Shallow water vent bacteria cured my… herpes?

Introduction

Extreme environments can lead to some highly diverse marine microorganisms. With this diversity comes a whole range of biomolecules that may not be produced by their less extreme relatives, which can be of use, for example, in microbial biotechnology or pharmaceuticals. Gugliandolo, et al. (2013) used the example of the herpes simplex virus type 2 (HSV-2) which is attributed as one of the most common and continuously occurring viral infections in humans, particularly due to the persistent latency of the virus after the first infection. Unfortunately with recurrent use of drug treatments, viral resistance comes hand in hand. This requires new variations of HSV fighting treatments to battle the new resistant strains. Isolation of a novel strain of Bacillus licheniformis T14 can yield new exopolysaccharides (EPSs) with antiviral properties useful for the production of these alternate treatments. The benefits extend to the thermophilic nature of the vent-dwelling bacteria, where proliferation rates would be much greater than its mesophilic or psychrophilic counterparts.

Methods

Isolation of B. lichenformis strain T14 occurred from a thermal fluid sample obtained from a shallow submarine vent of Panarea Island in the Eolian Islands, Italy. EPS1 was obtained after 48h of incubation from culture medium and purified using gel chromatography before characterisation of physiochemical properties. Human peripheral blood mononuclear cells (PBMC) were collected from healthy blood donors, washed in RPMI 1640 medium and cultured at 37°C. The PBMC were treated with 200, 300 and 400 micrograms per millilitre (ug ml^-1) of EPS1 and incubated for 24h at 37°C. Cytoxicity tests were done on PBMC and WISH cells, and colorimetric assays were done to determine the effect of the concentrations on the viability of the cells. In another series of experiments, the PBMC and WISH cells were plated and treated with EPS1 at the concentrations of 200, 300 and 400 ug ml^-1 and incubated at 37°C for 24h. The plates were then frozen and thawed three times to cause the intracellular virus to release.

Results

PBMC show a dose-dependent cytoxicity relationship with EPS1. 48h post treatment indicates that cytoxicity was not found at concentrations of 400 ug ml^-1 or below, but above cytoxicity increased with higher concentrations of EPS1. EPS1 exhibited antiviral properties on HSV-2 (PMBC) at 300 and 400 ug ml^-1 but not with lower concentrations, whereas with the WISH cell line, no significant inhibition was found at any concentration. High levels of cytokines were detected in EPS1-treated PBMC supernatants but on samples then infected with HSV-2, there was a significant down regulation of cytokine production.

Discussion

The EPS that B. licheniformis T14 produces contains both fructose and fucose. Fucose containing polysaccharides are highly marketable due to their rarity and value in pharmaceuticals and cosmetics, and have attributes including anti-inflammatory, anticarcinogenic, and immunomodulatory properties. EPS1 provides a knowledge that damaging immunological disorders caused by HSV-2 could be reversed. The key of this biomolecule is the relative ease of cultivation, particularly with B. licheniformis T14’s affinity to thrive at variable temperatures, pH’s and salinities due to its high stress tolerance which is attributed to organisms that exist in such extreme environments. The potential of this research is huge, and this paper presents vital data for the deriving of novel biomolecules for use in medicine and biotechnology, especially with resistant pathogenic strains on the rise. The author’s conclusions send a positive message to those afflicted with reoccurring viral infections and also the potential of strains of microorganisms yet undiscovered in the oceans and the ability they may have to produce biomolecules that can be used to aid in medical and pharmaceutical applications.

Ref: Gugliandolo, C., Spanò, A., Lentini, V., Arena, A. & Maugeri, T. L. (2013) Antiviral and immunomodulatory effects of a novel bacterial exopolysaccharide of shallow marine vent origin. Journal of Applied Microbiology. 116(4), 1028-1034. doi:10.1111/jam.12422