Orientadores: João Aristeu da Rosa, Mário Steindel / Tese (doutorado) - Universidade Estadual de Campinas, Instituto de Biologia / Made available in DSpace on 2018-08-27T12:48:03Z (GMT). No. of bitstreams: 1 Ribeiro_AlineRimoldi_D.pdf: 21726449 bytes, checksum: 28ac88cc86cc90e738eb70f9dca45f0b (MD5) Previous issue date: 2014 / Resumo: Trypanosoma cruzi, protozoário que faz parte da família Trypanosomatidae é o agente causador da doença de Chagas que afeta 6-8 milhões de pessoas na América Latina. A origem dessa família pode ser estudada por meio de técnicas moleculares, como a investigação da região V7V8 - SSUrRNA. Trypanosoma cruzi é subdividido em seis grupos independentes TcI-TcVI denominados Unidades Discretas de Tipagem (DTUs). A caracterização biológica e molecular de onze cepas de T. cruzi pertencentes aos grupos TcI (Bolívia; Tlenti; Tmelanocephala; SC90), TcII (Famema; SC96; SI8; Y) e TcIII (QMM3; QMM5; SI5) isoladas de cinco espécies de triatomíneos esclarece fatores biológicos por parâmetros como a cinética de crescimento, curva parasitêmica, taxa de infeção celular, caracterização molecular, ação de metaloproteinases, perfil protéico e sorologia. O objetivo do trabalho foi a caracterização biológica e molecular de cepas de T. cruzi isoladas de triatomíneos da Bahia, Rio Grande do Sul, Santa Catarina e São Paulo. O grupo TcII de T. cruzi mostrou maior capacidade multiplicativa em formas epimastigotas durante a cinética de crescimento, seguido por TcI e TcIII. A curva parasitêmica evidenciou variabilidade entre os camundongos Balb/c, contudo ao comparar os grupos TcI, TcII e TcIII de T. cruzi o perfil parasitêmico mostrou-se equivalente. Acrescentando os dados biológicos estudou-se a taxa de infecção de T. cruzi em linhagens celulares J774 e macrófagos peritoneais. O grupo TcI de T. cruzi apresentou maior taxa de infecção e menor tempo exigido para a multiplicação de formas amastigotas, assim como macrófagos peritoneias mostraram-se mais atrativos para T. cruzi. A caracterização molecular, por meio da região V7V8, mostrou que essas cepas pertencem às DTUs TcI, TcII e TcIII. A separação dos grupos torna-se evidente ao comparar o perfil protéico em formas epi e tripomastigotas de T. cruzi. O grupo TcI apresentou mais proteínas nos géis de acrilamida, particularidade que pode ser associada a intra-específicidade de TcI. A ação de metaloproteinases foi observada em formas epi e tripomastigotas sugerindo presença ativa e estável durante parte do ciclo do parasito. A reatividade sorológica foi comprovada nos grupos TcI, TcII e TcIII, por meio de ELISA em diluições de 1/100 até 1/12.800. A adição da técnica de Western Blotting aos ensaios por SDS-PAGE em soros de animais infectados após 50 dias mostrou o perfil protéico da cepa Y em membrana de nitrocelulose. Em conjunto, os resultados mostraram que as onze cepas de T. cruzi apresentaram diferenças entre os grupos do parasito. O grupo TcI mostrou maior taxa de infecção em células; TcII, os maiores valores para a cinética de crescimento e TcIII filogenéticamente próximo a TcV, grupo híbrido. A associação parasito-hospedeiro pode explicar diferenças biológicas e moleculares em cepas de T. cruzi, neste sentido o estudo de onze cepas isoladas de diferentes hospedeiros pode agregar informações a literatura e esclarecer alguns aspectos biológicos desse patógeno / Abstract: Trypanosoma cruzi, a protozoan from the family Trypanosomatidae, is responsible for Chagas disease which affects about 6 to 8 million people in Latin America. The origin of this family can be studied through molecular techniques, for instance the investigation of the region V7V8 ¿ SSurRNA. The protozoan is subdivided in six independents groups TcI-TcVI known as Discrete Typing of Units (DTUs). The biological and molecular characterization of eleven strains of T. cruzi from the