Genetic variability of Taenia solium cysticerci recovered from experimentally infected pigs and from naturally infected pigs using microsatellite markers

Abstract

The adult Taenia solium, the pork tapeworm, usually lives as a single worm in the small intestine of humans, its only known definitive host. Mechanisms of genetic variation in T. solium are poorly understood. Using three microsatellite markers previously reported [1], this study explored the genetic variability of T. solium from cysts recovered from experimentally infected pigs. It then explored the genetic epidemiology and transmission in naturally infected pigs and adult tapeworms recovered from human carriers from an endemic rural community in Peru. In an initial study on experimental infection, two groups of three piglets were each infected with proglottids from one of two genetically different tapeworms for each of the microsatellites. After 7 weeks, pigs were slaughtered and necropsy performed. Thirty-six (92.3%) out of 39 cysts originated from one tapeworm, and 27 (100%) out of 27 cysts from the other had exactly the same genotype as the parental tapeworm. This suggests that the microsatellite markers may be a useful tool for studying the transmission of T. solium. In the second study, we analyzed the genetic variation of T. solium in cysts recovered from eight naturally infected pigs, and from adult tapeworms recovered from four human carriers; they showed genetic variability. Four pigs had cysts with only one genotype, and four pigs had cysts with two different genotypes, suggesting that multiple infections of genetically distinct parental tapeworms are possible. Six pigs harbored cysts with a genotype corresponding to one of the identified tapeworms from the human carriers. In the dendrogram, cysts appeared to cluster within the corresponding pigs as well as with the geographical origin, but this association was not statistically significant. We conclude that genotyping of microsatellite size polymorphisms is a potentially important tool to trace the spread of infection and pinpoint sources of infection as pigs spread cysts with a shared parental genotype.

First Insights into Population Structure and Genetic Diversity Versus Host Specificity in Trypanorhynch Tapeworms Using Multiplexed Shotgun Genotyping

“…The results of this body of work are summarized by Herzog and Jensen (2022) . Comparable data from other species of tapeworms, however, suggest that infrapopulations comprised of genetically dissimilar individuals (i.e., “mixed infections”) are not uncommon (e.g., Lymbery and Thompson 1989 ; Nakao et al 2003 ; Pajuelo et al 2017 ). Theory and evidence to support why genetically heterogenous infrapopulations in definitive hosts should be expected for parasites with complex life-cycles have been advanced.…”

Genetic structure of Spirometra mansoni (Cestoda: Diphyllobothriidae) populations in China revealed by a Target SSR-seq method

“…SSRs, also known as microsatellites, are highly variable repetitive elements with nucleotide motifs of 1–6 bp and are ubiquitous in most eukaryotic organisms [ 17 ]. SSRs have been verified as suitable markers for inferring genetic variance and population differences in cestode species [ 14 , 18 – 22 ]. However, traditional analysis based on gel electrophoresis cannot distinguish base differences or changes correctly in SSR amplicons, often causing false positive or false negative results in SSR detection [ 23 ].…”

Genetic variation of Taenia saginata cyst isolates from Iraq based on mitochondrial COX1 sequences

“…In addition, the parasites' genetic population structure can help with epidemiological investigations and focus on their evolutionary history (Campbell et al, 2006;Anantaphruti et al, 2013). Knowing the parasite's population variations aids in the analysis of transmission patterns (Pajuelo et al, 2017). Several studies have looked into human taeniid tapeworm genetic variations, but most studies focused on T. solium and human cysticercosis (Rostami et al, 2015).…”

“…In addition, the parasites’ genetic population structure can help with epidemiological investigations and focus on their evolutionary history ( Campbell et al, 2006 ; Anantaphruti et al, 2013 ). Knowing the parasite’s population variations aids in the analysis of transmission patterns ( Pajuelo et al, 2017 ).…”