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Major histocompatibility complex class I allele-specific cooperative and competitive interactions between immune evasion proteins of cytomegalovirus.

Wagner M, Gutermann A, Podlech J, Reddehase MJ, Koszinowski UH - J. Exp. Med. (2002)

Bottom Line: Surface expression of a set of MHC class I molecules specified by haplotypes H-2(d) (K(d), D(d), and L(d)) and H-2(b) (K(b) and D(b)) was the parameter for evaluation of the interference with class I trafficking.The data show the following: first, there exists no additional MCMV gene of major influence on MHC class I surface expression; second, the strength of the inhibitory effect of immunoevasins shows an allele-specific hierarchy; and third, the immunoevasins act not only synergistically but can, in certain combinations, interact antagonistically.In essence, this work highlights the importance of studying the immunosubversive mechanisms of cytomegaloviruses in the context of gene expression during the viral replicative cycle in infected cells.

View Article: PubMed Central - PubMed

Affiliation: Max von Pettenkofer Institute, Department for Virology, Ludwig-Maximilians-Universität München, 80336 Munich, Germany.

ABSTRACT
Cytomegaloviruses (CMVs) deploy a set of genes for interference with antigen presentation in the major histocompatibility complex (MHC) class I pathway. In murine CMV (MCMV), three genes were identified so far: m04/gp34, m06/gp48, and m152/gp40. While their function as immunoevasins was originally defined after their selective expression, this may not necessarily reflect their biological role during infection. The three immunoevasins might act synergistically, but they might also compete for their common substrate, the MHC class I complexes. To approach this question in a systematic manner, we have generated a complete set of mutant viruses with deletions of the three genes in all seven possible combinations. Surface expression of a set of MHC class I molecules specified by haplotypes H-2(d) (K(d), D(d), and L(d)) and H-2(b) (K(b) and D(b)) was the parameter for evaluation of the interference with class I trafficking. The data show the following: first, there exists no additional MCMV gene of major influence on MHC class I surface expression; second, the strength of the inhibitory effect of immunoevasins shows an allele-specific hierarchy; and third, the immunoevasins act not only synergistically but can, in certain combinations, interact antagonistically. In essence, this work highlights the importance of studying the immunosubversive mechanisms of cytomegaloviruses in the context of gene expression during the viral replicative cycle in infected cells.

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Related in: MedlinePlus

Multistep virus growth curves in cell culture. NIH3T3 cells were infected with the indicated wt and mutant viruses at an MOI of 0.1 PFU per cell and virus titers in the supernatants were detected every 24 h after infection until day 5. All seven mutants show a virus productivity comparable to wt MCMV (MW97.01).
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fig3: Multistep virus growth curves in cell culture. NIH3T3 cells were infected with the indicated wt and mutant viruses at an MOI of 0.1 PFU per cell and virus titers in the supernatants were detected every 24 h after infection until day 5. All seven mutants show a virus productivity comparable to wt MCMV (MW97.01).

Mentions: Previous work has already shown that each of the immune evasion genes m04, m06, and m152 can be deleted without affecting virus growth in fibroblast cell cultures. However, since these genes could possibly substitute each other in an essential function, deletion of all three or of combinations of two might still abolish virus growth. In addition, an impaired viral replication could result from undesired spontaneous mutations that may have accumulated elsewhere in the viral genomes during the repeated mutagenesis procedures. To explore these possibilities, we have taken multistep growth curves for wt MCMV and the complete set of mutants (Fig. 3) . Specifically, NIH3T3 cells were infected at an MOI of 0.1 PFU per cell (without centrifugal enhancement), and virus titers in the supernatants were determined daily until day 5. All mutants, including the triple-deletion mutant Δm04+06+152-MCMV, were found to grow like wt MCMV. This finding excluded adverse effects of undesired mutations and confirmed that the three immune evasion genes are not essential for virus replication in fibroblasts in cell culture.


