Cloning and Identification of Common Carp () and Its Expression in Response to CyHV-3 Infection.

Phosphoinositide 3-kinases (PI3Ks) are a class of key regulatory factors in eukaryotes that can inhibit viral replication by influencing autophagy. Currently, cyprinid herpesvirus 3 (CyHV-3) poses a serious threat to common carp culture. However, PI3K has not yet been identified in common carp. In this study, full-length from common carp (), consisting of an open reading frame (ORF) of 2664 bp encoding a polypeptide of 887 amino acids, with a predicted molecular mass of 101.19 kDa and a theoretical isoelectric point (pI) of 5.97, was cloned. The amino acid and nucleotide sequences of CcPI3KC3 displayed high similarity to yellow catfish's () PI3KC3. The tissue expression profile revealed that the mRNA levels of in the liver, spleen, and head kidney were significantly greater than those in the brain, heart, intestines, gills, eyes, testes, and ovaries of common carp. We compared the expression patterns of between "Longke-11" mirror carp (CyHV-3-resistant carp) and German mirror carp (non-resistant to CyHV-3) at different times (0, 48, 96, 144 h, 192, 240, 288 h post-infection (hpi)) after CyHV-3 infection. The results revealed that mRNA expression significantly increased in the early infection stage. In the CyHV-3-resistant mirror carp variety, the relative expression of was significantly greater at 48, 96, and 144 hpi compared with the nonbreeding strain groups after infection ( < 0.001). These results indicate that the full-length sequence was successfully cloned from common carp for the first time, and it might play an important role in the immune system of common carp against CyHV-3 infection. This study provides a theoretical basis for the molecular mechanism of CyHV-3 resistance.