Cytotoxic T lymphocyte (CTL) responses to human cytomegalovirus pp65, IE1-exon4, gB, pp150, and pp28 in healthy individuals:: Reevaluation of prevalence of IE1-specific CTLs

The prevalence of human cytomegalovirus (HCMV) pp65-, pp150-, IE1-exon4-, gB- and pp28-specific cytotoxic T lymphocyte (CTL) responses was compared among 34 healthy individuals, grouped by neutralizing antibody titers, Moderately and highly seropositive donors showed predominantly pp65- and IE1-exon4-specific CTL responses (92% and 76% of the donors, respectively), with similar precursor frequencies in the 2 donors tested. In addition, highly seropositive and a few moderately seropositive donors showed CTL responses to gB and pp150 (33% and 30% of the donors, respectively). No individual recognized pp28 as a target in the CTL assay. Phenotypic analysis revealed a mixed effector population of CD4(+) and CD8(+) (1 donor) or only CD8(+) cells for pp65-specific effectors (2 donors). IE1-exon4- and pp150-specific effecters were CD8(+) (2 donors and 1 donor, respectively), whereas gB-specific CTLs were CD4(+) (1 donor). These data may help to design a cellular immunity-based vaccine effective against HCMV disease.