Entamoeba histolytica, the causative agent of amebiasis, is the third leading cause of death among parasitic diseases globally. Its life cycle includes encystation, which has been mostly studied in Entamoeba invadens, responsible of reptilian amebiasis. However, the molecular mechanisms underlying this process are not fully understood. Therefore, we focused on the identification and characterization of Myb proteins, that regulate the expression of encystation-related genes in various protozoan parasites. Through bioinformatic analysis, we identified 47 genes in E. invadens encoding MYB-domain-containing proteins. These were classified into single-repeat 1R (19), 2R-MYB proteins (27), and one 4R-MYB protein. The in silico analysis suggests that these proteins are multifunctional, participating in transcriptional regulation, chromatin remodeling, telomere maintenance, and splicing. Transcriptomic data analysis revealed expression signatures of eimyb genes, suggesting a potential orchestration in the regulation of early and late encystation-excystation genes. Furthermore, we identified 3135 probable target genes associated with reproduction, meiotic cell cycle, ubiquitin-dependent protein catabolism, and endosomal transport. In conclusion, our findings suggest that E. invadens Myb proteins regulate stage-specific proteins and a wide array of cellular processes. This study provides a foundation for further exploration of the molecular mechanisms governing encystation and unveils potential targets for therapeutic intervention in amebiasis.

Of the documented tick-borne diseases infecting humans in Mexico, Rocky Mountain spotted fever (RMSF), caused by the gram-negative bacterium Rickettsia rickettsia, is responsible for most fatalities. Given recent evidence of brown dog tick, Rhipicephalus sanguineus sensu lato, as an emerging vector of human RMSF, we aimed to evaluate dogs and their ticks for rickettsiae infections as an initial step in assessing the establishment of this pathosystem in a poorly studied region of northeastern Mexico while evaluating the use of dogs as sentinels for transmission/human disease risk. We sampled owned dogs living in six disadvantaged neighborhoods of Reynosa, Northern Mexico to collect whole blood and ticks. Of 168 dogs assessed, tick infestation prevalence was 53%, comprised of exclusively R. sanguineus s. l. (n=2,170 ticks). Using PCR and sequencing, we identified an overall rickettsiae infection prevalence of 4.1% (n=12/292) in ticks, in which eight dogs harbored at least one infected tick. Rickettsiae infections included R. amblyommatis and R. parkeri, both of which are emerging human pathogens, as well as candidatus R. andeanae. This is the first documentation of pathogenic Rickettsia in R. sanguineus s.l. collected on dogs from northeastern Mexico. Domestic dog infestation with Rickettsia-infected ticks indicates ongoing transmission, thus humans are at risk for exposure and underscores the importance of public and veterinary health surveillance for these pathogens.