Establishment of an in vitro system for testing cytomegalovirus-specific immune response

Ohiective To establish an in vitro test system for testing CMV specific immune response. Methods Human embryonic lung fibroblasts(HELF)infected with CMV-AD169 and a mutant strain RV-TB40E-4, respectively, were stained with anti-HLA-A * 0201-PE and then measured for the expression of HLA-A * 0201. The infected HELF were incubated with individual pp65 peptide NLVPMVATV and cultured together with PBMC,then intracellular IFN-γ was tested by flow cytometry(FCM). Results The expression of HLA-A * 0201 was markedly suppressed on AD169-infected fibroblasts, while it was not affected on RV-TB40E-4-infected cells. PBMC showing no response to AD169-infected cells responded significantly to RV-TB40E-4-infected cells. The HELF infected with AD169 and loaded with external peptides induced a significantly stronger response which was the sum of the induced response ratios of the infected HELF and the uninfected HELF loaded with peptides. Conclusion CMV-AD169 downregulates the expression of MHC Ⅰ, while it does not decrease the capacity of cells to present external peptides. RV-TB40E-4,a CMV mutant in which the gene of US2-6/US11 has been deleted, does not affect MHC Ⅰ expression, and therefore represents a more suitable tool to explore CMV-specific immune response. Key words: Cytomegalovirus; Specific immune response; Antigen presentation