Major histocompatibility complex class I allele-specific cooperative and competitive interactions between immune evasion proteins of cytomegalovirus.

Wagner M, Gutermann A, Podlech J, Reddehase MJ, Koszinowski UH - J. Exp. Med. (2002)

Multistep virus growth curves in cell culture. NIH3T3 cells were infected with the indicated wt and mutant viruses at an MOI of 0.1 PFU per cell and virus titers in the supernatants were detected every 24 h after infection until day 5. All seven mutants show a virus productivity comparable to wt MCMV (MW97.01).
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC2194048&req=5

fig3: Multistep virus growth curves in cell culture. NIH3T3 cells were infected with the indicated wt and mutant viruses at an MOI of 0.1 PFU per cell and virus titers in the supernatants were detected every 24 h after infection until day 5. All seven mutants show a virus productivity comparable to wt MCMV (MW97.01).
Mentions: Previous work has already shown that each of the immune evasion genes m04, m06, and m152 can be deleted without affecting virus growth in fibroblast cell cultures. However, since these genes could possibly substitute each other in an essential function, deletion of all three or of combinations of two might still abolish virus growth. In addition, an impaired viral replication could result from undesired spontaneous mutations that may have accumulated elsewhere in the viral genomes during the repeated mutagenesis procedures. To explore these possibilities, we have taken multistep growth curves for wt MCMV and the complete set of mutants (Fig. 3) . Specifically, NIH3T3 cells were infected at an MOI of 0.1 PFU per cell (without centrifugal enhancement), and virus titers in the supernatants were determined daily until day 5. All mutants, including the triple-deletion mutant Δm04+06+152-MCMV, were found to grow like wt MCMV. This finding excluded adverse effects of undesired mutations and confirmed that the three immune evasion genes are not essential for virus replication in fibroblasts in cell culture.

Bottom Line: Surface expression of a set of MHC class I molecules specified by haplotypes H-2(d) (K(d), D(d), and L(d)) and H-2(b) (K(b) and D(b)) was the parameter for evaluation of the interference with class I trafficking.The data show the following: first, there exists no additional MCMV gene of major influence on MHC class I surface expression; second, the strength of the inhibitory effect of immunoevasins shows an allele-specific hierarchy; and third, the immunoevasins act not only synergistically but can, in certain combinations, interact antagonistically.In essence, this work highlights the importance of studying the immunosubversive mechanisms of cytomegaloviruses in the context of gene expression during the viral replicative cycle in infected cells.

View Article: PubMed Central - PubMed

Affiliation: Max von Pettenkofer Institute, Department for Virology, Ludwig-Maximilians-Universität München, 80336 Munich, Germany.

ABSTRACT
Cytomegaloviruses (CMVs) deploy a set of genes for interference with antigen presentation in the major histocompatibility complex (MHC) class I pathway. In murine CMV (MCMV), three genes were identified so far: m04/gp34, m06/gp48, and m152/gp40. While their function as immunoevasins was originally defined after their selective expression, this may not necessarily reflect their biological role during infection. The three immunoevasins might act synergistically, but they might also compete for their common substrate, the MHC class I complexes. To approach this question in a systematic manner, we have generated a complete set of mutant viruses with deletions of the three genes in all seven possible combinations. Surface expression of a set of MHC class I molecules specified by haplotypes H-2(d) (K(d), D(d), and L(d)) and H-2(b) (K(b) and D(b)) was the parameter for evaluation of the interference with class I trafficking. The data show the following: first, there exists no additional MCMV gene of major influence on MHC class I surface expression; second, the strength of the inhibitory effect of immunoevasins shows an allele-specific hierarchy; and third, the immunoevasins act not only synergistically but can, in certain combinations, interact antagonistically. In essence, this work highlights the importance of studying the immunosubversive mechanisms of cytomegaloviruses in the context of gene expression during the viral replicative cycle in infected cells.

Show MeSH
Related in: MedlinePlus