group TcI (Bolivia; Tlenti; Tmelanocephala; SC90), TcII (Famema; SC96; SI8; Y) and TcIII (QMM3; QMM5; SI5) isolated from five different species of triatomine are able to elucidate biological factors through the kinetic growth, parasitemic curve, cell infection rate, molecular characterization, metalloproteinase action, proteic and serological profile. This investigation was conducted to provide a biological and molecular characterization of T. cruzi isolated from specimens of triatomines. The group TcII of T. cruzi demonstrated higher replicative capacity in epimastigotes forms during the kinetic growth curve, followed by TcI and TcIII. The parasitemic curve demonstrated variability between Balb/c mice; however, the groups TcI, TcII and TcIII showed equivalent parasitemic profile. Furthermore, the cell infection rate in J774 cellular lineages and peritoneal macrophages was used to corroborate the biological data. The group TcI of T. cruzi demonstrated higher infection rate and less time to amastigotes forms multiplication and the peritoneal macrophages showed more attractive to T. cruzi. The molecular characterization through the V7V8 region indicated that these strains belong to DTUs TcI, TcII and TcIII. The groups segregation is important to compare the proteic profile of epimastigotes and tripomastigotes forms of T. cruzi. The groups TcI presented more proteins in acrylamide gels, which can be associated with intra-specif of TcI. The metalloproteinase action was observed in epimastigotes and tripomastigotes forms, demonstrating active and stable presence at the parasite life cycle. The serological reactivity was proven in the groups TcI, TcII and TcIII through ELISA dilutions of 1/100 to 1/12.800. Moreover, the Western Blotting technique was added to SDS-PAGE experiments in infected animals¿ serum after 50 dias and the proteic profile of Y strain was observed in nitrocellulose membrane. The results demonstrated that these eleven strains of T. cruzi have differences between the groups of the parasite. The group TcI showed higher infection rate in cells; TcII, higher value for kinetic growth and TcIII is phylogenetically closer to TcV, which is a hybrid group. The association between parasite and host is able to explain the biological and molecular differences in T. cruzi strains; for this reason, the study of eleven strains isolated from different hosts can add information to the literature and clarify some of the biological aspects of the parasite / Doutorado / Parasitologia / Doutora em Parasitologia

Cercariae of the genus Trichobilharzia can penetrate not only the skin of definitive hosts (ducks), but they are also able to penetrate the skin of accidental hosts (mammals). As a result of the penetration, the inflammatory response known as cercarial dermatitis appears. The goal of our thesis is to detect parasite DNA in the serum and cerebrospinal fluid of infected ducks, and also in the serum of infected mice. By using PCR with primers designed for a tandem repeated sequence, we were able to detect 1 femtograms of parasite DNA isolated from sera of infected ducks. We were able to amplify parasite DNA only from 16 samples of sera and cerebrospinal fluid of the infected ducks, but we were not able to do so with the serum of mice. Sera of infected mice were also tested by ELISA and Western blot. The homogenates of T. regenti (TRhc), T. szidati (TShc) and S. mansoni (SMhc) cercariae were selected as an antigen. The results showed progressive increase in the level of IgM antibody from 10 days after 1st infection and also increase of the level of IgG from the 2nd infection. 10 days after the 4th infection, the level of IgM and IgG gradually declined, but the level of antibodies 100 days after the 4th infection was still higher if compared to uninfected mice. Results from Western blot analysis...

