A natural gene drive system influences bovine tuberculosis susceptibility in African buffalo: Possible implications for disease management

PLoS One. 2019 Sep 4;14(9):e0221168. doi: 10.1371/journal.pone.0221168. eCollection 2019.

Abstract

Bovine tuberculosis (BTB) is endemic to the African buffalo (Syncerus caffer) of Hluhluwe-iMfolozi Park (HiP) and Kruger National Park, South Africa. In HiP, the disease has been actively managed since 1999 through a test-and-cull procedure targeting BTB-positive buffalo. Prior studies in Kruger showed associations between microsatellite alleles, BTB and body condition. A sex chromosomal meiotic drive, a form of natural gene drive, was hypothesized to be ultimately responsible. These associations indicate high-frequency occurrence of two types of male-deleterious alleles (or multiple-allele haplotypes). One type negatively affects body condition and BTB resistance in both sexes. The other type has sexually antagonistic effects: negative in males but positive in females. Here, we investigate whether a similar gene drive system is present in HiP buffalo, using 17 autosomal microsatellites and microsatellite-derived Y-chromosomal haplotypes from 401 individuals, culled in 2002-2004. We show that the association between autosomal microsatellite alleles and BTB susceptibility detected in Kruger, is also present in HiP. Further, Y-haplotype frequency dynamics indicated that a sex chromosomal meiotic drive also occurred in HiP. BTB was associated with negative selection of male-deleterious alleles in HiP, unlike positive selection in Kruger. Birth sex ratios were female-biased. We attribute negative selection and female-biased sex ratios in HiP to the absence of a Y-chromosomal sex-ratio distorter. This distorter has been hypothesized to contribute to positive selection of male-deleterious alleles and male-biased birth sex ratios in Kruger. As previously shown in Kruger, microsatellite alleles were only associated with male-deleterious effects in individuals born after wet pre-birth years; a phenomenon attributed to epigenetic modification. We identified two additional allele types: male-specific deleterious and beneficial alleles, with no discernible effect on females. Finally, we discuss how our findings may be used for breeding disease-free buffalo and implementing BTB test-and-cull programs.

Publication types

  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, Non-P.H.S.

MeSH terms

  • Alleles
  • Animals
  • Buffaloes / genetics*
  • Cattle
  • Disease Susceptibility
  • Female
  • Gene Frequency
  • Genetic Association Studies
  • Haplotypes
  • Male
  • Microsatellite Repeats / genetics
  • South Africa
  • Tuberculosis, Bovine / genetics
  • Tuberculosis, Bovine / pathology*
  • Y Chromosome / genetics

Grants and funding

This study was funded by the US NSF Division of Environmental Biology (Grant number 0090323 awarded to Dr Wayne M. Getz) and the M3B2 DST/NRF SARChI Chair, University of Pretoria. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.