Cytotoxicity of human peripheral blood T-lymphocyte clones activated by hepatitis B virus surface antigen

Summary The present studies examined the cytotoxic activities of peripheral blood lymphocytes (PBL) from volunteers with (sero-positive) and without (sero-negative) circulating antibodies to hepatitis B virus surface antigen before and 30 days after vaccination with hepatitis B virus surface antigen (HBsAg). Long-term culture of monospecific hepatitis B surface (HBsAg)-responsive T-lymphocytes were isolated and grown in large numbers. The mechanism of T-cell mediated cytolysis, and the identification of the carbohydrate determinants on the surface of these effector cells responsible for the killing effect, are being examined.     

Peptide aptamers: exchange of the thioredoxin-A scaffold by alternative platform proteins and its influence on target protein binding

Peptide aptamers have emerged as powerful new tools for molecular medicine. They can specifically bind to and functionally inactivate a given target molecule under intracellular conditions. Typically, peptide aptamers are generated by screening a randomized peptide expression library, displayed from the Escherichia coli thioredoxin A (TrxA) protein. Here, we transferred peptide moieties from defined TrxA-based peptide aptamers to alternative scaffold proteins, such as the green fluorescent protein and staphylococcal nuclease. Yeast and mammalian two-hybrid assays as well as in vitro binding analyses show that the TrxA scaffold can be a major determinant for the binding of peptide aptamers. In addition, we demonstrate that TrxA can correctly display peptide sequences that correspond to the binding domains of natural interaction partners. Therefore, sequence analyses of TrxA-based peptide aptamers, isolated by two-hybrid screening from randomized expression libraries, should also be useful to find cellular binding partners for a given target protein, by homology. Received 1 August 2002; received after revision 17 September 2002; accepted 19 September 2002 RID="*" ID="*"Corresponding author.