Modulation of herpes simplex virus type 1 replication by human salivary secretions

Saliva functions to protect the oral cavity from pathogenic invasion by modulating the ability of microbes to colonize the oral surfaces or limiting their growth and/or viability. Although the role of salivary secretions in the modulation of the oral bacteria flora has received considerable attention, little is known concerning its role in viral pathogenesis. Accordingly, the purpose of this study was to assess the effect of salivary secretions on herpes simplex virus type 1 (HSV-1) replication. Initially, HSV-1 plaque and titer reduction assays were performed to determine the ability of human submandibular/sublingual (HSMSL) and parotid (HPS) salivas to inhibit the early stages of HSV-1 infection (adsorption and penetration). Our results suggested that both HSMSL and HPS possess cell-protective and virus neutralization activities, with HSMSL being more active than HPS. Additional experiments were performed to determine the effect of saliva on the yield of virus progeny. Again, HSMSL caused a greater reduction of HSV-1 replication than did HPS. A similar effect could not be obtained using vaccinia, suggesting that this inhibitory activity of human saliva is selective. Collectively, these results suggest that human salivary secretions can modulate the replication of HSV-1 in vitro.