Broomfield M A, Doyle E K, Kahn L P, Smith W D, Walkden-Brown S W
School of Environmental and Rural Science, University of New England, Armidale, NSW, 2350, Australia; Invetus Pty Ltd, Armidale, NSW, 2350, Australia.
School of Environmental and Rural Science, University of New England, Armidale, NSW, 2350, Australia.
Vet Parasitol. 2020 Sep 16;287:109243. doi: 10.1016/j.vetpar.2020.109243.
This study assessed the feasibility of altering the pre-weaning vaccination schedule of the commercially available Barbervax® vaccine directed against Haemonchus contortus, to avoid the 2 priming vaccination which typically falls between lamb marking and weaning. Merino lambs (n = 175) born to maiden ewes, located in the Northern Tablelands, New South Wales, were randomly allocated to treatment groups (n = 35) and subjected to five different vaccination regimes. One group remained as unvaccinated controls and another had the full set of three priming doses. The other three groups were vaccinated only at marking and weaning receiving a double dose of vaccine at marking and/or weaning. The hypothesis tested was that reducing the interval between lamb marking and weaning to 6 weeks, and providing a double dose of vaccine at marking, weaning or both would remove the need for the second priming vaccination between lamb marking and weaning. This priming vaccination in the vaccination protocol necessitates an additional mustering of ewes with young lambs at foot and is a time consuming and costly exercise which increases the risk of mis-mothering. Blood and faecal samples were collected at frequent intervals for worm egg count (WEC), larval differentiation and H. contortus vaccine specific ELISA antibody analysis. Overall, the results supported the hypothesis, and it was found that antibody titres and WEC reductions equivalent to the registered vaccine regimen were achieved by the alternative regimens. This finding requires further investigation under a wider range of conditions. Deviation from the registered vaccination protocol would constitute off-label usage, and at this time and until further evaluations are done these deviations are not recommended.
本研究评估了改变针对捻转血矛线虫的市售Barbervax®疫苗断奶前接种计划的可行性，以避免通常在羔羊打耳标和断奶之间进行的两次初次接种。在新南威尔士州北部台地出生的初产母羊所产的美利奴羔羊（n = 175）被随机分配到各治疗组（n = 35），并接受五种不同的接种方案。一组作为未接种对照，另一组接受全套三针初次接种。其他三组仅在打耳标和断奶时接种，在打耳标和/或断奶时接受双倍剂量的疫苗。所检验的假设是，将羔羊打耳标和断奶之间的间隔缩短至6周，并在打耳标、断奶或两者时提供双倍剂量的疫苗，将消除在羔羊打耳标和断奶之间进行第二次初次接种的必要性。接种方案中的这种初次接种需要额外召集带着幼羔的母羊，这是一项耗时且成本高昂的工作，会增加母羊错认幼羔的风险。定期采集血液和粪便样本进行虫卵计数（WEC）、幼虫鉴别以及捻转血矛线虫疫苗特异性ELISA抗体分析。总体而言，结果支持了该假设，并且发现替代方案实现了与注册疫苗方案相当的抗体滴度和WEC降低。这一发现需要在更广泛条件下进行进一步研究。偏离注册接种方案将构成超说明书用药，在此时以及在进行进一步评估之前，不建议进行这些偏离。
