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Nonequivalence of classical MHC class I loci in ability to direct effective antiviral immunity.

Pavelko KD, Mendez-Fernandez Y, Bell MP, Hansen MJ, Johnson AJ, David CS, Rodriguez M, Pease LR - PLoS Pathog. (2012)

Bottom Line: We hypothesize that classical class I loci differ in their ability to direct effective immunity against intracellular pathogens.Using a picornavirus infection model and chimeric H-2 transgenes, we examined locus specific functional determinants distinguishing the ability of class I sister genes to direct effective anti viral immunity.This finding provides a basis for understanding locus-specific differences in MHC polymorphism, characterized best in human populations.

View Article: PubMed Central - PubMed

Affiliation: Department of Immunology, Mayo Clinic, Rochester, Minnesota, USA.

ABSTRACT
Structural diversity in the peptide binding sites of the redundant classical MHC antigen presenting molecules is strongly selected in humans and mice. Although the encoded antigen presenting molecules overlap in antigen presenting function, differences in polymorphism at the MHC I A, B and C loci in humans and higher primates indicate these loci are not functionally equivalent. The structural basis of these differences is not known. We hypothesize that classical class I loci differ in their ability to direct effective immunity against intracellular pathogens. Using a picornavirus infection model and chimeric H-2 transgenes, we examined locus specific functional determinants distinguishing the ability of class I sister genes to direct effective anti viral immunity. Whereas, parental FVB and transgenic FVB mice expressing the H-2K(b) gene are highly susceptible to persisting Theiler's virus infection within the CNS and subsequent demyelination, mice expressing the D(b) transgene clear the virus and are protected from demyelination. Remarkably, animals expressing a chimeric transgene, comprised primarily of K(b) but encoding the peptide binding domain of D(b), develop a robust anti viral CTL response yet fail to clear virus and develop significant demyelination. Differences in expression of the chimeric K(b)α1α2D(b) gene (low) and D(b) (high) in the CNS of infected mice mirror expression levels of their endogenous H-2(q) counterparts in FVB mice. These findings demonstrate that locus specific elements other than those specifying peptide binding and T cell receptor interaction can determine ability to clear virus infection. This finding provides a basis for understanding locus-specific differences in MHC polymorphism, characterized best in human populations.

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Generation of FVB Kbα1α2Db transgenic mice.(A) Segments of H-2Kb EcoRI and H-2Db HindIII were used to generate a chimeric genomic construct with an H-2Db Sal I/XbaI fragment on an H-2Kb backbone. (B) Expression of the construct yields a chimeric MHC class I molecule composed of the α1α2 domain from H-2Db and the α3 domain from H-2Kb. (C) Verification of H-2Db and Kbα1α2Db transgene expression in 293T cells by flow cytometry. Data are mean fluorescence intensity of phycoerythrin labeled cells.
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ppat-1002541-g001: Generation of FVB Kbα1α2Db transgenic mice.(A) Segments of H-2Kb EcoRI and H-2Db HindIII were used to generate a chimeric genomic construct with an H-2Db Sal I/XbaI fragment on an H-2Kb backbone. (B) Expression of the construct yields a chimeric MHC class I molecule composed of the α1α2 domain from H-2Db and the α3 domain from H-2Kb. (C) Verification of H-2Db and Kbα1α2Db transgene expression in 293T cells by flow cytometry. Data are mean fluorescence intensity of phycoerythrin labeled cells.

Mentions: In order to study the structural properties of the H-2D and H-2K class I genes that are responsible for directing effective viral immunity against TMEV infection, we introduced genomic clones encoding the Kb or Db (Figure 1A) genes into susceptible FVB mice. To control for possible gene integration positional effects, multiple independent founder lines were analyzed. One founder line of the Kb transgene and three founder lines of the Db transgene were evaluated for susceptibility to TMEV induced demyelination. TMEV infected Kb transgenic animals developed focal areas of demyelination similar to non-transgenic animals (Figure 2A and B). Few of the Db transgenic mice demyelinated (Table 1), demonstrating resistance compared to the littermate controls (Figure 2C and D) which suggests that transfer of the genomic fragments faithfully reproduced the disease susceptibility phenotypes of interest.


