Multiple phosphatidylinositol 3-kinases regulate vaccinia virus morphogenesis.
Poxvirus morphogenesis is a complex process that involves the successive wrapping of the virus in host cell membranes. We screened by plaque assay a focused library of kinase inhibitors for those that caused a reduction in viral growth and identified several compounds that selectively inhibit phosphatidylinositol 3-kinase (PI3K). Previous studies demonstrated that PI3Ks mediate poxviral entry. Using growth curves and electron microscopy in conjunction with inhibitors, we show that that PI3Ks additionally regulate morphogenesis at two distinct steps: immature to mature virion (IMV) transition, and IMV envelopment to form intracellular enveloped virions (IEV). Cells derived from animals lacking the p85 regulatory subunit of Type I PI3Ks (p85alpha(-/-)beta(-/-)) presented phenotypes similar to those observed with PI3K inhibitors. In addition, VV appear to redundantly use PI3Ks, as PI3K inhibitors further reduce plaque size and number in p85alpha(-/-)beta(-/-) cells. Together, these data provide evidence for a novel regulatory mechanism for virion morphogenesis involving phosphatidylinositol dynamics and may represent a new therapeutic target to contain poxviruses.
Microbiology and Molecular Genetics Graduate Program, Emory University School of Medicine, Atlanta, Georgia, United States of America.
Shannon
S
McNulty
William
W
Bornmann
Jill
J
Schriewer
Chas
C
Werner
Scott K
SK
Smith
Victoria A
VA
Olson
Inger K
IK
Damon
R Mark
RM
Buller
John
J
Heuser
Daniel
D
Kalman
D002460:Cell Line; D049452:Green Fluorescent Proteins / Q000378:metabolism; D006801:Humans; D020128:Inhibitory Concentration 50; D009024:Morphogenesis / Q000187:drug effects; D019869:Phosphatidylinositol 3-Kinases / Q000172:deficiency / Q000378:metabolism*; D047428:Protein Kinase Inhibitors / Q000633:toxicity; D021381:Protein Transport / Q000187:drug effects; D014616:Vaccinia virus / Q000187:drug effects / Q000254:growth & development* / Q000648:ultrastructure; D014764:Viral Proteins / Q000096:biosynthesis; D014771:Virion / Q000187:drug effects / Q000378:metabolism / Q000648:ultrastructure
D047428:Protein Kinase Inhibitors; D014764:Viral Proteins; D049452:Green Fluorescent Proteins; D019869:Phosphatidylinositol 3-Kinases