title: Effective qPCR methodology to quantify the expression of virulence genes in Aeromonas salmonicida subsp. salmonicida.
abstract: OBJECTIVE
  This study aimed to select and validate different methodological strategies to quantify the expression of the virulence genes ascC and ascV by qPCR in Aeromonas salmonicida subsp. salmonicida (Aer. salmonicida).
  
  
  RESULTS
  Using the geNorm, Normfinder and BestKeeper algorithms, reference genes for the qPCR were selected based on their in vitro expression stabilities in three Aer. salmonicida strains. Gene amplification efficiency was calculated by Real-time PCR Miner and LinReg PCR programmes, which have not been used previously in the analysis of bacterial gene expression. The expression of the ascC and ascV virulence genes in a virulent Aer. salmonicida strain was evaluated by three quantification models, including single (least or most stable) or three most stable reference genes, combined with constant or specific gene amplification efficiency. The most stable reference genes were gyrB, proC and rpoC, while rpoD and fabD were the least stable. Quantification models showed different expression patterns.
  
  
  CONCLUSIONS
  The optimal strategy to quantify mRNA expression was to use a combination of the three algorithms and the quantification model including the three most stable reference genes. Real-time PCR Miner or LinReg PCR were valuable tools to estimate amplification efficiency.
  
  
  CONCLUSIONS
  The methods used in this study gave more reliable expression data using qPCR than previously published methods. The quantification and expression dynamics of virulence genes will contribute to a better understanding of how Aer. salmonicida interacts with its host and the environment, and therefore to the prevention of epizootics due to this pathogen.
authors.affiliation: Laboratorio de Microbiología Marina, Departamento de Biología Funcional y Ciencias de la Salud, Universidad de Vigo, Vigo, Spain.
authors.forename: L
authors.initials: L
authors.lastname: Rivera
authors.forename: M A
authors.initials: MA
authors.lastname: López-Patiño
authors.forename: D L
authors.initials: DL
authors.lastname: Milton
authors.forename: T P
authors.initials: TP
authors.lastname: Nieto
authors.forename: R
authors.initials: R
authors.lastname: Farto
mesh_terms: D048409:Aeromonas salmonicida / Q000235:genetics* / Q000378:metabolism; D001426:Bacterial Proteins / Q000235:genetics* / Q000378:metabolism; D060888:Real-Time Polymerase Chain Reaction / Q000379:methods*; D037521:Virulence Factors / Q000235:genetics* / Q000378:metabolism
chemical_list: D001426:Bacterial Proteins; D037521:Virulence Factors
keywords: Aeromonas salmonicida subsp. salmonicida; gene expression; normalization; qPCR; reference genes