Molecular epidemiology and development of vaccines against emerging pathogens for Brazilian fish farming: Streptococcus dysgalactiae and Weissella ceti

Detalhes bibliográficos
Ano de defesa: 2013
Autor(a) principal: Frederico Augusto de Alcântra Costa
Orientador(a): Não Informado pela instituição
Banca de defesa: Não Informado pela instituição
Tipo de documento: Tese
Tipo de acesso: Acesso aberto
Idioma: por
Instituição de defesa: Universidade Federal de Minas Gerais
UFMG
Programa de Pós-Graduação: Não Informado pela instituição
Departamento: Não Informado pela instituição
País: Não Informado pela instituição
Palavras-chave em Português:
Link de acesso: http://hdl.handle.net/1843/SMOC-9FFHUT
Resumo: Streptococcus dysgalactiae and Weissella ceti have been considered emergent pathogens for Brazilian Nile tilapia (Oreochromis niloticus) and rainbow trout (Onchorhynchus mykiss) farming, respectively. Both diseases cause great economic losses in fish farms. Disease prevention by vaccination is a fundamental method for pathogen control in aquaculture. The aims of this study were to evaluate the genetic diversity of S. dysgalactiae and W. ceti strains isolated from distinct geographic origins and to develop efficient vaccines against these pathogens. Different methods (REP-PCR, ERIC-PCR and PFGE) were used for the genetically characterization of strains of both bacteria, and sodA gene sequencing was also tested for genotyping of S. dysgalactiae isolates. Aqueous-based whole cell killed bacterin and oil-adjuvanted vaccine were tested. The PFGE was the best genotyping method for S. dysgalactiae and detected three different genetic profiles among the evaluated strains. The genetic variability of patterns was clearly associated with the geographic origin of isolates. According to the methods used, Brazilian W. ceti isolates was found to be highly homogeneous with a clonal population. Vaccines formulated with whole cell bacterin emulsified in oil adjuvant provided significant protection against S. dysgalactiae (RPS = 92,5) and W. ceti (RPS = 92,0) infections in Nile tilapia and rainbow trout, respectively. The present results provide scientific information for development of adequate methods to control two emerging infectious diseases that threaten Brazilian fish farming industry.