Vaccination of dogs with Trypanosoma rangeli induces antibodies against Trypanosoma cruzi in a rural area of Córdoba, Argentina

Dogs play a major role in the domestic cycle of Trypanosoma cruzi, acting as reservoirs. In a previous work we have developed a model of vaccination of dogs in captivity with nonpathogenic Trypanosoma rangeli epimastigotes, resulting in the production of protective antibodies against T. cruzi, with dramatic decrease of parasitaemia upon challenge with 100,000 virulent forms of this parasite. The aim of this work was to evaluate the immunogenicity of this vaccine in dogs living in a rural area. Domestic dogs, free from T. cruziinfection, received three immunisations with fixed T. rangeliepimastigotes. Dogs were not challenged with T. cruzi, but they were left in their environment. This immunisation induced antibodies againstT. cruzi for more than three years in dogs in their natural habitat, while control dogs remained serologically negative.

Medidas de prevenção e controle de infecções urinarias hospitalares em hospitais da cidade de São Paulo

Trata-se de parte de estudo onde avalia-se o conhecimento e a prática de enfermeiros e ocupacionais de enfermagem em relação a medidas de prevenção e controle de infecções hospitalares em vinte e nove hospitais gerais, da cidade de São Paulo. Objetiva, além de avaliar o conhecimento e a prática acerca das medidas de prevenção e controle das infecções, investigar se existem diferenças entre os níveis de conhecimento e de atuação prática dos enfermeiros e ocupacionais de enfermagem, quando lotados em diferentes grupos de hospitais: hospitais públicos com serviço de prevenção e controle de infecções hospitalares; hospitais públicos sem serviço de prevenção e controle de infecções hospitalares; hospitais privados com serviço e privados sem o referido serviço. Constata-se que existem lacunas no que se refere ao conhecimento e a prática acerca das medidas de prevenção e controle das infecções estudadas e que embora se detectem diferenças significativas para o conhecimento e a prática dos profissionais e ocupacionais de enfermagem, quando lotados em diferentes grupos de hospitais, a análise de perguntas isoladas nem sempre distingue, com significância, os mesmos grupos.

Avaliação das práticas de prevenção e controle de infecção da corrente sanguínea em um hospital governamental

O objetivo deste estudo foi avaliar as práticas de prevenção e controle de infecção da corrente sanguínea associada ao cateter venoso central (ICS-ACVC) de curta permanência, por meio da aplicação de indicadores clínicos processuais. A amostra foi constituída por 5.877 avaliações distribuídas entre as práticas selecionadas. Obteve-se ampla variação de conformidade: 91,6% - registro de indicação e tempo de permanência do CVC; 51,5% - cuidados e manutenção do curativo da inserção do CVC e seus dispositivos; 10,7% - higienização das mãos na realização de procedimentos de cuidado e manutenção do CVC; 0,0% - inserção do cateter venoso central (CVC). Os resultados demonstram necessidade de elaboração de novas estratégias que assegurem conformidade duradoura para a maioria das práticas de prevenção e controle de ICS-ACVC avaliadas. Conclui-se pela vantagem na aplicação de avaliação processual, pela possibilidade de não somente identificar seus índices de conformidade em relação à melhor prática esperada, como também favorecer, sobremaneira, reconhecimento das situações específicas que contribuíram para os valores encontrados.

Prevenção e controle das seqüelas bucais em pacientes irradiados por tumores de cabeça e pescoço

A cirurgia e a radioterapia são os principais métodos de tratamento das neoplasias de cabeça e pescoço. Dentre os efeitos colaterais resultantes da interação da radiação ionizante sobre os tecidos, temos dermatite, mucosite, xerostomia, candidíase, alteração do paladar, disfagia, cárie, trismo e osteorradionecrose. OBJETIVO: Avaliar a condição odontológica dos pacientes, através de protocolo que permita impedir ou minimizar os efeitos da radiação sobre os tecidos da cavidade bucal. MATERIAIS E MÉTODOS: Realizou-se acompanhamento odontológico, antes, durante e até 180 dias após a radioterapia, em 12 pacientes submetidos a cirurgia e radioterapia, ou radioterapia exclusiva. RESULTADOS: Efeitos como dermatite, mucosite, alteração do paladar e disfagia cresceram em proporção a partir da segunda semana de tratamento até o final das aplicações, decrescendo visivelmente quando do término, chegando próximos aos valores basais após 180 dias. Quanto à xerostomia, a redução ocorreu mais lentamente e com menor efetividade. Cárie, trismo e osteorradionecrose não foram observados durante o período de avaliação. CONCLUSÃO: O acompanhamento odontológico sistemático, junto com medidas preventivas como adequação bucal prévia, orientações sobre higienização, utilização de bochechos de água bicarbonatada, chá de camomila, aplicação tópica de flúor, contribuíram para promover melhores condições de restabelecimento em pacientes com neoplasia da região de cabeça e pescoço submetidos à radioterapia.

