Federal Republic of Germany

The regulation of antigen processing and presenta-tion to MHC c1ass I-restricted cytolytic T Iymphocytes was studled In cells Infected wlth murine cytomegalo-virus. Recognitlon by cytolytlc T Iymphocytes 01 the phosphoprotein pp89, the Immunodomlnant viral anti-gen expressed in the Immediate-early phase of infec-tion, was selectively prevented during the subsequent expression of viral early genes. The surface expres-sion 01 MHC class I glycoprotelns and their capaelty to present externally added pp89-derlved antigenie pep-tides were not affected. Because recognition of sev-eral other antigens oeeurred during the early phase, a general fallure In processlng and presentation was exeluded. Sinee neither rate 0 ' synthesls, amount, stabllity, nor nuclear transport 0 ' pp89 was modi'led