CSIRO Livestock Industries, St Lucia, Queensland, Australia.
Parasite Immunol. 2010 Feb;32(2):135-42. doi: 10.1111/j.1365-3024.2009.01168.x.
Limited prior evidence suggests that 5'-nucleotidase, an ectoenzyme principally located in the Malpighian tubules of the tick Rhipicephalus (Boophilus) microplus, could be an effective antigen in an anti-tick vaccine. To assess this, recombinant 5'-nucleotidase was expressed in Escherichia coli and used in vaccination trials with both sheep and cattle. Vaccinated sheep were challenged with freshly moulted adult ticks. Those with high titres of anti-nucleotidase antibodies showed significant protection against tick infestation, although protection was less than that found with the previously characterized antigen, Bm86. Cattle were vaccinated, in separate groups, with 5'-nucleotidase, Bm86 and both antigens combined. Cattle, as the natural host, were challenged with larval ticks. Although Bm86 showed typical efficacy, no significant protection was seen in cattle vaccinated with 5'-nucleotidase. Cattle receiving a dual antigen formulation were no better protected than those receiving Bm86 alone. One possible reason for the difference between host species, namely antibody titre, was examined and shown to be an unlikely explanation. This demonstrates a limitation of using a model host like sheep in vaccine studies.
先前的有限证据表明，5'-核苷酸酶，一种主要位于蜱虫 Rhipicephalus（Boophilus）microplus 的马氏管中的外切酶，可能是抗蜱疫苗中的有效抗原。为了评估这一点，重组 5'-核苷酸酶在大肠杆菌中表达，并在绵羊和牛的疫苗接种试验中使用。接种疫苗的绵羊用新蜕皮的成年蜱进行挑战。那些具有高滴度抗核苷酸酶抗体的绵羊表现出对蜱虫感染的显著保护，尽管保护效果不如先前表征的抗原 Bm86 好。牛在单独的组中分别用 5'-核苷酸酶、Bm86 和两种抗原组合进行疫苗接种。牛作为自然宿主，用幼虫蜱进行挑战。尽管 Bm86 表现出典型的功效，但用 5'-核苷酸酶接种的牛没有看到显著的保护。接受双抗原配方的牛与单独接受 Bm86 的牛一样没有得到更好的保护。检查了宿主物种之间的差异，即抗体滴度，认为这不是一个可能的解释。这表明在疫苗研究中使用绵羊等模型宿主存在局限性。
