Role of the Kruppel-like factor in Litopenaeus vannamei after white spot syndrome virus infection

White spot syndrome virus (WSSV) infection can cause a significant mortality to shrimp cultivation. Our previous study identified the first kruppel-like factor (PmKLF) in Penaeus monodon. Inhibition of PmKLF by double-stranded RNAs decreased the mortality in WSSV-infected shrimps. According to genomic database, the sequences of P. monodon and Litopenaeus vanname display highly identity. In this study, a KLF from L. vannamei was cloned and characterized. The full-length LvKLF gene is 1080 bp, encoding a polypeptide of 360 amino acids. Sequence analysis showed that the identity of LvKLF and PmKLF amino acids is 93% and the zinc-finger DNA binding domain are the same. Immunoblotting using the anti-KLF antibody indicated that the apparent molecular mass of LvKLF protein is about 40 kDa. Moreover, immunofluorescence analysis revealed that LvKLF is located in the nucleus as dots after overexpressing LvKLF in Sf9 insect cells. So far, fifteen WSSV candidate immediate early (IE) genes including wssv108、wssv126、wssv135、wssv136、wssv137、wssv140、wssv150、wssv154、wssv155、wssv156、wssv157、wssv159、wssv164、wssv234 and wssv304 in the Taiwan isolate had been identified. This study indicated that these IE genes were inhibited in WSSV-challenged shrimps that had been injected with double-stranded RNAs of LvKLF. Furthermore, the reporter assay by using predictive WSSV IE promoters revealed that LvKLF enhanced the promoter activities of wssv108, wssv126, wssv140, wssv164, wssv234 and wssv304. Hence, this study demonstrates that the kruppel-like factor in Litopenaeus vannamei plays a crucial role in WSSV infection.