Soroprevalência da infecção por Trypanosoma cruzi em cães de uma área rural do Estado de Mato Grosso do Sul

Doença de Chagas é uma antropozoonose causada por Trypanosoma cruzi que tem os cães como importante reservatório da doença na América do Sul. Este trabalho teve como objetivo avaliar a ocorrência da infecção natural pelo T. cruzi em cães de uma área rural do estado de Mato Grosso do Sul, Brasil. Foram utilizados os testes de imunofluorescência indireta (IFI) e ensaio imunossorvente ligado a enzima (ELISA) em 75 cães residentes na área. Foram detectados anticorpos em 45,3% (n=34) e 24,0% (n=18) nos testes de IFI e ELISA, respectivamente. A real prevalência da infecção foi confirmada como 22,7% (n=17) pelo critério de positividade em ambos os testes. Os resultados obtidos confirmam a infecção chagásica nos cães dessa região.

Caracterização clínica e laboratorial de cães naturalmente infectados com Trypanosoma cruzi no semiárido nordestino

Objetivou-se, com este estudo, evidenciar os sinais clínicos e laboratoriais desta enfermidade para auxiliar na caracterização da doença de forma natural na área semi-árida da região nordeste. Foram avaliados 10 cães positivos para Trypanosoma cruzi, identificados mediante análises sorológicas de reação de imunofluorescência indireta (RIFI) e enzyme linked immunosorbent assay (ELISA); análise molecular pela Reação em Cadeia Polimerase (PCR), microscopia direta e hemocultura. Os cães chagásicos foram submetidos à avaliação física, verificação da pressão arterial, exames eletrocardiográficos, radiográficos, hematológicos (eritrograma e leucograma) e bioquímicos (ureia, creatinina, ALT, AST, PT, albumina, globulina, CK, CK-MB e cTnI). O exame físico e os valores das pressões arteriais dos cães apresentaram dentro dos parâmetros de normalidade, enquanto que na eletrocardiografia observou-se FC normal com ritmo sinusal, com exceção de um cão, que apresentou taquicardia sinusal (168 bat/min). No ECG de oito cães houve aumento da duração de P (47±6,5ms) sugestivo de aumento atrial, não confirmado radiograficamente. Foi observado supradesnivelamento do segmento ST em um cão. Nos resultados hematológicos constatou-se trombocitopenia (187,4x10³ ±137,2x10³) e anemia (5,0x10(6) ±1,39x10(6)/uL). Os valores médios da hemoglobina (11±2,7g/dL) e do hematócrito (34±10,5%) estavam abaixo dos limites de normalidade. A série branca apresentou-se dentro dos limites de normalidade, com exceção da eosinofilia observada em três cães. Individualmente, registrou-se em dois cães, leucocitose, linfocitose e neutrofilia. Na avaliação bioquímica, registrou-se hiperproteinemia (7,2±0,9g/dL), hipoalbuminemia (2,2±0,4g/dL), hiperglobulinemia (5,1±1,0g/dL) e aumento da CK (196±171U/L). Não houve alteração nas enzimas ALT e AST. A isoenzima CK-MB e o cTnI alteraram somente em três cães. Os cães infectados naturalmente no semiárido nordestino apresentam características relacionáveis à forma crônica indeterminada, ou seja, cães assintomáticos. A identificação dos cães infectados naturalmente sem características patognomônicas da doença de Chagas ressalta a importância desta enfermidade no processo diagnóstico com as demais que manifestam perfis inespecíficos associados ou não às doenças cardiovasculares.

