Endotoxins and prednisolone alter replication of type 5 adenovirus and its temperature sensitive mutants

Latency, replication or transformation by adenoviruses require cooperation between their gene products and cellular factors, which are controlled by external stimuli. Clinical observations suggest that bacterial endotoxin (LPS) and steroid hormones have direct effects on the viral permissivity and activation. Therefore, HEp-2 cultures were infected with low multiplicity of wild type (WT) human adenovirus 5 (Ad-5) and its temperature-sensitive mutants ts18 and ts19 damaged in the phosphorylation of structural polypeptides VI and X at 39 degrees C, respectively. Cultures were treated at permissive (32 degrees C) and nonpermissive (39 degrees C) temperatures with native and radio-detoxified (RD) LPS, alpha-tocopherol and prednisolone alone or in combination. Titration of virus yields showed dose-dependent activation and enhanced replication of latent WT and ts mutants by both LPS preparations. alpha-Tocopherol diminished these processes. LPS was likewise unable to augment virus producing capacity of cells. Prednisolone, although activating no latent virus, resulted in augmenting Ad-5 production at 32 degrees C. No compounds activated mutants at 39 degrees C except synergistic effect of LPS and prednisolone resulted in limited but significant replication of mutant ts19. Deliberation of lysosomal enzymes, enhanced cGMP and tumour necrosis factor alpha (TNF-alpha) productions by LPS as well as interaction of Ad early gene expression with prednisolone-utilized cellular transcription factors including AP-1 (c-jun, c-fos) are implicated in these processes. Excluding the role in activation of Ad proteinase processing viral structural polypeptides draws attention to the importance of cellular factors in virus replication.