LOOP-MEDIATED ISOTHERMAL AMPLIFICATION – AN ASSAY FOR THE DETECTION OF ATYPICAL FURUNCULOSIS CAUSED BY AEROMONAS SALMONICIDA IN ATLANTIC COD, GADUS MORHUA

ABSTRACT

A loop-mediated isothermal amplification (LAMP)-based assay was developed for the detection of atypical furunculosis, caused by Aeromonas salmonicida in Atlantic cod, Gadus morhua. Gene gyrB encoding the B subunit of DNA gyrase present in the pathogen was selected for designing five sets of primers targeting the flanking regions of the gene. The primers were specific for the detection of A. salmonicida with no cross reactions to other bacterial pathogens commonly infecting Atlantic cod, e.g., Vibrio anguillarum, Francisella piscicida, Yersinia ruckeri and some endogenous bacteria found in the gut of Atlantic cod. The detection limit of the assay was 1 picogram of bacterial DNA mL⁻¹, whereas there was a decrease in detection limit by 1 log dilution in the presence of mucus as inhibitor. Because of its specificity and sensitivity, LAMP can be considered a useful tool in routine surveillance programs in aquaculture systems for monitoring atypical furunculosis in Atlantic cod and other marine species.

PRACTICAL APPLICATIONS

LAMP is a potential diagnostic technique that can be used for the rapid and early detection of atypical Aeromonas salmonicida, the causative agent of furunculosis in Atlantic cod. This technique does not require sophisticated equipment and can be performed under isothermal conditions. The assay is highly sensitive to enable detection of the pathogen prior to the onset of infection, thus, mitigating measures can be applied to prevent heavy losses of the cultured stock.