The aim of the present study was to evaluate the re-shedding of T. gondii oocysts in cats fed tissue cysts of homologous and heterologous strains 12, 24 and 36 months after the first infection. Thirteen cats were used in the present study and were divided into four groups: G1 (n=2), G2 (n=3), G3 (n=5), and G4 (n=3). G1, G3 and G4 cats were infected with brain cysts of ME49 and G2 with TgDoveBr8, both genotype II strains of T. gondii. The G1 and G2 cats were re-infected after twelve months with brain cysts of VEG strain (genotype III), and G3 cats were re-infected with TgDoveBr1 (genotype II). The G3 cats were re-infected a third time after 24 months from the second infection, and the G4 cats were re-infected 36 months after the initial infection with cysts of the VEG strain. The cats' feces were evaluated using fecal flotation and genotyped with PCR-RFLP. The serological responses for IgM, IgA and IgG were determined by ELISA. All cats shed oocysts after the initial infection. Only one G1 cat shed oocysts when re-infected after twelve months with the VEG strain. No G2 cats excreted oocysts after the second infection with VEG. G3 cats, when re-infected after twelve months with the TgDoveBr1 strain, did not shed oocysts. However, when challenged after a third time with the VEG strain, three out of four cats shed oocysts. In the G4 group, when re-infected after thirty-six months with the VEG strain, two out of three cats shed oocysts. All oocyst samples were genotyped and characterized as the same genotype from the inoculum. Protection against oocyst re-excretion occurred in 90%, 25%, and 33.4% of cats after 12, 24, and 36 months from the initial infection, respectively. Therefore, the environmental contamination by oocysts from re-infected adult cats is only 30% lower than from kittens. In conclusion, the excretion of T. gondii oocysts was higher in experimentally re-infected cats throughout the years, especially when a heterologous strain was used.

During this study, cats were immunized by the intranasal and rectal routes with crude rhoptry proteins of Toxoplasma gondii admixed with Quil-A. Twenty-five domestic short hair cats divided into five groups (n=5) were used during this evaluation: G1 and G3 cats received 200 μg of the rhoptry proteins with Quil-A (20 μg) by the intranasal and rectal routes, respectively; G2 and G4 cats received bovine serum albumin (BSA, 200 μg/dose) with Quil-A (20 μg); and G5 animals served as unvaccinated controls. All treatments were performed at days 0, 21, 42, and 63. The challenge was done with 800 cysts of the ME49 of T. gondii strain at day 70 (challenge day). The serum IgG, IgM, IgA, and fecal IgA antibody levels were evaluated by using the indirect enzyme-linked immunosorbent assay (ELISA). Some animals produced antibody levels beyond cut-off; however, two animals from G1 (OD(mean)=0.308, OD(cut-off)=0.200) and three from G3 (OD(mean)=0.254) demonstrated IgG levels on being challenged, with similar results occurring in two cats from G1 to IgM (OD(mean)=0.279, OD(cut-off)=0.200). Fecal IgA levels were detected in all G1 cats (OD(mean)=0.330, OD(cut-off)=0.065), and in one cat from G3 (OD(mean)=0.167). The serum and fecal humoral immune responses did not correlate with oocyst shedding. Oocyst shedding varied from 98.4% (G1), 87.5% (G2), 53.0% (G3), to 58% (G4), and was lower than that of G5 cats. The prepatent period of cats vaccinated intranasally (G1) was reduced from 6-9.6 to 2.8 days, suggesting protection of environmental contamination, considering cats as the primary source of contamination. The intranasally and rectally administered rhoptry vaccines were able to partially protect cats against T. gondii cysts on being challenged; however, the intranasal method of vaccination yielded better results relative to the rectal route.

