Each diseased freshwater-cultured P. vannamei sampled was
externally disinfected with 75% alcohol and dissected. A
0.20 ± 0.01 g hepatopancreas sample of each shrimp was cut and
streaked onto nutrient agar (NA) plates (Sinopharm Chemical
Reagent Co., Ltd.) as recommended by Cao et al. (2014). After incubation
for 24–48 h at 28 ± 1 C, the dominant uniform isolates were purified by streaking and re-streaking onto NA plates. Pure isolates of the dominant colonies were assessed by observation of the colony and cell morphology as described by the Institute of Agricultural Resources and Regional Planning, Chinese Academy of Agricultural Sciences (2005) and were stored at 80 C supplemented with 15% glycerol. A representative of the dominant isolates, isolate QH, was characterized further in the present study.