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-g-producing T cells.Universidade Federal de São Paulo (UNIFESP)Instituto Dante Pazzanese de Cardiologia do Estado de São PauloUNIFESPSciEL

Determination of the viability of Toxoplasma gondii oocysts by PCR real-time after treatment with propidium monoazide

This study aimed to investigate a methodology for discriminating viable and non-viable T. gondii oocysts in water. Analyses included two steps: (i) microscopic investigation with vital dyes; (ii) molecular investigation, using a real time PCR (qPCR), after parasite treatment (or not) with propidium monoazide (PMA). The method was called qPCR-PMA. Oocyst aliquots were incubated (15 min) at 25 ºC or 100 ºC and analyzed by microscopy, after trypan blue and neutral red staining. Microscopic investigation determined viable and non-viable oocysts. For the molecular investigation, both aliquots of oocysts were treated with PMA. Non-viable oocysts, after PMA treatment, exhibited an inhibition of DNA amplification by qPCR. Although analyses were carried out with oocysts treated experimentally, these results suggest that qPCR-PMA can be a useful strategy to distinguish viable and non-viable T. gondiioocysts in water safety testing, showing if water is safe to drink

Atypical disseminated leishmaniasis similar to post-kala-azar dermal leishmaniasis in a Brazilian AIDS patient infected with Leishmania (Leishmania) infantum chagasi: a case report

We report the case of an atypical disseminated leishmaniasis with similar clinical characteristics to post-kala-azar dermal leishmaniasis, an uncommon disease in South America. This occurred in a Brazilian patient with AIDS, 3 years after the first episode of American visceral leishmaniasis. (C) 2009 International Society for Infectious Diseases. Published by Elsevier B.V. All rights reserved.Inst Adolfo Lutz Registro, Parasitol Lab, BR-01246000 São Paulo, BrazilCtr Referencia DST, AIDS Santo Amaro, São Paulo, BrazilUniversidade Federal de São Paulo, São Paulo, BrazilHosp Ipiranga, São Paulo, BrazilUniversidade Federal de São Paulo, São Paulo, BrazilWeb of Scienc

Performance of cryptococcal antigen lateral flow assay in serum, cerebrospinal fluid, whole blood, and urine in HIV-infected patients with culture-proven cryptococcal meningitis admitted at a Brazilian referral center

Cryptococcal meningitis is the most common cause of opportunistic meningitis in HIV-infected patients in Brazil and causes unacceptable high mortality rates. In this study, HIV-infected patients with a first episode of culture-proven cryptococcal meningitis in cerebrospinal fluid (CSF) were prospectively included in order to evaluate sensitivity of cryptococcal antigen (CrAg) lateral flow assay (LFA) in serum, CSF, whole blood (fingerstick), and fresh urine. In addition, HIV-infected patients with other neurological confirmed diseases were included in order to evaluate the specificity of CrAg LFA in serum. Twenty patients with cryptococcal meningitis were included and in 19 of them, CrAg LFA in CSF, serum, and whole blood were positive (95% sensitivity). In 18 patients, India ink test was positive in CSF (90% sensitivity), and in 16 cases, CrAg LFA was positive in urine (80% sensitivity). Thirty-six HIV-infected patients with other neurological diseases had negative results of CrAg LFA in serum (100% specificity). In conclusion, CrAg LFA in serum, CSF, and whole blood showed high sensitivity and specificity. Whole blood CrAg LFA seems to be a good and reliable strategy to improve AIDS-related cryptococcal meningitis diagnosis in Brazil

The role of immune response to Trans-sialidase in Trypanosoma cruzi infection

O primeiro objetivo deste trabalho foi o de determinar as propriedades imunogenicas de uma proteina recombinante que contem o dominio catalitico da trans-sialidase (TS) de Trypanosoma cruzi. Observou-se que a imunizacao com esta proteina recombinante induziu a formacao de anticorpos capazes de inibir a atividade enzimatica da TS e de linfocitos T especificos. Camundongos A/Sn imunizados com a TS apresentaram uma reducao significativa na parasitemia e na mortalidade causada pela infeccao aguda por tripomastigotas. Esta imunidade conferida pela imunizacao com a TS foi revertida pelo tratamento dos animais com anticorpos anti-CD4 ou com inibidores da producao de oxido nitrico, sugerindo a participacao destes no controle da parasitemia e mortalidade. A reducao na parasitemia parece nao ser dependente da presenca de anticorpos inibidores da atividade enzimatica pois animais imunizados com a enzima desnaturada, nao produzem estes anticorpos e mesmo assim apresentam significativa reducao na parasitemia. A transferencia passiva de anticorpos de animais imunizados com a enzima integra tambem nao reduz a parasitemia, entretanto retarda a mortalidade indicando um papel para os anticorpos especificos na fase tardia da infeccao aguda. Na segunda parte deste trabalho estudou-se o papel protetor do acido sialico da superficie dos tripomastigotas contra a acao de anticorpos liticos chagasicos especificos paras residuos a-Gai (Ch-anti-a-Gai). Observou-se que parasitas sem acido sialico sao extremamente suscetiveis a acao litica dos anticorpos Ch-anti-a-Gal quando comparados aos tripomastigotas que contem acido siaiico na superficie. Esta protecao, causada pelo acido siaiico, e dependente da carga negativa exercida por este, pois a adicao de ions Mg 2+ favorece a acao dos anticorpos Ch-anti-a-Gal. O efeito protetor do acido siaiico na superficie dos tripomastigotas pode, eventualmente, ser generalizado na acao de outros ligantes e conferir uma vantagem para a sobrevivencia dos parasitas, principalmente nos momentos iniciais da infeccao. No soro de individuos com doenca de Chagas ha anticorpos Ch-anti-a-Gai e anticorpos que inibem a atividade TS. Neste caso, foi demonstrado que a inibicao da adicao de acido sialico por anticorpos anti-TS favorecem o efeito aglutinante e citotoxico dos anticorpos Ch-anti-a-GalBV UNIFESP: Teses e dissertaçõe

