Human submandibular saliva inhibits human immunodeficiency virus type 1 infection by displacing envelope glycoprotein gp120 from the virus

Human submandibular saliva reduces human immunodeficiency virus type 1 (HIV -1) infection in vitro. To define the mechanism of inhibition, virus was in cubated with saliva or medium, velocity sucrose gradient centrifugation was performed, and fractions were analyzed for p24 and gp120, The results show that after incubation with saliva, the envelope glycoprotein was displaced from both a laboratory-adapted and a low-passage clinical HIV-1 isolate, T o identify the salivary protein(s) responsible, submandibular saliva was fr actionated by anion- exchange chromatography, Protein fractions containing anti-HIV activity were assayed for their ability to strip gp120 from virus, The partially purified active fractions contained two high-molecular-weigh t sialyated glycoproteins identified as salivary agglutinin and mucin, as w ell as several lower-molecular-weight proteins. It thus appears that specif ic salivary proteins interact with HIV-1 to strip gp120 from the virus with a resultant decrease in infectivity.