HLA-A*0201, HLA-A*1101, and HLA-B*0702 Transgenic Mice Recognize Numerous Poxvirus Determinants from a Wide Variety of Viral Gene Products

Abstract

In virus models explored in detail in mice, CTL typically focus on a few immunodominant determinants. In this study we use a multipronged approach to understand the diversity of CTL responses to vaccinia virus, a prototypic poxvirus with a genome ∼20-fold larger than that of the model RNA viruses typically studied in mice. Based on predictive computational algorithms for peptide binding to HLA supertypes, we synthesized a panel of 2889 peptides to begin to create an immunomic map of human CTL responses to poxviruses. Using this panel in conjunction with CTLs from vaccinia virus-infected HLA transgenic mice, we identified 14 HLA-A*0201-, 4 HLA-A*1101-, and 3 HLA-B*0702-restricted CD8+ T cell determinants distributed over 20 distinct proteins. These peptides were capable of binding one or multiple A2, A3, and B7 supertype molecules with affinities typical of viral determinants. Surprisingly, many of the viral proteins recognized are predicted to be late gene products, in addition to the early intermediate gene products expected. Nearly all of the determinants identified have identical counterparts encoded by modified vaccinia virus Ankara as well as variola virus, the agent of smallpox. These findings have implications for the design of new smallpox vaccines and the understanding of immune responses to large DNA viruses in general.

Discovering protective CD8 T cell epitopes—no single immunologic property predicts it!

“…Despite these and numerous other similar studies (e.g. [30]) the breadth and depth of microbial determinants displayed by an MHC class I molecule remain unknown.…”

“…Whilst algorithms rapidly predict T cell epitopes, it neither predicts whether such peptides are presented during a natural infection nor their immunogenicity unless empirically determined [30–32]. The development of several transgenic (tg) mice expressing major HLA class I alleles [33 •• ] provides a preclinical, small animal model to validate the immunologic properties of the putative epitopes [30,34 • ].…”

“…The development of several transgenic (tg) mice expressing major HLA class I alleles [33 •• ] provides a preclinical, small animal model to validate the immunologic properties of the putative epitopes [30,34 • ]. Comparative analysis showed that there is some but not complete overlap between CD8 T cell epitopes recognized by immune HLA tg mouse and vaccinated volunteers, suggesting that with some limitations, such a model is suitable for studying HLA class I restricted immune epitopes [34 • ,35].…”

Immunodominance Changes as a Function of the Infecting Dengue Virus Serotype and Primary versus Secondary Infection

“…Mice transgenic for HLA are widely used to study T cell responses restricted by human major histocompatibility complex (MHC) molecules (16)(17)(18), and it has been shown that mice lacking the alpha/beta interferon receptor (IFN-␣/␤R) support a productive DENV infection (19)(20)(21)(22). To cover a wide range of HLA phenotypes, we backcrossed IFN-␣/␤R Ϫ/Ϫ mice with HLA A*0201, A*0101, B*0701, B*4001, and DRB1*0101 single-alleletransgenic mice.…”

Enhancing poxvirus vectors vaccine immunogenicity

“…93 Moreover, the transgene expression levels are also dependent on the route of immunization. 94 Considering that immunodominance is defined as the phenomenon whereby only a small fraction of all of the possible epitopes from a particular pathogen elicits an immune response in an infected individual, 95 it is possible to modulate such immunodominance hierarchy changing the timing and the quantity of intracellular antigen production. 96 In fact, it has been described that in VACV 90% of the most recognized antigens by CD8 + T cells were ranked in the top of 50% in terms of mRNA expression 97 and there is a correlation between viral gene expression and immunodominance hierarchy after a second immunization due to a mechanism of cross-competition between T cells specific for early and late viral epitopes.…”