Lally N C, Jenkins M C, Dubey J P
Parasite Immunobiology Laboratory, USDA, Beltsville, MD 20705, USA.
Mol Biochem Parasitol. 1996 Jan;75(2):169-78. doi: 10.1016/0166-6851(95)02530-8.
Neospora caninum is a recently described apicomplexan parasite which causes neuromuscular disease in dogs, and abortion and neonatal morbidity in cattle, sheep and horses. Morphological similarities and serological cross-reactivity between N. caninum and the closely related parasite Toxoplasma gondii, have resulted in the frequent misdiagnosis of neosporosis as toxoplasmosis. This report describes the isolation and characterization of an N. caninum cDNA clone encoding a 14-3-3 protein homologue. The 14-3-3 proteins are a class of proteins which show a high degree of amino acid sequence conservation across several eukaryotic taxa. Using less conserved regions of the N. caninum cDNA clone, nested primers were designed for the amplification of a 614-bp N. caninum DNA fragment by the polymerase chain reaction (PCR). The DNA fragment was amplified from N. caninum genomic DNA, but not from T. gondii, Sarcocystis muris, Sarcocystis tenella, or Sarcocystis cruzi genomic DNA. Additionally, the fragment was amplified from DNA prepared from the brains of N. caninum-infected mice, but not from the brain of a mouse infected with T. gondii. These results suggest that this PCR assay may be useful for the diagnosis of neosporosis.
犬新孢子虫是一种最近才被描述的顶复门寄生虫，可导致犬类出现神经肌肉疾病，以及牛、羊和马发生流产和新生仔畜发病。犬新孢子虫与密切相关的寄生虫刚地弓形虫在形态学上相似，且存在血清学交叉反应，这导致新孢子虫病经常被误诊为弓形虫病。本报告描述了一个编码14-3-3蛋白同源物的犬新孢子虫cDNA克隆的分离和鉴定。14-3-3蛋白是一类在多个真核生物分类群中显示出高度氨基酸序列保守性的蛋白质。利用犬新孢子虫cDNA克隆中保守性较低的区域，设计了巢式引物，通过聚合酶链反应（PCR）扩增出一个614 bp的犬新孢子虫DNA片段。该DNA片段可从犬新孢子虫基因组DNA中扩增出来，但不能从刚地弓形虫、鼠肉孢子虫、牛巴贝斯虫或克鲁斯肉孢子虫的基因组DNA中扩增出来。此外，该片段可从感染犬新孢子虫的小鼠脑组织制备的DNA中扩增出来，但不能从感染刚地弓形虫的小鼠脑组织中扩增出来。这些结果表明，这种PCR检测方法可能有助于新孢子虫病的诊断。
