一提起寄生虫，人们通常会联想到它们引发的各种疾病，其实寄生虫有时也有巧用途。英国研究人员最近就利用一种在牛体内生活的寄生虫为载体，给牛接种了能预防相关疾病的疫苗。
英国爱丁堡大学等机构研究人员在新一期网络期刊《科学公共图书馆—病原学》中报告说，这种可用作疫苗载体的寄生虫名为“泰氏锥虫”。它是一种无害寄生虫，研究人员对其进行了基因改造，使它携带具有疫苗效果的物质并能够在牛体内释放。由于它可以在牛的血液内长期繁衍，这种“寄生虫疫苗”具有长期的保护效果。
据介绍，这种“寄生虫疫苗”能用于预防多种牛类疾病，比如口蹄疫和牛结核病等。
研究人员认为，寄生虫载体不仅能用来给牛打疫苗，改进后也许还可用于向牛体内递送药物，直接治疗某些疾病。
领导此项研究的基斯·马修斯教授说，这种新方法在防治牛类疾病方面具有很大潜力，希望能以此帮助控制甚至消灭一些常见牛类疾病。（生物谷 Bioon）
doi:10.1371/journal.ppat.100
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Targeting Cattle-Borne Zoonoses and Cattle Pathogens Using a Novel Trypanosomatid-Based Delivery System
G. Adam Mott1, Raymond Wilson1, Anuruddika Fernando1, Ailie Robinson1, Paula MacGregor1, David Kennedy2, Dick Schaap3, Jacqueline B. Matthews2, Keith R. Matthews1*
Trypanosomatid parasites are notorious for the human diseases they cause throughout Africa and South America. However, non-pathogenic trypanosomatids are also found worldwide, infecting a wide range of hosts. One example is Trypanosoma (Megatrypanum) theileri, a ubiquitous protozoan commensal of bovids, which is distributed globally. Exploiting knowledge of pathogenic trypanosomatids, we have developed Trypanosoma theileri as a novel vehicle to deliver vaccine antigens and other proteins to cattle. Conditions for the growth and transfection of T. theileri have been optimised and expressed heterologous proteins targeted for secretion or specific localisation at the cell interior or surface using trafficking signals from Trypanosoma brucei. In cattle, the engineered vehicle could establish in the context of a pre-existing natural T. theileri population, was maintained long-term and generated specific immune responses to an expressed Babesia antigen at protective levels. Building on several decades of basic research into trypanosomatid pathogens, Trypanosoma theileri offers significant potential to target multiple infections, including major cattle-borne zoonoses such as Escherichia coli, Salmonella spp., Brucella abortus and Mycobacterium spp. It also has the potential to deliver therapeutics to cattle, including the lytic factor that protects humans from cattle trypanosomiasis. This could alleviate poverty by protecting indigenous African cattle from African trypanosomiasis.