D3392: Contrasting epigenetics of Ixodes scapularis populations

Ticks are efficient arthropod vectors that transmit a wide variety of pathogens, not only to humans but also to livestock and wildlife. Tick-borne diseases account for 77% of all vector-borne diseases transmitted in the US, with Lyme disease (LD) being the most prevalent. It is estimated that LD treatment in the US costs over USD 500 million annually. Northern states, such as Minnesota, report higher LD incidence than southern states, like Texas. Although no differences in vector competence have been reported between Northern and Southern haplotypes, differences in tick behavior are suspected to affect Lyme disease transmission within the US. That behavioral plasticity might be modulated by discrepancies in epigenetic mechanisms, such as differential DNA methylation level between populations. Thus, we hypothesize that the level of DNA methylation in different tick populations could explain the variations in Ixodes scapularis-borne disease incidence in the US. To detect and measure the level of DNA methylation between the south and north I. scapularis populations, we used enzyme-linked immunosorbent assays (ELISAs). Additionally, we identified homologous proteins of DNA methyltransferases (DNMTs) and Ten Eleven Translocation enzyme (TET) in I. scapularis to design primers that amplify those enzymes of interest in both populations and determine the differences among their expression in both I. scapularis populations. We found differences in percentage of 5-Methylcytosine between northern and southern populations and also among males of I. scapularis from both origins. Lastly, we describe differences in the expression of some of the enzymes involved in methylation.