Escape of Mutant Double-Stranded DNA Virus from Innate Immune Control (original) (raw)
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Journal of Experimental Medicine, 2019
CMVs efficiently target MHC I molecules to avoid recognition by cytotoxic T cells. However, the lack of MHC I on the cell surface renders the infected cell susceptible to NK cell killing upon missing self recognition. To counter this, mouse CMV (MCMV) rescues some MHC I molecules to engage inhibitory Ly49 receptors. Here we identify a new viral protein, MATp1, that is essential for MHC I surface rescue. Rescued altered-self MHC I molecules show increased affinity to inhibitory Ly49 receptors, resulting in inhibition of NK cells despite substantially reduced MHC I surface levels. This enables the virus to evade recognition by licensed NK cells. During evolution, this novel viral immune evasion mechanism could have prompted the development of activating NK cell receptors that are specific for MATp1-modified altered-self MHC I molecules. Our study solves a long-standing conundrum of how MCMV avoids recognition by NK cells, unravels a fundamental new viral immune evasion mechanism, and ...
Nature Genetics, 2005
Experimental infection with mouse cytomegalovirus (MCMV) has been used to elucidate the intricate host-pathogen mechanisms that determine innate resistance to infection. Linkage analyses in F 2 progeny from MCMV-resistant MA/My (H2 k ) and MCMV-susceptible BALB/c (H2 d ) and BALB.K (H2 k ) mouse strains indicated that only the combination of alleles encoded by a gene in the Klra (also called Ly49) cluster on chromosome 6, and one in the major histocompatibility complex (H2) on chromosome 17, is associated with virus resistance. We found that natural killer cell-activating receptor Ly49P specifically recognized MCMV-infected cells, dependent on the presence of the H2 k haplotype. This binding was blocked using antibodies to H-2D k but not antibodies to H-2K k . These results are suggestive of a new natural killer cell mechanism implicated in MCMV resistance, which depends on the functional interaction of the Ly49P receptor and the major histocompatibility complex class I molecule H-2D k on MCMV-infected cells.
PLoS Pathogens, 2013
It is becoming increasingly clear that many diseases are the result of infection from multiple genetically distinct strains of a pathogen. Such multi-strain infections have the capacity to alter both disease and pathogen dynamics. Infection with multiple strains of human cytomegalovirus (HCMV) is common and has been linked to enhanced disease. Suggestions that disease enhancement in multi-strain infected patients is due to complementation have been supported by transcomplementation studies in mice during co-infection of wild type and gene knockout strains of murine CMV (MCMV). Complementation between naturally circulating strains of CMV has, however, not been assessed. In addition, many models of multi-strain infection predict that co-infecting strains will compete with each other and that this competition may contribute to selective transmission of more virulent pathogen strains. To assess the outcome of multi-strain infection, C57BL/6 mice were infected with up to four naturally circulating strains of MCMV. In this study, profound within-host competition was observed between co-infecting strains of MCMV. This competition was MCMV strain specific and resulted in the complete exclusion of certain strains of MCMV from the salivary glands of multi-strain infected mice. Competition was dependent on Ly49H + natural killer (NK) cells as well as the expression of the ligand for Ly49H, the MCMV encoded product, m157. Strains of MCMV which expressed an m157 gene product capable of ligating Ly49H were outcompeted by strains of MCMV expressing variant m157 genes. Importantly, within-host competition prevented the shedding of the less virulent strains of MCMV, those recognized by Ly49H, into the saliva of multi-strain infected mice. These data demonstrate that NK cells have the strain specific recognition capacity required to meditate within-host competition between strains of MCMV. Furthermore, this within-host competition has the capacity to shape the dynamics of viral shedding and potentially select for the transmission of more virulent virus strains.
