Generation of cytomegalovirus-specific human T-lymphocyte clones by using autologous B-lymphoblastoid cells with stable expression of pp65 or IE1 proteins: a tool to study the fine specificity of the antiviral response

Cytotoxic T lymphocytes (CTLs) play a central role in the control of persis tent human cytomegalovirus (HCMV) infection in healthy virus carriers. Prev ious analyses of the specificity of HCMV-reactive CD8(+) CTLs drawn from in vitro models in which antigen-presenting cells were autologous fibroblasts infected with laboratory HCMV strains have shown focusing of CTL responses against the major tegument protein, pp65. By contrast, the 72-kDa major im mediate-early protein (IE1) was identified as a minor target for this respo nse. Here we have studied the fine specificity and T-cell-receptor features of T-cell clones generated against autologous B lymphoblastoid cell lines stably transfected with HCMV cDNA coding for either pp65 or a natural varia nt of IEL. This strategy allowed efficient generation of T cell clones agai nst IE1 and pp65 and led to the identification of several new IE1 and pp65 epitopes, including some located in polymorphic regions of IE1. Such an app roach may provide relevant information about the characteristics of the CTL response to IE1 and the effect of viral polymorphism on the immune respons e against HCMV.