Analysis of Venezuelan equine encephalitis replicon particles packaged in different coats.
BACKGROUND
The Venezuelan equine encephalitis (VEE) virus replicon system was used to produce virus-like replicon particles (VRP) packaged with a number of different VEE-derived glycoprotein (GP) coats. The GP coat is believed to be responsible for the cellular tropism noted for VRP and it is possible that different VEE GP coats may have different affinities for cells. We examined VRP packaged in four different VEE GP coats for their ability to infect cells in vitro and to induce both humoral and cellular immune responses in vivo.


RESULTS
The VRP preparations were characterized to determine both infectious units (IU) and genome equivalents (GE) prior to in vivo analysis. VRP packaged with different VEE GP coats demonstrated widely varying GE/IU ratios based on Vero cell infectivity. BALB/c mice were immunized with the different VRP based on equal GE titers and the humoral and cellular responses to the expressed HIV gag gene measured. The magnitude of the immune responses measured in mice revealed small but significant differences between different GP coats when immunization was based on GE titers.


CONCLUSIONS
We suggest that care should be taken when alternative coat proteins are used to package vector-based systems as the titers determined by cell culture infection may not represent accurate particle numbers and in turn may not accurately represent actual in vivo dose.
Kamrud
Kurt I
KI
AlphaVax, Inc., Research Triangle Park, North Carolina, United States of America. kamrud@alphavax.com
Alterson
Kim D
KD
Andrews
Chasity
C
Copp
Laura O
LO
Lewis
Whitney C
WC
Hubby
Bolyn
B
Patel
Deepa
D
Rayner
Jonathan O
JO
Talarico
Todd
T
Smith
Jonathan F
JF
D000818:Animals; D004666:Encephalitis Virus, Venezuelan Equine / Q000378:metabolism*; D004685:Encephalomyelitis, Venezuelan Equine / Q000821:virology; D004797:Enzyme-Linked Immunosorbent Assay; D005260:Female; D005822:Genetic Vectors; D016678:Genome; D006023:Glycoproteins / Q000737:chemistry; D007107:Immune System; D051379:Mice; D008807:Mice, Inbred BALB C; D009154:Mutation; D012093:Replicon; D020133:Reverse Transcriptase Polymerase Chain Reaction
D006023:Glycoproteins