Human α-defensin 5 is an antiviral peptide. Human α-defensin 5 blocks infection of non-enveloped viruses, including AdV, HPV , and polyomaviruses ( IC 50 : 0.6-1.25 μM for HPV16). Human α-defensin 5 can bind to the viral capsid and blocks escape of the virus from the endosome. Human α-defensin 5 increases HIV binding to the cell surface. Human α-defensin 5 also has parasiticidal activity.