Emerging Infectious Diseases • www.cdc.gov/eid • Vol. 14, No. 1, January 2008 peptides were used as antigens for cell-mediated immunity. Infl uenza virus (H5N1) was inactivated by exposure to UV light for 10 min, and complete inactivation of UV-exposed virus was checked by infecting MDCK monolayers with undiluted preparation and by back-titrating the infectivity after 5 days postinfection. Four synthetic peptides of the infl uenza (H5N1) were purchased from Biodesign International (Kennebunk, ME, USA). The sequence of these peptides is specifi c for H5-C-terminal (15 aa), H5-middle region (14 aa), and N1-C-terminal (15 aa) and for N1middle region (16 aa), with no cross-matching with other HA and NA sequences. These peptides can bind different HLA-DRB1 alleles, as established according to the SYF-PEITHI site (www.syfpeithi.de). Specifi cally, N1-specifi c peptides can bind the following HLA-DR alleles: HLA-DRB1*0101, B1*0301, B1*0401, B1*0701, B1*1101, B1*1501. The H5-specifi c peptide from the N-terminal region binds several HLA-DR alleles (HLA-DRB1*0101, B1*0301, B1*0401, B1*0701, B1*1101, B1*1501). In contrast, the H5-specifi c peptide from the middle region did not appear to bind any HLA-DR alleles. According to the HLA-DRB1 allele frequency in the local population, these peptides can be effi ciently presented by most (up to 84%) of study participants.