 Silver nanoparticles have antiviral activity against HIV-1 at non-cytotoxic concentrations, and their mechanism of action is elucidated using in vitro assays, suggesting that they act as a virusidal agent or an inhibitor of viral entry by binding to GP120 and preventing CD4, dependent virion binding, fusion, and infectivity. Silver nanoparticles also inhibit post-entry stages of the HIV-1 life cycle, making them a broad-spectrum agent that could be used preventively against circulating HIV-1 strains. This article was authored by Rodríguez Padilla-Cristina, Ixtapantur and Liliana, Ayala Núñez-Nilderví, and others.