Effects of Shield1 on the viral replication of varicella‑zoster virus containing FKBP‑tagged ORF4 and 48

The present study aimed to explore the effects of a stabilizing ligand, Shield‑1, on the replication of recombinant varicella‑zoster virus (VZV) containing FK506 binding protein (FKPB) tags in essential open reading frames (ORF) 4 and 48. A specific galactokinase (galK) selection method was conducted, following the addition of galK labels to VZV ORF4 and 48, using a SW102 VZV Bacterial artificial chromosome (BAC) system. Subsequently, recombinant VZV containing FKPB tags in ORF4 and 48 was constructed by counterselection and homologous recombination. Recombinant viral plasmids containing FKPB‑tagged VZV ORF4 and 48 were extracted and transfected into human acute retinal pigment epithelial ARPE‑19 cells. The results demonstrated that the FKPB‑tagged viral protein was rapidly degraded by proteases in recombinant virus‑infected ARPE‑19 cells. In addition, the recombinant VZVORF4‑FKBP‑ORF48‑FKBP virus could not grow if a synthetic ligand of FKBP, Shield1, was not added to the ARPE‑19 Cell Culture medium; however, the degradation of FKPB‑tagged viral protein was prevented if Shield1 was added to the ARPE‑19 Cell Culture medium, thereby allowing viral replication in ARPE‑19 cells. These results indicated that Shield1 may regulate replication of recombinant VZVORF4‑FKBP‑ORF48‑FKBP following transfection into human epithelial cells.