Enhancement of Leishmania amazonensis infection in BCG non-responder mice by BCG-antigen specific vaccine

Different patterns of cutaneous leishmaniasis can be induced when a challenge of alike dose of Leishmania amazonensis amastigotes in various inbred strains was applied. Two strains of mice, the Balb/c and C57 BL/10J, showed exceptional suscepbility, and 10(elevado a sexta potência) amastigotes infective dose lead, to ulcerative progressive lesions with cutaneous metastasis and loss by necrosis of leg on wich the footpad primary lesion occured. Lesions were also progressive but in a lower degree when C3H/HeN and C57BL/6 were infected. Lesions progress slowly in DBA/2 mice presenting lesions wich reach a discreet peack after 12 weeks, do not heal but do not uncerate. DBA/2 mice is, therefore, a good model for immunomodualtion. In attempt to determine the influence of BCG in vaccination schedule using microsomal fraction, DBA/2 became an excellent model, since it is also a non-responder to BCG. Vaccination of DBA/2 mice, receiving the same 10(elevado a sexta potência) BCG viable dose and 10 *g or 50 *g of protein content of microsomal fraction, lead to a progressive disease with time course similar to those observed in susceptible non-vaccinated C57BL/10J mice after 6 months of observation. An enhancement of infection in BCG non-responder mice suggests that use of BCG as immunostimulant in humans could be critical for both vaccination and immunoprophylactic strategies.

Non-immunologic methods of diagnosis of babesiosis

The diagnosis of tick-borne diseases such as babesiosis still depends on observing the parasite in the infected erythrocyte. Microscopic observation is tedious and often problematic in both early and carrier infections. Better diagnostic methods are needed to prevent clinical disease, especially when susceptible cattle are being moved into disease enzootic areas. This study evaluates two techniques for early diagnosis of Babesia bovis infections in cattle, DNA probes specific for the organism and fluorescent probes specific nucleic acid. The radioisotopically labeled DNA probes are used in slot blot hybridizations whith lysed blood samples, not purified DNA. Thusfar, the probe is specific for B. bovis and can detect as few as 1000 B. bovis parasites in 10µl of blood. The specificity of the fluorescent probe depends on the characteristic morphology of the babesia in whole blood samples, as determined microscopically. The fluorescent probe detects as afew as 10,000 B. bovis parasites in 10*l as blood. The application of each method for alboratory and field use is discussed.

T cell responses to repeat and non-repeat regions of the circumsporozoite protein detected in volunteers immunized with Plasmodium falciparum sporozoites

The design of malarial vaccine based on the circumsporozoite (CS) protein, a majuor surface antigen of the sporozoite stage of the malaria parasite, requires the identification of T and B cell epitopes for inclusion in recombinant or synthetic vaccine candidates. We have investigated the specificity and function of a series of T cell clones, derived from volunteers immunized with Plasmodium falciparum sporozoites in an effort to identify relevant epitopes in the immune response to the pre-erythrocytic stages of the parasite. CD4+ T cell clones were obtained wich specifically recognized a repetitive epitope located in the 5'repeat region of the CS protein. This epitope, when conjugated to the 3'repeat region in a synthetic MAPs construct, induced high titers of antisporozoite antibodies in C57B1 mice. A second T cell epitope, which mapped to aa 326-345 of the carboxy terminal, was recognized by lytic, as well as non-lytic, CD4+ T cells derived from the sporozoite-immunized volunteers. The demonstration of CD4+ CTL in the volunteers, and the recent studies inthe rodent model (Renia et al., 1991; Tsuji et al., 1990), suggested that CS-specific CD4+ T cells, in addition to their indirect role as helper cells in the induction of antibody and CD8 + effector cells, may also play a direct role in protection against sporozoite challenge by targeting EEF within the liver.

Histopathological alterations induced by non-viable cells and biochemical fractions from Paracoccidioides brasiliensis in mice

Non-viable cells and biochemical fractions from Paracoccidioides brasiliens were obtained for experimental inoculation in mice and posterior histopatological analysis. Dead total fungus, total fungus disrupted by sonorous waves, lipids of the fungus, supernatant of the lipid purification, integral and disrupted fungus free of lipids were obtained. The six preparations arised from masses of lyophilized yeasts of a recent isolate of P. brasiliensis (strain JT-1) and from a "Pool" equitably constituted by four strains maintained in laboratory for a long time (SN, 2, 18 and 192). Different doses of the 12 preparations were intraperitonially inoculated and histopathological analysis were done 30 days later. This analysis showed that all the inoculated preparations gave origin to inflamatory foci, except the one designated "supernatant of lipid purification". The alterations were detected exclusively in the liver of the animals and occurred from the smallest dose tested (1 mg), with exception of the lipids of the fungus, where the foci appeared only from a 3 mg dose onwards. No difference in the capacity of inducing histopathological alterations was found between the preparations obtained from the recent isolate (JT-1) and from the older ones ("Pool"). On the other hand, an increase of the number of inflammatory foci in function of the inoculated dose was observed.

