| Summary: | 碩士 === 國立陽明大學 === 口腔生物研究所 === 107 === Herpes simplex virus type 1 (HSV-1) is a highly prevalent and infectious virus, and can cause various diseases, such as herpetic gingivostomatitis and herpes labialis. Acyclovir is mainly used as an antiviral agent against HSV-1. However, studies have shown that the presence of acyclovir-resistant viral strains is found in immunocompromised patients. It is necessary to develop different therapeutic strategies against HSV-1. Caffeic acid has been shown to have antiviral and anti-inflammatory activities, and may inhibit the multiplication of HSV-1. However, the role of caffeic acid in HSV infection and regulative mechanisms are not clear. This study was to investigate the effects of caffeic acid on infection of HSV-1 in oral epithelial cells. The viral yield was determined by the plaque assay. The expression of viral proteins was examined using Western blotting assay. The intracellular levels of viral DNA were assayed using the real-time quantitative polymerase chain reaction (q-PCR). The secretion of cytokines was analyzed using the enzyme-linked immunosorbent assay (ELISA). The results of plaque assay showed that post-treatment with caffeic acid significantly decreased the viral yield of HSV-1 in infected OC3 cells. Caffeic acid decreased the expression of viral protein ICP5, whereas caffeic acid had little effect on the expression of the viral proteins, ICP0 or gD in oral epithelial cells. Moreover, the replication of HSV-1 DNA might be reduced by caffeic acid. Direct treatment of HSV-1 virions with caffeic acid reduced the infectivity of HSV-1 virons. In addition, the results of time-of-addition assay showed that viral yield was not effected when caffeic acid was added 6 hours post infection. The secretion of IL-6 and IL-8 was decreased in either mock- or HSV-1- infected oral epithelial cells after treated with caffeic acid. In summary, the results showed that caffeic acid decreased the viral yield of HSV-1-infected oral epithelial cells and could also directly inactivate the virion. The results of time-of-addition assay demonstrated that caffeic acid might interfere with the multiplication of HSV-1 before the completion of viral DNA replication.
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