1. The Inhibition of DNA Viruses by the Amphibian Antimicrobial Peptide Temporin G: A Virological Study Addressing HSV-1 and JPCyV
Maria Elena Marcocci, et al. Int J Mol Sci. 2022 Jun 28;23(13):7194. doi: 10.3390/ijms23137194.
Herpes simplex virus type-1 (HSV-1) and John Cunningham polyomavirus (JCPyV) are widely distributed DNA viruses causing mainly asymptomatic infection, but also mild to very severe diseases, especially when these viruses reach the brain. Some drugs have been developed to inhibit HSV-1 replication in host cells, but their prolonged use may induce resistance phenomena. In contrast, to date, there is no cure for JCPyV. The search for alternative drugs that can reduce viral infections without undermining the host cell is moving toward antimicrobial peptides (AMPs) of natural occurrence. These include amphibian AMPs belonging to the temporin family. Herein, we focus on temporin G (TG), showing that it strongly affects HSV-1 replication by acting either during the earliest stages of its life cycle or directly on the virion. Computational studies have revealed the ability of TG to interact with HSV-1 glycoprotein B. We also found that TG reduced JCPyV infection, probably affecting both the earliest phases of its life cycle and the viral particle, likely through an interaction with the viral capsid protein VP1. Overall, our results are promising for the development of short naturally occurring peptides as antiviral agents used to counteract diseases related to HSV-1 and JCPyV.
2. Temporin G, an amphibian antimicrobial peptide against influenza and parainfluenza respiratory viruses: Insights into biological activity and mechanism of action
M De Angelis, B Casciaro, A Genovese, D Brancaccio, M E Marcocci, E Novellino, A Carotenuto, A T Palamara, M L Mangoni, L Nencioni FASEB J. 2021 Feb;35(2):e21358. doi: 10.1096/fj.202001885RR.
Treatment of respiratory viral infections remains a global health concern, mainly due to the inefficacy of available drugs. Therefore, the discovery of novel antiviral compounds is needed; in this context, antimicrobial peptides (AMPs) like temporins hold great promise. Here, we discovered that the harmless temporin G (TG) significantly inhibited the early life-cycle phases of influenza virus. The in vitro hemagglutinating test revealed the existence of TG interaction with the viral hemagglutinin (HA) protein. Furthermore, the hemolysis inhibition assay and the molecular docking studies confirmed a TG/HA complex formation at the level of the conserved hydrophobic stem groove of HA. Remarkably, these findings highlight the ability of TG to block the conformational rearrangements of HA2 subunit, which are essential for the viral envelope fusion with intracellular endocytic vesicles, thereby neutralizing the virus entry into the host cell. In comparison, in the case of parainfluenza virus, which penetrates host cells upon a membrane-fusion process, addition of TG to infected cells provoked ~1.2 log reduction of viral titer released in the supernatant. Nevertheless, at the same condition, an immunofluorescent assay showed that the expression of viral hemagglutinin/neuraminidase protein was not significantly reduced. This suggested a peptide-mediated block of some late steps of viral replication and therefore the impairment of the extracellular release of viral particles. Overall, our results are the first demonstration of the ability of an AMP to interfere with the replication of respiratory viruses with a different mechanism of cell entry and will open a new avenue for the development of novel therapeutic approaches against a large variety of respiratory viruses, including the recent SARS-CoV2.
3. Antifungal Activity of the Frog Skin Peptide Temporin G and Its Effect on Candida albicans Virulence Factors
Felicia Diodata D'Auria, Bruno Casciaro, Marta De Angelis, Maria Elena Marcocci, Anna Teresa Palamara, Lucia Nencioni, Maria Luisa Mangoni Int J Mol Sci. 2022 Jun 6;23(11):6345. doi: 10.3390/ijms23116345.
The increasing resistance to conventional antifungal drugs is a widespread concern, and a search for new compounds, active against different species of fungi, is demanded. Antimicrobial peptides (AMPs) hold promises in this context. Here we investigated the activity of the frog skin AMP Temporin G (TG) against a panel of fungal strains, by following the Clinical and Laboratory Standards Institute protocols. TG resulted to be active against (i) Candida species and Cryptococcus neoformans, with MIC50 between 4 µM and 64 µM after 24 h of incubation; (ii) dermatophytes with MIC80 ranging from 4 to 32 µM, and (iii) Aspergillus strains with MIC80 of 128 µM. In addition, our tests revealed that TG reduced the metabolic activity of Candida albicans cells, with moderate membrane perturbation, as proven by XTT and Sytox Green assays, respectively. Furthermore, TG was found to be effective against some C. albicans virulence factors; indeed, at 64 µM it was able to inhibit ~90% of yeast-mycelial switching, strongly prevented biofilm formation, and led to a 50% reduction of metabolic activity in mature biofilm cells, and ~30-35% eradication of mature biofilm biomass. Even though further studies are needed to deepen our knowledge of the mechanisms of TG antifungal activity, our results suggest this AMP as an attractive lead compound for treatment of fungal diseases.
