Estudo da patogênese de Aeromonas spp. utilizando Caenorhabditis elegans como modelo de interação in vivo

• Main Author: Ferreira, Andréa Fonseca
• Publication Date: 2014
• Format: Master thesis
• Language: por
• Source: Biblioteca Digital de Teses e Dissertações da UERJ
• Download full: http://www.bdtd.uerj.br/handle/1/14445
• topic: Aeromonas spp; Caenorhabditis elegans; Bacterial pathogenesis; Virulence; Aeromonas spp; Caenorhabditis elegans; Patogênese bacteriana; Virulência; Aeromonas spp; Caenorhabditis elegans; Virulência; CNPQ::CIENCIAS BIOLOGICAS::MICROBIOLOGIA

Aeromonads are considered potential pathogens for humans and animals. The presence of Aeromonas spp. in food shows that it s an important vehicle of infection in humans. The pathology caused by aeromonads infection is complex and involves several virulence factors, mainly the ability of adherence and invasion. Several in vitro interaction studies have used cell lineages as a model for detection of these factors. However, there is no animal model established to study Aeromonas spp. pathogenesis. The nematode Caenorhabditis elegans has been used as a model to study pathogenesis of diverse microorganisms by mimicking the process in mammals and because of its easy cultivation in laboratory. The aim of this study was to analyze the pathogenicity of Aeromonas spp. strains using Caenorhabdtis elegans as an in vivo model of infection. The synchronization, infection assays and colonization assays protocols were standardized for evaluation of virulence of Aeromonas spp. in C. elegans. Nematodes at L4 larval stage were exposed to A. caviae and A. hydrophila strains isolated from fish and left interacting till 10 days at 20°C, with daily counts of living and dead animals. Evaluation of nematodes survival level was not possible in interaction assays using two A. hydrophila strains, once many animals disappeared; remaining strains significantly reduced the survival of nematodes infected and LT50 ranged from 2 to 9 days of interaction. The process that reduced survival of nematodes infected with Aeromonas spp. probably is the mechanism of "slow killing", result of intense bacterial accumulation in the animals gut. Body morphology of infected nematodes changed, such as development and reproductive behavior, resulting in a visual change of symptomatic infection. The strains carrying genes of polar and lateral flagellin synthesis flaA and lafA showed to be the most virulent. Under fluorescence microscopy, the intense gut colonization and intestinal obstruction were observed in animals exposed to a transformed strain of A. caviae for 48 hours. This study is pioneer in the use of Caenorhabdtis elegans as an in vivo model for research of virulence of Aeromonas caviae strains. This model can be used as a biological tool to identify potentially pathogenic strains to humans and other animals.