Abstracts (first author)
Understanding the genetic basis of drug resistance in Trichomonas vaginalis
In light of antimicrobial role in shaping genetic variation, understanding the regulation and control of drug resistance is imperative. Trichomonas vaginalis is the most widespread non-viral sexually transmitted pathogen in the world: it is commonly treated with the 5-nitroimidazole group of drug with pronounced resistance prevalence of up to 9.5%. The causes underlying resistance in T. vaginalis remain unknown. Our earlier studies of population structure in 46 clinical isolates using 21 microsatellite loci showed the drug resistance phenotype associated with genetic Type. This suggests a genetic component to 5-nitroimidazole resistance, although which genes are involved and whether recombination plays a role in acquiring drug resistance, remain to be determined. We started our studies by phenotyping a further 141 global isolates of T. vaginalis for metronidazole resistance using a minimum lethal concentration assay. Resistance was observed as follows: New York City: 22%; Mexico: 9%; Papua New Guinea: 8%; Africa: 4%; no resistant isolates were identified in 10 and 12 isolates from Australia and Italy, respectively. To obtain a detailed view of genome-wide variation in these total 187 isolates, we used double digest Restriction-Site Associated DNA (ddRAD) sequencing, which allows for partial genome sequencing and thus enables the highly repetitive regions of the T.vaginalis genome to be avoided. Using EcoRI (found to cut 5 times more frequently in unique regions of the genome) together with NIaIII enzymes for ddRAD library construction, we generate sequence data for 48 metronidazole resistant and sensitive T. vaginalis isolates using the Illumina HiSeq. The reference genome assembly and annotation served as a control. On average, 50% of high-quality reads mapped back to the reference assembly. A total of ~6,900 unique gene regions from ~57,000 were sequenced to 20X or more coverage. Variant discovery to uncover the genetic basis of drug resistance are in progress.