Low proviral load in the Kumamoto strain of Japanese Brown cattle infected with the bovine leukemia virus

Toshiaki Inenaga; Koh Fukuoka; Mikiya Sumida; Sakiko Aiba; Kohei Nishikaku; Yuta Matsuno; Tomoko Kobayashi; Kazuhiko Imakawa

doi:10.1186/s12917-023-03738-6

Low proviral load in the Kumamoto strain of Japanese Brown cattle infected with the bovine leukemia virus

BMC Vet Res. 2023 Oct 2;19(1):185. doi: 10.1186/s12917-023-03738-6.

Authors

Toshiaki Inenaga^{1

2}, Koh Fukuoka³, Mikiya Sumida⁴, Sakiko Aiba⁴, Kohei Nishikaku^{5

6}, Yuta Matsuno^{7

8}, Tomoko Kobayashi⁵, Kazuhiko Imakawa⁷

Affiliations

¹ Laboratory of Animal Management Science, Department of Animal Science, School of Agriculture, Tokai University, Sugido 871-12, Mashiki, Kumamoto, 861-2205, Japan. inenaga-t@tsc.u-tokai.ac.jp.
² Research Institute of Agriculture, Tokai University, Toroku 9-1-1, Higashi-ku, Kumamoto, 862-8652, Japan. inenaga-t@tsc.u-tokai.ac.jp.
³ Kumamoto Prefectural Central Kumamoto Livestock Sanitation Center, Shizume 1666-1, Jonan-machi, Minami-kuKumamoto, 861-4215, Japan.
⁴ Laboratory of Animal Management Science, Department of Animal Science, School of Agriculture, Tokai University, Sugido 871-12, Mashiki, Kumamoto, 861-2205, Japan.
⁵ Laboratory of Animal Health, Department of Animal Science, Faculty of Agriculture, Tokyo University of Agriculture, Funako 1737, Atsugi, Kanagawa, 243-0034, Japan.
⁶ National Institute of Health Sciences, Tonomachi 3-25-26, Kawasaki, Kanagawa, 210-9501, Japan.
⁷ Research Institute of Agriculture, Tokai University, Toroku 9-1-1, Higashi-ku, Kumamoto, 862-8652, Japan.
⁸ Department of Genetics, Albert Einstein College of Medicine, Bronx, N.Y., United States.

Abstract

Background: The Kumamoto strain of Japanese Brown (JBRK) cattle is a sub-breed of Wagyu and has a different genetic background than that of Japanese Black (JB) cattle. Bovine leukemia virus (BLV) is the pathogen causing enzootic bovine leukosis (EBL), the predominant type of bovine leukosis (BL). EBL is one of the most common bovine infectious diseases in dairy countries, including Japan. Some host genetic factors, including the bovine leukocyte antigen (BoLA)-DRB3 gene, have been associated with the proviral load (PVL) of BLV and/or onset of EBL. Here, we determined the number of BL cases by analyzing prefectural case records in detail. We measured the PVL of BLV-infected JBRK cattle and compared it with that obtained for other major breeds, JB and Holstein-Friesian (HF) cattle. Finally, the relationship between PVL levels and BoLA-DRB3 haplotypes was investigated in BLV-infected JBRK cattle.

Results: We determined the number of BL cases recorded over the past ten years in Kumamoto Prefecture by cattle breed. A limited number of BL cases was observed in JBRK cattle. The proportion of BL cases in the JBRK was lower than that in JB and HF. The PVL was significantly lower in BLV-infected JBRK cattle than that in the JB and HF breeds. Finally, in BLV-infected JBRK cattle, the PVL was not significantly affected by BoLA-DRB3 alleles and haplotypes. BoLA-DRB3 allelic frequency did not differ between BLV-infected JBRK cattle with low PVL and high PVL.

Conclusions: To our knowledge, this is the first report showing that BL occurred less in the JBRK population of Kumamoto Prefecture. After BLV-infection, the PVL was significantly lower in JBRK cattle than that in JB and HF breeds. The genetic factors implicated in maintaining a low PVL have yet to be elucidated, but the BoLA-DRB3 haplotypes are likely not involved.

Keywords: BoLA-DRB3; Bovine leukemia virus; Cattle; Enzootic bovine leukosis; Holstein-Friesian; Japanese Brown; Japanese black; Proviral load.

MeSH terms

Animals
Cattle
Cattle Diseases*
Enzootic Bovine Leukosis* / genetics
Gene Frequency
Histocompatibility Antigens Class II / genetics
Leukemia Virus, Bovine* / genetics
Proviruses / genetics

Substances

Histocompatibility Antigens Class II