Literature concerning the time frames for detection of various seminal components commonly tested for in forensic laboratories in sexual assault cases is limited in quantity and in scope. Determining a more accurate time since intercourse (TSI) interval based on an extensive review of forensic case work would provide investigators with a tool for estimating the time elapsed between the occurrence of a sexual assault and the collection of a Sexual Assault Evidence Collection Kit (SAECK) which could be vital information in certain cases. This study demonstrates that the presence of intact spermatozoa is a significant finding on microscope slides prepared from vaginal, anorectal, and oral swabs and that the percentage of intact sperm cells decreases over time. This study also proved that sperm tails are lost during the preparation of microscope slides from SAECK swabs by directly comparing medical personnel-prepared smear slides and analyst-prepared extract slides from 95 Boston Police Department (BPD) Crime Laboratory Unit cases. Additionally, this study presents maximum TSI values for the persistence of sperm heads, intact spermatozoa, and prostate specific antigen (P30) through a retrospective examination of 355 cases processed by the BPD Crime Laboratory Unit over 5 years. The maximum persistence values for P30 in the vaginal, anorectal, and oral cavities were 19 hours, 17 hours, and 20 hours, respectively. In the vaginal cavity, maximum persistence values for intact spermatozoa were 43 hours for smear slides and 41.5 hours for extract slides. The maximum persistence of sperm heads was equivalent for vaginal smear and extract slides at 105 hours. In the anorectal cavity, maximum persistence values for intact spermatozoa were 43 hours for smear slides and 13 hours for extract slides. The maximum persistence of sperm heads was equivalent for anorectal smear and extract slides at 43 hours. In the oral cavity, maximum persistence values for intact spermatozoa were 3.75 hours for smear slides and 5 hours for extract slides. The maximum persistence of sperm heads were equivalent for oral smear and extract slides at 24 hours.

The spotted fever group rickettsiae are emerging diseases. They cause damage in their hosts by invading the endothelium in small to medium-sized blood vessels, which results in vasculitis that can cause clinical manifestations from most organs. The present thesis describes the prevalence of Rickettsia helvetica in ticks, the incidence of rickettsial infection based on seroreactivity and seroconversion in humans and their symptoms, from different parts of Sweden and the Åland Islands in Finland. This was accomplished through serological analysis of both retrospective and prospective serum samples from confirmed and suspected tick-bitten individuals compared to individuals with no knowledge of tick exposure (blood donors). We found a comparable seroprevalence to Rickettsia spp. in different geographical areas where ticks are present; it was also comparable to the seroprevalence of Borrelia spp. Seroprevalence was also more common, as suspected, in the tick-exposed group compared to blood donors. In comparison with co-infections with other tick-borne infections (Anaplasma spp. and Borrelia spp.), we could conclude that co-infections do exist and that, based on clinical findings, it is difficult to distinguish which microorganism causes certain clinical manifestations. For reliable conclusions regarding the causative microorganism, the diagnosis should basically rely on diagnostic tests. In comparison with Borrelia spp., seroconversion to Rickettisa spp. was more common in the areas we investigated, indicating that rickettsiosis is a common tick-borne infection in Sweden and most likely underdiagnosed. When investigating patients with meningitis, we found R. felis in cerebrospinal fluid from two patients with subacute meningitis. This was the first report in which R. felis was found and diagnosed in patients in Sweden. The patients recovered without sequelae and without causal treatment. To provide guidelines on when to treat Rickettisa spp. infections, more investigations are needed. The present thesis shows that Rickettsia spp. are common in ticks and do infect humans. Rickettsial infection should be considered in both non-specific or specific symptoms after a tick bite. It was also shown in the thesis that flea-borne rickettsiosis (R. felis) occurs in Sweden and may cause invasive infections

