A Mutation in the HLA-B^*2705-Restricted NP_383-391Epitope Affects the Human Influenza A Virus-Specific Cytotoxic T-Lymphocyte Response In Vitro

Functional Compensation of a Detrimental Amino Acid Substitution in a Cytotoxic-T-Lymphocyte Epitope of Influenza A Viruses by Comutations

“…The R384G mutation resulted in the loss of the anchor residue and as a result ablated recognition by CTLs (15,17). The loss of this epitope affected the human in vitro CTL response significantly (1). During this study, it appeared that the R384G substitution in the NP gene of influenza virus strain A/Hong Kong/2/68 (A/HK/68) prevented rescue of virus by reverse genetics, indicating that it was detrimental to viral fitness.…”

“…The bidirectional reverse genetics plasmids pHW181 through pHW188 for the transcription of viral gene segments of influenza virus A/WSN/33 were kindly provided by R. G. Webster (5). For the generation of viruses, the NP constructs of A/NL/94 or A/HK/68 were transfected into 293T cells together with pHMG-NP and all A/WSN/33 genomic constructs except the one encoding the NP gene segment, as described previously (1). Twenty-four hours after transfection, virus was passaged in Madin-Darby canine kidney (MDCK) cells and infectious virus titers were determined as described previously (14).…”

“…Of these three, the substitution at position 375 was in closest proximity to the CTL epitope, and the effect of this comutation on NP functionality and fitness of viruses with and without the R384G mutation was studied. Also in human immunodeficiency virus type 1 CTL escape mutants, clustered mutations have been observed with a mutation in an HLA-B27-restricted CTL epitope in the gag protein (6) For the generation of recombinant influenza viruses with R384 and G384, respectively, the NP gene segments of influenza viruses A/HK/68 and A/Netherlands/18/94 (A/NL/94) were amplified by reverse transcription-PCR as described previously (1) and inserted between the human polymerase I promoter and the hepatitis delta virus ribozyme sequence of plasmid pSP72-PhuThep (3). Site-directed mutagenesis of the respective NP genes was performed by PCR as previously described (16).…”

HLA class I molecules consistently present internal influenza epitopes

“…It is well documented that antibodies which recognize the HA and NA molecules of one influenza strain may not sufficiently bind to HA and NA molecules of older and/or future strains (2)(3)(4). Viral peptides presented by class I HLA and targeted by CTL likewise exhibit variability through the emergence of viral escape mutants (5,6). Although our knowledge of class I-presented influenza epitopes is incomplete, extensive variability has been reported in some of the viral sequences so far reported as CTL targets (5)(6)(7).…”

Immunogenicity of novel consensus-based DNA vaccines against avian influenza

“…The promiscuity of CD4 and CD8 T cell receptors could allow them to recognize epitopes even after the addition of a point mutation. While escape from CTLs is possible and observable [8][9][10][11], also observable are T cells that recognize a range of peptide sequences . In addition, the functional constraints placed on internal structural genes, inaccessible to antibodies, limit their ability to mutate.…”