Nonequivalence of classical MHC class I loci in ability to direct effective antiviral immunity.

Pavelko KD, Mendez-Fernandez Y, Bell MP, Hansen MJ, Johnson AJ, David CS, Rodriguez M, Pease LR - PLoS Pathog. (2012)

Generation of FVB Kbα1α2Db transgenic mice.(A) Segments of H-2Kb EcoRI and H-2Db HindIII were used to generate a chimeric genomic construct with an H-2Db Sal I/XbaI fragment on an H-2Kb backbone. (B) Expression of the construct yields a chimeric MHC class I molecule composed of the α1α2 domain from H-2Db and the α3 domain from H-2Kb. (C) Verification of H-2Db and Kbα1α2Db transgene expression in 293T cells by flow cytometry. Data are mean fluorescence intensity of phycoerythrin labeled cells.
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC3285594&req=5

ppat-1002541-g001: Generation of FVB Kbα1α2Db transgenic mice.(A) Segments of H-2Kb EcoRI and H-2Db HindIII were used to generate a chimeric genomic construct with an H-2Db Sal I/XbaI fragment on an H-2Kb backbone. (B) Expression of the construct yields a chimeric MHC class I molecule composed of the α1α2 domain from H-2Db and the α3 domain from H-2Kb. (C) Verification of H-2Db and Kbα1α2Db transgene expression in 293T cells by flow cytometry. Data are mean fluorescence intensity of phycoerythrin labeled cells.
Mentions: In order to study the structural properties of the H-2D and H-2K class I genes that are responsible for directing effective viral immunity against TMEV infection, we introduced genomic clones encoding the Kb or Db (Figure 1A) genes into susceptible FVB mice. To control for possible gene integration positional effects, multiple independent founder lines were analyzed. One founder line of the Kb transgene and three founder lines of the Db transgene were evaluated for susceptibility to TMEV induced demyelination. TMEV infected Kb transgenic animals developed focal areas of demyelination similar to non-transgenic animals (Figure 2A and B). Few of the Db transgenic mice demyelinated (Table 1), demonstrating resistance compared to the littermate controls (Figure 2C and D) which suggests that transfer of the genomic fragments faithfully reproduced the disease susceptibility phenotypes of interest.

Bottom Line: We hypothesize that classical class I loci differ in their ability to direct effective immunity against intracellular pathogens.Using a picornavirus infection model and chimeric H-2 transgenes, we examined locus specific functional determinants distinguishing the ability of class I sister genes to direct effective anti viral immunity.This finding provides a basis for understanding locus-specific differences in MHC polymorphism, characterized best in human populations.

View Article: PubMed Central - PubMed

Affiliation: Department of Immunology, Mayo Clinic, Rochester, Minnesota, USA.

ABSTRACT
Structural diversity in the peptide binding sites of the redundant classical MHC antigen presenting molecules is strongly selected in humans and mice. Although the encoded antigen presenting molecules overlap in antigen presenting function, differences in polymorphism at the MHC I A, B and C loci in humans and higher primates indicate these loci are not functionally equivalent. The structural basis of these differences is not known. We hypothesize that classical class I loci differ in their ability to direct effective immunity against intracellular pathogens. Using a picornavirus infection model and chimeric H-2 transgenes, we examined locus specific functional determinants distinguishing the ability of class I sister genes to direct effective anti viral immunity. Whereas, parental FVB and transgenic FVB mice expressing the H-2K(b) gene are highly susceptible to persisting Theiler's virus infection within the CNS and subsequent demyelination, mice expressing the D(b) transgene clear the virus and are protected from demyelination. Remarkably, animals expressing a chimeric transgene, comprised primarily of K(b) but encoding the peptide binding domain of D(b), develop a robust anti viral CTL response yet fail to clear virus and develop significant demyelination. Differences in expression of the chimeric K(b)α1α2D(b) gene (low) and D(b) (high) in the CNS of infected mice mirror expression levels of their endogenous H-2(q) counterparts in FVB mice. These findings demonstrate that locus specific elements other than those specifying peptide binding and T cell receptor interaction can determine ability to clear virus infection. This finding provides a basis for understanding locus-specific differences in MHC polymorphism, characterized best in human populations.

Show MeSH
Related in: MedlinePlus