A infecção por Cryptosporidium serpentis é uma das enfermidades mais importantes em répteis e se caracteriza por infecção crônica, clínica ou subclínica, e presença de gastrite hipertrófica severa, regurgitação, perda de peso progressiva, mortalidade eventual e eliminação contínua e intermitente de oocistos em fezes. O objetivo deste estudo foi padronizar um teste imunoenzimático (ELISA) indireto para detecção de anticorpos contra C. serpentis, e acompanhar a evolução clínica, parasitológica e da resposta imune humoral em serpentes naturalmente infectadas com C. serpentis. Foram utilizadas 21 serpentes naturalmente infectadas com C. serpentis e alojadas no Instituto Butantan, São Paulo, Brasil. As análises clínica e parasitológica foram realizadas em 21 serpentes por meio do registro diário dos sinais clínicos apresentados e pesquisa mensal da eliminação fecal de oocistos, em lâminas coradas pela técnica de Kinyoun. A avaliação sorológica foi realizada mensalmente utilizando o ELISA indireto para pesquisa de anticorpos anti-C. serpentis, pelo período de 12 meses em 8 animais, 8 meses em 3 animais e 6 meses em 1 animal. O ELISA indireto foi padronizado em bloco com utilização de antígeno produzido a partir de oocistos de C. serpentis, IgY de galinha anti-gamaglobulinas de serpentes e conjugado contendo IgG de coelho anti-IgY de galinha ligada à peroxidase. Os sintomas clínicos observados foram regurgitação, inapetência alimentar e perda de peso progressiva. A análise parasitológica revelou eliminação de quantidade variável de oocistos, de forma intermitente, em todas as serpentes, com positividade de 92% (116/126). O ELISA indireto apresentou positividade em 42,9% (54/126) das amostras. Foi observada resposta imune humoral na maioria dos animais, no entanto, com presença título flutuante de anticorpos e alternância de resultados positivos e negativos, em um mesmo animal. / Infection by Cryptosporidium serpentis is one of the most important diseases in reptiles, and is characterized by chronic infection, clinical or subclinical, and the presence of severe hypertrophic gastritis, food regurgitation, progressive weight loss, mortality, and intermittent and continuous shedding of oocysts in feces. The objective of this study was to standardize an indirect enzyme immunoassay (ELISA) to detect antibodies against C. serpentis, and evaluate the clinical, parasitological and humoral immune response in snakes naturally infected with C. serpentis. Twenty one snakes naturally infected with C. serpentis and housed at the Instituto Butantan, São Paulo, Brazil, were used for accomplish clinical and parasitological analyzes of C. serpentis infection, through the daily record of clinical signs and monthly survey of fecal shedding of oocysts using Kinyoun staining technique. The serological evaluation was performed monthly using the indirect ELISA for the detection of anti-C. serpentis antibodies, for a period of 12 months in eight animals, eight months in three animals, and six months in one animal. The indirect ELISA was standardized on the basis of block titration using antigen produced from oocysts of C. serpentis, chicken IgY anti-snake gamaglobulins and a conjugate containing rabbit IgG anti-chicken IgY linked to peroxidase. Clinical symptoms consisted in food regurgitation, inappetence, and progressive weight loss. The parasitological analysis revealed intermittent fecal shedding of variable number of oocysts in all snakes, with positivity in 92% (116/126) of the samples. The indirect ELISA was positive in 42.9% (54/126) of the samples. Humoral immune response was observed in most animals, however, fluctuating antibodies levels with rotation of positive and negative results were observed in some snakes.

