Abstract
Extreme marine environments, such as the submarine shallow vents of the Eolian Islands (Italy), offer an almost unexplored source of microorganisms producing unexploited and promising biomolecules for pharmaceutical applications. Thermophilic and thermotolerant bacilli isolated from Eolian vents are able to produce exopolysaccharides (EPSs) with antiviral and immunomodulatory effects against Herpes simplex virus type 2 (HSV-2). HSV-2 is responsible for the most common and continuously increasing viral infections in humans. Due to the appearance of resistance to the available treatments, new biomolecules exhibiting different mechanisms of action could provide novel agents for treating viral infections. The EPSs hinder the HSV-2 replication in human peripheral blood mononuclear cells (PBMC) but not in WISH (Wistar Institute Susan Hayflic) cells line, indicating that cell-mediated immunity was involved in the antiviral activity. High levels of Th1-type cytokines were detected in PBMC treated with all EPSs, while Th2-type cytokines were not induced. These EPSs are water soluble exopolymers able to stimulate the immune response and thus contribute to the antiviral immune defense, acting as immunomodulators. As stimulants of Th1 cell-mediated immunity, they could lead to the development of novel drugs as alternative in the treatment of herpes virus infections, as well as in immunocompromised host.
Highlights
Marine hydrothermal systems are considered “extreme environments”since they are characterized by high temperatures and unusual chemical conditions that are prohibitive for most organisms
This review focuses on the marine prokaryotes producers of EPSs exhibiting antiviral and immunomodulatory effects with particular attention paid to bacilli from Eolian shallow vents and their anti-herpes virus activities
Other marine bacteria have been reported to be producers of EPSs with biotechnological potentiality, the EPSs produced by the three bacilli isolated from vents of the Eolian Islands are among the few biopolymers described to exhibit antiviral and immunomodulatory effects
Summary
Marine hydrothermal systems (shallow and deep-sea vents) are considered “extreme environments”. The Mediterranean Sea presents several shallow hydrothermal areas, of which those located at the Eolian Islands (Italy) and the Aegean Volcanic Arc (Greece) have been studied over more than a decade These sites can be considered as excellent natural fields to investigate how microorganisms respond at elevated temperatures and salinity, high concentrations of CO2, and low pH, to isolate novel extremophiles, and to study the effects of the acidification and temperature increasing in the oceans. Shallow hydrothermal systems of Eolian Islands (Italy), characterized by unusual conditions (high temperature, low pH, high concentrations of CO2, H2S, hydrocarbons, heavy metals, etc.) for the majority of organisms, represent easy accessible fields to isolate novel bacteria able to produce new biometabolites [1,2,3]. Their immunostimulant and immunomodulatory effects make them potential novel drugs in the anti-herpes virus therapy
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