DOMINANT RECOGNITION BY HUMAN CD8(-LYMPHOCYTES OF DENGUE VIRUS NONSTRUCTURAL PROTEINS NS3 AND NS1.2A() CYTOTOXIC T)

A severe complication of dengue virus infection, dengue hemorrhagic fe ver (DHF), is hypothesized to be immunologically mediated and virus-sp ecific cytotoxic T lymphocytes (CTLs) may trigger DHF. It is also like ly that dengue virus-specific CTLs are important for recovery from den gue virus infections. There is little available information on the hum an CD8(+) T cell responses to dengue viruses. Memory CD8(+)CTL respons es were analyzed to determine the diversity of the T cell response to dengue virus and to identify immunodominant proteins using PBMC from e ight healthy adult volunteers who had received monovalent, live-attenu ated candidate vaccines of the four dengue serotypes, All the donors h ad specific T cell proliferation to dengue and to other flaviviruses t hat we tested, CTLs were generated from the stimulated PBMC of all don ors, and in the seven donors tested, dengue virus-specific CD8(+)CTL a ctivity was demonstrated. The nonstructural (NS3 and NS1.2a) and envel ope (E) proteins were recognized by CD8(+)CTLs from six, five, and thr ee donors, respectively, All donors recognized either NS3 or NS1.2a. I n one donor who received a dengue 4 vaccine, CTL killing was seen in b ulk culture against the premembrane protein (prM). This is the first d emonstration of a CTL response against the prM protein. The CTL respon ses using the PBMC of two donors were serotype specific, whereas all o ther donors had serotype-cross-reactive responses, For one donor, CTLs specific for E, NS1.2a, and NS3 proteins were all HLA-B44 restricted, For three other donors tested, the potential restricting alleles for recognition of NS3 were B38, A24, and/or B62 and B35. These results in dicate that the CD8(+)CTL responses of humans after immunization with one serotype of dengue virus are diverse and directed against a variet y of proteins. The NS3 and NS1.2a proteins should be considered when d esigning subunit vaccines for dengue.