title: Identification and ultrastructural characterization of the Wolbachia symbiont in Litomosoides chagasfilhoi.
abstract: BACKGROUND
  Filarial nematodes are arthropod-transmitted parasites of vertebrates that affect more than 150 million people around the world and remain a major public health problem throughout tropical and subtropical regions. Despite the importance of these nematodes, the current treatment strategies are not efficient in eliminating the parasite. The main strategy of control is based on chemotherapy with diethylcarbamazine, albendazole and ivermectin. In the 1970s, it was found that some filarids possess endosymbiotic bacteria that are important for the development, survival and infectivity of the nematodes. These bacteria belong to the genus Wolbachia, which is a widespread and abundant intracellular symbiont in worms. Knowledge about the structure of the bacteria and their relationship with their nematode hosts may allow new perspectives for the control of filarial nematodes.
  
  
  METHODS
  In this study, we used transmission electron microscopy combined with three-dimensional approaches to observe the structure of the endosymbiont of the filarial nematode Litomosoides chagasfilhoi, an experimental model for the study of lymphatic filariasis. In addition, the bacterium was classified based on PCR analyses.
  
  
  RESULTS
  The bacterium was mainly found in the hypodermis and in the female reproductive system in close association with host cell structures, such as the nucleus and endoplasmic reticulum. Our ultrastructural data also showed that the symbiont envelope is composed of two membrane units and is enclosed in a cytoplasmic vacuole, the symbiosome. Molecular data revealed that the bacterium of L. chagasfilhoi shares 100% identity with the Wolbachia endosymbiont of Litomosoides galizai.
  
  
  CONCLUSIONS
  Here we described ultrastructural aspects of the relationship of the Wolbachia with the filarial nematode Litomosoides chagasfilhoi and the findings lead us to consider this relationship as a mutualistic symbiosis.
authors: Laboratório de Biologia de Helmintos Otto Wucherer, Instituto de Biofísica Carlos Chagas Filho, Universidade Federal do Rio de Janeiro, 21941-902, Rio de Janeiro, RJ, Brazil. vanessamoutinho@biof.ufrj.br.|Laboratório de Ultraestrutura Celular Hertha Meyer, Instituto de Biofísica Carlos Chagas Filho, Universidade Federal do Rio de Janeiro, 21941-590, Rio de Janeiro, RJ, Brazil. vanessamoutinho@biof.ufrj.br.|Instituto Nacional de Ciência e Tecnologia em Biologia Estrutural e Bioimagens, Rio de Janeiro, Brazil. vanessamoutinho@biof.ufrj.br.
authors: Vanessa Aparecida
authors: VA
authors: Chagas-Moutinho
authors: Laboratório de Metabolismo Macromolecular Firmino Torres de Castro, Instituto de Biofísica Carlos Chagas Filho, Universidade Federal do Rio de Janeiro, 21941-590, Rio de Janeiro, RJ, Brazil. silvaros@biof.ufrj.br.
authors: Rosane
authors: R
authors: Silva
authors: Laboratório de Biologia de Helmintos Otto Wucherer, Instituto de Biofísica Carlos Chagas Filho, Universidade Federal do Rio de Janeiro, 21941-902, Rio de Janeiro, RJ, Brazil. wsouza@biof.ufrj.br.|Laboratório de Ultraestrutura Celular Hertha Meyer, Instituto de Biofísica Carlos Chagas Filho, Universidade Federal do Rio de Janeiro, 21941-590, Rio de Janeiro, RJ, Brazil. wsouza@biof.ufrj.br.|Instituto Nacional de Ciência e Tecnologia em Biologia Estrutural e Bioimagens, Rio de Janeiro, Brazil. wsouza@biof.ufrj.br.|Diretoria de Metrologia Aplicada às Ciências da Vida, Instituto Nacional de Metrologia, Qualidade e Tecnologia- INMETRO, Duque de Caxias, RJ, Brazil. wsouza@biof.ufrj.br.
authors: Wanderley
authors: W
authors: de Souza
authors: Laboratório de Ultraestrutura Celular Hertha Meyer, Instituto de Biofísica Carlos Chagas Filho, Universidade Federal do Rio de Janeiro, 21941-590, Rio de Janeiro, RJ, Brazil. motta@biof.ufrj.br.|Instituto Nacional de Ciência e Tecnologia em Biologia Estrutural e Bioimagens, Rio de Janeiro, Brazil. motta@biof.ufrj.br.
authors: Maria Cristina Machado
authors: MC
authors: Motta
mesh_terms: D000818:Animals; D005260:Female; D005370:Filarioidea / Q000382:microbiology* / Q000502:physiology; D008297:Male; D046529:Microscopy, Electron, Transmission; D010802:Phylogeny; D040521:Subcutaneous Tissue / Q000382:microbiology; D013559:Symbiosis; D020577:Wolbachia / Q000235:genetics / Q000302:isolation & purification* / Q000502:physiology* / Q000648:ultrastructure
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