Antiviral Activity and Mucosal Safety of Novel Human-Milk-Inspired Antimicrobial Peptides.

Background: Sexually transmitted infections (STIs) remain a major global health concern, with over one million new curable cases reported daily and limited long-term treatment options. Additionally, there are limited treatment options for women with bacterial vaginosis (BV), a dysbiotic condition predisposing them to STIs. Computationally designed human-milk-inspired antimicrobial peptides (AMPs) are promising candidates for novel antiviral and antibacterial therapies. This study evaluated the cervicovaginal mucosal safety and antiviral activity of three human-milk-inspired AMPs (MAT-006, UCD-MAT-001, and UCD-MAT-002) previously shown to exhibit antimicrobial activity against BV-causing pathogens. Methods: AMP cytotoxicity and inflammatory responses were assessed in relevant genital tract cell lines and cervicovaginal tissues in vitro. AMP anti-HIV-1 and anti-HSV-2 activities were characterized in female genital tract cell lines, TZM-bl cells and HEC-1-A cells, respectively, and in time-of-addition (pre-, co-, and post-HIV-1 challenge; and post-HSV-2 challenge) experiments. The impact of seminal plasma on AMPs' activity was also evaluated. Results: At the concentrations tested, all three AMPs showed minimal cytotoxicity and no pro-inflammatory responses in cellular and ectocervical tissue explant models. In both co- and post-exposure models, all three AMPs inhibited HIV-1 and HSV-2 replication with IC50 values ranging from 0.78 to 7.72 mg/mL. MAT-006 further showed pre-exposure anti-HIV-1 activity after 6 h (IC50 = 1.07 ± 0.515 mg/mL) and 24 h (IC50 = 0.69 ± 0.152 mg/mL) of incubation. Seminal plasma did not significantly impair MAT-006 and UCD-MAT-001 antiviral activity under experimental conditions. Conclusions: These findings demonstrate the antiviral activity of human-milk-inspired AMPs against HIV-1 and HSV-2 at concentrations that are safe to the cervicovaginal mucosa in vitro, warranting further preclinical evaluation as microbicide candidates with dual antibacterial and antiviral properties.