ena-STUDY-PONDICHERRY UNIVERSITY-04-04-2019-12:41:30:480-89
Isolation and identification of secondary etiologic agent from WSSV affected shrimp Penaeus monodon from India
This study aims to identifyand characterize opportunistic bacterial pathogens in cultivated ponds reported with mid culture outbreaks later identified as white spot syndrome virus (WSSV) infected shrimp Penaeusmonodonin the farms located insoutheast coast of India.The bacterial isolates from thehepatopancreas of diseased Penaeusmonodonsamples were screened for extracellular virulence factors includehydrolytic enzymes (protease, gelatinase, chitinase and phospholipase); adhesion factors (aggregation, cell surface hydrophobicity-CSH and biofilm formation), haemolysin and luminescence. The primary screening results showed that the isolates SK2, SK4, SK5, SK9 and SK11 were highly virulent and pathogenic in nature. Based onProbit analysis, the LD50 of SK4 and SK11 wasrecorded as 104 and 103CFU/ml respectively in animal model.The strainsSK4 and SK11were highly pathogenic and responsible for the opportunistic infections associated with WSSV and mass mortality. The clinical signs were observed throughout the experiment and the infectivity dose (ID50) was determined as 103 and 102forSK4 and SK11 respectively. The mortality rate and pathogenicity indexwas nearly 100% in challenged shrimp with SK11 strain which was identified as Aliivibriofischeribased physiological, biochemical and molecular phylogenetic analysis. The emergence of Aliivibriofischerias an opportunistic etiological agent in WSSV outbreak was a first report from Indian shrimp farms.
This study aims to identifyand characterize opportunistic bacterial pathogens in cultivated ponds reported with mid culture outbreaks later identified as white spot syndrome virus (WSSV) infected shrimp Penaeusmonodonin the farms located insoutheast coast of India.The bacterial isolates from thehepatopancreas of diseased Penaeusmonodonsamples were screened for extracellular virulence factors includehydrolytic enzymes (protease, gelatinase, chitinase and phospholipase); adhesion factors (aggregation, cell surface hydrophobicity-CSH and biofilm formation), haemolysin and luminescence. The primary screening results showed that the isolates SK2, SK4, SK5, SK9 and SK11 were highly virulent and pathogenic in nature. Based onProbit analysis, the LD50 of SK4 and SK11 wasrecorded as 104 and 103CFU/ml respectively in animal model.The strainsSK4 and SK11were highly pathogenic and responsible for the opportunistic infections associated with WSSV and mass mortality. The clinical signs were observed throughout the experiment and the infectivity dose (ID50) was determined as 103 and 102forSK4 and SK11 respectively. The mortality rate and pathogenicity indexwas nearly 100% in challenged shrimp with SK11 strain which was identified as Aliivibriofischeribased physiological, biochemical and molecular phylogenetic analysis. The emergence of Aliivibriofischerias an opportunistic etiological agent in WSSV outbreak was a first report from Indian shrimp farms.