Hunt JF, Fang K, Malik R, Snyder A, Malhotra N, Platts-Mills TA, Gaston B. of male-to-female HIV-1 transmission has been estimated to be 1 in every 1,000 episodes of sexual intercourse, reflecting the high degree of safety conferred from the genital mucosa. However, the contribution of different sponsor factors to the safety against HIV-1 at mucosal surfaces remains poorly defined. Here, we statement for the first time that acidic ideals of pH enable the plasma protein histidine-rich glycoprotein (HRG) to strongly inhibit HIV-1 illness. Because cervicovaginal secretions usually display low pH ideals, our observations suggest that HRG might represent a constitutive antiviral mechanism in the vaginal mucosa. Interestingly, illness by other viruses, such as respiratory syncytial disease and herpes simplex virus 2, was also markedly inhibited by HRG at low pH ideals, suggesting that extracellular acidosis enables HRG to display broad antiviral activity. = 4 to 8) are demonstrated. (B, C, E, F, H, and I) Results are indicated as the mean SEM from 4 to 8 experiments. *, = Neomangiferin 3). MFI, mean fluorescence intensity. Low pH enables HRG to inhibit early cellular events associated with HIV-1 illness. The stratified squamous epithelium that lines the vagina and ectocervix represents an important physical barrier to incoming HIV-1 (21). These cells are not susceptible to HIV-1 illness but are able to bind viral particles advertising the = 3) are demonstrated in panels A and B. In panels C to H, the results are indicated as the mean SEM from 3 to 5 5 experiments. *, = 3 to 5 5) are demonstrated. FSC-A, ahead scatter area; rHRG, recombinant HRG. HRG exerts an irreversible deleterious effect on viral particles. Having demonstrated that low pH enables HRG to efficiently interact with the viral surface, we then analyzed whether this connection resulted in an irreversible loss of viral infectivity. In these experiments, HIV-1 was exposed to HRG at pH 7.3 or 6.0 for 90?min at 37C. After this period, the viral suspension cultured with HRG at pH 6.0 was neutralized back to pH 7.3. Pretreatment of HIV-1 with HRG at low pH ideals for 90?min did not impact the binding Neomangiferin of disease Neomangiferin particles to Jurkat cells (Fig. 6A) but markedly reduced viral infectivity (Fig. 6B). Rabbit Polyclonal to IR (phospho-Thr1375) Interestingly, the antiviral effect induced by HRG was not reversed when the viral particles that had been preincubated with HRG at pH 6.0 for 90?min were further incubated for 90 or 180?min at pH 7.3 before infecting Jurkat cells. On the contrary, a progressive loss of infectivity was observed (Fig. 6C). Neomangiferin Open in a separate windowpane FIG 6 HRG exerts an irreversible deleterious effect on the viral particles. (A) HIV-1 NL4-3CEGFP (10?ng of p24/well) was preincubated or not preincubated with 125?g/ml of HRG at pH 7.3 or 6.0 for 90?min at 37C. After this Neomangiferin period, the viral suspension cultured with HRG at pH 6.0 was neutralized back to pH 7.3. Then, Jurkat cells were exposed to these viral suspensions for 90?min at 4C, washed, and lysed with RIPA lysing buffer, and the amount of p24 antigen was evaluated by ELISA with dedication of the absorbance at 450?nm. (B) HIV-1 NL4-3CEGFP (10?ng of p24/well) was preincubated or not preincubated with 125?g/ml of HRG at pH 7.3 or 6.0 for 90?min at 37C. After this period, the viral suspension cultured with HRG at pH 6.0 was neutralized back to pH 7.3. Then, Jurkat cells were exposed to these viral suspensions for 90?min at 37C and pH 7.3. The cells were washed and cultured for 3?days at pH 7.3, and illness was revealed by circulation cytometry. (C) HIV-1 NL4-3CEGFP (10?ng of p24/well) was preincubated or not preincubated with 125?g/ml of HRG at pH 6.0 for 90?min at 37C. Then, the pH was neutralized back to pH 7.3, and Jurkat cells were exposed to these viral suspensions for 90?min at 37C and pH 7.3 immediately or after further incubation at pH 7.3 of the viral suspensions for 90?min and 180?min. Then, the cells were washed and cultured for 3?days at pH 7.3, and the illness was revealed by circulation cytometry. Results.