Os vírus da influenza A (IA) provocam epidemias e pandemias em humanos. As aves selvagens são os reservatórios naturais desses vírus, dentre essas, as migratórias possuem um importante papel como transmissores da doença. A região subantártica abriga populações de aves marinhas, as quais reproduzem-se no verão austral formando colônias com milhares de aves, o que potencializa a importância do estudo do vírus IA em aves marinhas neste ambiente. Os objetivos deste trabalho foram analisar a presença do vírus IA em swabs orotraqueal e cloacal, e de anticorpos anti-IA em soro de aves marinhas da região subantártica, caracterizar molecularmente as amostras positivas, e conhecer mais a ecologia deste vírus. Foram coletadas amostras biológicas de pinguim-papua, pinguim-de-barbicha, pinguim-de-adelie, skua-subantártica, pomba-do-cabo, e petrel-gigante-do-sul, entre 2010-13, nas ilhas Elefante e Rei George. Das 615 amostras de swab, 13 foram positivas por One Step Real Time RT-PCR, e uma foi caracterizada como H6N8. Das 673 amostras de soro, 108 foram positivas por Ensaio Imonoenzimático competitivo (cELISA). O estudo contribuiu para o conhecimento do vírus IA na região e foram feitas recomendações para a prevenção a introdução de patógenos na Antártica. / Influenza A (IA) viruses cause epidemics and pandemics in humans. Wild birds are the natural reservoir of these viruses, among these, migratory ones have an important role as transmitters of disease. The subantarctic region is home to seabird populations, which breed in the austral summer forming colonies with thousands of birds, which enhances the importance of the study of AI viruses in waterfowl in this environment. The objectives of this study were to analyze the presence of IA virus in tracheal and cloacal swabs, and anti-IA antibodies in serum of seabirds from subantarctic region, molecular characterization of positive samples, and learn more about this virus ecology. Biological samples were collected of gentoo penguin, chinstrap penguin, adelie penguin, brown skua, cape petrel, and southern giant petrel, from Elephant and King George islands, between 2010-13.Of the 615 swab samples, 13 were positive by Real Time One Step RT-PCR, and one was characterized as H6N8. Of the 673 serum samples, 108 were positive by competitive enzyme-linked immunosorbent assay (cELISA). The study contributed to AI virus knowledge in the region and recommendations for preventing the introduction of pathogens in Antarctica were made.

This study evaluated two methods for the isolation and purification of anti-DNA antibodies. A two-step affinity purification with streptavidin (SA) biotinylated oligodeoxythymidine (dT) M-280 and protein G Dynabeadsª was compared to a two step method using Melon(TM) Gel and cellulose DNA. Although Melon gel allowed for faster antibody purification and a higher recovery rate it gave a product of less purity than the magnetic bead method. Further characterization of the antibodies was done by PhastGel(TM) non-reducing SDS-PAGE and isoelectric focusing in order to analyze purity and confirm the polyclonal nature of anti-DNA antibodies. Agilent 2100, with a higher resolution then SDS-PAGE, revealed possible subclasses of different MW not detected by SDS-PAGE. ELISA showed that all four IgG antibody subclasses were present, while Western blot confirmed the presence of human IgGs. Ultraviolet spectroscopy, Agilent, and fluorescence based assays were used to demonstrate DNA hydrolytic activity of purified anti-DNA antibody. / by Anna M. Kats. / Thesis (M.S.)--Florida Atlantic University, 2008. / Includes bibliography. / Electronic reproduction. Boca Raton, FL : 2008 Mode of access: World Wide Web.

