Between 1985 and 2000, epidemiological surveys of the American tegumentary leishmaniasis (ATL) were carried out in several rural and urban communities in Espírito Santo, Brazil. A total of 100 stocks of Leishmania (comprising isolates from both human and canine hosts with ATL) were identified by two methods of molecular characterization, using specific monoclonal antibodies and multilocus enzyme electrophoresis. Parasite isolates from 19 municipalities were found to belong to the same zymodeme and serodeme type as of the Leishmania (Viannia) braziliensis reference strain. In contrast, our genotyping studies have shown intra-specific variation among these parasites (comparisons of the variability of the internal transcribed spacers between the small and large subunits of the rRNA genes of the 22 stocks studiedrevealed at least 11 genotypes). Two main clusters of L. (V.) braziliensis genotypes were observed, representing parasites collected from different endemic regions in the state, where transmission reflects distinct eco-epidemiological features. Infection with this pathogen was associated with the characteristic disease forms, but neither the clinical outcome nor the response to treatment could be related to the genetic polymorphism of the isolates, as defined by using the proposed methodology.

We have compared the efficacy of two Leishmania (Leishmania) major vaccines, one genetically attenuated (DHFR-TS deficient organisms), the other inactivated [autoclaved promastigotes (ALM) with bacillus Calmete-Guérin (BCG)], in protecting rhesus macaques (Macaca mulatta) against infection with virulent L. (L.) major. Positive antigen-specific recall proliferative response was observed in vaccinees (79% in attenuated parasite-vaccinated monkeys, versus 75% in ALM-plus-BCG-vaccinated animals), although none of these animals exhibited either augmented in vitro gamma interferon (IFN-<FONT FACE=Symbol>g</font>) production or positive delayed-type hypersensitivity (DTH) response to the leishmanin skin test prior to the challenge. Following challenge, there were significant differences in blastogenic responses (p < 0.05) between attenuated-vaccinated monkeys and naïve controls. In both vaccinated groups very low levels of antibody were found before challenge, which increased after infective challenge. Protective immunity did not follow vaccination, in that monkeys exhibited skin lesion at the site of challenge in all the groups. The most striking result was the lack of pathogenicity of the attenuated parasite, which persisted in infected animals for up to three months, but were incapable of causing disease under the conditions employed. We concluded that both vaccine protocols used in this study are safe in primates, but require further improvement for vaccine application.

Seven rhesus macaques were infected intradermally with 10(7) promastigotes of Leishmania (Leishmania) major. All monkeys developed a localized, ulcerative, self-healing nodular skin lesion at the site of inoculation of the parasite. Non-specific chronic inflammation and/or tuberculoid-type granulomatous reaction were the main histopathological manifestations of the disease. Serum Leishmania-specific antibodies (IgG and IgG1) were detected by ELISA in all infected animals; immunoblot analyses indicated that numerous antigens were recognized. A very high degree of variability was observed in the parasite-specific cell-mediated immune responses [as detected by measuring delayed-type hypersensitivity (DTH) reaction, in vitro lymphocyte proliferation, and gamma interferon (IFN-gamma) production] for individuals over time post challenge. From all the recovered monkeys (which showed resolution of the lesions after 11 weeks of infection), 57.2% (4/7) and 28.6% (2/7) animals remained susceptible to secondary and tertiary infections, respectively, but the disease severity was altered (i.e. lesion size was smaller and healed faster than in the primary infection). The remaining monkeys exhibited complete resistance (i.e. no lesion) to each rechallenge. Despite the inability to consistently detect correlates of cell-mediated immunity to Leishmania or correlation between resistance to challenge and DTH, lymphocyte transformation or IFN-gamma production, partial or complete acquired resistance was conferred by experimental infection. This primate model should be useful for measuring vaccine effectiveness against the human disease.

