Abstract:
New World alphaviruses belonging to the family Togaviridae are known to infect humans
and equines and cause encephalitic disease. The New World alphaviruses are classified as
emerging infectious agents and Category B select agents. There are concentrated efforts
dedicated to the development of medical countermeasures to New World alphavirus
infections including therapeutics and vaccines. Our current study is focused on the role of
the host extracellular signal-regulated kinase (ERK) in the infectious process of New
World alphaviruses. We demonstrate that infection of human astrocytoma cells by
Venezuelan equine encephalitis virus (VEEV) results in the activation of many signaling
molecules of the ERK-signaling cascade. Inhibition of ERK1/2 by the small molecule
inhibitor Ag-126 results in inhibition of viral multiplication. Time of addition studies
reveal that Ag-126-mediated inhibition of VEEV occurs during early and later stages of
the infectious process, likely affecting early, post-entry events and late, exit events. While our studies revealed that expression of viral structural proteins was modestly downregulated
in Ag-126 treated cells, we did not observe any influence of Ag-126 on the
nuclear and cytoplasmic distribution of the viral capsid protein. Studies focused on the
survival of host cells in the presence of Ag-126 indicated an increased percentage of cells
that survived the infection in the presence of Ag-126. Finally, extending our studies to
virulent strains of VEEV, Eastern and Western equine encephalitis viruses (EEEV and
WEEV) revealed that Ag-126 exerted a broad-spectrum inhibitory effect on New World
alphavirus multiplication, thus indicating that the host kinase, ERK, is a broad-spectrum
candidate for development of novel therapeutics against New World alphaviruses.
