Risk Assessment of Bovine Major Histocompatibility Complex Class II DRB3 Alleles for Perinatal Transmission of Bovine Leukemia Virus.

Liushiqi Borjigin,Naoko Tanaka,Rania Hamada,Yoko Aida,Michihito Inokuma,Yasuo Shinozaki,Shuji Yoneyama,Shin-Nosuke Takeshima,Risa Yamanaka,Lanlan Bai,Chieh-Wen Lo,Munehito Mimura,Anna Yasui,Hirotaka Sato,Sohei Yasuda

doi:10.3390/pathogens10050502

Abstract

Perinatal transmission plays a critical role in the spread of bovine leukemia virus (BLV) infection in cattle herds. In the Holstein breed, we previously identified BLV resistant and susceptible bovine leukocyte antigen (BoLA)-DRB3 alleles, including BoLA-DRB3*009:02 and *014:01:01 with a low BLV proviral load (PVL), and *015:01 and *012:01 with a high PVL. Here, we evaluated the perinatal BLV transmission risk in dams with different BoLA-DRB3 alleles. BoLA-DRB3 alleles of 120 dam-calf pairs from five dairy farms in Japan were identified; their PVL was quantified using the BLV-Coordination of Common Motifs (CoCoMo)-qPCR-2 assay. Ninety-six dams were BLV-positive, and 29 gave birth to BLV-infected calves. Perinatal transmission frequency was 19% in dams with resistant alleles suppressed to a low PVL level, and 38% and 25% in dams with susceptible and neutral alleles that maintained high PVL levels, respectively. Notably, all calves with resistant alleles were BLV free, whereas 30% of calves with susceptible genes were infected. Thus, vertical transmission risk was extremely lower for dams and calves with resistant alleles compared to those with susceptible alleles. Our results can inform the development of effective BLV eradication programs under field conditions by providing necessary data to allow for optimal selection of dams for breeding.

Highlights

Bovine leukemia virus (BLV) belongs to the family Retroviridae together with human T-leukemia virus types 1 and 2 (HTLV-1 and -2), and causes enzootic bovine leucosis (EBL), the most common neoplastic disease affecting cattle worldwide [1]
We identified of the previously reported bovine leukocyte antigen (BoLA)-DRB3 alleles (the Immuno Polymorphism Database (IPD)-major histocompatibility complex (MHC) database), of which two were resistant alleles, (BoLA-DRB3*009:02 and *014:01:01), and two were susceptible alleles (BoLA-DRB3*012:01 and *015:01)
We compared the frequency of BoLA-DRB3 genotypes including resistance and susceptible alleles

Summary

Introduction

Bovine leukemia virus (BLV) belongs to the family Retroviridae (genus Deltaretrovirus) together with human T-leukemia virus types 1 and 2 (HTLV-1 and -2), and causes enzootic bovine leucosis (EBL), the most common neoplastic disease affecting cattle worldwide [1]. In several countries where compulsory eradication or control strategies have not been implemented, the spread of BLV infection continues owing to the absence of effective treatments or vaccines. BLV infection commonly affects the cattle industry worldwide and causes considerable economic loss owing to premature death of animals by lymphomas [9], carcass condemnation at slaughter [10], reduction in milk yield [6,11,12], and decreased immunity [13], as well as effects on reproductive capacities [14] and longevity [6,12]. The economic loss due to reduced milk production of BLV-infected cattle alone was estimated at 525 million USD annually in the US dairy industry [11]. It was estimated that the annual mean partial net revenue from BLV-infected dairy cattle was 635 CAD less than that from BLV-free cattle [15]

Methods

Results

Discussion

Conclusion