![]() ![]() It is strongly hemolytic, but other virulence factors such as TCP, zonula ocludens toxin, and thermo-stable toxin ST are absent (Coelho et al. cholerae Amazonia is an O1, non-toxigenic strain, isolated from more than 20 patients. One particular new strain was described from a localized outbreak, and denominated the Amazonia strain (Coelho et al. cholerae were isolated from patients with cholera symptoms. Probably due to increased surveillance during the first epidemic year in Brazil, other V. cholerae are thus encoded on mobile genetic elements, probably acquired via horizontal gene transfer (Faruque & Mekalanos 2003).Ĭholera in Latin America was caused by a seventh pandemic El Tor strain (Salles et al. Genes encoding CT reside in the lysogenic phage CTXF, and those encoding products for the biosynthesis of TCP constitute a pathogenicity island, VPI (Waldor & Mekalanos 1996, Karaolis et al. The bacteria adhere and colonize the epithelium of the small intestine by means of the TCP, and release CT in the vicinity of their target cells (Lee et al. The ongoing seventh pandemics started in 1961 in Indonesia, and reached Latin America in 1991, after a century of absence of reported cholera cases in this continent.Īlthough there are no known absolute markers that define epidemic strains, as a general rule they produce both the cholera toxin (CT) and toxin-regulated pilus (TCP) (Faruque et al. Cholera occurs in outbreaks, frequently affecting whole countries, and seven pandemics have been recorded (Barua 1992). The disease is characterized by voluminous watery stools, dehydration, and hypovolemic shock. cholerae is the etiological agent of cholera, a severe diarrheal disease, with high morbidity and mortality, if left untreated (Sack et al. ![]() 2002), and survive in the aquatic life cycle. They are released through feces in the water, in a highly infectious stage (Merrell et al. These pathogenic strains have acquired the capacity to survive adverse conditions in the host, and to multiply in the human small intestine, after ingestion of contaminated food and water. cholerae have been identified, only a few (O1 and O139) are related to epidemic human disease (Glenn Morris et al. Vibrio cholerae is a Gram-negative bacterium that lives in aquatic environments, often associated with plankton and other marine organisms (Colwell et al. Key words: Vibrio cholerae - Amazonia strain - neuraminidase - sialidase - nanH - pathogenicity island A2-105, Ilha do Fundão, 21944-970 Rio de Janeiro, RJ, Brasil IIDepartamento de Clínica Médica, Faculdade de Medicina, Universidade Federal do Rio de Janeiro, Av. E-mail: de Genética, Instituto de Biologia, Universidade Federal do Rio de Janeiro, Av. Sonia Catarina de Abreu Figueiredo I,II Anna Cristina Neves-BorgesI, 2 2 Fellowship Faperj, Ana Coelho I, 1 1 Corresponding author. The neuraminidase gene is present in the non-toxigenic Vibrio cholerae Amazonia strain: a different allele in comparison to the pandemic strains Vibrio cholerae Amazonia strain neuraminidase sialidase nanH pathogenicity island Based on the presence of nanH in the same region of the genome, and similarity of the adjacent sequences to VPI-2 sequences, it is proposed that the pathogenicity island VPI-2 is present in this strain. The most variable domain of the Amazonia NanH is the second lectin wing, comprising 13 out of 17 amino acid substitutions. This is the first description of an O1 strain with a different nanH allele. The sequence is different from those of pandemic strains, with 72 nucleotide substitutions. The Amazonia strain nanH was sequenced (Genbank accession No. The presence of nanH in a non-toxigenic strain is an exception to this rule. Association of the pathogenicity island VPI-2, carrying nanH and other genes, with toxigenic strains has been described by other authors. This NotI fragment is positioned inside 630 kb SfiI and 1900 kb I-CeuI fragments of chromosome 1. Its location has been assigned to a 150 kb NotI DNA fragment, with the use of pulsed-field gel electrophoresis and DNA hybridization. The neuraminidase gene, nanH, is present in the O1, non-toxigenic Vibrio cholerae Amazonia strain.
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