Herpes simplex virus-type 2 infectivity and agents that block gap junctional intercellular communication

Area of Science:

• Virology
• Cell Biology
• Biochemistry

Background:

• Herpes simplex virus-type 2 (HSV-2) infection is known to attenuate gap junctional intercellular communication (GJIC).
• Protein kinase C (PKC) inhibitors represent a potential therapeutic avenue for viral infections.

Purpose of the Study:

• To investigate the effect of the PKC inhibitor H7 on HSV-2 infectivity and GJIC in rat liver epithelial (WB) cells.
• To elucidate the mechanism by which H7 affects viral infectivity and GJIC.

Main Methods:

• WB cells were treated with H7 and other GJIC inhibitors (octanol, 18-beta-glycyrrhetinic acid, staurosporine).
• GJIC was assessed using dye transfer assays.
• Viral infectivity was measured by plaque-forming unit (pfu) assays.
• Connexin 43 (Cx43) phosphorylation and localization were analyzed by Western blotting and indirect immunofluorescence.
• Protein phosphorylation was examined in infected and H7-treated cells.

Main Results:

• H7 significantly reduced HSV-2 infectivity and GJIC in a dose-dependent manner, with 100% plaque reduction at 40 microM without cytotoxicity.
• Other GJIC inhibitors did not affect viral infectivity.
• H7 decreased GJIC but did not alter Cx43 phosphorylation or membrane localization in uninfected cells.
• HSV-2 infection led to Cx43 loss from the membrane and increased serine phosphorylation, particularly in the nucleus.
• H7 treatment reduced the viral infection-induced increase in nuclear serine phosphorylation.

Conclusions:

• H7 attenuates both GJIC and HSV-2 infectivity in WB cells.
• The antiviral effects of H7 are attributed to the reduction of nuclear protein phosphorylation, rather than direct modulation of Cx43 phosphorylation or localization.
• H7 represents a potential therapeutic agent against HSV-2 by targeting host cell phosphorylation pathways.