title: Peptide impurities in commercial synthetic peptides and their implications for vaccine trial assessment.
abstract: The advent of T-cell assay methodologies that are amenable to high throughput coupled with the availability of large libraries of overlapping peptides have revolutionized the fields of vaccine efficacy testing and cellular immune response assessment. Since T-cell assay performance is critically dependent upon the quality and specificity of the stimulating peptides, assurance of high-quality and reliable input peptides is an important aspect of assay validation. Herein, we demonstrate that individual peptides from large human immunodeficiency virus (HIV)-based peptide library sets obtained directly from two independent custom peptide suppliers contained contaminating peptides capable of giving false-positive results, which were consistent with nominal antigen-specific CD8+ T-cell responses. In-depth investigation of the cellular response in terms of responding CD8+ T-cell frequency and human leukocyte antigen (HLA) restriction led to the conclusion that one set of HIV type 1 (HIV-1)-derived peptides was contaminated with a peptide from human cytomegalovirus (HCMV), which is commonly used in cellular immunology research applications. Analytical characterization of the original stock of the suspect HIV-1 peptide confirmed the presence of approximately 1% by weight of the HCMV peptide. These observations have critical implications for quality assurance (QA) and quality control (QC) of peptides used in clinical trials where cellular immune-based assays are important end-point determinants. We propose a simple schema of biological QA/QC protocols to augment the standard biochemical QA/QC analyses as a means to circumvent this and other problems that can affect cellular immune-based assay outcome and interpretation.
authors: U.S. Military HIV Research Program, Rockville, Maryland 20850, USA. jcurrier@hivresearch.org
authors: Jeffrey R
authors: JR
authors: Currier
authors: Lynee M
authors: LM
authors: Galley
authors: Holger
authors: H
authors: Wenschuh
authors: Vivian
authors: V
authors: Morafo
authors: Silvia
authors: S
authors: Ratto-Kim
authors: Clive M
authors: CM
authors: Gray
authors: Leonard
authors: L
authors: Maboko
authors: Michael
authors: M
authors: Hoelscher
authors: Mary A
authors: MA
authors: Marovich
authors: Josephine H
authors: JH
authors: Cox
mesh_terms: D016915:AIDS Vaccines / Q000276:immunology*; D018414:CD8-Positive T-Lymphocytes / Q000276:immunology*; D019411:Clinical Laboratory Techniques / Q000592:standards*; D003587:Cytomegalovirus / Q000737:chemistry; D004340:Drug Contamination; D006678:HIV; D015497:HIV-1 / Q000276:immunology*; D006801:Humans; D019151:Peptide Library; D011785:Quality Assurance, Health Care; D011786:Quality Control; D014764:Viral Proteins / Q000032:analysis
chemical_list: D016915:AIDS Vaccines; D019151:Peptide Library; D014764:Viral Proteins