RESUMO
Sera of 11 wild Cerdocyon thous foxes from an endemic area for American visceral leishmaniasis were tested for the presence of antibodies against salivary gland homogenates (SGH) of Lutzomyia longipalpis. All foxes had higher levels of anti-Lu. longipalpis SGH antibodies than foxes from non-endemic areas, suggesting contact between foxes and the vector of visceral leishmaniasis. Sera of humans and dogs living in the same area were also tested for reactivity against Lu. longipalpis SGHs and had a lower proportion of reactivity than foxes. Antibodies against Leishmania chagasi were not detected in any of the foxes, but three foxes showed the presence of parasites in the bone marrow by direct examination, PCR or by infecting the vector. Both humans and dogs had higher levels of anti-Le. chagasi IgG antibodies than C. thous. The finding of an antibody response against saliva of Lu. longipalpis among C. thous together with the broad distribution of the vector in resting areas of infected foxes suggests that the natural foci of transmission of Le. chagasi exists independently of the transmission among dogs and humans.
Assuntos
Anticorpos Antiprotozoários/sangue , Raposas/parasitologia , Leishmania infantum/imunologia , Psychodidae/imunologia , Saliva/parasitologia , Animais , Western Blotting , Medula Óssea/parasitologia , Cães , Ensaio de Imunoadsorção Enzimática , Humanos , Imunidade Celular , Camundongos , Reação em Cadeia da Polimerase/métodos , Saliva/imunologia , Glândulas Salivares/parasitologiaRESUMO
In the present study we evaluated Canavalia brasiliensis (ConBr), Pisum arvense (PAA) and Artocarpus integrifolia (KM+) lectins as immunostimulatory molecules in vaccination against Leishmania amazonensis infection. Although they induced IFN-gamma production, the combination of the lectins with SLA antigen did not lead to lesion reduction. However, parasite load was largely reduced in mice immunized with KM+ lectin and SLA. KM+ induced a smaller inflammatory reaction in the air pouch model and was able to inhibit differentiation of dendritic cells (BMDC), but to induce maturation by enhancing the expression of MHC II, CD80 and CD86. These observations indicate the modulatory role of plant lectins in leishmaniasis vaccination may be related to their action on the initial innate response.
Assuntos
Adjuvantes Imunológicos/farmacologia , Antígenos de Protozoários/imunologia , Leishmania/imunologia , Leishmaniose/imunologia , Lectinas de Plantas/farmacologia , Adjuvantes Imunológicos/administração & dosagem , Estruturas Animais/parasitologia , Animais , Antígenos de Protozoários/administração & dosagem , Artocarpus , Canavalia , Células Dendríticas/química , Células Dendríticas/imunologia , Feminino , Antígenos de Histocompatibilidade Classe II/análise , Interferon gama/biossíntese , Interleucina-12/biossíntese , Leishmaniose/patologia , Linfócitos/imunologia , Masculino , Camundongos , Camundongos Endogâmicos BALB C , Lectinas de Plantas/administração & dosagemRESUMO
Saliva of bloodfeeding arthropods has been incriminated in facilitating the establishment of parasite in their host. We report on the leukocyte chemoattractive effect of salivary gland homogenate (SGH) from Lutzomyia longipalpis on saliva-induced inflammation in an air pouch model. SGH (0.5 pair/animal) was inoculated in the air pouch formed in the back of BALB/c or C57BL/6 mice. L. longipalpis SGH induced a significant influx of macrophages in BALB/c but not in C57BL/6 mice. SGH-induced cell recruitment reached a peak at 12 h after inoculation and was higher than that induced by the LPS control. This differential cell recruitment in BALB/c mice was directly correlated to an increase in CCL2/MCP-1 expression in the air pouch lining tissue. In fact, treatment with bindarit, an inhibitor of CCL2/MCP-1 synthesis, and also with a specific anti-MCP-1 mAb resulted in drastic reduction of macrophage recruitment and inhibition of CCL2/MCP-1 expression in the lining tissue. CCL2/MCP-1 production was also seen in vitro when J774 murine macrophages were exposed to L. longipalpis SGH. The SGH effect was abrogated by preincubation with serum containing anti-SGH IgG Abs as well as in mice previously sensitized with L. longipalpis bites. Interestingly, the combination of SGH with Leishmania chagasi induced an increased recruitment of neutrophils and macrophages when compared with L. chagasi alone. Taken together these results suggest that SGH not only induces the recruitment of a greater number of macrophages by enhancing CCL2/MCP-1 production but also synergizes with L. chagasi to recruit more inflammatory cells to the site of inoculation.
