Conclusion

The range of DNA techniques now available for the study of genetic variation in E. granulosus and the molecular epidemiology of cystic echinococcosis is impressive, and much valuable information on the molecular categorization of the different genotypes is now available. Importantly, in many cases, molecular techniques have validated the genetic basis of important morphological and other biological differences that can now be used with confidence as a reliable and simple means of identifying and differentiating between strains and species of Echinococcus. The recent publication of the complete sequences of the mt genomes of the horse and sheep strains of E. granulosus[9] and E. multilocularis[18] and mt DNA sequences for a number of other E. granulosus genotypes[9] has provided additional genetic information that can be used for even more in-depth strain characterization and phylogeny of Echinococcus spp. Already, the availability of sequence information has provided a solid molecular basis for revising the taxonomy of the genus Echinococcus.[4,19]

Furthermore, the accumulating genetic data may allow insight to several other unresolved questions such as confirming the presence and precise nature of the G9 genotype and its reservoir in Poland, whether it occurs elsewhere, why the camel strain (G6 genotype) appears to affect humans in certain geographical areas but not others, more precise delineation of the host and geographic ranges of the genotypes characterized to date, and whether additional genotypes of E. granulosus remain to be identified. In this context, an important recent study by Gonzalez et al.[20] highlights the complexity and genomic organization differences in E. granulosus. Based on two E. granulosus DNA multiplex-PCR amplification fragments they developed three PCR protocols (Eg9-PCR, Eg16-PCR, and Eg9-PCR-RFLP) for discrimination of

E. granulosus genotypes. They used the approach to identify distinct G1 and G7 genotypes within E. granulosus Spanish pig isolates. Sequencing of the nadl and coxl genes and ITS1-PCR coupled to RFLP confirmed these observations. The Eg9-PCR-RFLP and Eg16-PCR protocols could thus be used as additional methods to discriminate the recognized E. granulosus genotypes and they might be especially useful for resolving the issue of the G7/G9 genotypes and human infection in Poland.

Finally, it should be emphasized that as well as proving of value for investigating genetic variation in Echinococ-cus and in the detection of parasite nucleic acids in clinical samples, molecular approaches can be used to identify and discriminate Echinococcus eggs (deposited in the feces of dogs and other carnivores) from those of other taeniid eggs in definitive hosts. A PCR-based assay has been developed for detecting DNA of E. multilocularis in fecal samples of foxes after isolation of the parasite eggs by a sieving procedure.[21] There is no similar test available yet for E. granulosus although one is being developed.[22] The copro-PCR is a valuable method for confirmation of positive coproantigen results by ELISA and for diagnosis in individual animals.

Getting Started With Dumbbells

Getting Started With Dumbbells

The use of dumbbells gives you a much more comprehensive strengthening effect because the workout engages your stabilizer muscles, in addition to the muscle you may be pin-pointing. Without all of the belts and artificial stabilizers of a machine, you also engage your core muscles, which are your body's natural stabilizers.

Get My Free Ebook


Post a comment