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190 Defining Host Cell Surface Proteins Incorporated into Virus-Like Particles Following Transfection with a Multi-Gene HIV-1 DNA Vaccine Construct
B. Li*1, J. Smith2, H. Robinson2, T. Folks1, S. Butera1, and D. Ellenberger1
1CDC, Atlanta, GA, USA and 2Vaccine Res. Ctr. of Emory Univ., Atlanta, GA, USA
Background: During the budding process, an assembling retrovirus acquires host proteins in the envelope. The assembly and budding process excludes some host proteins from the surface, whereas other host proteins may be enriched in the budding virus. By defining the host proteins incorporated into virus-like particles (VLPs) following transfection with an HIV-1 DNA vaccine and determining the antigenic phenotype, we may be able to improve the immunogenicity of the candidate vaccine and thus provide beneficial effects.
Methods: Two different cell lines (BJAB and 293T) were transiently transfected with multi-gene HIV-1 DNA vaccine constructs, including HIV-1 subtypes B and A/G. A modified vaccine construct (truncated-env) was also analyzed. An immunomagnetic capture assay, using a panel of monoclonal antibodies targeting various host cell-surface antigens, was employed to capture VLPs recovered from the culture supernatant. VLP quantification was measured by detection of HIV-1-specific p24 core antigen. Host cell surface molecule expression on transfected and untransfected cells was analyzed by FACS.
Results: HLA class II molecules but not class I were detected on the membrane of VLPs recovered from BJAB transfections. The amount of the HLA class II varied depending on the DNA constructs used to transfect the cells. Antibodies to other antigens expressed at high level on both transfected and untransfected cells did not significantly capture VLPs. HLA class I and class II maintained the same level of expression in BJAB cells following transfection of the DNA vaccine construct.
Conclusions: HLA class II antigens are incorporated into VLPs produced by HIV-1 DNA vaccines. CD54, CD55, CD71, and HLA class I molecules could not be detected in the VLPs suggesting selective exclusion from the VLP envelope of other host proteins.
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