Antiviral activities in human saliva

Abstract

In this review, the authors survey the large number of antibacterial and antiviral proteins present in human saliva. Of interest, most of these antibacterial proteins display antiviral activity, typically against specific viral pathogens. The review focuses on one protein that interacts with both bacteria and viruses-gp340, originally referred to as salivary agglutinin. In the oral cavity, soluble gp340 binds to and aggregates a variety of bacteria, and this is thought to increase bacterial clearance from the mouth. However, when bound to the tooth surface, gp340 promotes bacterial adherence. In the oral cavity, most gp340 is found soluble in saliva and can function as a specific inhibitor of infectivity of HIV-1 and influenza A. In contrast, in the female reproductive track, most gp340 is bound to the cell surface, where it can promote HIV-1 infection.

Fig. 1.

Timeline of salivary agglutinin (SAG; i.e., gp340) antibacterial and anti-HIV-1 activity.

Fig. 2.

Tertiary structure model for the active bacterial-binding motif in a scavenger receptor cysteine-rich (SRCR) domain that is proposed as being responsible for anti-HIV activity.

Fig. 3.

Space filling (A) and wire frame (B) models showing the putative interactions of the active peptides on an scavenger receptor cysteine-rich (SRCR) domain with the V3 loop of gp120. The positions of tryptophan and tyrosine on the intersecting face are indicated.