Characterization Of Immune-related Genes, LVAKT And LVFLOT, From Shrimp Litopenaeus Vannamei

Litopenaeus vannamei is one of the most popular cultured shrimp species in China.However, diseases caused by virus harass the development of shrimp aquacultureseriously. And white spot syndrome virus (WSSV) is one of the most devastatingpathogens of shrimps. In order to control the disease, more studies on mechanisms ofshrimp-WSSV interaction are needed to be done.The PI3K–AKT pathway is an intracellular signaling pathway that regulates adiverse range of cellular events, including anti-apoptosis, protein synthesis, cellcycling and so on. Growing evidences show that viruses have evolved variousmechanisms to modulate this pathway to facilitate propagation. In the present study,we reported the cloning of AKT gene from Litopenaeus vannamei and theidentification of its involvement in the virus infection and host defense. The deduced511amino acid LVAKT was highly conservative, and contained a PH domain, acatalytic domain and a hydrophobic domain. Real-Time Quantitative PCR analysisshowed that lvakt was upregulated early during WSSV infection. Moreover, thePI3K-specific inhibitor, LY294002, could reduce the viral gene transcription of WSSV,implying that PI3K-AKT pathway might be hijacked by WSSV for its viral processes.Our results suggested that LVAKT might play an important role in WSSV infection,and it might be utilized by WSSV in early stage of infection.In the second part of the study, we investigated the roles of LVFLOT in WSSVinfection. The flotillins localize at cytoplasmic side of plasma membrane and atmembranes of intracellular compartments. Increasing evidences suggest that flotillinsdefine clathrin-independent endocytic pathway, which might be involved in virusinvasion. In the sutdy, we cloned two flotillin genes, lvflot1and lvflot2, fromLitopenaeus vannamei. LVFLOT1and LVFLOT2were composed of427and439amino acids, respectively. They shared40%sequence similarities and both of themcontained a SPFH domain at the N terminus. Real-Time Quantitative PCR analysis showed that lvflot2was upregulated significantly during WSSV infection, whilelvflot1was also increased in a relatively small scale. Subsequently, the lvflot1andlvflot2were suppressed by RNAi, which resulted in the inhibition of transcription ofviral genes. The results indicated that lvflot had an important role in WSSV infection.Furthermore, the role of the lvflot in endocytosis will be investigated to elucidate therelationship between host and virus, which will be helpful for disease control.