O Papaya ringspot virus (PRSV) é uma espécie do gênero Potyvirus, sendo que a maioria dos isolados pertence a duas estirpes distintas: "papaya" (P) e "watermelon" (W). O Papaya ringspot virus - estirpe W (PRSV-W) tem sido considerado um dos vírus mais importantes no cultivo de cucurbitáceas pela predominância e pelos prejuízos significativos que causa no Brasil. O controle do mosaico da abobrinha-de-moita, causado pelo PRSV-W, tem sido obtido de forma satisfatória através da premunização com as três estirpes fracas, designadas PRSV-W-1, PRSV-W-2 e PRSV-W-3. O principal objetivo desse estudo foi comparar essas estirpes fracas com estirpes severas PRSV-W-C, PRSV-W-PR e PRSV-W-PE, com base na seqüência de nucleotídeos do gene que codifica a proteína da capa protéica e na mobilidade dessa proteína em SDS-PAGE. A seqüência de nucleotídeos da capa protéica das estirpes fracas PRSV-W-1 e PRSV-W-2 apresentou 100 % de homologia. Quando comparadas com a estirpe fraca PRSV-W-3, a homologia foi de 98 %. As estirpes fracas PRSV-W-1 e PRSV-W-2 apresentaram 95 % de homologia com as estirpes severas PRSV-W-C e PRSV-W-PE. Essas duas estirpes severas, por sua vez, apresentaram respectivamente, 93 e 95 % de homologia com a estirpe fraca PRSV-W-3. O alinhamento das seqüências de nucleotídeos entre as estirpes fracas e as severas evidenciou a inserção de 6 nucleotídeos na região conservada desse gene nas estirpes fracas. Essa inserção refletiu na adição de dois amino ácidos (Asn e Asp) na seqüência de amino ácidos deduzidos dessa proteína. A mobilidade da capa protéica em SDS-PAGE foi semelhante para todas as estirpes estudadas. / Papaya ringspot virus (PRSV), a species of the enus Potyvirus, is classified into two strains: "papaya" (P) and "watermelon" (W). Papaya ringspot virus - type W (PRSV-W) has been considered one of the most important viruses infecting cucurbits in Brazil due to its predominance and significative damage caused on the crops. The control of the disease caused by this virus has been efficiently achieved by means of cross protection with three mild strains, namely PRSV-W-1, PRSV-W-2, and PRSV-W-3. The main purpose of the present study was to compare these mild strains with the severe strains PRSV-W-C, PRSV-W-PR, and PRSV-W-PE, based on the nucleotide sequence of the coat protein gene and on the mobility of the capsid protein in SDS-PAGE. The nucleotide sequence of the coat protein gene of the mild strains PRSV-W-1 and PRSV-W-2 showed 100 % of homology. When compared with the coat protein gene of the mild strain PRSV-W-3, the homology was 98 %. The mild strains PRSV-W-1 and PRSV-W-2 showed 95 % of homology with the severe strains PRSV-W-C and PRSV-W-PE. These two severe strains, otherwise, showed respectively, 93 and 95 % of homology with the mild strain PRSV-W-3. The alignment of the nucleotide sequences of the mild and the severe strains indicated an insertion of 6 nucleotides in the conserved region of the coat protein gene of the mild strains. This insertion reflected on the addition of two amino acids (Asn e Asp) in the amino acid deduced sequence of this protein. The mobility of the coat protein in SDS-PAGE was similar for all the strains studied.

In this thesis I develop and implement “antibody landscapes”, a method to profile immunity against a pathogen as a function of antigenic differences between a range of strains. Theoretically applicable to any antigenically variable pathogen and measurement of immunity, the work here focusses on antibody-mediated immunity against the A/H3N2 influenza subtype. Applying the methodology to study annual serum samples from individuals monitored for influenza infection over a period of six years, patterns of influenza immunity were found to be remarkably distinct and maintained almost unchanged over time in the absence of influenza exposure. Upon infection, the initial response is strikingly antigenically broad, including responses against viruses far beyond the extent of cross-reactivity observed after a primary infection. Analysis of two vaccination cohorts, one receiving an antigenically advanced vaccine strain and one a more typical vaccine strain choice, revealed many of the same patterns of response as seen with infection. Antigenically advanced vaccination generated greater responses against later strains but surprisingly, due to equivalent boosting of prior immunity, this came at no cost to responses generated against contemporary or older strains. Exploring in more detail the development of immunity over time, analysis of a cohort of children demonstrated that - in contrast to adults with diverse exposure histories - antibody responses to a first infections were remarkably similar in pattern and magnitude. Interestingly, for second infections, although post-infection antibody titres against circulating strains were comparable to those after first infections, overall cross-reactivity of the response against future antigenic variants appeared to be diminished. The findings here underline the significant role prior-immunity plays in affecting the response to new exposures and the importance of understanding it. An important conclusion is that by failing to account for it, current approaches to influenza vaccine strain selection may be suboptimal and pre-emptive vaccine strain updates may improve overall vaccine efficacy where immunity to current strains already exists in the population. Building on the work presented here should help to optimise strain choice and vaccine efficacy even further.

