The Role of Zoothamnium penaei Crude Protein as an Immunostimulant to Improve Non-Specific Immunity and Survival Rate of Pacific White Shrimp (Litopenaeus vannamei) Against White Spot Syndrome Virus

The immunogenic crude protein of Zoothamnium penaei (CPZp) has the potential to be developed as an immunostimulant agent in preventing white spot syndrome virus (WSSV) infection. This study aimed to evaluate the effectiveness of CPZp administration on the hematology, gene expression related immunity, and survival rates of the Pacific white shrimp (Litopenaeus vannamei) infected with WSSV. This study used a pre- and post-test  laboratory experimental study design with two treatments P1 (3 ppm CPZp + WSSV infection) and P2 (without CPZp + WSSV infection). The observation was carried out for 7 days, while the CPZp booster was administered on the 4^th day. The observed hematological parameters consisted of total hemocyte counts (THC), differential hemocyte counts (DHC), phenoloxidase (Po) enzyme, and gene expression related-immunity. WSSV was injected into shrimp on the first day (24 hours) after CPZp administration followed by quantitave analysis using qRT-PCR. Overall, the treatment of 3ppm CPZp increased the hematological parameters of the Pacific white shrimp. In addition, CPZp administration significantly increased the Po enzyme, as well as the expression of genes related to immunity, specifically proPO and c-type lectin, when compared to the control group. The survival rate of shrimp with 3ppm CPZp against WSSV (P1) was significantly higher when compared to control (P2) with 90 and 10%, respectively. Our results indicated an increase in resistance to WSSV infection as a result of the CPZp treatment.