Identification of aCD4 T cell epitope in the pneumonia virus of mice glycoprotein and characterization of its role in protective immunity

Pneumonia virus of mice (PVM) causes bronchiolitis and pneumonia in mice. Infection is associated with high levels of viral replication in the lungs and results in the functional inactivation of pulmonary virus-specific CD8 T cells. Due to its similarity to severe human respiratory syncytial virus (RSV) infection, PVM infection in mice has been proposed as an alternative RSV model. Here, we have delineated the minimal requirements for protective T cell immunity in the PVM model. Immunization with a CD8 T cell epitope from the PVM phosphoprotein P, combined with the ovalbumin (OVA) CD4 T cell epitope, did not confer protective immunity against lethal PVM challenge, suggesting a possible role of cognate CD4 T cell immunity. To determine the role of PVM-specific CD4 T cell responses, we mapped a PVM CD4 T cell epitope in the glycoprotein G, using a panel of overlapping peptides. Although immunization with this epitope provided some protection, solid protective immunity was only observed after immunization with a combination of the PVM-specific CD4 and CD8 T cell epitopes. Analysis of post-challenge T cell responses in immunized mice indicated that G-specific pulmonary CD4 T cells displayed a mixed Th1/Th2 phenotype, which was characterized by the presence of both IL-5 and IFN-gamma secreting cells, in the absence of overt pathology

Identification of aCD4 T cell epitope in the pneumonia virus of mice glycoprotein and characterization of its role in protective immunity

Pneumonia virus of mice (PVM) causes bronchiolitis and pneumonia in mice. Infection is associated with high levels of viral replication in the lungs and results in the functional inactivation of pulmonary virus-specific CD8 T cells. Due to its similarity to severe human respiratory syncytial virus (RSV) infection, PVM infection in mice has been proposed as an alternative RSV model. Here, we have delineated the minimal requirements for protective T cell immunity in the PVM model. Immunization with a CD8 T cell epitope from the PVM phosphoprotein P, combined with the ovalbumin (OVA) CD4 T cell epitope, did not confer protective immunity against lethal PVM challenge, suggesting a possible role of cognate CD4 T cell immunity. To determine the role of PVM-specific CD4 T cell responses, we mapped a PVM CD4 T cell epitope in the glycoprotein G, using a panel of overlapping peptides. Although immunization with this epitope provided some protection, solid protective immunity was only observed after immunization with a combination of the PVM-specific CD4 and CD8 T cell epitopes. Analysis of post-challenge T cell responses in immunized mice indicated that G-specific pulmonary CD4 T cells displayed a mixed Th1/Th2 phenotype, which was characterized by the presence of both IL-5 and IFN-gamma secreting cells, in the absence of overt pathology

Identification of a CD4 T cell epitope in the pneumonia virus of mice glycoprotein and characterization of its role in protective immunity.

Pneumonia virus of mice (PVM) causes bronchiolitis and pneumonia in mice. Infection is associated with high levels of viral replication in the lungs and results in the functional inactivation of pulmonary virus-specific CD8 T cells. Due to its similarity to severe human respiratory syncytial virus (RSV) infection, PVM infection in mice has been proposed as an alternative RSV model. Here, we have delineated the minimal requirements for protective T cell immunity in the PVM model. Immunization with a CD8 T cell epitope from the PVM phosphoprotein P, combined with the ovalbumin (OVA) CD4 T cell epitope, did not confer protective immunity against lethal PVM challenge, suggesting a possible role of cognate CD4 T cell immunity. To determine the role of PVM-specific CD4 T cell responses, we mapped a PVM CD4 T cell epitope in the glycoprotein G, using a panel of overlapping peptides. Although immunization with this epitope provided some protection, solid protective immunity was only observed after immunization with a combination of the PVM-specific CD4 and CD8 T cell epitopes. Analysis of post-challenge T cell responses in immunized mice indicated that G-specific pulmonary CD4 T cells displayed a mixed Th1/Th2 phenotype, which was characterized by the presence of both IL-5 and IFN-γ secreting cells, in the absence of overt pathology

Genetic variability among complete human respiratory syncytial virus subgroup A genomes : bridging molecular evolutionary dynamics and epidemiology

Human respiratory syncytial virus (RSV) is an important cause of severe lower respiratory tract infections in infants and the elderly. In the vast majority of cases, however, RSV infections run mild and symptoms resemble those of a common cold. The immunological, clinical, and epidemiological profile of severe RSV infections suggests a disease caused by a virus with typical seasonal transmission behavior, lacking clear-cut virulence factors, but instead causing disease by modifying the host's immune response in a way that stimulates pathogenesis. Yet, the interplay between RSV-evoked immune responses and epidemic behavior, and how this affects the genomic evolutionary dynamics of the virus, remains poorly understood. Here, we present a comprehensive collection of 33 novel RSV subgroup A genomes from strains sampled over the last decade, and provide the first measurement of RSV-A genomic diversity through time in a phylodynamic framework. In addition, we map amino acid substitutions per protein to determine mutational hotspots in specific domains. Using Bayesian genealogical inference, we estimated the genomic evolutionary rate to be 6.47 × 10(-4) (credible interval: 5.56 × 10(-4), 7.38 × 10(-4)) substitutions/site/year, considerably slower than previous estimates based on G gene sequences only. The G gene is however marked by elevated substitution rates compared to other RSV genes, which can be attributed to relaxed selective constraints. In line with this, site-specific selection analyses identify the G gene as the major target of diversifying selection. Importantly, statistical analysis demonstrates that the immune driven positive selection does not leave a measurable imprint on the genome phylogeny, implying that RSV lineage replacement mainly follows nonselective epidemiological processes. The roughly 50 years of RSV-A genomic evolution are characterized by a constant population size through time and general co-circulation of lineages over many epidemic seasons - a conclusion that might be taken into account when developing future therapeutic and preventive strategies

Dynamics of human respiratory virus-specific CD8+ T cell responses in blood and airways during episodes of common cold.

