title: Effects of rapid antigen degradation and VEE glycoprotein specificity on immune responses induced by a VEE replicon vaccine.
abstract: Genetic vaccines are engineered to produce immunogens de novo in the cells of the host for stimulation of a protective immune response. In some of these systems, antigens engineered for rapid degradation have produced an enhanced cellular immune response by more efficient entry into pathways for processing and presentation of MHC class I peptides. VEE replicon particles (VRP), single cycle vaccine vectors derived from Venezuelan equine encephalitis virus (VEE), are examined here for the effect of an increased rate of immunogen degradation on VRP vaccine efficacy. VRP expressing the matrix capsid (MA/CA) portion of SIV Gag were altered to promote rapid degradation of MA/CA by various linkages to co-translated ubiquitin or by destabilizing mutations and were used to immunize BALB/c mice for quantitation of anti-MA/CA cellular and humoral immune responses. Rapid degradation by the N-end rule correlated with a dampened immune response relative to unmodified MA/CA when the VRP carried a glycoprotein spike from an attenuated strain of VEE. In contrast, statistically equivalent numbers of IFNgamma(+)T-cells resulted when VRP expressing unstable MA/CA were packaged with the wild-type VEE glycoproteins. These results suggest that the cell types targeted in vivo by VRP carrying mutant or wild type glycoprotein spikes are functionally different, and are consistent with previous findings suggesting that wild-type VEE glycoproteins preferentially target professional antigen presenting cells that use peptides generated from the degraded antigen for direct presentation on MHC.
authors: Carolina Vaccine Institute, University of North Carolina, Chapel Hill, NC 27599, USA. meagan_fluet@med.unc.edu
authors: M E
authors: ME
authors: Fluet
authors: A C
authors: AC
authors: Whitmore
authors: D A
authors: DA
authors: Moshkoff
authors: K
authors: K
authors: Fu
authors: Y
authors: Y
authors: Tang
authors: M L
authors: ML
authors: Collier
authors: A
authors: A
authors: West
authors: D T
authors: DT
authors: Moore
authors: R
authors: R
authors: Swanstrom
authors: R E
authors: RE
authors: Johnston
authors: N L
authors: NL
authors: Davis
mesh_terms: D000818:Animals; D000914:Antibodies, Viral / Q000097:blood; D000918:Antibody Specificity; D000956:Antigens, Viral / Q000235:genetics / Q000276:immunology / Q000378:metabolism*; D036022:Capsid Proteins / Q000235:genetics / Q000276:immunology / Q000378:metabolism; D002460:Cell Line; D006224:Cricetinae; D004666:Encephalitis Virus, Venezuelan Equine / Q000235:genetics* / Q000502:physiology; D015683:Gene Products, gag / Q000737:chemistry; D005822:Genetic Vectors; D006023:Glycoproteins / Q000235:genetics / Q000276:immunology*; D007114:Immunization; D007371:Interferon-gamma / Q000096:biosynthesis; D051379:Mice; D008807:Mice, Inbred BALB C; D012093:Replicon / Q000235:genetics / Q000276:immunology*; D013601:T-Lymphocytes / Q000276:immunology; D013997:Time Factors; D025801:Ubiquitin / Q000235:genetics / Q000378:metabolism; D014763:Viral Matrix Proteins / Q000235:genetics / Q000276:immunology / Q000378:metabolism; D014765:Viral Vaccines / Q000008:administration & dosage / Q000276:immunology*; D014771:Virion / Q000276:immunology / Q000378:metabolism
chemical_list: D000914:Antibodies, Viral; D000956:Antigens, Viral; D036022:Capsid Proteins; D015683:Gene Products, gag; D006023:Glycoproteins; D025801:Ubiquitin; D014763:Viral Matrix Proteins; D014765:Viral Vaccines; D007371:Interferon-gamma