Clearance-inducing antibodies are responsible for protection against the acute phase of Trypanosoma cruzi infection in mice

A study was conducted on mice infected with strains Y and CL of Trypanosoma cruzi. The ability of anti-Y and anti-CL sera to induce complement-mediated lysis, immune clearance and protection against the acute phase of the infection was studied using homologous anti-Y or anti-CL serum tested with the Y or CL strain, or heterologous anti-Y serum tested with the CL strain or anti-CL serum tested with the Y strain. Complement-mediated lysis was induced by both homologous and heterologous antisera but protection was afforded only by homologous antisera. Immune clearance was induced by homologous but not by heterologous antisera. Antisera with high clearance ability were able to confer protection whereas antisera with high lytic ability were not. These results show a high correlation between the antibody ability to induce clearance and to confer protection and suggest that clearance rather than lysis is responsible for protection against the acute phase of the infection. The mechanism of antibody protection against the acute phase of the infection is discussed.

Molecular mimicry between cardiac myosin and Trypanosoma cruzi antigen B13: identification of a B13-driven human T cell clone that recognizes cardiac myosin

Previous reports from our group have demonstrated the association of molecular mimicry between cardiac myosin and the immunodominant Trypanosoma cruzi protein B13 with chronic Chagas' disease cardiomyopathy at both the antibody and heart-infiltrating T cell level. At the peripheral blood level, we observed no difference in primary proliferative responses to T. cruzi B13 protein between chronic Chagas' cardiopathy patients, asymptomatic chagasics and normal individuals. In the present study, we investigated whether T cells sensitized by T. cruzi B13 protein respond to cardiac myosin. T cell clones generated from a B13-stimulated T cell line obtained from peripheral blood of a B13-responsive normal donor were tested for proliferation against B13 protein and human cardiac myosin. The results showed that one clone responded to B13 protein alone and the clone FA46, displaying the highest stimulation index to B13 protein (SI = 25.7), also recognized cardiac myosin. These data show that B13 and cardiac myosin share epitopes at the T cell level and that sensitization of a T cell with B13 protein results in response to cardiac myosin. It can be hypothesized that this also occurs in vivo during T. cruzi infection which results in heart tissue damage in chronic Chagas' disease cardiomyopathy

The role of IL-12 in experimental Trypanosoma cruzi infection

Host resistance to Trypanosoma cruzi infection is dependent on both natural and acquired immune responses. During the early acute phase of infection in mice, natural killer (NK) cell-derived IFN-E="Symbol">g is involved in controlling intracellular parasite replication, mainly through the induction of nitric oxide biosynthesis by activated macrophages. We have shown that IL-12, a powerful inducer of IFN-E="Symbol">g production by NK cells, is synthesized soon after trypomastigote-macrophage interaction. The role of IL-12 in the control of T. cruzi infection in vivo was determined by treating infected mice with anti-IL-12 monoclonal antibody (mAb) and analyzing both parasitemia and mortality during the acute phase of infection. The anti-IL-12 mAb-treated mice had higher levels of parasitemia and mortality compared to control mice. Also, treatment of infected mice with mAb specific for IFN-E="Symbol">g or TNF-E="Symbol">a inhibited the protective effect of exogenous IL-12. On the other hand, TGF-ß and IL-10 produced by infected macrophages inhibited the induction and effects of IL-12. Therefore, while IL-12, TNF-E="Symbol">a and IFN-E="Symbol">g correlate with resistance to T. cruzi infection, TGF-ß and IL-10 promote susceptibility. These results provide support for a role of innate immunity in the control of T. cruzi infection. In addition to its protective role, IL-12 may also be involved in the modulation of T. cruzi-induced myocarditis, since treatment of infected mice with IL-12 or anti-IL-12 mAb leads to an enhanced or decreased inflammatory infiltrate in the heart, respectively. Understanding the role of the cytokines produced during the acute phase of T. cruzi infection and their involvement in protection and pathogenesis would be essential to devise new vaccines or therapies.

