Oura C A L, Bishop R, Asiimwe B B, Spooner P, Lubega G W, Tait A
Institute for Animal Health, Pirbright Laboratory, Ash Road, Woking GU24ONF, Surrey.
Parasitology. 2007 Aug;134(Pt 9):1205-13. doi: 10.1017/S0031182007002557. Epub 2007 Mar 13.
The 'Muguga cocktail' live vaccine, delivered by an infection and treatment protocol, has been widely deployed in Eastern, Central and Southern Africa to protect cattle against East Coast fever, caused by Theileria parva. The vaccine contains 3 component stocks (Muguga, Serengeti-transformed and Kiambu 5). In a previous study, parasites from vaccinated and unvaccinated animals were genotyped with a panel of micro- and minisatellite markers (Oura et al. 2004a) and it was shown that only the Kiambu 5 stock establishes a long-term carrier state but there was no evidence for the transmission of this stock. Also parasite genotypes different from the 3 component vaccine stocks were identified in vaccinated animals. We now report a follow-up study on the same farm, some 4 years after the initial vaccination, aimed at establishing the source of the novel parasite genotypes identified in vaccinated cattle, determining the longevity of the carrier state established by the Kiambu 5 vaccine stock and re-examining whether vaccine transmission can occur over a longer time-scale. To do this, samples were taken from vaccinated and unvaccinated cattle and the parasites were genotyped with a series of micro- and minisatellite markers. The data indicate that the vaccine stabilates contain at least 6 parasite genotypes, the Kiambu 5 stock can be detected in many but not all vaccinated cattle for up to 4 years and can be transmitted to unvaccinated cattle which share grazing and that some of the vaccinated animals become infected with local genotypes without causing overt disease.
通过感染和治疗方案接种的“穆古加鸡尾酒”活疫苗已在东非、中非和南非广泛使用，以保护牛免受由小泰氏锥虫引起的东海岸热的侵害。该疫苗包含3种成分毒株（穆古加、塞伦盖蒂转化株和基安布5株）。在之前的一项研究中，使用一组微卫星和小卫星标记对接种疫苗和未接种疫苗动物体内的寄生虫进行了基因分型（奥拉等人，2004年a），结果表明只有基安布5株能建立长期携带状态，但没有证据表明该毒株会传播。在接种疫苗的动物中还鉴定出了与3种成分疫苗毒株不同的寄生虫基因型。我们现在报告在同一农场进行的一项后续研究，该研究在初次接种疫苗约4年后开展，旨在确定接种疫苗牛体内鉴定出的新型寄生虫基因型的来源，确定基安布5疫苗毒株建立的携带状态的持续时间，并再次检查疫苗是否能在更长的时间范围内传播。为此，从接种疫苗和未接种疫苗的牛身上采集样本，并用一系列微卫星和小卫星标记对寄生虫进行基因分型。数据表明，疫苗冻干株至少包含6种寄生虫基因型，在许多但并非所有接种疫苗的牛体内都能检测到基安布5株，长达4年，并且可以传播给共享牧场的未接种疫苗的牛，一些接种疫苗的动物感染了当地基因型但未引发明显疾病。