Contains fulltext : 70459.pdf (publisher's version ) (Closed access)We determined the dynamics of CD8(+) T cells specific for influenza virus and respiratory syncytial virus in blood and tracheostoma aspirates of children during the course of respiratory infections. We showed that during localized respiratory infections the ratio of activated effector CD8(+) T cells to resting memory/naive CD8(+) T cells in peripheral blood increased significantly. Furthermore, the number of effector/memory T cells specific for respiratory viruses declined in blood and increased in the airways, suggesting that these T cells redistributed from blood to airways. T cells specific for the infecting virus were present in the airways for longer periods at increased levels than nonspecifically recruited bystander T cells. After clearance of the infection, the ratio of resting memory and naive CD8(+) T cells normalized in peripheral blood and also memory T cell numbers specific for unrelated viruses that declined during the infection due to bystander recruitment were restored. Taken together, these results showed a significant systemic T cell response during relatively mild secondary infections and extensive dynamics of virus-specific and nonspecific Ag-experienced T cells

Characterization of the CD8+ T cell responses directed against respiratory syncytial virus during primary and secondary infection in C57BL/6 mice.

The BALB/c mouse model for human respiratory syncytial virus infection has contributed significantly to our understanding of the relative role for CD4+ and CD8+ T cells to immune protection and pathogenic immune responses. To enable comparison of RSV-specific T cell responses in different mouse strains and allow dissection of immune mechanisms by using transgenic and knockout mice that are mostly available on a C57BL/ 6 background, we characterized the specificity, level and functional capabilities of CD8+ T cells during primary and secondary responses in lung parenchyma, airways and spleens of C57BL/6 mice. During the primary response, epitopes were recognized originating from the matrix, fusion, nucleo- and attachment proteins, whereas the secondary response focused predominantly on the matrix epitope. C57BL/6 mice are less permissive for hRSV infection than BALB/c mice, yet we found CD8+ T cell responses in the lungs and bronchoalveolar lavage, comparable to the responses described for BALB/c mice. © 2006 Elsevier Inc. All rights reserved. Keywords: Respiratory syncytial virus; C57BL/6; CD8+ T cells; Inactivation; Tetrame

Identification of a CD4 T cell epitope in the pneumonia virus of mice glycoprotein and characterization of its role in protective immunity.

Pneumonia virus of mice (PVM) causes bronchiolitis and pneumonia in mice. Infection is associated with high levels of viral replication in the lungs and results in the functional inactivation of pulmonary virus-specific CD8 T cells. Due to its similarity to severe human respiratory syncytial virus (RSV) infection, PVM infection in mice has been proposed as an alternative RSV model. Here, we have delineated the minimal requirements for protective T cell immunity in the PVM model. Immunization with a CD8 T cell epitope from the PVM phosphoprotein P, combined with the ovalbumin (OVA) CD4 T cell epitope, did not confer protective immunity against lethal PVM challenge, suggesting a possible role of cognate CD4 T cell immunity. To determine the role of PVM-specific CD4 T cell responses, we mapped a PVM CD4 T cell epitope in the glycoprotein G, using a panel of overlapping peptides. Although immunization with this epitope provided some protection, solid protective immunity was only observed after immunization with a combination of the PVM-specific CD4 and CD8 T cell epitopes. Analysis of post-challenge T cell responses in immunized mice indicated that G-specific pulmonary CD4 T cells displayed a mixed Th1/Th2 phenotype, which was characterized by the presence of both IL-5 and IFN-γ secreting cells, in the absence of overt pathology

CD8+ T cell responses in bronchoalveolar lavage fluid and peripheral blood mononuclear cells of infants with severe primary respiratory syncytial virus infections.

Contains fulltext : 52901.pdf (publisher's version ) (Closed access)A protective role for CD8+ T cells during viral infections is generally accepted, but little is known about how CD8+ T cell responses develop during primary infections in infants, their efficacy, and how memory is established after viral clearance. We studied CD8+ T cell responses in bronchoalveolar lavage (BAL) samples and blood of infants with a severe primary respiratory syncytial virus (RSV) infection. RSV-specific CD8+ T cells with an activated effector cell phenotype: CD27+CD28+CD45RO+CCR7-CD38+HLA-DR+Granzyme B+CD127- could be identified in BAL and blood. A high proportion of these CD8+ T cells proliferated and functionally responded upon in vitro stimulation with RSV Ag. Thus, despite the very young age of the patients, a robust systemic virus-specific CD8+ T cell response was elicited against a localized respiratory infection. RSV-specific T cell numbers as well as the total number of activated effector type CD8+ T cells peaked in blood around day 9-12 after the onset of primary symptoms, i.e., at the time of recovery. The lack of a correlation between RSV-specific T cell numbers and parameters of disease severity make a prominent role in immune pathology unlikely, in contrast the T cells might be involved in the recovery process