Isolation and Genotyping of Toxoplasma gondii in Brazilian Dogs

Abstract

Strains of Toxoplasma gondii in Brazil are highly genetically diverse compared to strains from North America and Europe. Dogs are epidemiologically important because they act as sentinels for T. gondii infections in humans and are good indicators of environmental contamination. The aim of this study was to isolate and genetically characterize T. gondii strains from tissues of naturally infected Brazilian dogs. For this study, 21 blood samples were collected from dogs at the Zoonosis Control Centers of Ilhéus and Itabuna cities, Bahia, Brazil. The sera were examined for T. gondii antibodies using the indirect hemagglutination test. Brains and hearts of seropositive dogs were bioassayed in mice to isolate and characterize T. gondii parasites by PCR-RFLP using 10 genetic markers (SAG1, newSAG2, SAG3, BTUB, c22-8, c29-2, GRA6, PK1, APICO, and L358). However, T. gondii was isolated from only 4 (57.1%) dogs, designated TgDgBr6, 13, 17, and 21. All strains were virulent, causing clinical changes (rough hair coat, lethargy, and abdominal distention) and the death of all mice within 8–20 days after inoculation. Genetic analysis of these 4 T. gondii isolates revealed 4 distinct genotypes with different clonal lineage combinations (types I, II, and III) and 2 atypical alleles. Using PCR-RFLP with several markers, this study contributes to evaluations of the genetic diversity of strains circulating in Brazil.

Clinical Toxoplasmosis in Dogs and Cats: An Update

“…On the top of that, there is a wide genetic diversity within the parasites isolated from asymptomatic dogs (73, 74) and cats (72, 75), corresponding to a complex epidemiology shown in different geographical areas [(76), http://toxodb.org/toxo/].…”

Dogs (Canis familiaris) as Sentinels for Human Infectious Disease and Application to Canadian Populations: A Systematic Review

“…This suggests that, while dogs did not prove to be a good indicator of foodborne disease in people, they may be a reliable indicator of environmental infection. Other studies have also concluded that dogs may be used as environmental sentinels [50,51,52]. Results from a study in Ubatuba, São Paulo State [53] utilized dogs as sentinels to demonstrate that toxoplasmosis was linked to sanitary problems (largely cooking of food), rather than the presence of rodents or untreated water.…”

Virulence of atypical Toxoplasma gondii strains isolated in French Guiana in a murine model

“…Some experiments are much more focused on analyzing the correlation between clinical data and biological markers of acute, chronic or secondary infections involving European or North-American strains [27], while others attempt to demonstrate the basic patterns of T. gondii pathophysiological mechanisms using transgenic mice [11, 19, 44] or other advanced technologies, such as bioluminescence imaging [7]. Some general reviews reported data from experimental assays and overviewed hypotheses underlying toxoplasma virulence based on general comparisons between different genotypic strains including the clonal reference ones [18, 21, 35, 50]. Recently, Saraf et al [43], proposed a standardized methodology for future studies in order to enable more efficient and effective analysis of genetics and virulence patterns for T. gondii .…”