Cytokines in innate and acquired immunity to Trypanosoma cruzi infection

Resistance to Trypanosoma cruzi infections is critically dependent on cytokine-mediated activation of cell-mediated immune effector mechanisms. This review focuses on the role of IL-10, TNF-E="Symbol">a, IFN-E="Symbol">g and IL-12 in controlling T. cruzi replication by the innate and specific immune systems of the vertebrate host. A study performed on mice with disrupted recombinase-activating genes (RAG/KO), which lack T and B lymphocytes, revealed the importance of IL-12, IFN-E="Symbol">g and TNF-E="Symbol">a in the resistance against T. cruzi mediated by the innate immune system. In addition, data from experiments using IL-10 KO, RAG/KO and double RAG/IL-10 KO mice indicating an in vivo regulatory role of IL-10 in innate and T. cruzi-specific immunity are discussed

Trypanosoma cruzi: amastigote polymorphism defined by monoclonal antibodies

We have raised monoclonal antibodies (mAbs) directed towards amastigote forms of Trypanosoma cruzi, and shown that mAbs 1D9 and 4B9 are carbohydrate while mAb 4B5 activity is resistant to periodate oxidation of the antigen. Here we used an ELISA to quantitate and compare the expression of surface epitopes on fixed parasites among different parasite isolates. The expression of markers varied among T. cruzi amastigotes isolated from infected cells or after extracellular differentiation of trypomastigotes. Moreover, we also observed an extensive polymorphic expression of these epitopes among amastigotes derived from different strains and clones. For instance, mAb 2C2 strongly and evenly reacted with 9 strains and clones (G, Y, CL, Tulahuen, MD, and F, and clones Sylvio X-10/4, D11, and CL.B), with absorbance at 492 nm (A492 nm) from 0.6 to 0.8. By contrast, mAb 4B5 had a higher expression in Tulahuen amastigotes (around 0.9 at 492 nm) whereas its reactivity with amastigotes from clones CL.B, Sylvio X-10/4 and D11 was much lower (around 0.4). mAb 1D9 displayed an interesting pattern of reactivity with amastigotes of the different strains and clones (A492 nm of G>D11E="Symbol">³Sylvio X-10/4 = MD>Tulahuen = F = Y>CL>CL.B). Finally, we observed that mAb 4B9 had the lowest reaction with the parasites studied, with higher values of A492 nm with Y strain (around 0.6) and lower values with Tulahuen, F and CL.B strains (around 0.2). Immunoblotting analysis also showed extensive variations among amastigotes of the various parasite isolates and mAbs 4B9, 1D9 and 4B5 revealed significant differences in expression between clones and parental strains. These data describe a previously uncharacterized polymorphism of T. cruzi amastigote surface components.

Trans-sialidase delivered as a naked DNA vaccine elicits an immunological response similar to a Trypanosoma cruzi infection

Trypanosoma cruzi, the protozoan parasite that causes Chagas' disease, does not synthesize sialic acid, but expresses a trans-sialidase (TS) that catalyzes the transfer of sialic acid from host glycoconjugates to the parasite surface. Here, we review studies that characterize the immune response to the catalytic domain of the enzyme in humans during Chagas' disease or in mice following immunization with the TS gene. In both cases, there are antibodies that strongly inhibit the enzymatic activity and generation of interferon-E="Symbol">g-producing T cells.

Expression of extracellular matrix components and their receptors in the central nervous system during experimental Toxoplasma gondii and Trypanosoma cruzi infection

Alterations in extracellular matrix (ECM) expression in the central nervous system (CNS) usually associated with inflammatory lesions have been described in several pathological situations including neuroblastoma and demyelinating diseases. The participation of fibronectin (FN) and its receptor, the VLA-4 molecule, in the migration of inflammatory cells into the CNS has been proposed. In Trypanosoma cruzi infection encephalitis occurs during the acute phase, whereas in Toxoplasma infection encephalitis is a chronic persisting process. In immunocompromised individuals such as AIDS patients, T. cruzi or T. gondii infection can lead to severe CNS damage. At the moment, there are no data available regarding the molecules involved in the entrance of inflammatory cells into the CNS during parasitic encephalitis. Herein, we characterized the expression of the ECM components FN and laminin (LN) and their receptors in the CNS of T. gondii- and T. cruzi-infected mice. An increased expression of FN and LN was detected in the meninges, leptomeninges, choroid plexus and basal lamina of blood vessels. A fine FN network was observed involving T. gondii-free and T. gondii-containing inflammatory infiltrates. Moreover, perivascular spaces presenting a FN-containing filamentous network filled with E="Symbol">a4+ and E="Symbol">a5+ cells were observed. Although an increased expression of LN was detected in the basal lamina of blood vessels, the CNS inflammatory cells were E="Symbol">a6-negative. Taken together, our results suggest that FN and its receptors VLA-4 and VLA-5 might be involved in the entrance, migration and retention of inflammatory cells into the CNS during parasitic infections.

