A Toxoplasma gondii atypical isolate reveals similar behaviour to the most virulent reference strain

BERNSTEIN, M.; PARDINI, L.; MORÉ, G.; CAMPERO, L. M.; UNZAGA, J.M.; VENTURINI, M.C.

Conferencia; The 26th International Conference of the World Association for the Advancement of Veterinary Parasitology (WAAVP 2017); 2017

WAAVP

Diverse T. gondii genotypes have shown different virulence in mouse model. The aim of this study was to evaluate the in vitro invasion and replication of an atypical T. gondii isolate obtained from Macropus rufrogriseus (TgMR) in Argentina. A plaque assay using the reference strains RH (type I), ME49 (type II) and VEG (type III) was conducted. Vero cells were cultured in 24-well plates (105/well) for 24 hours and infected with 105 tachyzoites/well. The plaque was incubated for 18 hours at 37°C and fixed with cold-methanol. Immunofluorescence with anti-T. gondii-Alexa Fluor and DAPI staining were used. Invasion and replication were determined by counting parasitophorous vacuoles (PV) and the number of tachyzoites/PV, respectively. Significant differences in the invasion capacity (p ˂ 0.05, Kruskal-Wallis test) among strains were detected, being lower in both TgMR and RH (average 211 PV) compared to ME49 and VEG (1265 and 540 PVs, respectively). The ME49 and VEG strains had low replication capacity (1 or 2 parasites/PV), whereas RH and TgMR strains had high replication (≥4 parasites/PV). The TgMR genotype is III for most markers and I for C 29-2 (#14 or 138 TOXO-DB). Similar genotype was isolated from chickens from South America and a human in Argentina. The TgMR isolate has a similar in vitro behavior to RH strain: lower invasion capacity than ME49 and VEG strains, but a higher replication rate. These results suggest TgMR as a potential high virulent isolate, however further studies in mouse model should be conducted.