Cell mediated immunity against RSV and influenza in a human experimental challenge model
Lead Research Organisation:
Imperial College London
Department Name: National Heart and Lung Institute
Abstract
Influenza and respiratory syncytial virus (RSV) are among the most common causes of lung infection. They affect around 664 million people each year worldwide, causing an estimated 500,000 and 160,000 deaths respectively. Current influenza vaccines need to change every year to overcome rapid viral mutation, and there is still no RSV vaccine. Further research is therefore urgently needed. T cells are important in controlling viral infections, but there is not enough known about their role in humans with influenza and RSV. Furthermore, there is evidence that the T cell response to RSV is not fully protective, leading to multiple infections with the same strain of RSV in some people.
This work will be carried out at the Centre for Respiratory Infection, Imperial College London within Professor Peter Openshaw‘s department. Healthy volunteers will be infected with either RSV or a weakened strain of influenza in order to examine the response of the T cells in their blood and lung secretions. By observing the changes in T cells following each infection, and comparing the responses to influenza and RSV, we aim to identify the essential components of an effective T cell response so that they can be used to create better vaccines.
This work will be carried out at the Centre for Respiratory Infection, Imperial College London within Professor Peter Openshaw‘s department. Healthy volunteers will be infected with either RSV or a weakened strain of influenza in order to examine the response of the T cells in their blood and lung secretions. By observing the changes in T cells following each infection, and comparing the responses to influenza and RSV, we aim to identify the essential components of an effective T cell response so that they can be used to create better vaccines.
Technical Summary
Background
Influenza and respiratory syncytial virus (RSV) are among the most common causes of viral respiratory infection, causing widespread morbidity and mortality particularly at the extremes of age and exacerbating conditions such as asthma. Vaccine development remains an urgent priority. While cell mediated immunity (CMI) is important in viral clearance and may enhance vaccine efficacy, its relative contribution in humans has not been fully determined. We aim to elucidate its role by comparing the human T cell responses to influenza and RSV. These differ in that re-infection with antigenically identical strains of influenza does not occur, while within 2 months of RSV challenge even subjects with high antibody levels may be re-infected with the same strain. The reasons for this are unclear but may involve immune modulation by viral products or impaired antigen presentation by RSV-infected dendritic cells leading to impaired T cell numbers function.
Hypotheses & aims
1. To test the hypothesis that RSV and influenza lead to quantitative and functional differences in T-cell responses.
2. To identify the mechanisms underlying poor antigen-specific CMI to RSV by comparing the transcriptional changes in T-cells following experimental challenge with RSV and live attenuated influenza vaccine (LAIV).
Study design
Healthy adult volunteers will be challenged with RSV Memphis 37 or LAIV. Samples will be collected periodically from blood, broncho-alveolar lavage (BAL) and nose. After 6 months, a second dose of virus will be administered and further samples obtained to examine the recall response.
The number of virus-specific T-cells will be analysed by ELISPOT and by MHC/peptide multimer staining. Differential effector functions will be studied including surface protein expression, cytokine production and proliferative capacity by CFSE staining. Flow cytometry will be used to characterize activation markers, co-stimulatory molecules, cytokines, and cytotoxic molecules. Nasal and bronchial fluid will be analysed for cytokine levels using multiplex bead arrays and Luminex. Using microarrays, we will identify transcriptional changes that occur during T-cell activation and following re-stimulation with RSV and LAIV. These data will recapitulate the predicted functional defects in RSV-infected T cells and will allow us to make inferences regarding underlying mechanisms via differential expression of signalling intermediates in TCR signal transduction.
CMI is important against both influenza and RSV infection, but protection against RSV is incomplete. By identifying correlates of immunity absent from the CMI response to RSV we aim to elucidate the basis for previous vaccine failures as well as novel approaches to vaccination.
Influenza and respiratory syncytial virus (RSV) are among the most common causes of viral respiratory infection, causing widespread morbidity and mortality particularly at the extremes of age and exacerbating conditions such as asthma. Vaccine development remains an urgent priority. While cell mediated immunity (CMI) is important in viral clearance and may enhance vaccine efficacy, its relative contribution in humans has not been fully determined. We aim to elucidate its role by comparing the human T cell responses to influenza and RSV. These differ in that re-infection with antigenically identical strains of influenza does not occur, while within 2 months of RSV challenge even subjects with high antibody levels may be re-infected with the same strain. The reasons for this are unclear but may involve immune modulation by viral products or impaired antigen presentation by RSV-infected dendritic cells leading to impaired T cell numbers function.
Hypotheses & aims
1. To test the hypothesis that RSV and influenza lead to quantitative and functional differences in T-cell responses.
2. To identify the mechanisms underlying poor antigen-specific CMI to RSV by comparing the transcriptional changes in T-cells following experimental challenge with RSV and live attenuated influenza vaccine (LAIV).
Study design
Healthy adult volunteers will be challenged with RSV Memphis 37 or LAIV. Samples will be collected periodically from blood, broncho-alveolar lavage (BAL) and nose. After 6 months, a second dose of virus will be administered and further samples obtained to examine the recall response.
The number of virus-specific T-cells will be analysed by ELISPOT and by MHC/peptide multimer staining. Differential effector functions will be studied including surface protein expression, cytokine production and proliferative capacity by CFSE staining. Flow cytometry will be used to characterize activation markers, co-stimulatory molecules, cytokines, and cytotoxic molecules. Nasal and bronchial fluid will be analysed for cytokine levels using multiplex bead arrays and Luminex. Using microarrays, we will identify transcriptional changes that occur during T-cell activation and following re-stimulation with RSV and LAIV. These data will recapitulate the predicted functional defects in RSV-infected T cells and will allow us to make inferences regarding underlying mechanisms via differential expression of signalling intermediates in TCR signal transduction.
CMI is important against both influenza and RSV infection, but protection against RSV is incomplete. By identifying correlates of immunity absent from the CMI response to RSV we aim to elucidate the basis for previous vaccine failures as well as novel approaches to vaccination.
