Genotyping of Brazilian Giardia duodenalis human axenic isolates

Abstract

Abstract:Giardia duodenalis is a complex species that comprises at least seven distinct genetic groups (A to G), but only genotypes A and B are known to infect humans and a wide variety of other mammals. Regardless of biological, biochemical and antigenic analysis, several isolates maintained in vitro were not genetically typed yet. So, in the present study, five Brazilian axenic isolates obtained from asymptomatic and symptomatic patients were typed in order to determine the major genetic groups to which the isolates belonged. DNA was extracted from axenic trophozoites, fragments of glutamate dehydrogenase (gdh) and triosephosphate isomerase (tpi) genes were amplified by PCR and the isolate genotyping was carried out using restriction fragment length polymorphism (RFLP) and DNA sequencing for both genes. The results revealed that all isolates were assigned to genotype A at both analyzed loci. Indeed, DNA sequence analysis classified the four isolates obtained from asymptomatic individuals into subtype AII, while the isolate obtained from the symptomatic patient was typed as subtype AI. Despite of the limited number of isolates assessed, the findings presented herein provide interesting insights on the occurrence of Giardia genotypes in Brazil and hold the perspective for future molecular and epidemiological investigations.

The Predominance of Giardia duodenalis AII sub-assemblage in young children from Salvador, Bahia, Brazil

“…In Rio de Janeiro, Volotao, et al 25 , identified only assemblage A, mostly classified as AII. In Sao Paulo, the analysis of five isolates of axenic trophozoites had the same results as in Rio, i.e., only assemblage A, mostly AII 26 . However, in another study conducted in Sao Paulo with isolates from children in day care centers, assemblage B predominated 27 while in Fortaleza, Kohli, et al .…”

“…However, in studies conducted in Amazonas 49 , Rio de Janeiro 30 , Sao Paulo 50 , and Santa Catarina 51 , assemblages A and B were found in similar proportions. It is important to note that the majority of studies in Brazil performed molecular characterization of less than 50 G. duodenalis isolates 26 , 29 , 48 , 50 - 53 . In contrast, in our study, 80 isolates of G. duodenalis from different groups of children were analyzed.…”

Identification of genotypes of Giardia duodenalis human isolates in Isfahan, Iran, using polymerase chain reaction - Restriction Fragment Length polymorphism

“…[16] Genetic heterogeneity of the parasite determined by several molecular studies reveals that G.duodenalis is a complex species consisting of several genotypes. [247] The distribution of genotypes varies in human and animal hosts; and also it differs for various geographic areas[246171819]…”

“…[7] Molecular studies on human isolates from different geographic areas show that in almost all cases only assemblages A and B of G. duodenalis are associated with human infections. The prevalence of the mentioned genotypes varies from country to country and even between different geographic areas in a country.…”

Predominance of Giardia duodenalis Assemblage AII in Fresh Leafy Vegetables from a Market in Southern Brazil

“…Little is known about the geographical distribution of zoonotic genotypes A and B in Brazil (3,4,11,17,28). In this context, the presence of G. duodenalis and its respective genotypes was investigated in vegetables that are consumed raw and sold in a market known as ''market of the Maringá producer,'' which is distinct from most street markets of Brazil because the producers themselves display and sell their produce, and their business has relied upon technical and sanitary assistance at various levels of production and distribution for at least 20 years.…”