of monocytes. Similar biomarkers were found in AD-II and SD, such as, higher levels of immunoglobulins IgG, IgG2, IgM and IgA and higher concentrations of eosinophils. High frequencies of T lymphocytes and CD4 + T cells were observed in both AD-I and AD-II compared to SD, whereas CD8 + T cells were higher only in AD-II compared with SD. Analysis of B lymphocytes revealed an increased frequency of this cell type only in AD-II animals compared with SD. Asymptomatic dogs appear to have a dichotomous infection spectrum that can influence the humoral and cellular immunological status during canine visceral leishmaniasis.
Memórias do Instituto Oswaldo Cruz, 2011
Domestic dogs are considered to be the main reservoirs of zoonotic visceral leishmaniasis. In this work, we evaluated a protocol to induce Leishmania infantum/Leishmania chagasi-specific cellular and humoral immune responses in dogs, which consisted of two injections of Leishmania promastigote lysate followed by a subcutaneous inoculation of viable promastigotes. The primary objective was to establish a canine experimental model to provide positive controls for testing immune responses to Leishmania in laboratory conditions. After inoculation of viable promastigotes, specific proliferative responses of peripheral blood mononuclear cells (PBMCs) to either Leishmania lysate or recombinant proteins, the in vitro production of interferon-γ by antigen-stimulated PBMCs and a significant increase in circulating levels of anti-Leishmania antibodies were observed. The immunized dogs also displayed positive delayed-type hypersensitivity reactions to Leishmania crude antigens and to purified recombinant proteins. An important finding that supports the suitability of the dogs as positive controls is that they remained healthy for the entire observation period, i.e., more than seven years after infection. Following the Leishmania antigen lysate injections, the infection of dogs by the subcutaneous route appears to induce a sustained cellular immune response, leading to an asymptomatic infection. This provides a useful model for both the selection of immunogenic Leishmania antigens and for immunobiological studies on their possible immunoprotective activities.
Veterinary Immunology and Immunopathology, 2007
Canine infections with Leishmania infantum represent a considerable veterinary medical and public health problem. In this study, immunoglobulin G1 (IgG1) and IgG2 specific humoral responses were measured and compared with the delayed type hypersensitivity (DTH) cellular response to a leishmanin, in three groups of dogs clinically and serologically characterised as: (I) asymptomatic and direct agglutination test (DAT)-seronegative; (II) asymptomatic and DAT-seropositive; (III) DAT-seropositive and symptomatic. IgG2 was regarded as a marker of disease, since significantly higher levels of this subclass were recorded in the symptomatic dogs. In contrast, the IgG1 response could not be related to clinically relevant infection. A high correlation was observed between IgG2 level and DAT titre; the correlations between IgG1 and IgG2 levels, and between IgG1 level and DAT titre were lower. This may indicate that IgG2 is the main subclass in the specific humoral response which is detected by the DAT. A reduced IgG2 response, albeit not significantly different, was recorded among dogs with clear cellular immune responses detected by a DTH positive reaction. Furthermore, no correlations were observed between cellular response measured by DTH and humoral responses quantified by DAT titre or IgG1 and IgG2 levels. Combining serology and DTH skin test is a practical procedure to assess anti-Leishmania immune responses in dogs.
Revista do Instituto de Medicina Tropical de São Paulo, 2007
The Western blot technique was used to demonstrate the presence of antibodies in the blood of dogs that presented canine visceral leishmaniasis. This technique was used against some specific molecules present in the lysate of the promastigote form of Leshmania chagasi.Through the association of the results of the Western blot technique with the morphological alterations seen as a result of the serum neutralization technique performed in McCoy cells (which mimetizes the macrophage) it was possible to observe the role of some molecules of great relevance in determining the disease in symptomatic dogs as well as that of some other molecules associated with asymptomatic infected dogs that may become transmitters as well as differentiating them as asymptomatic resistant dogs. In the sera analyses carried out during the immunobloting a variation of 9 to 27 immunoreacting bands was observed, which were then compared using Dice's similarity coefficient. In the dendrogram constructed on ...
Scientific reports, 2017
Canine Visceral Leishmaniasis (CVL) is caused by Leishmania infantum, which in the New World is transmitted by Lutzomyia longipalpis. While prospective clinical and immunological assessments of dogs experimentally challenged with L. infantum have been previously reported over a relatively short follow-up period, the long-term characterization of infected animals has not been performed to date. We evaluated dogs in a subclinical state for six years following experimental infection with L. infantum and Lu. longipalpis saliva, via an intradermal route, to characterize clinical, parasitological and immunological parameters arising from L. infantum experimental infection. We also assess these parameters in a group of naturally infected animals. The immune profiles of the experimentally and naturally infected animals exhibited increases of IFN-γ, IL-6 and IL-18, and decreases in TNF, IL-2, IL-8 and CXCL1, compared to controls. Our results indicate that over a six-year follow-up post-chall...