Case Study:
Researchers at the University of Manitoba use PEPscreen® Library for Epitope Mapping

McKinnon, LR. et al. (2005). Cross-clade CD8(+) T-cell responses with a preference for the predominant circulating clade. Acquired Immune Deficiency Syndrome. 40(3): 245-249. [PubMed ID: 16249696]

elispot A PEPscreen® custom peptide library was used for epitope mapping experiments in a study of CD8+ T cell responses in HIV-infected patients. The HIV Env peptide sequence library comprised of 158 15mers overlapping by 10 amino acids and represented the sequence of the HIV clade A recombinant vaccinia (vp1489). Peptide ELISPOT assays to determine interferon gamma production were performed and individual peptide responses were confirmed in separate ELISPOT assays. Results from the epitope mapping experiments indicated CD8+ T cell recognition of conserved regions of Env.

There is evidence to suggest that CD8+ T cells play an important role in containing HIV infection and several vaccine candidates are aimed at CD8+ T cell responses. A better understanding of cross-clade CD8+ T cell responses to HIV may help to predict whether a successful vaccine could be used to stop geographically and genetically distinct HIV epidemics.

In a related study PEPscreen® custom peptide libraries were constructed to investigate the T cell responses of HIV-resistant individuals. In this case the PEPscreen® library consisted of peptides 9 amino acids in length, overlapping by one amino acid. It provided the opportunity to screen the immunological responsiveness of every conceivable optimal-length epitope in the HIV Env vaccinia protein and was applied in a number of immunological assays. Further use of PEPscreen® peptide libraries was made by the group to study how HIV diversity affects cellular immune responses. The PEPscreen® peptides were used in ELISPOT, flow cytometric and cell culture assays. A library was designed to test variations in the most common version of a particular epitope in order to investigate how specific amino acid mutations affect T cell recognition.

Strategies involving the investigation of T cell responses and epitope mapping, combined with determining the HIV sequence infecting the patient will provide a better understanding of the interaction between the immune system and HIV evolution.