Assuntos
Quimiocina CCL2/genética , Quimiotaxia , Macrófagos/fisiologia , Psychodidae/imunologia , Saliva/imunologia , Animais , Regulação da Expressão Gênica , Inflamação/etiologia , Leishmania/imunologia , Camundongos , Camundongos Endogâmicos BALB C , Camundongos Endogâmicos C57BL , Especificidade da EspécieRESUMO
In this study, we compare the development of infection and/or disease in Beagle dogs intradermally infected with Leishmania chagasi, in the presence or absence of Lutzomyia longipalpis saliva, with those of intravenously infected animals. Spleen samples of all the animals inoculated with parasites had positive polymerase chain reaction tests for Leishmania DNA. Positive spleen cultures for Leishmania were detected earlier (P < or = 0.018) and were more frequent (five out of the five animals) in intravenously infected animals than in the intradermally infected animals, in presence (two out of the six animals) or absence (three out of the five animals) of salivary gland lysate of L. longipalpis. Significant increase in serum antibodies against Leishmania was observed only in the intravenously infected group (P = 0.004). In addition, dogs with infection confirmed by isolation of amastigotes or detection of parasite DNA were, nevertheless, negative for anti-Leishmania antibodies up to 5 months or more after infection. Only animals of the intravenously infected group developed progressive decreases in hematocrit (Pearson r = -0.8076, P = -0.0026) and hemoglobin (Pearson r = -0.8403, P = 0.0012) during the infection period. No significant difference in the course of infection was observed between groups of intradermally infected animals. The data presented herein confirms that the intradermal inoculation of dogs with Leishmania produces an asymptomatic form of infection. It also fails to show an advantage in using L. longipalpis saliva as an infection-enhancing agent in experimental canine leishmaniasis.
Assuntos
Doenças do Cão/parasitologia , Insetos Vetores/química , Leishmania/fisiologia , Leishmaniose Visceral/veterinária , Psychodidae/química , Animais , Anticorpos Antiprotozoários/sangue , DNA de Protozoário/análise , Modelos Animais de Doenças , Doenças do Cão/imunologia , Cães , Ensaio de Imunoadsorção Enzimática/veterinária , Feminino , Seguimentos , Leishmania/genética , Leishmania/imunologia , Leishmaniose Visceral/imunologia , Leishmaniose Visceral/parasitologia , Ativação Linfocitária , Reação em Cadeia da Polimerase/veterinária , Saliva , Baço/parasitologiaRESUMO
Antibody responses to salivary gland sonicate (SGS) from Lutzomyia longipalpis were investigated using serum samples from individuals living in an area where visceral leishmaniasis is endemic. Individuals were classified into 2 groups, according to the alteration of their responses to Leishmania chagasi antigen over the course of 6 months. Group 1 included children who experienced anti-L. chagasi seroconversion from negative to positive; group 2 included children who experienced delayed-type hypersensitivity (DTH) response to L. chagasi antigen conversion from negative to positive. Individuals who experienced seroconversion against L. chagasi antigens did not have increased anti-saliva antibody response, whereas those who developed a positive anti-L. chagasi DTH response had increased immunoglobulin (Ig) G, IgG1 and IgE anti-SGS antibody levels. Despite wide variation, serum samples from individuals in group 2 recognized more bands in SGS than did those from individuals in group 1. This simultaneous appearance of anti-saliva humoral response and anti-L. chagasi cell-mediated immunity supports the hypothesis that induction of immune response against SGS can facilitate induction of a protective response against leishmaniasis.
Assuntos
Doenças Endêmicas , Hipersensibilidade Tardia/imunologia , Imunoglobulina G/imunologia , Leishmania/imunologia , Leishmaniose/imunologia , Psychodidae/imunologia , Animais , Formação de Anticorpos/imunologia , Criança , Humanos , Imunidade Celular/imunologia , Leishmaniose/epidemiologia , Glândulas Salivares/imunologiaRESUMO
In Brazil, programs based on elimination of infected dogs have not curtailed the spread of visceral leishmaniasis (VL), suggesting that other reservoirs of infection exist. Persons with active VL can infect the sand fly vector, but in endemic areas, persons with asymptomatic infections, whose infectivity to sand flies is unknown, are far more numerous. In this study, a polymerase chain reaction-based assay detected kinetoplast DNA of Leishmania chagasi in the blood of eight of 108 asymptomatic persons living with patients with recently diagnosed VL. These eight persons had low or unmeasurable levels of IgG antibodies to Leishmania, demonstrating the insensitivity of serology for subclinical infection. All eight persons had positive leishmanin skin test results, as did 70% of persons living in households of persons with active VL. Even if a small proportion of such asymptomatic persons are infective to sand flies, they represent a formidable reservoir of infection in endemic areas.