English (United Kingdom)

https://curated-unify.zendy.io/wp-json/zendy-region/v1/featured_content/oa?rat=en

https://curated-unify.zendy.io/wp-json/zendy-region/v1/highlighted_journal/

Global: Zendy Plus annual

Presents the access of premium content as premium feature

Premium Content

Presents the keyphrase highlighting as premium feature

Keyphrase Highlighting

Presents the summarisation as premium feature

Summarisation

Insights

Presents the pdf analysis as premium feature

PDF Analysis

Presents the zaia usage as premium feature

ZAIA

Global: Zendy Tools annual

Global: Zendy Free Plan

Global: Zendy Tools monthly

Global: Zendy Plus monthly

Residual immunity to the smallpox virus raises key questions about the persistence of long-term immune memory in the absence of antigen, since vaccination ended in 1980. IFN-gamma-producing effector-memory and proliferative memory T cells were compared in 79 vaccinees 13-25 yr after their last immunization and in unvaccinated individuals. Only 20% of the vaccinees displayed both immediate IFN-gamma-producing effector-memory responses and proliferative memory responses at 6 d; 52.5% showed only proliferative responses; and 27.5% had no detectable vaccinia-specific responses at all. Both responses were mediated by CD4 and CD8 T cells. The vaccinia-specific IFN-gamma-producing cells were composed mainly of CD4Pos CD45RANeg CD11aHi CD27Pos and CCR7Neg T cells. Their frequency was low but could be expanded in vitro within 7 d. Time since first immunization affected their persistence: they vanished 45 yr after priming, but proliferative responses remained detectable. The number of recalls did not affect the persistence of residual effector-memory T cells. Programmed revaccination boosted both IFN-gamma and proliferative responses within 2 mo of recall, even in vaccinees with previously undetectable residual effector-memory cells. Such long-term maintenance of vaccinia-specific immune memory in the absence of smallpox virus modifies our understanding of the mechanism of persistence of long-term memory to poxviruses and challenges vaccination strategies.

Distinct Time Effects of Vaccination on Long-Term Proliferative and IFN-γ–producing T Cell Memory to Smallpox in Humans