ANTIVIRAL AND IMMUNOMODULATORY EFFECTS OF BIOPOLYMERS BY MARINE EXTREMOPHILI BACILLI AGAINST HERPES SIMPLEX VIRUS TYPE-2

Herpes simplex virus type 2 (HSV-2) has know to be responsible
of 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 immune response against HSV-2 involves intricate and
multifactorial aspects to whom viruses have developed various
mechanisms to evade them. Biopolymers (BPs) from two novel
thermotolerant Bacillus horneckiae strains (APA and SBP3) isolated
from shallow vents of Panarea Island (Italy), were evaluated
for their antiviral and immunomodulatory effects against HSV-2.
The BPs were used at the concentration of 400 μg mL–1 that
resulted not-cytotoxic towards human peripheral blood mononuclear
cells (PBMC) and WISH cells. Both BPs hindered the HSV-
2 replication in PBMC, showing 60 and 80% of viral inhibition
for BP-SBP3 and BP-APA, respectively, but they did not in WISH
cells. To verify if the antiviral activity was related to the immune
response involved in controlling viral replication, the production
of cytokines was evaluated on PBMC. Higher levels of Th1-type
cytokines (INF-γ, INF-α TNF-α, IL-12 and IL-18) were detected in
PBMC treated with BP-APA than in those treated with BP-SBP3.
Th2-type cytokines (IL-4 and IL-10) were not induced by BP-APA.
Therefore, the antiviral effects of BPs were related to the pattern
of cytokines induced. As stimulators of Th1 cell-mediated immunity,
BPs from the two novel thermotolerant bacilli could be considered
powerful sources for the development of prophylactic
and therapeutic strategies against herpes virus infection.