The comparative inhibitory potency of salivary mucins against human immunodeficiency virus type 1.

MUC5B and MUC7 salivary mucins are reported to inhibit HIV-1 entry into target cells in vitro; however, their relative inhibitory potencies have not been quantitively compared. There is also conflicting evidence regarding whether HIV-1 infection diminishes mucins' inhibitory efficacy. We explored the effect of donor HIV-1 status upon the anti-HIV-1 potency of purified MUC5B and MUC7 while comparing their relative inhibitory potential using a pseudovirus-based neutralization assay. HIV status of sample donors had no detectable effect on HIV-1 inhibition by salivary mucins. MUC5B (median IC50 50 µg/ml, IQR 10-116 µg/ml) exhibited significantly more potent HIV-1 inhibition than MUC7 (median IC50 458 µg/ml, IQR 192->2000 µg/ml; Mann-Whitney U p < 0.0001). We suggest that larger size, gel-forming properties and extensive glycosylation of MUC5B allow more effective binding and aggregation of viral particles. MUC5B is also more abundant in the saliva and is therefore likely to make a substantially greater contribution to it's anti-HIV-1 properties.