2.2. Virus and Viral Inoculum

We used WSSV (GenBank Accession no. {"type":"entrez-nucleotide","attrs":{"text":"AF440570","term_id":"19481591","term_text":"AF440570"}}AF440570) isolated in 1994 in Taiwan from infected Penaeus monodon [7]. The haemolymph was collected from experimentally WSSV-infected shrimps (L. vannamei; mean weight: 15 g), diluted 1:4 with PBS, and frozen at −80℃. The shrimp were inoculated with the virus by feeding with infected shrimp meat, and the natural infection was monitored. The infected shrimp meat was prepared as follows: specific pathogen-free shrimp were treated with 100 μL WSSV (1.7 × 10⁵ copy number/ng) via intramuscular injection, and infected shrimp were collected 7 days into the virus challenge. Then, the shrimp meat was extracted, chopped, and mixed evenly, and 0.5 g of infected shrimp meat transferred to a new microcentrifuge tube and stored at −20 °C. The WSSV content of the infected shrimp meat was measured using the Innocreate Bioscience WSSV QD Kit (Innocreate Bioscience, New Taipei City, Taiwan) and estimated according to the relevant standards and formulas provided in the kit. The viral content was maintained at 10⁵ copies/μL.