Performance of Glutamate Dehydrogenase and Triose Phosphate Isomerase Genes in the Analysis of Genotypic Variability of Isolates ofGiardia duodenalisfrom Livestocks

Giardia duodenalisis a small intestinal protozoan parasite of several terrestrial vertebrates. This work aims to assess the genotypic variability ofGiardia duodenalisisolates from cattle, sheep and pigs in the Southeast of Brazil, by comparing the standard characterization between glutamate dehydrogenase (gdh) and triose phosphate isomerase (tpi) primers. Fecal samples from the three groups of animals were analyzed using the zinc sulphate centrifugal flotation technique. Out of 59 positive samples, 30 were from cattle, 26 from sheep and 3 from pigs. Cyst pellets were stored and submitted to PCR and nested-PCR reactions withgdhandtpiprimers. Fragment amplification ofgdhandtpigenes was observed in 25 (42.4%) and 36 (61.0%) samples, respectively. Regarding the sequencing, 24 sequences were obtained withgdhand 20 withtpi. For both genes, there was a prevalence of E specific species assemblage, although some isolates have been identified as A and B, by thetpisequencing. This has also shown a larger number of heterogeneous sequences, which have been attribute to mixed infections between assemblages B and E. The largest variability of inter-assemblage associated to the frequency of heterogeneity provided bytpisequencing reinforces the polymorphic nature of this gene and makes it an excellent target for studies on molecular epidemiology.