Haemocyanin content of shrimp (Fenneropenaeus chinensis) associated with white spot syndrome virus and Vibrio harveyi infection process

•A double antibody sandwich ELISA was established for haemocyanin (Hc) determination.•Hc content in Fenneropenaeus chinensis peaked at 12–36 h after WSSV or Vibrio harveyi infection.•Total protein content of hemolymph varied similarly to Hc content after infection.•Hc content at 6–36 h PI might be a reference threshold for shrimp infection.

Haemocyanin (Hc) is frequently reported to vary significantly by physiological status and environmental stress in Crustaceans. In this paper, the shrimp Fenneropenaeus chinensis was infected with different concentrations of white spot syndrome virus (WSSV) and Vibrio harveyi. Then, the variation of Hc and total protein content of the haemolymph (TPCH) were investigated using the established double antibody sandwich enzyme linked immunosorbent assay (DAS-ELISA) and Coomassie brilliant blue method, respectively. The results showed that the Hc content peaked at 12 h post-infection (PI) in the 10−2, 10−4 and 10−6 viral supernatant (VS) groups, and the maximum was 93.03 ± 2.55 mg ml−1, 77.57 ± 6.02 mg ml−1 and 70.25 ± 3.96 mg ml−1, respectively. TPCH reached the maximum of 108.18 ± 1.36 mg ml−1 and 103.49 ± 1.33 mg ml−1 at 12 h PI in the 10−2 and 10−4 VS groups, respectively. The maximum was 96.94 ± 1.06 mg ml−1 at 24 h PI in the 10−6 VS group. In the V. harveyi infection groups, the Hc content reached a maximum of 87.97 ± 4.39 mg ml−1 at 36 h PI in the 106 CFU ml−1 group, 73.74 ± 4.38 mg ml−1 and 72.47 ± 2.09 mg ml−1 at 12 h PI in the 107 and 108 CFU ml−1 groups, respectively. TPCH reached a maximum of 111.16 ± 0.86 mg ml−1 at 36 h PI in the 106 CFU ml−1 group, 100.41 ± 0.51 mg ml−1 and 101.94 ± 0.47 mg ml−1 at 12 h PI in the 107 and 108 CFU ml−1 groups, respectively. These data showed that both Hc content and TPCH varied as the same extent after infection. The up-regulation of the Hc content at 6–36 h PI might be a reference threshold for shrimp infection.