Analysis of T helper cell response to glycoprotein H (gpUL75) of human cytomegalovirus: evidence for strain-specific T cell determinants.

The proliferative response of helper T cells against glycoprotein H (gH; gpUL75) of human cytomegalovirus (HCMV) was determined in T cell lines from 5 healthy HCMV-seropositive donors. A differential response in two lines was noted when gH from strain AD169 or Towne was used as antigen. T cell-reactive domains between aa 15 and 510 were identified using beta-galactosidase fusion proteins containing overlapping fragments of gH, and they were confirmed with synthetic peptides as stimulating antigen. T cell proliferation was observed with antigens containing aa 34-51, 111-142, 284-302, 324-342, and 454-510 of gH. None of the determinants stimulated all donors. The T cell epitope defined by aa 34-51 is located in close proximity to a strain-specific dominant B cell epitope; however, no strain dependence for this T cell determinant was observed. In contrast, the dominant T cell response against aa 284-302, which was observed in three T cell lines, was strain specific.