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Updated: Jul 19, 2026
Peptide-based Identification of Functional Motifs and their Binding Partners
Published on: June 30, 2013
Replicating Ad-recombinants encoding non-myristoylated rather than wild-type HIV Nef elicit enhanced cellular
Bo Peng1, Rebecca Voltan, Anthony D Cristillo
1Vaccine Branch, Center for Cancer Research, National Cancer Institute, 41 Medlars Drive, Bethesda, MD 20892, USA.
Objective:
To determine if immunization with non-myristoylated nef would elicit enhanced cellular immune responses resulting from improved presentation of Nef peptides by MHC-I on the cell surface, and enhanced T-cell help.
Design:
The myristoylation site of HIV and SIV Nef is required for several Nef functions that modulate the immune response in an infected host, including downregulation of MHC-I, MHC-II, and CD4, and increased expression of the invariant chain on the cell surface. We constructed replication-competent Ad5- and Ad7-HIV recombinants encoding wild-type nef (nefWT) or a nef mutant (nefNM) lacking 19 amino-terminal amino acids, including the myristoylation site, and sequentially immunized chimpanzees mucosally, first with Ad5-HIVnef recombinants and subsequently with Ad7-HIVnef recombinants.
Methods:
Peripheral blood lymphocytes were evaluated over the immunization course for Nef-specific cellular immune responses by interferon (IFN)-gamma ELISPOT and T-cell proliferation assays. Nef-specific CD4 and CD8 memory T cells that produced intracellular IFN-gamma, interleukin-2, and tumor necrosis factor (TNF)-alpha were assessed by flow cytometry.
Results:
In comparison to immunization with Ad-HIVnefWT, Ad-HIVnefNM elicited statistically significant increases in numbers of IFN-gamma-secreting cells after the Ad7-HIVnefNM immunization and increased T-cell proliferative responses following both Ad5- and Ad7-HIVnefNM immunizations. Nef-specific CD4 and CD8 memory T-cell populations secreting TNF-alpha were also significantly increased in the Ad-HIVnefNM immunization group.
Conclusions:
The results support the hypothesis that immunization with Ad-recombinants encoding HIVnefNM rather than HIVnefWT elicits enhanced cellular immunity resulting from improved antigen presentation and greater T-cell help.
