Herpesviruses are highly prevalent in the human population, and frequent reactivations occur throughout life. Despite
antiviral drugs against herpetic
infections, the increasing appearance of drug-resistant viral strains and their adverse effects prompt the research of novel antiherpetic drugs for treating lesions.
Peptides obtained from natural sources have recently become of particular interest for
antiviral therapy applications. In this work, we investigated the
antiviral activity of the
peptide A-3302-B, isolated from a marine bacterium, Micromonospora sp., strain MAG 9-7, against herpes simplex virus type 1, type 2, and human cytomegalovirus. Results showed that the
peptide exerted a specific inhibitory activity against HSV-2 with an EC50 value of 14 μM. Specific
antiviral assays were performed to investigate the mechanism of action of
A-3302-B. We demonstrated that the
peptide did not affect the expression of
viral proteins, but it inhibited the late events of the HSV-2 replicative cycle. In detail, it reduced the cell-to-cell virus spread and the transmission of the extracellular free virus by preventing the egress of HSV-2 progeny from the infected cells. The dual
antiviral and previously reported anti-inflammatory activities of
A-3302-B, and its effect against an
acyclovir-resistant HSV-2 strain are attractive features for developing a therapeutic to reduce the transmission of HSV-2
infections.