Table 2: Evidence for a role of CTLs in cross-protective immunity against influenza virus infections.

Subtype used
PrimingChallengeSpeciesExperimentCommentsRef

H1N1H1N1MouseAdoptive transferSplenocytes depleted from CD8+ T cells failed to protect against infection.[25]
H1N1 or H3N2H1N1 or H3N2MouseAdoptive transferT cells afford protection against infection with heterosubtypic strain.[48]
H3N2H3N2Nude mouseAdoptive transferImmune spleen cells from Balb-c mice mediated more rapid clearance of virus infection and correlated with cytolytic activity.[49]
H3N2H1N1
H3N2
H2N2
MouseAdoptive transferMouse NP-specific CTL clone afforded protection.[50]
NP from H3N2H1N1MouseNP priming promoted recovery and was attributed to cross-reactive CTLs.[51]
H2N2H1N1MouseAdoptive transferCross-reactive CTL clones conferred protection.[52]
H3N2H3N2MouseAdoptive transferNP-specific CTL clone reduced lung virus titers and mortality rates.[53]
H1N1H3N2MouseDepletion of T cellsCTLs conferred heterosubtypic immunity and reduced virus titers in the respiratory tract.[54]
H3N2H1N1MouseProtection correlated with CTL response.[45]
H9N2H5N1MouseProtection correlated with CTL response to NP or PB2.[46]
H1N1H2N2Mice KO for Ig or γ/δ T cellsAcute depletion of CD8+ T cellsIn absence of Ig or T cells, CTLs conferred protection.[44]
H1N1H3N2MouseProtection correlated with CTL response to NP.[43]
H3N2H5N1MouseProtection correlated with CTL response to NP and PA.[42]
Gamma-irradiated virusesH1N1MouseAdoptive transfer of CD8+ T cellsCTL but not B cells afforded protection.[36]
H3N22009 pH1N1MouseDepletion of CD8+ T cellsCTL conferred heterosubtypic immunity to 2009 pH1N1 virus.[55]
H3N22009 pH1N1MouseAdoptive transfer of CD8+ and CD4+ T cellsCTL conferred heterosubtypic immunity to 2009 pH1N1 virus.[22]

H9N2H5N1ChickenAdoptive transfer of CD8+ T cellsCTLs reduced mortality rates.[56]
H9N2H5N1ChickenDepletionCTLs reduced mortality rates.[57]

H3N2H5N1FerretProtection correlated with CTL response.[58]

H1N1HumanCTL activity correlated with protection in absence of antibodies.[37]