Viral MHC class I-like molecule allows evasion of NK cell effector responses in vivo
Journal of immunology (Baltimore, Md. : 1950), 2014
The outcome of mouse CMV (MCMV) infection varies among different inbred mouse strains depending on NK cell effector functions governed through recognition receptor triggering. NK cells from different mouse strains possess diverse repertoires of activating or inhibitory Ly49 receptors, which share some of their polymorphic MHC class I (MHC-I) ligands. By examining the NK cell response to MCMV infection in novel BALB substrains congenic for different MHC (or H-2 in mice) haplotypes, we show that recognition of viral MHC-I-like protein m157 by inhibitory Ly49C receptor allows escape from NK cell control of viral replication. Dominant inhibition by Ly49C bound to self-H-2(b) encoded MHC-I molecules masks this effect, which only becomes apparent in distinct H-2 haplotypes, such as H-2(f). The recognition of m157-expressing cells by Ly49C resulted in both decreased NK cell killing in vitro and reduced rejection in vivo. Further, control of infection with m157-deletant (Δm157) MCMV was imp...
Journal of Virology, 2000
Several early genes of murine cytomegalovirus (MCMV) encode proteins that mediate immune evasion by interference with the major histocompatibility complex class I (MHC-I) pathway of antigen presentation to cytolytic T lymphocytes (CTL). Specifically, the m152 gene product gp37/40 causes retention of MHC-I molecules in the endoplasmic reticulum (ER)-Golgi intermediate compartment. Lack of MHC-I on the cell surface should activate natural killer (NK) cells recognizing the "missing self." The retention, however, is counteracted by the m04 early gene product gp34, which binds to folded MHC-I molecules in the ER and directs the complex to the cell surface. It was thus speculated that gp34 might serve to silence NK cells and thereby complete the immune evasion of MCMV. In light of these current views, we provide here results demonstrating an in vivo role for gp34 in protective antiviral immunity. We have identified an antigenic nonapeptide derived from gp34 and presented by the MHC-I molecule D d . Besides the immunodominant immediate-early nonapeptide consisting of IE1 amino acids 168-176 (IE1 168-176 ), the early nonapeptide m04 243-251 is the second antigenic peptide described for MCMV. The primary immune response to MCMV generates significant m04-specific CD8 T-cell memory. Upon adoptive transfer into immunodeficient recipients, an m04-specific CTL line controls MCMV infection with an efficacy comparable to that of an IE1-specific CTL line. Thus, gp34 is the first noted early protein of MCMV that escapes viral immune evasion mechanisms. These data document that MCMV is held in check by a redundance of protective CD8 T cells recognizing antigenic peptides in different phases of viral gene expression.
MCMV glycoprotein gp40 confers virus resistance to CD8+ T cells and NK cells in vivo
Nature Immunology, 2002
The susceptibility of certain inbred mouse strains to murine cytomegalovirus (MCMV) is related to their inability to generate a strong natural killer (NK) cell response. We addressed here whether the MCMV susceptibility of the BALB/c strain is due to viral functions that control NK cell activation in a strain-specific manner. MCMV expresses two proteins, gp48 and gp40, that are encoded
Journal of acquired immune deficiency syndromes and human retrovirology : official publication of the International Retrovirology Association, 1995
Mice exhibiting T cell immunodeficiency and lymphadenopathy induced by LP-BM5 MuLV (MAIDS) were assessed for their ability to control murine cytomegalovirus (MCMV) infection. Elevated replication of MCMV was observed in spleens 4-6 days after MCMV infection. Production of interferon alpha/beta in response to MCMV was abrogated by MAIDS and natural killer (NK) cell activity, assessed by lysis of YAC-1 target cells, was correspondingly depressed on Day 1. However, this was elevated at later times. As previous studies attribute early control of MCMV in C57BL mice with splenic NK1.1 cells, we confirmed that YAC-1 lysis declines and MCMV titres are elevated in M- mice given antibodies to NK1.1 or asialo GM1. However, M+ mice were less severely affected by these regimes. Hence M+ mice may acquire cells that do not express NK1.1 or asialo GM1, but are able to lyse YAC-1 target cells and partially control MCMV replication. MCMV was essentially cleared from the spleens and livers of M+ and M...