Molecular typing of canine Giardia duodenalis isolates from Minas Gerais, Brazil.

Giardia duodenalis (syn. Giardia intestinalis and Giardia lamblia) is a widespread intestinal parasite in mammals, including humans and pets worldwide. It should be considered a species complex and comprises eight assemblage (A-H). This works aimed to determine the genotypic variability among G. duodenalis isolates from dogs from Minas Gerais state, Brazil. Fecal samples of 97 dogs, from 1-to-10 months old from 15 commercial kennels, were collected and analyzed by the zinc sulfate centrifugal flotation technique, to determine their positivity for G. duodenalis cysts. Cysts pellets were stored and submitted to PCR and nested-PCR reactions with gdh and tpi primers, and then sequencing. Among positive samples (n = 19), fragment amplifications of gdh and tpi genes was observed in 16 (84,2%) and 14 (73,6%), respectively. In total, 30 sequences were obtained. Sequencing analysis showed that for gdh, all isolates were identified as host-specific genotype D, and for tpi, besides host-specific genotype C, were also observed zoonotic genotypes A and B. This study provides, for the first time, current information about genetic characterization of G. duodenalis isolates found in dogs in Minas Gerais state.

Performance of glutamate dehydrogenase and triose phosphate isomerase genes in the analysis of genotypic variability of isolates of Giardia duodenalis from livestocks.

Giardia duodenalis is a small intestinal protozoan parasite of several terrestrial vertebrates. This work aims to assess the genotypic variability of Giardia duodenalis isolates 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 with gdh and tpi primers. Fragment amplification of gdh and tpi genes was observed in 25 (42.4%) and 36 (61.0%) samples, respectively. Regarding the sequencing, 24 sequences were obtained with gdh and 20 with tpi. For both genes, there was a prevalence of E specific species assemblage, although some isolates have been identified as A and B, by the tpi sequencing. 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 by tpi sequencing reinforces the polymorphic nature of this gene and makes it an excellent target for studies on molecular epidemiology.