Toxoplasma gondii: isolation, biological and molecular characterisation of samples from free-range Gallus gallus domesticus from countryside Southeast Brazil

Abstract

Toxoplasma gondii presents a high prevalence worldwide, infecting several animals. Felines are considered the definitive hosts and among the intermediate hosts we highlight mammals and birds. The man can become infected by ingesting tissue cysts present in birds and mammals. Biological and molecular aspects of T. gondii allows a better understanding of the epidemiology of toxoplasmosis. This work is a serologic screening of 58 chickens grown (Gallus gallus domesticus) for human consumption in Espírito Santo State, by means of indirect haemagglutination assay (IHA). Thirteen chickens tested positive for anti-T. gondii antibodies. The heart and brain of five positive chickens were harvested, treated with pepsin and inoculated separately, in two Swiss mice, intraperitoneally. Tachyzoites were observed in the peritoneum of all the animals, between seven and 10 days after the inoculum. Ten isolates were obtained and biologically characterised in BALB/c mice inoculated with 101 to 104 tachyzoites. All isolates were classified as virulent or intermediately virulent. Isolates were genotyped by means of polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) analysis, revealing three different genotypes. None of the isolates exhibited the clonal type I, II or III genotype. No genotypic differences were observed between the isolates from the brain or heart from the same bird.

Congenital human toxoplasmosis caused by non-clonal Toxoplasma gondii genotypes in Argentina

“…Aunque no se encontraron diferencias entre las dosis empleadas, el aislamiento TgMr ocasionó signología severa en los ratones, a menor tiempo que el aislamiento TgSb. Debido a ello, se propone utilizar dosis con mayor diferencia de carga parasitaria entre ellas, como fue sugerido por otros autores (Ferreira et al, 2018;Saraf et al, 2017), con el fin de detectar posibles diferencias ante distintas cargas parasitarias o dosis de infección. Estudios de este tipo (con rangos de dosis mayores y utilizando incluso 1 y 10 parásitos por ratón) podrían indicar que en casos de brotes de toxoplasmosis con signología severa no solo tendría que ver el genotipo/fenotipo del parásito y la susceptibilidad de la especie animal afectada, sino también la carga inicial en la fuente de infección (Dubey, 2010;Pardini et al, 2019;Saraf et al, 2017).…”

“…La virulencia observada se relacionaría a una sobreproducción de las citoquinas dependientes del perfil Th1 (IFN-Ꝩ, FNT-α e IL-12), que a su vez se requieren para la protección contra el parásito (Mordue et al, 2001). En Brasil, se han hecho múltiples ensayos en ratones con aislamientos provenientes de diferentes hospedadores y caracterizados genéticamente como atípicos resultando en diversos grados de virulencia para el ratón (Dubey et al, 2006;Dubey et al, 2008;Ferreira et al, 2001;Ferreira et al, 2018;Pena et al, 2008;Shwab et al, 2014;Silva et al, 2014). Aislamientos de T. gondii a partir de pollos asintomáticos de Brasil fueron patógenos para los ratones, independientemente del genotipo (Dubey et al, 2006).…”

Isolation and molecular characterization of Toxoplasma gondii from placental tissues of pregnant women who received toxoplasmosis treatment during an outbreak in southern Brazil

“…In addition to confirming the presence of T. gondii in the placenta, the isolation in mice allows the virulence evaluation of genotypes present in the samples [26], since virulent strains usually cause acute infection with clinical signs in mice [3]. Signs which are characteristic of acute toxoplasmosis such as ascites, bristly hair, and photophobia were seen in all mice inoculated with placental samples from the patients in this study.…”

Genotyping of viable Toxoplasma gondii from the first national survey of feral swine revealed evidence for sylvatic transmission cycle, and presence of highly virulent parasite genotypes

“…Ten of the 14 isolates identified in Hawaii belong to #24, which accounted for 71% (10/14) of those isolates (Table 2). Genotype #24 has previously been identified in chickens from Costa Rica and Brazil (Dubey et al ., 2006; Ferreira et al ., 2018), and in bobcats from Mississippi, USA (Verma et al ., 2017), suggesting it is widely distributed in the USA. Bioassays in mice indicate #24 strains are not highly virulent to mice (Tables 3 and 4).…”