Orientador: Karin Werther / Banca: Rosangela Zacarias Machado / Banca: Deise Aparecida de Oliveira Silva / Resumo: O presente trabalho objetivou estudar a susceptibilidade do carcará (Caracara plancus) frente à infecção experimental pela amostra ME49 de Toxoplasma gondii pela observação da sintomatologia clínica, análise dos parâmetros hematológicos, estudo da cinética de anticorpos IgG anti-T. gondii, e constatação da presença do parasito nos diversos tecidos utilizando a imunoistoquímica, imunofluorescência direta em tecidos, bioensaio em camundongos e PCR. Sete carcarás soronegativos para anticorpos anti-T. gondii foram separados em dois grupos: G1 (grupo infectado - 5 aves) e G2 (grupo controle - 2 aves). As aves do grupo G1 foram alimentadas durante três dias consecutivos com roedores Calomys callosus previamente infectados com T. gondii e as aves do grupo G2 foram alimentadas com roedores não infectados. As aves infectadas não apresentaram sintomas clínicos de toxoplasmose, tampouco alterações nos parâmetros hematológicos. Todas as aves infectadas soroconverteram. A soroconversão das aves experimentalmente infectadas ocorreu a partir do sétimo dia pós-infecção, os picos iniciais na produção de anticorpos IgG anti-T. gondii ocorreram entre 15 e 30 dias pós-infecção sendo que em seguida houve uma tendência de queda dos títulos de anticorpos. No momento da necropsia não foram encontradas lesões sugestivas da infecção por T. gondii. Não foi observado no exame histopatológico a presença do parasito nos diversos tecidos amostrados das aves infectadas, entretanto em uma das aves do grupo não infectado e sorologicamente negativa para anticorpos anti-T. gondii, foi encontrado um cisto tecidual na musculatura. Pelas técnicas de imunoistoquímica e imunofluorescência direta em tecidos o parasito foi encontrado em pequeno número em diversos tecidos, porém tanto nas aves do grupo infectado quanto nas aves do grupo controle. Utilizando o bioensaio em camundongos... (Resumo completo, clicar acesso eletrônico abaixo) / Abstract: The present study aimed to evaluate the susceptibility of crested caracara (Caracara plancus) to experimental infection with ME49 strain of Toxoplasma gondii, through clinical symptoms, hematological parameter analysis, kinetics of specific IgG antibodies to T. gondii, and parasite detection by immunohistochemistry, direct immunofluorescence, bioassay, and PCR. Seven crested caracara, seronegative to T. gondii antibodies, were separated into two groups: G1 (infected group - 5 birds), and G2 (control group - 2 birds). G1 birds were fed during three successive days with Calomys callosus previously infected with T. gondii, and G2 birds were fed with non-infected rodents. The infected birds did not present clinical symptoms, nor significant changes in hematological parameters. All infected birds had antibody titers to T. gondii. IgG antibodies to T. gondii were first detected at 7 dpi, with production peaks between 15 and 30 dpi, which were followed by a sharp decrease in detectable antibodies. No gross lesions sugestive of T. gondii infection were observed. By histopatological examination, it was not possible to observe the presence of the parasite in the infected birds' organs, however, in one bird of the control group, a T. gondii tissue cyst was visualized in muscle. By immunohistochemistry and direct immunofluorescence, the parasite was found in small number in different organs, although in animals from both groups. The presence of T. gondii was confirmed in heart samples of two bioassayed birds, both from the infected group. In this study, the experimentally infected crested caracaras did not show clinical symptoms, alteration on hematological parameters and the parasite was found in small numbers in the organs of the birds, for these reasons the crested caracara were resistant to T. gondii infection. / Mestre