Eared doves (Zenaida auriculata), which are common in urban, rural and wild areas in many regions of Brazil, are frequently prey for domestic cats. Therefore Toxoplasma gondii isolates obtained from doves may reflect greater environmental diversity than those from other hosts. The aim of the present study was to evaluate T. gondii seroprevalence, isolate and genotype strains from Z. auriculata. Serum and tissue samples were collected from 206 doves for use in the modified agglutination test (MAT) and mouse bioassay. The prevalence of T. gondii antibodies in the doves was 22.3% (46/206), with titers ranging from 16 to 4096, and T. gondii strains were isolated from 12 of these doves. Five genotypes were detected by means of PCR-RFLP, including ToxoDB genotypes #1, #6, #17 and #65, and one genotype that had not previously been described (ToxoDB#182). This was the first report on isolation of T. gondii from Z. auriculata. This study confirmed the genetic diversity of T. gondii isolates and the existence of clonal type II (ToxoDB genotype #1) in Brazil.Keywords: Toxoplasma gondii, eared doves, genotyping, PCR-RFLP, MAT, Biossay. ResumoPombos silvestres (Zenaida auriculata), comuns em áreas urbanas, rurais e selvagens em muitas regiões do Brasil, são frequentemente predados por gatos domésticos. Sendo assim, os isolados de T. gondii obtidos de pombos podem refletir uma maior diversidade ambiental do que os outros hospedeiros. O objetivo do presente estudo foi avaliar a soroprevalência, isolar e genotipar T. gondii de Z. auriculata. Amostras de soro e tecido foram coletadas de 206 pombos para o teste de aglutinação modificado (MAT) e o bioensaio em camundongos. A prevalência de anticorpos contra T. gondii em pombos foi 22,3% (46/206), com títulos variando de 16 a 4096, e T. gondii foi isolado de 12 pombos. Cinco genótipos foram detectados por PCR-RFLP, incluindo os genótipos ToxoDB #1, #6, #17, #65 e um genótipo não descrito anteriormente (ToxoDB#182). Esse é o primeiro relato de isolamento de T. gondii de Z. auriculata. Este estudo também confirmou a diversidade dos isolados de T. gondii e a presença de tipo clonal II (ToxoDB #1) no Brasil.

The parasite Haemonchus contortus is one of the most pathogenic for small ruminants in tropical and subtropical regions worldwide, including Brazil. The objective of this study was to evaluate the structural changes induced in adult H. contortus after in vitro contact with Acacia mearnsii extract (AE), using scanning electron microscopy. Adult nematodes were collected from a naturally infected lamb. In the in vitro assay the parasites were placed in contact with AE (100 mg ml -1 ), for two hours at 37 o C. The nematodes used in the assays (exposed to AE and the negative controls) were analyzed using an electron scanning microscope (quadruplicate per treatment). In all replicates, similar morphological alterations were observed on the entire extension of the cuticle of the specimens that remained in contact with the EA in vitro assays, none significant lesion was observed in the negative control (not exposed to AE). These results indicate the direct action of EA on the cuticle of H. contortus in in vitro trials. Key words: Gastrointestinal nematodes, scanning electron microscopy, structural changes, tannins ResumoHaemonchus contortus é um dos parasitos mais patogênicos para pequenos ruminantes em regiões tropicais e subtropicais em todo o mundo, inclusive no Brasil. O objetivo do trabalho foi analisar alterações ultraestruturais na cutícula de H. contortus após contato com extrato de Acacia mearnsii. Os parasitos expostos ao extrato de Acacia mearnsii (EA) e os controles negativos foram analisados ao microscópio eletrônico de varredura. No teste in vitro, adultos de H. contortus foram coletados de um ovino naturalmente infectado, e os parasitos foram colocados em contato com o EA (100 mg mL -1 ), durante duas horas à 37 o C. Os nematódeos expostos ao EA apresentaram alterações morfológicas em toda a extensão da cutícula. As alterações morfológicas não foram observadas no controle negativo. Estes resultados indicam a ação direta do EA na cutícula de H. contortus.

The current study aimed to evaluate serology, and isolate and genotype Toxoplasma gondii strains from pregnant dairy cows, slaughtered in an abattoir for human consumption, and their fetuses. Blood from 60 pregnant dairy cows and blood and tissue samples (brain, lung, heart, and liver) from their fetuses were collected and analyzed in a mouse bioassay. Antibodies against T. gondii were observed in 48.3% of cows and 3.7% of fetuses (IFAT, titers ≥ 50 for cows and 25 for fetuses were considered positive). Fourteen fetuses (23.3%) and six cows (10.0%) were identified as positive in the bioassay. T. gondii was isolated from a blood sample of a cow older than 4 years old in the 6th month of pregnancy, and from a blood sample of a fetus in the 6th month of gestation. These isolates were identified by polymerase chain reaction (PCR) as being of T. gondii and both strains showed type II alleles for all PCR-restriction fragment length polymorphism (PCR-RFLP) markers tested. T. gondii type II strain from cattle was isolated for the first time in Brazil. The current study also showed that transplacental transmission of T. gondii naturally occurs in dairy cows (23.3%) from Southern Brazil.