Can cloning and sequencing help to genotype positive Toxoplasma gondii clinical samples? Results and validation using SAG3 as a model

Genotyping of Toxoplasma gondii in domestic animals from Campeche, México, reveals virulent genotypes and a recombinant ROP5 allele

“…Considering all typed markers, there is a predominance of type I and III alleles (with the exception of ToxoDB #116, which has a type II allele at c22-8). Our results are in agreement with most of the isolates that have been obtained in the Mexican Neotropical region and with what has been reported from Central and South American countries with a predominance of strains related to genotypes I and III but few or no type II variants (Rajendran et al, 2012;Valenzuela-Moreno et al, 2020, 2022aRico-Torres et al, 2023) For the virulence markers, we identified three ROP18/ROP5 virulence profiles in 7 samples (3 tissue samples and 4 T. gondii isolates), 2 of which had predicted high virulence in a murine model (4/1 and 1/3) and one with unknown virulence due to the new ROP5 combination (3/1&3). The virulence profile of the strains from the heart of chicken #1, TgCkMxCam1a and TgCkMxCam1b coincides with the profile described for the other ToxoDB #38 isolates from Colombia (TgCtCo4, 10, 11 and TgDgCo17), a genotype that remains unaltered for the 5 PCR-RFLP virulence markers, despite the locations being over 2400 km away from each other and more than 17 years having elapsed since the profile was first described (Dubey et al, 2006(Dubey et al, , 2007.…”

“…Four out of 6 of these isolates were the archetypal type III clone (ToxoDB #2). Several isolates have also been obtained from dogs, demonstrating 4 different genotypes (ToxoDB #8, #28, #73 and #74) (Dubey et al ., 2009 ; Valenzuela-Moreno et al ., 2020 ; Rico-Torres et al ., 2023 ). Similarly, we described the ToxoDB #116 genotype in 2 Bennett's wallabies ( Macropus rufogriseus ) from the centre plateau of México that had died due to acute disseminated toxoplasmosis.…”

“…Considering all typed markers, there is a predominance of type I and III alleles (with the exception of ToxoDB #116, which has a type II allele at c22-8 ). Our results are in agreement with most of the isolates that have been obtained in the Mexican Neotropical region and with what has been reported from Central and South American countries with a predominance of strains related to genotypes I and III but few or no type II variants (Rajendran et al ., 2012 ; Valenzuela-Moreno et al ., 2020 , 2022 a ; Rico-Torres et al ., 2023 )…”

“…Finally, we found the combination 4/1 ROP18 / ROP5 again in México. This fact is highly significant because this pattern can cause up to 100% mortality in the murine model, and it has only been reported a couple of times previously, suggesting that some Mexican strains could pose a high risk to the human and nonhuman animal populations (Shwab et al ., 2016 ; Rico-Torres et al ., 2023 ).…”