Administration of interferon-g to pregnant rats reverses the depressed adjuvant-induced arthritis of their chronically Trypanosoma cruzi-infected offspring

We demonstrated that administration of interferon gamma (IFN-E="Symbol">g) to the inbred "l" strain of pregnant rats conferred partial resistance on their offspring to challenge with Trypanosoma cruzi. We now examine if this intervention also modifies the reportedly immunodepressed cellular responses which occur during chronic infection. Offspring were born to mothers undergoing one of the following procedures during gestation: subcutaneous injections of recombinant rat IFN-E="Symbol">g, 50,000 IU/rat, five times/week for 3 weeks, which was started on the day of mating (IFN-Mo); infection with 106 trypomastigotes of T. cruzi at 7, 14, and 21 days after mating plus IFN-E="Symbol">g treatment as given to the former group (TcIFN-Mo); the same protocol except that physiological saline was injected instead of IFN-E="Symbol">g (Tc-Mo); injection of physiological saline only (control-Mo). All offspring groups (N = 8-10/group) were infected at weaning and were assessed 90 days later for their adjuvant-induced arthritic response or levels of major T cell subsets in spleen and lymph nodes. TcIFN-Mo and IFN-Mo offspring showed a reestablished arthritic response, which remained within the range seen in controls. Immunolabeling studies on parallel groups of 90-day-infected offspring showed that the inverse CD4/CD8 cell ratio that is usually seen in lymphoid organs from these chronically infected rats (median 0.61) appeared to have recovered in the TcIFN-Mo and IFN-Mo groups (median 1.66 and 1.78, respectively) and was not different from uninfected controls (1.96). These studies indicate that early stimulation with IFN-E="Symbol">g is able to reverse the immunosuppressive state that is usually present during the chronic period of the experimental infection.

Signal transduction induced in Trypanosoma cruzi metacyclic trypomastigotes during the invasion of mammalian cells

Penetration of Trypanosoma cruzi into mammalian cells depends on the activation of the parasite's protein tyrosine kinase and on the increase in cytosolic Ca2+ concentration. We used metacyclic trypomastigotes, the T. cruzi developmental forms that initiate infection in mammalian hosts, to investigate the association of these two events and to identify the various components of the parasite signal transduction pathway involved in host cell invasion. We have found that i) both the protein tyrosine kinase activation, as measured by phosphorylation of a 175-kDa protein (p175), and Ca2+ mobilization were induced in the metacyclic forms by the HeLa cell extract but not by the extract of T. cruzi-resistant K562 cells; ii) treatment of parasites with the tyrosine kinase inhibitor genistein blocked both p175 phosphorylation and the increase in cytosolic Ca2+ concentration; iii) the recombinant protein J18, which contains the full-length sequence of gp82, a metacyclic stage surface glycoprotein involved in target cell invasion, interfered with tyrosine kinase and Ca2+ responses, whereas the monoclonal antibody 3F6 directed at gp82 induced parasite p175 phosphorylation and Ca2+ mobilization; iv) treatment of metacyclic forms with phospholipase C inhibitor U73122 blocked Ca2+ signaling and impaired the ability of the parasites to enter HeLa cells, and v) drugs such as heparin, a competitive IP3-receptor blocker, caffeine, which affects Ca2+ release from IP3-sensitive stores, in addition to thapsigargin, which depletes intracellular Ca2+ compartments and lithium ion, reduced the parasite infectivity. Taken together, these data suggest that protein tyrosine kinase, phospholipase C and IP3 are involved in the signaling cascade that is initiated on the parasite cell surface by gp82 and leads to Ca2+ mobilization required for target cell invasion.