Inhibition of HIV Infection by Salivary Proteins

It has been know for some time that transmission of HIV via the oral cavity is at best a very rare event. This observation prompted Phil Fox (then at NIDCR) to add HIV to saliva in vitro and demonstrate a loss of infectivity. Since those landmark studies in 1988, numerous investigators have identified specific factors in human saliva that inhibit HIV infection in vitro including, mucins, SLPI, defensins, lactoferrin, lysozyme, thrombospondin-1, proline rich proteins and salivary agglutinin (also known as gp340 or DMBT1). Our own studies have focused on gp340, a member of the scavenger receptor cysteine rich (SRCR) family of proteins. We have demonstrated that gp340 is specific for HIV-1, and it binds to a highly conserved sequence of gp120 (env). We are in the process of identifying the smallest portion of this high molecular weight glycoprotein that still has anti-HIV activity. Data will be presented to show the approach taken and also to compare the biology of gp340 in the oral cavity (where it appears to inhibit HIV infection) versus the biology in the female reproductive track (where it appears to enhance infectivity).