Aspects of immunity for the AMA-1 family of molecules in humans and non-human primates malarias

The apical membrane antigen (AMA-1) family of malaria merozoite proteins is characterised by a high degree of inter-species conservation. Evidence that the protein (PK66/AMA-1) from the simian parasite Plasmodium knowlesi was protective in rhesus monkeys suggested that the 83kDa P. falciparum equivalent (PF83/AMA-1) should be investigated for protective effects in humans. Here we briefly review pertinent comparative data, and describe the use of an eukaryotic full length recombinant PF83/AMA-1 molecule to develop a sensitive ELISA for the determination of serological responses in endemic populations. The assay has revealed surprisingly high levels of humoral response to this quantitatively minor antigen. We also show that PK66/AMA-1 inhibitory mAb's are active against merozoites subsequent to release from schizont-infected red cells, further implicating AMA-1 molecules in red cell invasion.

Simian malaria at two sites in the Brazilian Amazon: I-The infection rates of Plasmodium brasilianum in non-human primates

The parasite that causes simian malaria in the Brazilian Amazon, Plasmodium brasilianum, is infective to man. In this region, where humans live within and in close proximity to the forest, it was suspected that this parasite could be the cause of a zoonosis. A study was performed in the areas surrounding two hydroelectric plants in the Amazon, Balbina and Samuel, aiming at determining the zoonotic potential of this parasite. P. brasilianum was detected in, respectively, 15.8% and 9.9% of 126 and 252 primates belonging to seven and eight species examined from Balbina and Samuel. The highest malaria infection rates were found among the red-howler monkey Alouatta seniculus straminea (32.3%), the bearded-saki Chiropotes satanas chiropotes (50%) and the spider-monkey Ateles paniscus paniscus (2[1+]) from Balbina and in the squirrel-monkey Saimiri ustus (21%) and the black-faced-spider-monkey Ateles paniscus chamek (28.6%) from Samuel.

Triatoma infestans is more efficient than Panstrongylus megistus in obtaining blood meals on non Anaesthetized mice

We compared the influence of the bug density in the capacity of Triatoma infestans and Panstrongylus megistus in obtaining blood meal in non anaesthetized mice. The regression anlysis for increase in body weight (mg) versus density (no. of bugs/mouse) showed that in experiments with anaesthetized mice (AM), no correlation was observed. In experiments with non anaesthetized mice (NAM) the weight increase was inversely proportional to density. The regression slope for blood meal size on density was less steep for T. infestans than for P. megistus (-1.9 and -3.0, respectively). The average weight increase of P. megistus nymphus in experiments with AM was higher than for T. infestans nymphs; however, in experiments with NAM such results were inverted. Mortality of P. megistus was significantly higher than of T. infestans with NAM. However, in experiments with AM very low mortality was observed. Considering the mortality and the slope of regression line on NAM, T. infestans is more efficient than P. megistus in obtaining blood meal in similar densities, possibly because it caused less irritation of the mice. The better exploitation of blood source of T. infestans when compared with P. megistus in similar densities, favours the maintenance of a better nutritional status in higher densities. This could explain epidemiological findings in which T. infestans not only succeeds in establishing larger colonies but also dislodges P. megistus in human dwellings when it is introduced in areas where the latter species prevails.

A Comparison of Two Brazilian Populations of Culex quinquefasciatus (Say, 1823) from Endemic and Non-endemic Areas to Infection with Wuchereria bancrofti (Cobbold, 1877)

Culex quinquefasciatus is known to be an efficient insect host of Wuchereria bancrofti. In Brazil Cx. quinquefasciatus is widely distributed throughout the country and is often abundant in and around human habitations. In contrast, Bancroftian filariasis is limited to three foci in Brazil. Experiments were undertaken to compare the vector capacities of Cx. quinquefasciatus originating from Maceió (Alagoas), one of the endemic areas of W. bancrofti infection in Brazil, and Belo Horizonte (Minas Gerais), a non endemic area. Laboratory-reared Cx. quinquefasciatus were dissected 20 days after blood feeding on microfilaraemic patients. Survival rates and the number of infective larvae that developed did not differ in female mosquitoes of different origins. Thus both populations of Culex were susceptible to infection with W. bancrofti

