The Peptide A-3302-B Isolated from a Marine Bacterium Micromonospora sp. Inhibits HSV-2 Infection by Preventing the Viral Egress from Host Cells

Abstract

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.

Identification of a βCD-Based Hyper-Branched Negatively Charged Polymer as HSV-2 and RSV Inhibitor

“…The respiratory syncytial virus (RSV) A2 strain (ATCC ® VR-1540), the human rotavirus (HRoV) strain Wa (ATCC ® VR-2018), and the herpes simplex virus type 2 (HSV-2) strain MS (ATCC ® VR-540) were propagated in Hep2, MA104, and Vero cells, respectively [ 67 , 68 ]. The human influenza virus type A strain A/New Caledonia/20/99 (FluVA-H1N1; Italian National Institute of Health) was propagated in canine kidney epithelial MDCK cells (ATCC ® NBL-2) with a culture medium supplemented with 0.5 µg/mL of porcine pancreas trypsin (Sigma-Aldrich; St. Louis, MO, USA) [ 69 ].…”

“…The human influenza virus type A strain A/New Caledonia/20/99 (FluVA-H1N1; Italian National Institute of Health) was propagated in canine kidney epithelial MDCK cells (ATCC ® NBL-2) with a culture medium supplemented with 0.5 µg/mL of porcine pancreas trypsin (Sigma-Aldrich; St. Louis, MO, USA) [ 69 ]. After propagation, the obtained viral progenies were clarified out of cell debris, aliquoted, and stored at −80 °C prior to virus titration by standard plaque assay or focus reduction assay, dependently on the viral agent considered [ 67 , 68 ].…”

“…After two washes, the infected A549 and MA104 cells were incubated with a fresh medium for 16 h or 24 h, respectively, at 37 °C, while the infected Hep-2 and Vero cells were overlaid with a 1.2% methylcellulose medium for 72 h or 24 h, respectively. A549, MA104, and Hep-2 cells were fixed with cold acetone-methanol (50:50) and the FluVA-, HRoV-, and RSV-infected cells were detected by means of indirect immunostaining [ 67 , 68 ]. Immunostained viral foci were microscopically counted and results were reported as percentages of controls.…”

Current Landscape of Methods to Evaluate Antimicrobial Activity of Natural Extracts

“…Instead of aiming at the entire viral life cycle, other cell-based assays have been developed to screen viral inhibitors that target specific steps of the infectious process [ 171 , 172 , 173 ]. For instance, classic methods to screen inhibitors of viral entry include cell–cell fusion assays and cell–virus fusion assays.…”

Fascinating Molecular and Immune Escape Mechanisms in the Treatment of STIs (Syphilis, Gonorrhea, Chlamydia, and Herpes Simplex)

“…Transmission electron microscopy revealed that this peptide diminishes the viral spread by containing the herpetic virions escape from the infected cells and suppresses the herpetic cytopathic effect. Furthermore, it is potent against acyclovir-resistant HSV-2 [ 145 ].…”