Eastern Regional Station of Indian veterinary Research Institute, 37 Belgachia Road, Kolkata, West Bengal, India.
Asian Pac J Trop Med. 2011 Aug;4(8):589-93. doi: 10.1016/S1995-7645(11)60152-1.
Gastrointestinal (GI) parasitism is the most serious constraint throughout the world in small ruminants which causes significant production loss in animals. GI parasites are major contributor to reduce productivity in terms of meat, milk and wool in animals. Control of GI parasite is done primarily by anthelmintic treatment where choice and schedule of treatment is done after identification and quantitation of individual parasite. Identification of GI parasites is done through microscopic method by identifying specific morphological characteristics of egg and larva (L(3)). Since most of parasite eggs are having similar morphological characteristics, identification up to species level through microscopy is not possible in most of cases. To address this issue, molecular techniques are the viable alternative for identification of species as well as molecular level differences within a species (isolates) of parasites. Different DNA based molecular techniques viz. PCR, AFLP, RAPD, RFLP, PCR-SSCP, real time PCR, DNA microarray etc. have been used for identification and to assess the genetic diversity among parasite population. For identification of species, the characteristic sequence of genomic DNA of different species should differ to allow the delineation of species, but at the same time, no/minor variation within the species should exist. In contrast, for purpose of identifying population variants (strains/isolates), a considerable degree of variation in the sequence should exist within a species. Various target regions, including nuclear ribosomal DNA (rDNA), mitochondrial DNA (mtDNA) or repetitive DNA elements (microsatellite loci), which show considerable variation in the number of repeats within individuals have been employed to achieve the identification of parasites species or strain.
胃肠道寄生虫病是全世界小反刍动物最严重的限制因素，它导致动物生产损失巨大。胃肠道寄生虫是降低动物肉类、牛奶和羊毛产量的主要因素。对胃肠道寄生虫的控制主要通过驱虫治疗来实现，在进行驱虫治疗时，需要根据个体寄生虫的鉴定和定量结果来选择和安排治疗方案。胃肠道寄生虫的鉴定是通过显微镜方法进行的，通过识别卵和幼虫（L3）的特定形态特征来进行鉴定。由于大多数寄生虫卵具有相似的形态特征，因此在大多数情况下，通过显微镜无法鉴定到种的水平。为了解决这个问题，分子技术是鉴定物种以及种内（分离株）寄生虫分子水平差异的可行替代方法。不同的基于 DNA 的分子技术，如 PCR、AFLP、RAPD、RFLP、PCR-SSCP、实时 PCR、DNA 微阵列等，已被用于鉴定和评估寄生虫种群的遗传多样性。为了鉴定物种，不同物种基因组 DNA 的特征序列应该有所不同，以允许物种的划分，但同时，物种内应该没有/只有微小的变异。相比之下，为了鉴定种群变异体（菌株/分离株），物种内的序列应该存在相当大的变异。已经使用了各种目标区域，包括核核糖体 DNA（rDNA）、线粒体 DNA（mtDNA）或重复 DNA 元件（微卫星基因座），这些区域在个体内部的重复次数上显示出相当大的变异，以实现寄生虫物种或菌株的鉴定。
