Differentiated Oral Epithelial Cells Support the HPV Life Cycle.

Human Papillomavirus (HPV) associated oral disease continues to increase, both in the context of immune competence and of immune suppression. There are few models of oral HPV infection and current models are laborious. We hypothesized that differentiated oral epithelial cells could support the HPV life cycle. Clinical HPV16 cloned episomes were introduced into differentiated oral epithelial cells (OKF6tert1). Viral and cellular gene expression was assessed in the presence or absence of sodium butyrate, a differentiating agent that moved the cells to full terminal differentiation. Detection of keratin 10, cross-linked involucrin, and loricrin in the presence and absence of sodium butyrate confirmed terminal differentiation. Increasing sodium butyrate concentrations in the absence of HPV, were associated with decreased suprabasal markers and increased terminal differentiation markers. However, in the presence of HPV and of increasing sodium butyrate concentrations, both mitotic and suprabasal markers were increased and the terminal differentiation marker, loricrin, decreased. In this unique differentiated state, early and late viral gene products were detected including spliced mRNAs for E6*, E1^E4, and L1. E7 and L1 proteins were detected. The ratio of late (E1^E4) to early (E6/E7) transcripts in HPV16+ OKF6tert1 cells was distinct compared to HPV16+ C33a cells. Consistent with permissive HPV replication, DNA damage responses (phospho-chk2, gamma-H2AX), HPV E2-dependent LCR transactivation, and DNase-resistant particles were detected and visualized by transmission electron microscopy. In sum, monolayers of differentiated immortalized oral epithelial cells supported the full HPV life cycle. HPV may optimize the differentiation state of oral epithelial cells to facilitate its replication.

Antibacterial activity of polysaccharide gel extract from fruit rinds of Durio zibethinus Murr. against oral pathogenic bacteria.

AIM: The polysaccharide gel (PG) extract from durian fruit rinds (Durio zibethinus Murr. "Monthong") is a pectic polysaccharide with antibacterial activity. This study aimed to investigate the in vitro antibacterial activity of PG against oral pathogens, Streptococcus mutans (S.mutans) and Aggregatibacter actinomycetemcomitans (A.actinomycetemcomitans). METHODS: The inhibitory activity of PG at 50, 100, and 150 mg/mL against S.mutans (American Tissue Culture Collection 25175) and A. actinomycetemcomitans (American Tissue Culture Collection 43718) was determined after 1- and 5-min exposure by broth macrodilution susceptibility test and scanning electron microscopy. Normal saline or culture broth medium and 0.1% chlorhexidine were used as negative and positive controls, respectively. RESULTS: For 1-min exposure, 150 mg/mL PG or 0.1% chlorhexidine significantly possessed bactericidal activity against both tested bacteria (P=0.037), while PG at 100 mg/mL possessed significant bactericidal activity against S.mutans (P=0.037) and inhibitory activity against A.actinomycetemcomitans (P=0.05). Blebs, irregular-shaped cells, and disrupted cells were found in bacteria treated with either 0.1% chlorhexidine or 50-150mg/mL PG under scanning electron microscopy. CONCLUSION: The bactericidal activity of PG at 150 mg/mL against oral bacteria at 1-min exposure suggests its possibility to be used as a natural antibacterial ingredient in oral hygiene products.