Objective: We studied the regulating effect of human bocavirus 1 (HBoV1) nonstructural protein NP1 on the activity of cellular transcription factors and the expression of inflammatory cytokine TNF-alpha and IL-6.
Methods: The modulation of NP1 was measured by the Dual Luciferase Reporter Assay System and the expression of cytokines TNF-alpha and IL-6 was detected by ELISA and Real-time PCR. The luciferase based mammalian two-hybrid system was used to analyze whether the function of NP1 protein aroused from oligomerization.
Results: The transcription factors AP-1, STAT3 and STAT1 but not NF-kappaB were up-regulated by NP1, which was evidenced by approximately 2-3-fold increase of the luciferase activity compared to the control vector. Moreover, NP1 increased the TNF-alpha mRNA expression, but not contributed to cytokine IL-6 secretion. We also found that the self-interaction did not exist when NPI was solely expressed in 293T cells.
Conclusion: This study demonstrates for the first time that NP1 may play important roles in activation of transcription factors and up-regulation of inflammatory cytokines expression, suggesting that NP1 be involved in HBoV1 pathogenesis.