Fragmentation of SIV-gag vaccine induces broader T cell responses.
Fragmentation of SIV-gag vaccine induces broader T cell responses.
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DOI：
10.1371/journal.pone.0048038
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发表时间：
2012
期刊：
影响因子：
3.7
通讯作者：
Patterson S
中科院分区：
文献类型：
--
作者：
Benlahrech A;Meiser A;Herath S;Papagatsias T;Athanasopoulos T;Li F;Self S;Bachy V;Hervouet C;Logan K;Klavinskis L;Dickson G;Patterson S
人类免疫缺陷病毒（HIV）的高突变率允许逃避T细胞识别，从而阻碍了有效T细胞疫苗的开发。诱导多种T细胞免疫反应的疫苗将有助于克服这一问题。使用SIV gag作为模型疫苗，我们研究了两种增加CD8 T细胞反应广度的方法。即，将疫苗基因与泛素融合以靶向蛋白酶体，并增加MHC I类肽复合物的水平和基因片段化，以克服表位之间的呈递和识别竞争。对三种疫苗进行了比较：全长未修饰的SIV-mac239 gag、全长在n端与泛素融合的gag和7个大小相等的gag片段，这些gag片段横跨整个gag片段，泛素与每个片段的n端融合。将基因克隆到复制缺陷腺病毒载体中，并在体外人引物系统中评估其免疫原性。通过IFN-γ-ELISPOT评估CD8 T细胞反应的广度（由不同表位的数量定义），并通过流式细胞术评估记忆表型和细胞因子产生。我们观察到与泛素融合的全长gag相比，泛素融合片段中识别的表位数量增加了2到6倍。相比之下，虽然实现了蛋白酶体靶向，但与未修饰的全长基因相比，融合泛素的全长gag中识别的表位数量明显减少，但未泛素化的全长gag和融合泛素的mini基因诱导的表位应答数量没有差异。碎片化和泛素化不影响T细胞记忆分化和多功能性，尽管大多数应答是针对Ad5载体的。片段化而不与泛素融合增加了CD8 T疫苗对SIV-mac239 gag的反应广度。因此，HIV疫苗的基因片段化可能使反应最大化。
High mutation rates of human immunodeficiency virus (HIV) allows escape from T cell recognition preventing development of effective T cell vaccines. Vaccines that induce diverse T cell immune responses would help overcome this problem. Using SIV gag as a model vaccine, we investigated two approaches to increase the breadth of the CD8 T cell response. Namely, fusion of vaccine genes to ubiquitin to target the proteasome and increase levels of MHC class I peptide complexes and gene fragmentation to overcome competition between epitopes for presentation and recognition. Three vaccines were compared: full-length unmodified SIV-mac239 gag, full-length gag fused at the N-terminus to ubiquitin and 7 gag fragments of equal size spanning the whole of gag with ubiquitin-fused to the N-terminus of each fragment. Genes were cloned into a replication defective adenovirus vector and immunogenicity assessed in an in vitro human priming system. The breadth of the CD8 T cell response, defined by the number of distinct epitopes, was assessed by IFN-γ-ELISPOT and memory phenotype and cytokine production evaluated by flow cytometry. We observed an increase of two- to six-fold in the number of epitopes recognised in the ubiquitin-fused fragments compared to the ubiquitin-fused full-length gag. In contrast, although proteasomal targeting was achieved, there was a marked reduction in the number of epitopes recognised in the ubiquitin-fused full-length gag compared to the full-length unmodified gene, but there were no differences in the number of epitope responses induced by non-ubiquitinated full-length gag and the ubiquitin-fused mini genes. Fragmentation and ubiquitination did not affect T cell memory differentiation and polyfunctionality, though most responses were directed against the Ad5 vector. Fragmentation but not fusion with ubiquitin increases the breadth of the CD8 T vaccine response against SIV-mac239 gag. Thus gene fragmentation of HIV vaccines may maximise responses.
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