Bovine leukemia virus (BLV) proviral load is controlled by T-cell responses, which require vitamin A (VA) derived from food. However, whether dietary VA restriction for marbling impairs the T-cell responses that control BLV proviral load in beef cattle is unknown. We assessed T-cell subsets, interferon (IFN)-γ gene expression, and BLV proviral load in naturally BLV-infected Japanese Black cattle that were fed a diet with decreased VA levels. We found that the percentage of CD4⁺ T cells increased over time during dietary VA restriction. In addition, BLV proviral load was negatively correlated with the percentage of CD4⁺ T cells and with the level of IFN-γ gene expression. These observations suggest that dietary VA restriction for marbling enhances T-cell responses that control BLV proviral load and thus does not promote leukemogenesis in fattening beef cattle.

牛白血病病毒 (BLV) 前病毒载量由 T 细胞反应控制，这需要从食物中提取的维生素 A (VA)。然而，对于大理石花纹的饮食 VA 限制是否会损害控制肉牛 BLV 前病毒载量的 T 细胞反应尚不清楚。我们评估了天然 BLV 感染的日本黑牛的 T 细胞亚群、干扰素 (IFN)-γ 基因表达和 BLV 前病毒载量，这些黑牛喂食了 VA 水平降低的饮食。我们发现，在饮食 VA 限制期间，CD4 ⁺ T 细胞的百分比随时间增加。此外，BLV 前病毒载量与 CD4 ^{+百分比呈负相关}T细胞与IFN-γ基因表达水平有关。这些观察结果表明，大理石花纹的饮食 VA 限制增强了控制 BLV 前病毒负荷的 T 细胞反应，因此不会促进育肥肉牛的白血病发生。