Immunomic Analysis of the Repertoire of T-Cell Specificities for Influenza A Virus in Humans

ABSTRACT Continuing antigenic drift allows influenza viruses to escape antibody-mediated recognition, and as a consequence, the vaccine currently in use needs to be altered annually. Highly conserved epitopes recognized by effector T cells may represent an alternative approach for the generation of a more universal influenza virus vaccine. Relatively few highly conserved epitopes are currently known in humans, and relatively few epitopes have been identified from proteins other than hemagglutinin and nucleoprotein. This prompted us to perform a study aimed at identifying a set of human T-cell epitopes that would provide broad coverage against different virus strains and subtypes. To provide coverage across different ethnicities, seven different HLA supertypes were considered. More than 4,000 peptides were selected from a panel of 23 influenza A virus strains based on predicted high-affinity binding to HLA class I or class II and high conservancy levels. Peripheral blood mononuclear cells from 44 healthy human blood donors were tested for reactivity against HLA-matched peptides by using gamma interferon enzyme-linked immunospot assays. Interestingly, we found that PB1 was the major target for both CD4+ and CD8+ T-cell responses. The 54 nonredundant epitopes (38 class I and 16 class II) identified herein provided high coverage among different ethnicities, were conserved in the majority of the strains analyzed, and were consistently recognized in multiple individuals. These results enable further functional studies of T-cell responses during influenza virus infection and provide a potential base for the development of a universal influenza vaccine.

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HLA Class I Binding 9mer Peptides from Influenza A Virus Induce CD4+ T Cell Responses

PLoS ONE ◽

10.1371/journal.pone.0010533 ◽

2010 ◽

Vol 5 (5) ◽

pp. e10533 ◽

Cited By ~ 17

Author(s):

Mingjun Wang ◽

Mette V. Larsen ◽

Morten Nielsen ◽

Mikkel Harndahl ◽

Sune Justesen ◽

...

Keyword(s):

T Cell ◽

Influenza A Virus ◽

Influenza A ◽

T Cell Responses ◽

Hla Class I ◽

Cd4 T Cell ◽

Class I ◽

Cell Responses

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Assessment of Seasonal Influenza A Virus-Specific CD4 T-Cell Responses to 2009 Pandemic H1N1 Swine-Origin Influenza A Virus

Journal of Virology ◽

10.1128/jvi.02226-09 ◽

2010 ◽

Vol 84 (7) ◽

pp. 3312-3319 ◽

Cited By ~ 80

Author(s):

Xinhui Ge ◽

Venus Tan ◽

Paul L. Bollyky ◽

Nathan E. Standifer ◽

Eddie A. James ◽

...

Keyword(s):

T Cells ◽

Influenza Virus ◽

Amino Acid ◽

T Cell ◽

Influenza A Virus ◽

Influenza A ◽

Seasonal Influenza ◽

T Cell Responses ◽

Pandemic H1n1 ◽

Cell Responses

ABSTRACT Very limited evidence has been reported to show human adaptive immune responses to the 2009 pandemic H1N1 swine-origin influenza A virus (S-OIV). We studied 17 S-OIV peptides homologous to immunodominant CD4 T epitopes from hemagglutinin (HA), neuraminidase (NA), nuclear protein (NP), M1 matrix protein (MP), and PB1 of a seasonal H1N1 strain. We concluded that 15 of these 17 S-OIV peptides would induce responses of seasonal influenza virus-specific T cells. Of these, seven S-OIV sequences were identical to seasonal influenza virus sequences, while eight had at least one amino acid that was not conserved. T cells recognizing epitopes derived from these S-OIV antigens could be detected ex vivo. Most of these T cells expressed memory markers, although none of the donors had been exposed to S-OIV. Functional analysis revealed that specific amino acid differences in the sequences of these S-OIV peptides would not affect or partially affect memory T-cell responses. These findings suggest that without protective antibody responses, individuals vaccinated against seasonal influenza A may still benefit from preexisting cross-reactive memory CD4 T cells reducing their susceptibility to S-OIV infection.

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Increased Protein Degradation Improves Influenza Virus Nucleoprotein-Specific CD8+T Cell ActivationIn Vitrobut Not in C57BL/6 Mice

Journal of Virology ◽

10.1128/jvi.01633-16 ◽

2016 ◽

Vol 90 (22) ◽

pp. 10209-10219 ◽

Cited By ~ 5

Author(s):

Arwen F. Altenburg ◽

Carolien E. van de Sandt ◽

Stella E. van Trierum ◽

Heidi L. M. De Gruyter ◽

Peter R. W. A. van Run ◽

...

Keyword(s):

T Cells ◽

Influenza Virus ◽

T Cell ◽

Influenza A ◽

T Cell Responses ◽

Influenza Viruses ◽

Antigenic Drift ◽

Influenza Vaccines ◽

Cell Responses ◽

Modified Vaccinia Virus Ankara

ABSTRACTDue to antigenic drift of influenza viruses, seasonal influenza vaccines need to be updated annually. These vaccines are based on predictions of strains likely to circulate in the next season. However, vaccine efficacy is greatly reduced in the case of a mismatch between circulating and vaccine strains. Furthermore, novel antigenically distinct influenza viruses are introduced into the human population from animal reservoirs occasionally and may cause pandemic outbreaks. To dampen the impact of seasonal and pandemic influenza, vaccines that induce broadly protective and long-lasting immunity are preferred. Because influenza virus-specific CD8+T cells are directed mainly against relatively conserved internal proteins, like nucleoprotein (NP), they are highly cross-reactive and afford protection against infection with antigenically distinct influenza virus strains, so-called heterosubtypic immunity. Here, we used modified vaccinia virus Ankara (MVA) as a vaccine vector for the induction of influenza virus NP-specific CD8+T cells. To optimize the induction of CD8+T cell responses, we made several modifications to NP, aiming at retaining the protein in the cytosol or targeting it to the proteasome. We hypothesized that these strategies would increase antigen processing and presentation and thus improve the induction of CD8+T cell responses. We showed that NP with increased degradation rates improved CD8+T cell activationin vitroif the amount of antigen was limited or if CD8+T cells were of low functional avidity. However, after immunization of C57BL/6 mice, no differences were detected between modified NP and wild-type NP (NPwt), since NPwt already induced optimal CD8+T cell responses.IMPORTANCEDue to the continuous antigenic drift of seasonal influenza viruses and the threat of a novel pandemic, there is a great need for the development of novel influenza vaccines that offer broadly protective immunity against multiple subtypes. CD8+T cells can provide immunity against multiple subtypes of influenza viruses by the recognition of relatively conserved internal antigens. In this study, we aimed at optimizing the CD8+T cell response to influenza A virus by making modifications to influenza A virus nucleoprotein (NP) expressed from the modified vaccinia virus Ankara (MVA) vaccine vector. These modifications resulted in increased antigen degradation, thereby producing elevated levels of peptides that can be presented on major histocompatibility complex (MHC) class I molecules to CD8+T cells. Although we were unable to increase the NP-specific immune response in the mouse strain used, this approach may have benefits for vaccine development using less-immunogenic proteins.

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