SELECTION OF A DIVERSE TCR REPERTOIRE IN RESPONSE TO AN EPSTEIN-BARR-VIRUS-ENCODED TRANSACTIVATOR PROTEIN BZLF1 BY CD8(-LYMPHOCYTES DURING PRIMARY AND PERSISTENT INFECTION() CYTOTOXIC T)

We investigated the CD8(+) cytotoxic T lymphocyte (CTL) repertoire to an HLA B8-restricted peptide, RAKFKQLLQ, located in the Epstein-Barr v irus (EBV) immediate-early protein, BZLF1, Repertoire selection was mo nitored by determining the TCR beta chain sequences of RAKFKQLLQ-speci fic CTL established from primary infected and healthy virus carriers, PCR analysis of spontaneous EBV-transformed lymphoblastoid cell lines (LCL) from three individuals with primary infection showed that two we re infected with type A and one with type B EBV. Polyclonal and clonal CTL that were generated by stimulating peripheral blood mononuclear c ells with an HLA B8(+) homozygous LCL lysed T cell blasts pulsed with the peptide, RAKFKQLLQ; lysis of certain HLA B8(+) LCL targets was ass ociated with the abundance of BZLF1 transcripts, TCR beta analysis sho wed that while there was loop length restriction in the putative pepti de contact site of all responding beta chains, diverse and unique (non -recurrent) TCR beta clonotypes were selected in individuals during pr imary infection and continued to emerge after long-term virus exposure , TCR-contact site heterogeneity was excluded as the selective force i n diversity generation since the epitope-encoded sequences were found to be identical within endogenous virus isolates. In this first study of TCR repertoire selection for an EBV lytic antigen, a BZLF1-reactive component of diverse clonotypes was identified in primary type A or t ype B EBV infection which was sustained in the EBV-specific memory res ponse throughout life-long infection. This diversity selection is like ly to play a critical role in maintaining a balanced viral load throug hout EBV persistence.