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

BACKGROUND: Identification of human leukocyte antigen class I (HLA-I) restricted cytotoxic T cell (CTL) epitopes from influenza virus is of importance for the development of new effective peptide-based vaccines. METHODOLOGY/PRINCIPAL FINDINGS: In the present work, bioinformatics was used to predict 9mer peptides derived from available influenza A viral proteins with binding affinity for at least one of the 12 HLA-I supertypes. The predicted peptides were then selected in a way that ensured maximal coverage of the available influenza A strains. One hundred and thirty one peptides were synthesized and their binding affinities for the HLA-I supertypes were measured in a biochemical assay. Influenza-specific T cell responses towards the peptides were quantified using IFNgamma ELISPOT assays with peripheral blood mononuclear cells (PBMC) from adult healthy HLA-I typed donors as responder cells. Of the 131 peptides, 21 were found to induce T cell responses in 19 donors. In the ELISPOT assay, five peptides induced responses that could be totally blocked by the pan-specific anti-HLA-I antibody W6/32, whereas 15 peptides induced responses that could be completely blocked in the presence of the pan-specific anti-HLA class II (HLA-II) antibody IVA12. Blocking of HLA-II subtype reactivity revealed that 8 and 6 peptide responses were blocked by anti-HLA-DR and -DP antibodies, respectively. Peptide reactivity of PBMC depleted of CD4(+) or CD8(+) T cells prior to the ELISPOT culture revealed that effectors are either CD4(+) (the majority of reactivities) or CD8(+) T cells, never a mixture of these subsets. Three of the peptides, recognized by CD4(+) T cells showed binding to recombinant DRA1*0101/DRB1*0401 or DRA1*0101/DRB5*0101 molecules in a recently developed biochemical assay. CONCLUSIONS/SIGNIFICANCE: HLA-I binding 9mer influenza virus-derived peptides induce in many cases CD4(+) T cell responses restricted by HLA-II molecules

Commodity risk assessment of black pine (Pinus thunbergii Parl.) bonsai from Japan

The EFSA Panel on Plant health was requested to deliver a scientific opinion on how far the existing requirements for the bonsai pine species subject to derogation in Commission Decision 2002/887/EC would cover all plant health risks from black pine (Pinus thunbergii Parl.) bonsai (the commodity defined in the EU legislation as naturally or artificially dwarfed plants) imported from Japan, taking into account the available scientific information, including the technical information provided by Japan. The relevance of an EU-regulated pest for this opinion was based on: (a) evidence of the presence of the pest in Japan; (b) evidence that P.\ua0thunbergii is a host of the pest and (c) evidence that the pest can be associated with the commodity. Sixteen pests that fulfilled all three criteria were selected for further evaluation. The relevance of other pests present in Japan (not regulated in the EU) for this opinion was based on (i) evidence of the absence of the pest in the EU; (ii) evidence that P.\ua0thunbergii is a host of the pest; (iii) evidence that the pest can be associated with the commodity and (iv) evidence that the pest may have an impact in the EU. Three pests fulfilled all four criteria and were selected for further evaluation (Crisicoccus pini, Sirex nitobei and Urocerus japonicus). For the selected 19 pests, the risk mitigation measures proposed in the technical dossier were evaluated. Limiting factors on the effectiveness of the measures were documented. For each of the 19 pests, an expert judgement is given on the likelihood of pest freedom taking into consideration the risk mitigation measures acting on the pest, including any uncertainties. For all evaluated pests, the median likelihood of the pest freedom is 99.5% or higher and within the 90% uncertainty range it is 99% or higher