- Georg-Speyer-Haus (3) (remove)
- Optimization and antiviral analysis of peptide ligands for the HIV-1 packaging signal PSI (2006)
- Oral presentations Background: We selected peptide ligands for the HIV-1 packaging signal PSI by screening phage displayed peptide libraries. Peptide ligands were optimized by screening spot synthesis peptide membranes. The aim of this study is the functional characterization of these peptide ligands with respect to inhibition of HIV-1 replication. Methods: Phage displayed peptide libraries were screened with PSI-RNA structures. The Trp-rich peptide motifs were optimized for specific binding on spot synthesis peptide membranes. The best binding peptide was expressed intracellularly in fusion with RFP or linked to a protein transduction domain (PTD) for intracellular delivery. The effects on virion production were analyzed using pseudotyped lentiviral particles. Results: After positive and negative selection rounds, phages binding specifically to PSI-RNA were identified by ELISA. Peptide inserts contained conserved motifs of aromatic amino acids known to be implicated in binding of PSI-RNA by the natural Gag ligand. The filter assay identified HKWPWW as the best binding ligand for PSI-RNA, which is delivered into several cell lines by addition of a PTD. Compared to a control peptide, the HKWPWW peptide inhibited HIV-1 replication as deduced from reduced titers of culture supernatants. As HKWPWW also binds to the TAR-RNA like the natural nucleocapsid PSI-RNA ligand, the effect on Tat-TAR inhibition will also be analyzed. Currently T-cell lines are established which stably express HKWPWW as well as a control peptide, which will be infected with HIV-1 to monitor the ability of HKWPWW to inhibit wild type HIV-1 replication. Conclusion: The selection of a peptide ligand for PSI-RNA able to inhibit HIV-1 replication proves the suitability of the phage display technology for the selection of peptides binding to RNA-structures. This enables the indentification of peptides serving as leads to interfere with additional targets in the HIV-1 replication cycle.
- Ökosystem statt Nutzwald (2011)
- Functional Characterization of Two scFv-Fc Antibodies from an HIV Controller Selected on Soluble HIV-1 Env Complexes: A Neutralizing V3- and a Trimer-Specific gp41 Antibody (2014)
- HIV neutralizing antibodies (nAbs) represent an important tool in view of prophylactic and therapeutic applications for HIV-1 infection. Patients chronically infected by HIV-1 represent a valuable source for nAbs. HIV controllers, including long-term non-progressors (LTNP) and elite controllers (EC), represent an interesting subgroup in this regard, as here nAbs can develop over time in a rather healthy immune system and in the absence of any therapeutic selection pressure. In this study, we characterized two particular antibodies that were selected as scFv antibody fragments from a phage immune library generated from an LTNP with HIV neutralizing antibodies in his plasma. The phage library was screened on recombinant soluble gp140 envelope (Env) proteins. Sequencing the selected peptide inserts revealed two major classes of antibody sequences. Binding analysis of the corresponding scFv-Fc derivatives to various trimeric and monomeric Env constructs as well as to peptide arrays showed that one class, represented by monoclonal antibody (mAb) A2, specifically recognizes an epitope localized in the pocket binding domain of the C heptad repeat (CHR) in the ectodomain of gp41, but only in the trimeric context. Thus, this antibody represents an interesting tool for trimer identification. MAb A7, representing the second class, binds to structural elements of the third variable loop V3 and neutralizes tier 1 and tier 2 HIV-1 isolates of different subtypes with matching critical amino acids in the linear epitope sequence. In conclusion, HIV controllers are a valuable source for the selection of functionally interesting antibodies that can be selected on soluble gp140 proteins with properties from the native envelope spike.