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| Author(s): |
Mauricio Durigan
Total Authors: 1
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| Document type: | Doctoral Thesis |
| Press: | Campinas, SP. |
| Institution: | Universidade Estadual de Campinas (UNICAMP). Instituto de Biologia |
| Defense date: | 2015-02-24 |
| Examining board members: |
Anete Pereira de Souza;
André Victor Lucci Freitas;
Gisela de Aragão Umbuzeiro;
Maria Helena Matte;
Paulo Eduardo Martins Ribolla
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| Advisor: | Anete Pereira de Souza |
| Abstract | |
Giardia duodenalis is a flagellate protozoan that that parasites humans and several domestic and wild animals. This parasite causes giardiasis, one of the most common waterborne diseases in the world responsible for, approximately 280 million cases per year. There is a great genetic diversity in this species and its isolates have been grouped into eight distinct genetic assemblages (A-H). While groups A and B parasitize different hosts and have zoonotic potential, groups C, D, E, F, G and H usually found in animals and show greater specificity to the parasitized host. Environmental contamination for Giardia has been widely reported however, most of these studies have been performed only at species level. The present study aimed to contribute to the knowledge of the genetic diversity of the species Giardia duodenalis. In the first chapter of this document, multilocus sequence-based genotyping using three gene loci assigned most of the samples as belonging to human genotypes although isolates with zoonotic potential have also been identified in environmental and non-human clinical samples. A high percentage (25%) of mixed assemblages and a high number of different haplotypes were detected, which indicates high genetic diversity of this parasite in this region. In the second chapter, a population genetics study was performed with clinical samples from hospital, day-car center and a center for zoonosis control of the city and environmental samples from hospital sewage, effluent of a wastewater treatment plant and important water samples from rivers and urban streams. With the exception of the canine population, population genetic analysis showed consistent similarity between clinical and environmental populations. In the last chapter, we performed a search for microsatellites (SSRs) in the published genomes of Giardia to develop and characterize the polymorphism of new microsatellite markers. Our group identified 506, 438, 402 and 507 microsatellites of the genomes AI, AII, B and E, respectively. We have selected 80 markers specific to the genetic assemblages A, B and E (40, 20 and 20, respectively) and 36 shared SSRs between the three genomes. Analysis of amplification reactions confirmed the existence of specific loci of each genetic assemblage as well as shared loci among assemblages. Characterization of all loci allowed the detection of 12 polymorphic loci for group A and seven polymorphic loci for group B. Among the shared markers, GduABE01 presented polymorphism. The polymorphic markers can be used in future population genetic studies and the developed markers can contribute to the identification of the main genetic assemblages of G. duodenalis in clinical and environmental samples. The results presented here contribute to a better understanding of the genetic diversity of the parasite as well as the presence of zoonotic potential genotypes, related in different regions. The new molecular markers provided can contribute with population genetic studies in a high level of discrimination that allows identifying the source of contamination and molecular tracking of the disease (AU) | |