Biological role of Trypanosoma cruzi trans-sialidase

Inst Dante Pazzanese Cardiol Estado Sao Paulo, Lab Xenodiagnost, BR-04012180 Sao Paulo, BrazilUNIFESP, Dept Microbiol Immunol & Parasitol, BR-04023062 Sao Paulo, BrazilUNIFESP, Dept Microbiol Immunol & Parasitol, BR-04023062 Sao Paulo, BrazilWeb of Scienc

Fase aguda da infecção por Toxoplasma gondii: avaliação do parasitismo sanguíneo e resposta humoral em camundongos isogênicos AS/n

AIMS: To analyze experimentally the humoral immune response in acute and recent chronic infections by Toxoplasma gondii and its correlation with the blood parasitism. METHODS: Ten female mice AS/n inbred strain orally infected with 10 cysts per animal from Toxoplasma gondii ME-49 strain were evaluated during 60 days. Blood collections were made in each 3-4 days. Blood parasitism was evaluated by polymerase chain reaction, and antibody titres by enzyme-linked immunosorbent assay and indirect immunofluorescence. RESULTS: Positive polymerase chain reaction was detected around seven day-intervals until the 28th day and was negative after the 30th day pos-infection. Sera assayed by immunofluorescence presented IgM antibodies after the 7th day of infection and high titers were found between the 18th and 27th day. After 30 days, IgM titers were low until the 60th day. IgG antibodies were produced around the 14th day and were high until the 60th day. The avidity and kinetic exhibited by IgG antibody levels increased from the 14th day and the avidity percents increased with maximum peak after 28 days, establishing the chronic infection. CONCLUSIONS: These data emphasize that tachyzoites can be detected in blood during the acute phase of toxoplasmosis, even though the protective immune response was already developed.OBJETIVOS: analisar experimentalmente a evolução da resposta imune humoral nas fases aguda e crônica recente da infecção por Toxoplasma gondii e sua correlação com o parasitismo sanguíneo. MÉTODOS: foram analisados, por 60 dias, 10 camundongos fêmeas da linhagem AS/n infectados, por via oral, com 10 cistos por animal da cepa ME-49 de Toxoplasma gondii. As coletas de sangue foram feitas a cada 3-4 dias. O parasitismo sanguíneo foi avaliado pela reação em cadeia da polimerase e os títulos de anticorpos por enzimaimunoensaio e imunofluorescência indireta. RESULTADOS: a reação em cadeia da polimerase foi positiva em amostras com intervalos de aproximadamente 7 dias até o 28º dia, e a seguir, negativas até o 60º dia. Os soros avaliados pela imunofluorescência indireta apresentaram anticorpos IgM após o 7º dia, com pico entre o 18º e 27º dia. Após o primeiro mês os títulos foram baixos até o 60º dia. Anticorpos IgG surgiram no 14º dia e persistiram em altos títulos até o 60º dia. A cinética dos anticorpos IgG, bem como a avidez destes, demonstrou que os níveis de anticorpos aumentaram a partir do 14º dia e as porcentagens de avidez evoluíram com pico máximo após 28 dias, estabelecendo-se então a fase crônica da infecção. CONCLUSÕES: os dados aqui demonstrados enfatizam que taquizoítos podem estar presentes na circulação sanguínea durante toda a fase aguda da toxoplasmose, mesmo que já se tenha instalado a resposta imune protetora

GENOTYPE CHARACTERIZATION OF Leishmania (Viannia) braziliensis ISOLATED FROM HUMAN AND CANINE BIOPSIES WITH AMERICAN CUTANEOUS LEISHMANIASIS

Introduction:American tegumentary leishmaniasis (ATL) can be caused by Leishmania (Viannia) braziliensis complex. The evolution of ATL initially results in lesions and can develop into disseminated or diffuse forms. The genetic diversity of L. (V.) braziliensis in some endemic areas of Brazil has been poorly studied, such as in the state of São Paulo. This study analyzed the genetic diversity of L. (V.) braziliensis isolates collected from patients and dogs with LTA from the state of São Paulo.Methods:Leishmaniasis diagnosis was determined by PCR. The 132 biopsies were collected in different regions of Sao Paulo State, Brazil (36 municipalities). The genetic characterization of L. (V.) braziliensis isolates was tested by RFLP-PCR using DNA extracted from biopsies. The primer set amplified a specific region of Leishmania internal transcribed spacers of the ribosomal DNA locus.Results:Of the 132 samples, 52 (40%) were completely genotyped by RFLP-PCR (44 from human patients and eight from dogs). The results showed nine distinct patterns. The majority of the genotyped samples were from Sorocaba (30), and the others were distributed among 14 other municipalities. The first pattern was more frequent (29 samples), followed by pattern 2 (nine samples) and pattern 3 (three samples). Patterns 4, 6, 7, 8 and 9 were composed of two samples each and pattern 5 of one sample.Conclusion:These results suggest that polymorphic strains of L. (V.) braziliensis circulate in the state of São Paulo. These data agree with studies from other regions of Brazil, showing great variability among the natural populations of endemic foci