The role of crude saliva and purified salivary mucins in the inhibition of the Human Immunodeficiency Virus type 1

Master Thesis


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University of Cape Town

Sub- Saharan Africa is the world's worst HIV-AIDS affected region. More interventions to manage this pandemic are urgently required. Transmission of the virus through an exchange of saliva is rarely known to occur. The role of saliva and its mucus in this inhibition requires clarification. This project sought to verify the previous findings in our laboratory (Habte et al. , 2006; Peacocked et al. (manuscript under revision)), that crude saliva from uninfected individuals together with its purified mucin components inhibited HIV-1 in an in vitro assay. Mucins from infected saliva did not show inhibition in this assay. Mucus was extracted in 6M guanidinium hydrochloride and a cocktail of protease inhibitors, pH 6.5. Sepharose CL-4B gel filtration separated MUC5B and MUC7 in saliva. Mucins were purified by density gradient ultra-centrifugation in caesium chloride. Western blotting and amino acid analysis determined the size, charge and identity of the mucins. The inhibitory activity of crude saliva, salivary mucin components MUC5B and MUC7 from HIV-negative and HIV-positive donors, was tested by their incubation in an in vitro HIV-neutralisation assay using a pseudovirus of Subtypes A and C, and infection of susceptible epithelial tumour cells (genetically modified TZM- bl cells). Glycosylation analysis by HPLC was also performed on each group. The presence of MUC5B and MUC7 in saliva was confirmed and it was shown that there was inter-individual variation in their amounts and electrophoretic behaviour between and within groups. Crude HIV-negative and HIV-positive saliva and its purified mucins MUC5B and MUC7 significantly inhibited the infection of HIV-1 in an in vitro pseudoviral assay in a dose-response manner. HPLC revealed two glycoforms of salivary MUC5B.

Includes bibliographical references.