Human alpha-defensins block papillomavirus infection

Area of Science:

• Virology
• Immunology
• Microbiology

Background:

• Sexually transmitted human papillomaviruses (HPVs) are a major cause of cervical cancer.
• Papillomaviral pseudoviruses (PsVs) enable high-throughput screening for infection inhibitors.
• The antiviral activity of human antimicrobial peptides against non-enveloped viruses like HPVs is largely unexplored.

Purpose of the Study:

• To screen human peptides, particularly those involved in innate immunity, for their ability to inhibit human papillomavirus (HPV) infection.
• To investigate the efficacy of human alpha-defensins and beta-defensins against various HPV types.

Main Methods:

• Utilized papillomaviral pseudoviruses (PsVs) to screen a library of human peptides for anti-HPV activity.
• Evaluated the inhibitory potential of human alpha-defensins 1-3 (human neutrophil peptides 1-3) and human alpha-defensin 5 (HD-5).
• Conducted microscopic studies to elucidate the mechanism of PsV inhibition by alpha-defensins.

Main Results:

• Human alpha-defensins 1-3 (HNPs 1-3) and human alpha-defensin 5 (HD-5) demonstrated potent antagonism against both cutaneous and mucosal HPV types.
• HD-5 exhibited significant activity against sexually transmitted HPV types, with low ng/ml inhibitory doses.
• Alpha-defensins were found to inhibit HPV infection by blocking virion escape from endocytic vesicles, not by preventing initial binding or internalization.

Conclusions:

• Human alpha-defensins (HNPs 1-3 and HD-5) are effective inhibitors of HPV infection, acting at a post-internalization stage.
• The presence of these peptides in the female genital tract suggests a natural defense mechanism against HPV sexual transmission.
• Alpha-defensins show promise as a basis for developing broad-spectrum topical microbicides against HPV.