1182. Dynasore Blocks HSV Capsid Formation, Viral Egress and Cell-to-Cell Spread: Novel Strategy to Prevent Primary and Reactivating HSV Infection
Session: Poster Abstract Session: New Approaches to Anti-Viral Therapy
Saturday, October 22, 2011
Room: Poster Hall B1
Background: HSV enters cells either by direct fusion at the cell surface or endocytosis, although the importance of endocytosis as an entry pathway in human cells is controversial. We tested the inhibitory activity of dynasore, which inhibits the GTPase activity of dynamin and is a selective inhibitor of endocytosis, against a panel of human cells. Dynasore inhibited viral infection of all cells including those in which HSV entry occurs by fusion. Therefore, the current study was designed to identify the mechanism underlying dynasore’s anti-HSV activity.

Methods: Primary human fetal neuronal (neurons and astrocytes), SK-N-SH (human neuroblastoma) and CaSki (human cervical epithelial) cells were tested for susceptibility to HSV infection in the presence or absence of dynasore.  Heparin, a competitive inhibitor of HSV binding, was included as a control. To determine which steps in the viral life cycle were blocked, binding studies, confocal microscopy with GFP-labeled virus to assess entry, Western blots to assess viral protein synthesis, electron microscopy, and cell-to-cell spread imaging studies were performed.

Results: Dynasore inhibited HSV infection of both serotypes by 70-90% when added prior to or at the same time of viral exposure in all cells at non-cytotoxic concentrations.  Dynasore was more potent when added post-entry and maintained in culture medium throughout the infection and completely blocked the release of infectious progeny into culture supernatants. Dynasore had little or no effect on viral binding, entry, or viral protein expression within the first 8 hours post-infection.  However, electron microscopy revealed only a few viral capsids within the nucleus in dynasore-treated cells compared to control cells, where abundant capsids were visualized throughout the nucleus, cytoplasm and at the plasma membrane. Moreover, dynasore blocked the spread of HSV between epithelial cells and from neuronal to epithelial cell.

Conclusion: Dynasore is a highly potent inhibitor of HSV infection that acts post-entry to impair viral capsid formation and prevent viral egress and cell-to-cell spread. Further identification of its precise target(s) will promote the development of a novel class of drugs to block primary and reactivating HSV infection.


Subject Category: V. Virology including clinical and basic studies of viral infections, including hepatitis

Mascha Mues, MD, Natalia Cheshenko, PhD, Duncan W. Wilson, PhD, Leslie Gunther-Cummins and Betsy C. Herold, MD, FIDSA, Albert Einstein College of Medicine, Bronx, NY

Disclosures:

M. Mues, None

N. Cheshenko, None

D. W. Wilson, None

L. Gunther-Cummins, None

B. C. Herold, None

Findings in the abstracts are embargoed until 12:01 a.m. EST Thursday, Oct. 20 with the exception of research findings presented at IDSA press conferences.