Host Mouse Strain Is Not Selective for a Laboratory Adapted Strain of Schistosoma mansoni

Blank, Walter; Liu, Shi Fan; Prasad, J.K.; Blanton, Ronald E.

doi:10.1645/ge-2671.1

Cited by 2 publications

(5 citation statements)

References 27 publications

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“…Another caveat for any interpretation is that the marker panel used is not large and does not provide dense coverage of the genome. We are, however, able to show infrapopulation variation within these small communities, genetic drift within a laboratory strain (Blank et al, 2010), and demonstrate variation between subsamples of an S. mansoni laboratory population using a marker panel of similar size (Blank et al, 2011). Finally, there is a precedent for selection producing detectable differentiation across neutral unlinked markers (Merilä and Crnokrak; Freeland et al, 2010; Johansson et al, 2010).…”

Section: Discussionmentioning

confidence: 90%

“…Mean error rates for allele frequency estimates of pooled samples range from 2–11% in these studies. Furthermore, we have shown in laboratory infections of mice that the allele frequencies obtained from eggs also reflect the allele frequencies of the infecting worms (Blank et al, 2011). Genetic differentiation indices using these allele frequencies also follow the known population dynamics of S. mansoni laboratory strains (Blank et al, 2010).…”

Section: Introductionmentioning

confidence: 99%

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Schistosoma mansoni population structure and persistence after praziquantel treatment in two villages of Bahia, Brazil

Blanton

Blank

Costa

et al. 2011

International Journal for Parasitology

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Praziquantel has been used to treat schistosome infections since 1979 and currently is the only chemotherapeutic agent in production for this purpose, raising concerns about the potential for the emergence of drug resistance. In practice, 10–20% of infected patients will continue to excrete eggs after treatment. It is not understood to what degree this represents selection of a resistant population or incomplete elimination due to the presence of immature worms at the time of treatment. We used a population genetics approach to test whether or not persistent Schistosoma mansoni parasites were drawn from the same population as susceptible parasites. In this study, stool samples were collected from 96% of individuals in two small Brazilian communities (populations 482 and 367) and examined for S. mansoni eggs. The combined prevalence of S. mansoni infections in the villages was 41%. Total egg DNA was extracted from each sample and was genotyped at 15 microsatellite markers. Day-to-day variation of the infrapopulation from an individual human host was low (median differentiation using Jost’s D = 0.010), so that a single stool was representative of the genotypes present in stool eggs, at least in the short term. Average pairwise analysis of D among all pre-treatment infrapopulations suggested moderate differentiation (mean D = 0.082 and 0.122 for the two villages), whereas the pre-treatment component population differentiation between the two communities was 0.047. The differentiation of the component population remaining after treatment from the fully susceptible component population was low (mean D = 0.007 and 0.020 for the two villages), suggesting that the persistent parasites were not selected by praziquantel treatment. We will continue to follow these communities for evidence of selection or changes in population structure.

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Section: Discussionmentioning

confidence: 90%

Section: Introductionmentioning

confidence: 99%

Schistosoma mansoni population structure and persistence after praziquantel treatment in two villages of Bahia, Brazil

Blanton

Blank

Costa

et al. 2011

International Journal for Parasitology

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“…An important issue for these conclusions is the sensitivity of the methods employed for differentiating parasite subpopulations. We do know that our approach is sensitive enough to differentiate the component population for the two villages, and that in the laboratory, different laboratory-maintained S. mansoni populations from the same laboratory and different lots of parasites from the same life cycle can be distinguished [12] . We were able to genotype at least 1 sample from 67% of those infected.…”

Section: Discussionmentioning

confidence: 99%

“…They were, therefore, less likely to contribute significantly to the genetic composition of their component populations. The relative relationship of the genetic composition of eggs to adult worms is unknown in natural infections, but in laboratory infections in mice, allele frequencies between these two stages were very similar [12] .…”

Section: Discussionmentioning

confidence: 99%

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Characteristics of the Human Host Have Little Influence on Which Local Schistosoma mansoni Populations Are Acquired

et al. 2013

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BackgroundBrazil remains the country in the Americas with the highest prevalence of schistosomiasis. A combination of control efforts and development, however, has sharply reduced its intensity and distribution. The acquisition of specific schistosome populations may be dependent on host characteristics such as sex, age, geography, work, habits and culture. How these and other host characteristics align with parasite subpopulations may guide approaches to improve control.MethodologyA cohort of more than 90% of the residents in two rural communities in Brazil participated in an epidemiologic survey of demographic, socio-economic and behavioral characteristics. The variables sex, age, intensity of infection, socio-economic index, % lifetime spent on site, previous infection, and trips outside the district were used to group parasites infecting individuals. Schistosoma mansoni infection status was determined by examination of stools submitted on 3 different days. The aggregate of eggs collected from the whole stool was used to determine degree of population differentiation from allele frequencies for 15 microsatellites.Conclusions/SignificanceInfection prevalence was 41% for these communities, and the epidemiologic characteristics were similar to many of the endemic areas of Brazil and the world. Parasite population structuring was observed between the two communities (Jost's D 0.046, CI95% 0.042–0.051), although separated by only 8 km and connected by a highway. No structuring was observed when infected individuals were stratified by host's biologic, demographic or epidemiologic characteristics. Those most heavily infected best reflected the communities' overall parasite diversity. The lack of differentiation within villages suggests that individuals are likely to get infected at the same sites or that the same parasite multilocus genotypes can be found at most sites. The geographic structuring between villages and the lack of structuring by age of the host further supports the impression of a population little affected by migration or drift.

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Host Mouse Strain Is Not Selective for a Laboratory Adapted Strain of Schistosoma mansoni

Cited by 2 publications

References 27 publications

Schistosoma mansoni population structure and persistence after praziquantel treatment in two villages of Bahia, Brazil

Schistosoma mansoni population structure and persistence after praziquantel treatment in two villages of Bahia, Brazil

Characteristics of the Human Host Have Little Influence on Which Local Schistosoma mansoni Populations Are Acquired

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