Methods in molecular biology (Clifton, N.J.) 02/2002; 182:67-70.
ABSTRACT: The antigenic polymorphism of HIV-1 is a major obstacle in developing an effective vaccine. Accordingly, we screened random peptide libraries (RPLs) displayed on phage with antibodies from HIV-infected individuals and identified an array of HIV-specific epitopes that behave as antigenic mimics of conformational epitopes of gp120 and gp41 proteins. We report that the selected epitopes are shared by a collection of HIV-1 isolates of clades A-F. The phage-borne epitopes are immunogenic in rhesus macaques, where they elicit envelope-specific antibody responses. Upon intravenous challenge with 60 MID50 of pathogenic SHIV-89.6PD, all monkeys became infected; however, in contrast to the naive and mock-immunized monkeys, four of five mimotope-immunized monkeys experienced lower levels of peak viremia, followed by viral set points of undetectable or transient levels of viremia and a mild decline of CD4+ T cells, and were protected from progression to AIDS-like illness. These results provide a new approach to the design of broadly protective HIV-1 vaccines.
Nature Medicine 12/2001; · 22.46 Impact Factor
ABSTRACT: We report the characterization of a CAAT enhancer-binding protein (C/EBP) (NF-IL6) element encompassing the region from −174
to −166 of the U3 long terminal repeat (LTR) region of HIV-1. This C/EBP cis sequence was found to bind to C/EBPβ and C/EBPδ factors in DNA band shift assay. Transfection of NTera-2 cells with a HIV-1-LTR
CAT construct (pC15CAT), together with C/EBPβ or C/EBPδ expression plasmids showed that C/EBP proteins strongly activated
the HIV-1 promoter. Deletions encompassing the C/EBP-binding site resulted in the enhancement of the LTR activation mediated
by C/EBP proteins, suggesting that other sequences located 3′ to −170 were indeed the target for C/EBP factors. This possibility
was confirmed by using the pCD54E9CAT plasmid, in which the NF-κB enhancer was inserted 5′ to the HIV-1 LTR TATA box. A NF-κB1(p50)
expression plasmid was also utilized to test for functional co-operation between NF-κB and C/EBP factors. We observed that
p50·C/EBPβ and p50·C/EBPδ complexes were generated in tested cells and strongly activated the HIV-1 LTR by binding to the
NF-κB sequences. The physical association of NF-κB1(p50) with C/EBP factors was assayed by direct interaction of in vitro translated p50 proteins with C/EBPβ or C/EBPδ produced as glutathione S-transferase fusion proteins. Moreover, p50·C/EBPβ complexes were observed in vivo by using DNA affinity studies with biotinylated NF-κB oligonucleotides. By using mutant forms of p50 or C/EBPβ proteins we
found that the transactivation of HIV-1 LTR by p50·C/EBPβ complexes required the DNA-binding domain of p50 and the transcription
activation domain of C/EBPβ.
Journal of Biological Chemistry 09/1996; 271(37):22479-22486. · 4.77 Impact Factor