SREL Reprint #3825

Exploring the genetic basis of wild boar (Sus scrofa) and its connection to classical swine fever spread

Rie Saito1,2,3, Natsuko Ito Kondo4, Yui Nemoto5, Toshimasa Takeda6, Kosuke Kanda3,
Nobuyoshi Nakajima4, James C. Beasley2,7, and Masanori Tamaoki4,6

1Department of Animal Science, Faculty of Agriculture, Iwate University, 18-8 Ueda 3-chome, Morioka, Japan
2Savannah River Ecology Laboratory, University of Georgia, P.O. Drawer E, Aiken, South Carolina 29802, USA
3Fukushima Prefectural Centre for Environmental Creation, 10-2 Fukasaku, Miharu-machi 963-7700, Japan
4Biodiversity Division, National Institute for Environmental Studies, 16-2 Onogawa, Tsukuba 305-8506, Japan
5Okutama Practice Forest, Tokyo University of Agriculture, Hikawa 2137, Okutama 198-0212, Japan
6Fukushima Regional Collaborative Research Center, National Institute for Environmental Studies
10-2 Fukasaku, Miharu-machi 963-7700, Japan
7Warnell School of Forestry and Natural Resources, University of Georgia, 180 East Green St, Athens, Georgia, USA

Abstract: Classical swine fever (CSF) is the one of the most devastating contagious diseases in domestic swine and wild boar/pigs (Sus scrofa). Population genetics is often used to estimate animal dispersal and can also help evaluate host population connectivity, which is crucial for understanding pathogen dispersal. We surveyed genetic population structure of boars using MIG-seq analysis to clarify the geographic barriers that influence boar dispersal in north-central Japan and to demonstrate the relationship between the spread of CSF infection among boars and their population structure. We obtained 382 single-nucleotide polymorphisms from 348 wild boar samples, and the results of STRUCTURE analysis indicated that the highest △K value was at K=2, followed by K=4. Based on these results, it is evident that the Abukuma river, a major river within north-central Japan, does not act as a barrier to the gene flow of boars, but rather that human infrastructure hinders their dispersal. Further, according to the time series change in the capture site of CSF-infected wild boar and the sum of the probability of belonging to each of the four clades in individual CSF-infected wild boar, our results indicated that the genetic structure of boar populations was correlated with the outbreak pathway of CSF across our study region. Our study suggests that predictions of disease spread, especially for widely distributed host species, is challenging because of the risk of cryptic breaks and changes in wide range connectivity; however, understanding the genetic population structure of wild boar can be a useful tool for predicting the spread of CSF. We concluded that genetic analysis of host population structure may have the possibility to improve predictions of the future dynamics of disease spread.

SREL Reprint #3825

Saito, R., N. I. Kondo, Y. Nemoto, T. Takeda, K. Kanda, N. Nakajima, J. C. Beasley, and M. Tamaoki. 2025. Exploring the genetic basis of wild boar (Sus scrofa) and its connection to classical swine fever spread. Transboundary and Emerging Diseases (9881511).

This information was provided by the University of Georgia's Savannah River Ecology Laboratory (srel.uga.edu).