Study On The Apoptotic Function Of Herpes Simplex Virus Type 2 ICP27 In Vero Cells

Herpes simplex virus type 2 (HSV-2) is a ubiquitous human pathogen mainly causing genital herpes (GH). As a neurotropic virus, HSV-2 is able to remain latent in the neurons of its host for life and can be reactivated to cause lesions at or near the initial site of infection. Reactivation from the latent state results in productive infection that ultimately leads to the lytic destruction of distal epithelial cells. Antiviral drugs have been used in the treatment of HSV-2 infection, but they could not clear the latent HSV-2, and unfortunately, prophylactic vaccine of HSV-2 has not launched. All for these are that the mechanism of HSV-2 reactivation from latent was not well understood.Among IE gene products, HSV ICP27 is a 63kDa nuclear phosphprotein consisting of 512 amino acid residues. During infection, ICP27 performs multiple function, including shuttling between the nucleus and cytoplasm to promote viral RNA nuclear export, inhibiting typeⅠsignaling to facilitate immune escape, increasing translation a subset of viral early and late mRNAs. In the latent period, the HSV genome remains a circular DNA. The latent virus may be reactivated by various stimuli. To maintain viral latency, the apoptosis of virus-infected cells should be prevented. Latent associated transcript (LAT) has been reported to involve in protecting neurons from apoptosis. In the reactivation of the latent HSV, ICP27 has been reported to induce apoptosis by activation p38 and JNK signaling. Thus, ICP27 might play a role in the reactivation of HSV.In this study, HSV-2 genome was extracted and used as a template to amplify ICP27 gene with PCR. Then, the ICP27 gene was inserted into pEGFPC2 by DNA ligase after cleaved by BamH I and EcoR I, so the pEGFP-ICP27 recombinant plasmid was constructed. pEGFP-ICP27 was transfected into Vero cells with Xfect regents, Vero cells was collected for isolating total RNA and protein to detect the transcript and expression of ICP27 in Vero cells by RT-PCR and western blot at 48h after transfection, respectively. pEGFP-ICP27 was expressed abundantly in Vero cells from 24h to 48h after transfection.Comparing with Vero cells transfected with pEGFPC2 and normal cultured, the cell activity and caspase-3 activity significantly reduced and increased in Vero cells transfected with pEGFP-ICP27 detected by MTT assay and caspase-3 kits, respectively. And nucleus detected by Gimesa strain. Bax increased, while Bcl-2 decreased in Vero cells transfected with pEGFPC2-ICP27. Compared with Vero cells normal cultured and transfected with pEGFPC2, Bax/Bcl-2 significantly increased.Taking these results into consideration, HSV-2 ICP27 might induce apoptosis by destabilizing Bax/Bcl-2 in the course of reactivation from latent.