title: Induction of HIV-1 envelope (gp120)-specific cytotoxic T lymphocyte responses in mice by recombinant CHO cell-derived gp120 is enhanced by enzymatic removal of N-linked glycans.
abstract: Priming of CD8+ cytotoxic T lymphocyte (CTL) responses with recombinant proteins has been facilitated by the development of novel adjuvants that deliver antigens into the class I major histocompatibility complex (MHC) pathway. However, the extent to which secondary structure or glycosylation of these proteins prevents priming of class I MHC-restricted CTL responses is not clear. To address this issue, recombinant HIV-1 gp120 envelope proteins produced in yeast insect, or mammalian cells were compared for the ability to elicit CD8+ CTL activity in mice. Envelope-specific CD8+ T lymphocytes were detected in BALB/c mice immunized with env 2-3, a 55-kDa yeast-derived envelope protein that is not glycosylated and lacks a native conformation. This response was directed against a previously described epitope in the V3 region of gp120, as well as a newly identified epitope located near the carboxy-terminus of the molecule. Similar levels of V3-directed CTL activity were observed in mice immunized with recombinant gp120 produced in insect (Spodoptera fugiperda) cells using a baculovirus expression system (gp120BAC). In contrast, induction of CTL responses was considerably less efficient when mice were immunized with gp120CHO, a native, fully glycosylated envelope protein produced in mammalian CHO cells. Denaturation of gp120CHO prior to immunization was not sufficient to prime CTL responses. However, envelope-specific CD8+ CTL activity was elicited when N-linked glycans were removed by treatment with an endoglycosidase. Possible mechanisms by which N-linked glycans influence delivery or processing of recombinant proteins for class I MHC presentation, and the implications of these findings for the design of subunit vaccines, are discussed.
authors.affiliation: Department of Virology, Chiron Corporation, Emeryville, CA 94608.
authors.forename: B
authors.initials: B
authors.lastname: Doe
authors.forename: K S
authors.initials: KS
authors.lastname: Steimer
authors.forename: C M
authors.initials: CM
authors.lastname: Walker
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D003602:Cytotoxicity, Immunologic; D000939:Epitopes; D005260:Female; D006023:Glycoproteins / Q000276:immunology*; D015699:HIV Envelope Protein gp120 / Q000737:chemistry* / Q000276:immunology; D015497:HIV-1 / Q000276:immunology*; D007111:Immunity, Cellular; D051379:Mice; D008807:Mice, Inbred BALB C; D008969:Molecular Sequence Data; D010455:Peptides / Q000737:chemistry; D011994:Recombinant Proteins / Q000737:chemistry / Q000276:immunology*; D013329:Structure-Activity Relationship; D013602:T-Lymphocytes, Cytotoxic / Q000276:immunology*
chemical_list: D000939:Epitopes; D006023:Glycoproteins; D015699:HIV Envelope Protein gp120; D010455:Peptides; D011994:Recombinant Proteins