Ausência do endosimbionte Wolbachia SP. em dois metastrongilídeos: Angiostrongylus costaricensis e Angiostrongylus cantonensis

• Ano de defesa: 2007
• Autor(a) principal: Ben, Renata
• Orientador(a): Graeff-Teixeira, Carlos
• Tipo de documento: Dissertação
• Tipo de acesso: Acesso aberto
• Idioma: por
• Instituição de defesa: Pontifícia Universidade Católica do Rio Grande do Sul; Porto Alegre
• Palavras-chave em Português: ZOOLOGIA; PARASITOS; NEMATÓDEOS; VERMES
• Link de acesso: http://hdl.handle.net/10923/5343

Abdominal angiostrongyliasis is caused by Angiostrongylus costaricensis, an intra-arterial nematode, that lives in the ileocecal region in wild rodents. This parasite has been detected from southern United States to northern Argentina. Man is an accidental host and is infected ingesting third stage larvae (L3) that are eliminated with mucous secretions by the intermediate host (veronicelid slugs). Another species, that also may infect man is Angiostrongylus cantonensis, a rat pulmonary worm, responsabile for eosinophilic meningitis, in Asia and Pacific islands. Parasites of parasites are currently being studied not only to open new therapeutics possibilities, but also in order to improve diagnostic techniques. The interest for Wolbachia, a gram-negative endosimbiont bacterium, increased when the mutualistic character of its association with filarias was described. These considerations led to new ideas for treatment of these parasitosis through the use of antibacterial drugs. The main objective of this work is to verify the Wolbachia sp presence in A. costaricensis and A. cantonensis, and study its contribution for the humoral immune response of the vertebrate host. The first step was to look for evidences in favor of the presence of Wolbachia sp. Nucleic acids, through the PCR technique. In some experiments amplification products were obtained, what could be an indication of the presence of the bacterium, but these data must be confirmed by electronic microscopy and immunohistology. Because of the difficulties to get Wolbachia sp. antigen, alternatively serum samples from individuals with abdominal angiostrongyliasis were tested against Escherichia coli antigen, because it is a common bacterium species in vertebrates’ microbiota that could eventually colonize the worm. Through a western-blot analysis it was clearly demonstrated a reactivity not exclusively associated to A. costaricensis’ infected individuals. Moreover, fragments of worms were introduced in bacterial culture medium in order to study the microbiota of the Angiostrongylus adult worm. The fact of being found only one species of a grampositive bacillum in this experiment seems to confirm the hypothesis that in intravascular environment, with a low tolerance for bacteria, the worm’s microbiota is reduced in number and diversity. From the experiments we were not able to identify the presence of Wolbachia sp neither in A. costaricensis nor in A. cantonensis. It remains open to further investigations the contribution of other bacteria or simbionts of helminthes, for antigenic recognition by the vertebrate host, with potential implications for diagnosis, pathogenesis and treatment