The role of the eosinophil-selective chemokine, eotaxin, in allergic and non-allergic airways inflammation

Blood eosinophilia and tissue infiltration by eosinophils are frequently observed in allergic inflammation and parasitic infections. This selective accumulation of eosinophils suggested the existence of endogenous eosinophil-selective chemoattractants. We have recently discovered a novel eosinophil-selective chemoattractant which we called eotaxin in an animal model of allergic airways disease. Eotaxin is generated in both allergic and non-allergic bronchopulmonary inflammation. The early increase in eotaxin paralled eosinophil infiltration in the lung tissue in both models. An antibody to IL-5 suppressed lung eosinophilia, correlating with an inhibition of eosinophil release from bone marrow, without affecting eotaxin generation. This suggests that endogenous IL-5 is important for eosinophil migration but does not appear to be a stimulus for eotaxin production. Constitutive levels of eotaxin observed in guinea-pig lung may be responsible for the basal lung eosinophilia observed in this species. Allergen-induced eotaxin was present mainly in the epithelium and alveolar macrophages, as detected by immunostaining. In contrast there was no upregulation of eotaxin by the epithelial cells following the injection of Sephadex beads and the alveolar macrophage and mononuclear cells surrounding the granuloma were the predominant positive staining cells. Eotaxin and related chemokines acting through the CCR3 receptor may play a major role in eosinophil recruitment in allergic inflammation and parasitic diseases and thus offer an attractive target for therapeutic intervention.

Serotypes of Vibrio cholerae Non-O1 Isolated from Water Supplies for Human Consumption in Campeche, México and their Antibiotic Susceptibility Pattern

The presence of Vibrio cholerae non-O1 in water supplies for human consumption in the city of Campeche and rural locality of Bécal was investigated. V. cholerae non-O1 was detected in 5.9% of the samples obtained in deep pools of Campeche. Studies conducted in Bécal and neighbourhood of Morelos in Campeche indicated that collected samples harbored V. cholerae non-O1 in 31.5% and 8.7% respectively. There was a particular pattern of distribution of V. cholerae non-O1 serotypes among different studied regions. Accordingly, V. cholerae non-O1 serotype O14 predominated in the deep pools of Campeche and together with V. cholerae non-O1, O155 were preferentially founds in samples taken from intradomiciliary faucets in the neighbourhood of Morelos. Samples from Bécal predominantly presented the serotype O112. 60% and 53.8% of all studied strains of V. cholerae non-O1 proved to be resistant to ampicillin and carbenicillin. 3.1%, 7.7% and 6.2% presented resistant to doxycycline, trimethoprim-sulfamethoxazole and erythromycin respectively. The study showed the necessity of performing a strong epidemiologic surveillance for emergence and distribution of V. cholerae non-O1

Immune Dysfunction and the Pathogenesis of AIDS-associated non-Hodgkin's Lymphoma

Much has been learned about how HIV-induced immune dysfunction contributes to B cell hyperactivation, and potentially, to the pathogenesis of AIDS-lymphoma. However, further studies are needed to fully understand how HIV infection and immune dysfunction promote B cell hyperactivation and the development/growth of AIDS-lymphoma. In particular, studies are needed to define the role of HHV8 vIL6, IL6 receptor-expression, and lymphocyte surface stimulatory molecules, in promoting B cell hyperactivation or lymphoma cell growth.

The Office International des Epizooties ad hoc Group on Non Tsetse Animal Trypanosomoses: Its Origin, Scope and Perspectives

A summary of the goals and activities of the ad hoc group on Non Tsetse Transmitted Animal Trypanosomosis belonging to the Office International des Epizooties is presented.

Distribution of Sandflies (Diptera:Psychodidae) on Tree-trunks in a Non-flooded Area of the Ducke Forest Reserve, Manaus, AM, Brazil

Sandflies were collected in the base of tree-trunks in the seasons of high and least rainfall in the Ducke Forest Reserve, near Manaus in the State of Amazonas. Lutzomyia umbratilis was the most abundant sandfly species. Caryocar villosum, Chrysophyllum amazonicum, Dinizia excelsa, Eschweilera atropetiolata and Parkia multijuga were the tree species on which most sandflies were collected and relative abundance were related to trunk characteristics. Seasonal patterns of sandfly distribution in the forest were observed.