Journal: PLOS Pathogens

Article Title: A major locus confers triclabendazole resistance in Fasciola hepatica and shows dominant inheritance

doi: 10.1371/journal.ppat.1011081

Figure Lengend Snippet: (A) Schematic of the in vivo work to produce an F2 cross from Fh LivS1 (a clonal population of susceptible parasites) and Fh LivR1 (a clonal population of resistant parasites). The parental parasites Fh LivS1 and Fh LivR1 were produced separately and used to co-infect sheep (n = 2). Some of these parental parasites would cross-fertilise to produce an F1 cross of Fh LivS1 and Fh LivR1. Eggs were collected from the adult parasites within these sheep. A single miracidium (obtained from these eggs) was used to infect snails (n = 28) and produce clonal F1 populations. The metacercariae were genotyped to ensure they were from an F1 cross and then combined together and used to infect sheep (n = 4). Some of these F1 parasites would cross-fertilise to produce an F2 recombinant population. Eggs were collected from the adult parasites within these sheep. Snails (n = 41 and n = 44 for Experiment 1 and 2, respectively) were exposed to multiple miracidia obtained from these eggs and combined to produce a common pool of F2 metacercariae. For each experiment, two groups of animals were infected with metacercariae from this common pool. Once the infection had reached patency, one group of animals in each experiment was treated with triclabendazole (TCBZ) at a dose of 10mg/kg. At post mortem, those animals which received no treatment had a mixture of triclabendazole susceptible (TCBZ-S) and triclabendazole resistant (TCBZ-R) parasites, whilst those animals that were treated had only TCBZ-R parasites remaining. These parasites were then used for pooled genotyping. (B) A haplotype schematic to show the genetic principle behind the in vivo F2 cross. The F1 cross consists of one haplotype from the susceptible parent: Fh LivS1 ( Fh LivS1.Hap1 or Fh LivS1.Hap2) and one haplotype from the resistant parent: Fh LivR1 ( Fh LivR1.Hap1 or Fh LivR1.Hap2). In the subsequent F2 generation, recombination events take place and the resistant haplotype becomes introgressed amongst the susceptible haplotype producing an F2 recombinant population for study. (C) Plot to show the reduction in the number of F2 parasites recovered from treated animals compared to untreated animals in Experiments 1 and 2. Boxplot indicates the median number of parasites, upper and lower quartiles, and outliers; overlaid points indicate the number of parasites in each animal. In both experiments a significant difference (Mann-Whitney W = 25 p < 0.05) is seen in the number of F2 parasites from untreated and treated animals.

Article Snippet: Assay design and genotyping was conducted by LGC Genomics (Hertfordshire, UK) using KASP genotyping chemistry.

Techniques: In Vivo, Produced, Recombinant, Infection, MANN-WHITNEY

Journal: PLOS Pathogens

Article Title: A major locus confers triclabendazole resistance in Fasciola hepatica and shows dominant inheritance

doi: 10.1371/journal.ppat.1011081

Figure Lengend Snippet: Genotyping of individual F2 parasites to determine inheritance of parental SNP haplotypes.

Article Snippet: Assay design and genotyping was conducted by LGC Genomics (Hertfordshire, UK) using KASP genotyping chemistry.

Techniques: