Prevalência da toxoplasmose em ovinos e caracterização molecular de isolados de Toxoplasma gondii (Nicolle & Manceaux, 1909) obtidos de animais de produção no Estado do Rio Grande do Norte

Abstract

This work aimed to evaluate the seroprevalence and risk factors for toxoplasmosis in sheep from the state of Rio Grande do Norte, Brazil, as well as to characterize the isolates of Toxoplasma gondii obtained from production animals (sheep, goats, swine, and free-range chickens) naturally infected in the state. Thus, serum samples of 930 sheep originated from two mesoregions with distinct climatic characteristics were tested by ELISA. In addition, two questionnaires requesting information from the farm and each individual animal were applied. Anti T. gondii antibodies were found in 205 (22.04%) of the 930 sheep tested. The risk factors associated to the infection were: presence of cats, age of sheep, and use of source of water not exposed to these animals,characterizing the existence of transmission of the infection associated to sporulated oocysts of T.gondii in the environment. Evaluation of avidity of IgG antibodies in 205 positive samples by conventional ELISA showed that 168 (81.95%) of the animals presented high-avidity IgG antibodies, and 37 (18.05%) low-avidity antibodies. These results suggest the presence of sheep in acute phase of toxoplasmosis in the state ofRio Grande do Norte. To isolate T. gondii, serum samples of 223 sheep of 4 municipalities, 50 goats from 3 municipalities, 18 swine from 3 municipalities and 47 free-range chickens from one municipality, slaughtered for human consumption in the state of Rio Grande do Norte, were tested through ELISA to detect the presence of anti-T. gondii antibodies. Of the seropositive animals, a bioassay was carried out in mice and 19 isolates were obtained: 01 isolate from goats, 05 from swine, and 13 from free-range chickens. T. gondii was not isolated from sheep. The isolates were divided into two groups according to the phenotype of virulence for mice. Seventeen isolates (89.5%)were characterized as virulent and two (10.5%) were identified as non-virulent. No isolates with phenotype of intermediary virulence were identified. The genetic variability of the isolates was analyzed by Restriction fragment length polymorphism (PCR-RFLP) in 11 loci (SAG1, 53SAG2, SAG2 alt, SAG3, BTUB, GRA6, c22-8, c29-2, L358, PK1 and Apico). The strains RH (Type I), ME49 (Type II) and VEG (Type III) were used as reference strains. Six different genotypes were identified, withthree new genotypes. No type I, II, or III archetype genotype was identified in the isolates studied. No association between virulence and isolate genotyping of the isolates was observed. This study confirms the genotypic variability of T. gondii in Brazil.