14-3-3 proteins are known to play a pivotal role in a diverse array of cellular events such as cell survival, apoptosis, and signal transduction. Numerous 14-3-3 ζ have been cloned and characterized from a host of eukaryotic organisms including human, plants, yeast, fruit fly and silkworm. However, no study on Spodoptera exigua 14-3-3ζ in conjunction with virus infection has so far been reported in insects. It appears that expression of Se14-3-3ζ was decreased starting 24 h post-SeNPV infection as SeNPV titers seemed to increase as evidenced by intense bands of SeNPV IAP3. Interestingly, confocal microscopic analysis revealed that Se14-3-3ζ is expressed at the apical side of the NPV-uninfected gut cells, whereas it was detected mainly in the nucleus of the NPV-infected cells. Thus, despite the biological significance of Se14-3-3ζ in S. exigua in conjunction with molecular interactions between SeNPV and S. exigua is unclear now, our data suggest that Se14-3-3 ζ protein plays a role to protect S. exigua from the infection or inhibit replication of SeNPV.

Janus kinase-signal transducer and activator of transcription (JAK-STAT) signaling pathway is known to play a pivotal role in various cellular events and antiviral responses in both vertebrates and insects. In an attempt to elucidate the potential involvement of STAT on S. exigua-SeNPV interactions, the full length cDNA of SeSTAT was cloned from S. exigua. Analysis of temporal expression patterns shows that SeSTAT is expressed in all stages of life cycle such as larvae, pupae, and adult. Spatial expression analysis shows that it is highly expressed in fat body and Malpighian tubule. Interestingly, SeSTAT is induced at 24 h in response to either laminarin or LTA injection in larvae. Electrophoretic mobility shift assay (EMSA) shows that the binding of nuclear extracts from fat body cells immune-challenged with LTA to STAT5 probe was observed. In addition, SeSTAT was nuclear-translocalized in both fat body and gut cells that were challenged with LTA and laminarin, respectively. Finally, gene silencing of SeSTAT shows that SeNPV number appears to be increased. It suggests that SeSTAT may act as a negative regulator against SeNPV in midgut.