The cellular nature of the infiltrate in cutaneous lesion of rhesus monkeys experimentally infected with Leishmania (L.) amazonensis was characterized by immunohistochemistry. Skin biopsies from infected animals with active or healing lesions were compared to non-infected controls (three of each type) to quantitate inflammatory cell types. Inflammatory cells (composed of a mixture of T lymphocyte subpopulations, macrophages and a small number of natural killer cells and granulocytes) were more numerous in active lesions than in healing ones. T-cells accounted for 44.7 ± 13.1% of the infiltrate in active lesions (versus CD2+= 40.3 ± 5.7% in healing lesions) and T-cell ratios favor CD8+ cells in both lesion types. The percentage of cells expressing class II antigen (HLA-DR+) in active lesions (95 ± 7.1%) was significantly higher (P < 0.005) from the healing lesions (42.7 ± 12.7%). Moreover, the expression of the activation molecules CD25 (@ 16%), the receptor for interleukin-2, suggests that many T cells are primed and proliferating in active lesions. Distinct histopathological patterns were observed in lesions at biopsy, but healing lesions contained more organized epithelioid granulomas and activated macrophages, followed by fibrotic substitution. The progression and resolution of skin lesions appears to be very similar to that observed in humans, confirming the potential for this to be used as a viable model to study the immune response in human cutaneous leishmaniasis.

Durante os anos de 1982 a 1986, a investigação sobre mamíferos comensais e silvestres, da periferia da cidade de Jacobina, Bahia, mostrou, ao lado do escasso número de exemplares, uma reduzida variedade específica dessa fauna. Capturou-se apenas 11 espécies, entre as quais, predominou o Didelphis albiventris, que abrangeu 44% dos 213 espécimens capturados. Entre os 193 com exames já concluídos, 84 eram exemplares de D. albiventris e 2 estavam infectados pela Leishmania donovani senso lato, 1 por L. mexicana amazonensis, 1 por L. braziliensis, subespécie e 3 por Trypanosoma cruzi Também foram observadas formas suspeitas de serem amastigotas de leishmanics, nos esfregaços de órgãos de 3 exemplares de Dasyprocta aguti, 1 Cercomys cunicularius - e 1 Oryzomys eliurus. 0 restante dos exemplares, inclusive 14 de Lycalopex vetulus, estava negativo para flagelados. Apesar de reforçado por outros indicadores epidemiológicos, como a predominância específica, a freqüência domiciliar, a atratividade para a vetora Lutzomyia longipalpis, e a concomitância com casos humanos nos mesmos locais, o índice de 2,3% de infecção natural do Didelphis albiventris, não autoriza a conclusão definitiva de ser o marsupial o mais importante reservatório natural da leishmaniose visceral em Jacobina.

From 1982 to 1986, investigations on the natural infection with leishmanias of the sylvatic and commensal mammals were carried out around the city of Jacobina, Bahia, one of the oldest endemic foci of visceral leishmaniasis in Brazil. The species of Marsupialia Didelphis albiventris predominated, with the rate of 44%, over the total of 213 specimens belonging to only 11 different species of mammals collected there. Among the 84 specimens of D. albiventris examined, 2(2.3%) were infected with Leishmania donovani sensu lato; 1 with L. mexicana amazonensis, 1 with L. braziliensis sub species, and 3 with Trypanosoma cruzi. Also, amastigote suspected bodies were seen in the smears of spleens and livers of 3 Dasyprocta aguti, 1 Cercomys cunnicularius and 1 Oryzomys sp. Although strengthened by some epidemiological evidences, such as specific predominancy, peri domestic and domestic occurrence, attractivenessfor the vector Lutzomyia longipalpis and the concomitancy with human cases of visceral leishmaniasis at the same place, the low rate of the natural infection of D. marsupialis still do not allow a definitive conclusion that the oppossum is a primary and the most important reservoir of visceral leishmaniasis in Jacobina.

Foi identificada pela primeira vez a presença de L. mexicana em Didelphis marsupialis aurita, no Estado de São Paulo — Município de Conchas, através de caracterização bioquímica.