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
✍ Scribed by Barbara Doe; Kathelyn S. Steimer; Christopher M. Walker
- Publisher
- John Wiley and Sons
- Year
- 1994
- Tongue
- English
- Weight
- 856 KB
- Volume
- 24
- Category
- Article
- ISSN
- 0014-2980
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✦ Synopsis
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.