Cattle maintaining a low proviral load (LPL) status after bovine leukaemia virus (BLV) infection have been recognized as BLV controllers and non-transmitters to uninfected cattle in experimental and natural conditions. LPL has been associated with host genetics, mainly with the BoLA class II DRB3 gene. The aim of this work was to study the kinetics of BLV and the host response in Holstein calves carrying different BoLA-DRB3 alleles. Twenty BLV-free calves were inoculated with infected lymphocytes. Two calves were maintained uninfected as controls. Proviral load, total leukocyte and lymphocyte counts, anti-BLVgp51 titres and BLVp24 expression levels were determined in blood samples at various times post-inoculation. The viral load peaked at 30 days post-inoculation (dpi) in all animals. The viral load decreased steadily from seroconversion (38 dpi) to the end of the study (178 dpi) in calves carrying a resistance-associated allele (*0902), while it was maintained at elevated levels in calves with *1501 or neutral alleles after seroconversion. Leukocyte and lymphocyte counts and BLVp24 expression did not significantly differ between genetic groups. Animals with < 20 proviral copies/30 ng of DNA at 178 dpi or < 200 proviral copies at 88 dpi were classified as LPL, while calves with levels above these limits were considered to have high proviral load (HPL) profiles. All six calves with the *1501 allele progressed to HPL, while LPL was attained by 6/7 (86%) and 2/6 (33%) of the calves with the *0902 and neutral alleles, respectively. One calf with both *0902 and *1501 developed LPL. This is the first report of experimental induction of the LPL profile in cattle.

中文翻译：

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牛白血病病毒感染后，具有主要组织相容性复合体DRB3基因不同等位基因的犊牛的早期事件。

牛白血病病毒（BLV）感染后维持低前病毒载量（LPL）的牛在实验和自然条件下被公认为是未感染牛的BLV控制者和非传播者。LPL与宿主遗传学有关，主要与BoLA II类DRB3基因有关。这项工作的目的是研究携带不同BoLA-DRB3等位基因的荷斯坦犊牛的BLV动力学和宿主反应。二十只无BLV的小牛接种了感染的淋巴细胞。保持两只小牛未感染作为对照。在接种后的不同时间测定血样中的前病毒载量，总白细胞和淋巴细胞计数，抗BLVgp51滴度和BLVp24表达水平。在所有动物中，病毒载量在接种后30天（dpi）达到峰值。在携带抗性相关等位基因（* 0902）的小牛中，从血清转化（38 dpi）到研究结束（178 dpi），病毒载量稳定下降，而在* 1501或中性等位基因后的小牛中，病毒载量保持较高水平血清转化。基因组之间的白细胞和淋巴细胞计数和BLVp24表达没有显着差异。在178 dpi时具有<20原病毒拷贝/ 30 ng DNA或在88 dpi中具有<200原病毒拷贝的动物被分类为LPL，而水平高于这些限制的犊牛被认为具有较高的原病毒载量（HPL）。具有* 1501等位基因的所有六头犊牛均进展为HPL，而具有* 0902和中性等位基因的小牛分别达到LPL的6/7（86％）和2/6（33％）。一头同时带有* 0902和* 1501的小牛开发了LPL。