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postgraduate thesis: The role of virus-specific human T cells in influenza A virus infection

TitleThe role of virus-specific human T cells in influenza A virus infection
Authors
Issue Date2011
PublisherThe University of Hong Kong (Pokfulam, Hong Kong)
Citation
Guan, J. [管静]. (2011). The role of virus-specific human T cells in influenza A virus infection. (Thesis). University of Hong Kong, Pokfulam, Hong Kong SAR. Retrieved from http://dx.doi.org/10.5353/th_b4729546
AbstractInfluenza A virus infection is a major cause of human morbidity and mortality. T cell immunity is believed to play critical roles for host defenses against influenza A infection. Once intracellular influenza A infection is established, viral clearance is mainly dependent on virus-specific CD8+ T cells. CD4+ T cells are important for adaptive immunity to natural influenza A infection or vaccination by providing help to B cells for antibody production and also providing help to CD8+ T cells for the generation of cytotoxicity. In addition, virusspecific CD4+ and CD8+ T cells are rich sources of effector cytokines, such as IFN-and TNF-, which can promote the function of antigen presenting cells and have direct antiviral activity. Cross-subtype reactive CD4+ and CD8+ memory T cells also affect the clearance of virus infection even in those who lack virus-specific antibodies. Therefore, the aim of our study is to assess the influenza virus-specific T cell responses and define their possible protective role in pandemic H1N1 virus and seasonal influenza infection in human. First we determined whether healthy adults have the cross-reactivity of memory CD4+ and CD8+ T cells against pandemic virus. In April of 2009, 7 pandemic H1N1 infected patients and 17 their healthy contacts who had no pandemic influenza infection were recruited in this study. By using intracellular IFN-staining and flow cytometry, we examined their pandemic H1N1 virus and seasonal influenza H1N1-specific CD4+ and CD8+ T cell responses. Healthy contacts did have measurable but low frequencies of cross-reactive influenza-specific CD4+ and CD8+ T cells, though the frequencies of these T cells specific to pandemic H1N1 virus were slightly lower than that specific to seasonal H1N1 virus. Furthermore, when compared the pandemic H1N1-specific T cell responses between healthy contacts and patients with pandemic H1N1 infection, we can found that the healthy contacts have higher pandemic H1N1 specific-T cell responses than patients, suggesting these pre-existing pandemic H1N1 specific-T cells may have protection from pandemic influenza virus infection. In addition, we conducted a prospective T cell immunity and influenza surveillance study in a cohort of more than 200 healthy volunteers before the influenza season and investigated whether the pre-existing T cell immunity is related to the protection from influenza infection in the next coming influenza season. Using intracellular IFN-staining assay, we examined their pre-existing seasonal influenza H1N1, H3N2, seasonal influenza B virus-specific CD4+ and CD8+ T cell responses. Due to the small number of cases of influenza infection in the coming influenza season, the results only showed a trend that the subjects who have higher frequency of influenza virus strain-specific T cells may have lower chance to suffer from same strain of influenza infection, which to some extent, reflect the pre-exist memory T cells have association with the protection in the coming influenza season. In conclusion, T cells play an important role in defensing against influenza infection. The higher influenza virus specific-T cells response activity in healthy adults may have a protection against influenza virus infection.
DegreeMaster of Philosophy
SubjectInfluenza A virus
T-cells
Dept/ProgramPaediatrics and Adolescent Medicine
Persistent Identifierhttp://hdl.handle.net/10722/208423

 

DC FieldValueLanguage
dc.contributor.authorGuan, Jing-
dc.contributor.author管静-
dc.date.accessioned2015-03-09T02:47:46Z-
dc.date.available2015-03-09T02:47:46Z-
dc.date.issued2011-
dc.identifier.citationGuan, J. [管静]. (2011). The role of virus-specific human T cells in influenza A virus infection. (Thesis). University of Hong Kong, Pokfulam, Hong Kong SAR. Retrieved from http://dx.doi.org/10.5353/th_b4729546-
dc.identifier.urihttp://hdl.handle.net/10722/208423-
dc.description.abstractInfluenza A virus infection is a major cause of human morbidity and mortality. T cell immunity is believed to play critical roles for host defenses against influenza A infection. Once intracellular influenza A infection is established, viral clearance is mainly dependent on virus-specific CD8+ T cells. CD4+ T cells are important for adaptive immunity to natural influenza A infection or vaccination by providing help to B cells for antibody production and also providing help to CD8+ T cells for the generation of cytotoxicity. In addition, virusspecific CD4+ and CD8+ T cells are rich sources of effector cytokines, such as IFN-and TNF-, which can promote the function of antigen presenting cells and have direct antiviral activity. Cross-subtype reactive CD4+ and CD8+ memory T cells also affect the clearance of virus infection even in those who lack virus-specific antibodies. Therefore, the aim of our study is to assess the influenza virus-specific T cell responses and define their possible protective role in pandemic H1N1 virus and seasonal influenza infection in human. First we determined whether healthy adults have the cross-reactivity of memory CD4+ and CD8+ T cells against pandemic virus. In April of 2009, 7 pandemic H1N1 infected patients and 17 their healthy contacts who had no pandemic influenza infection were recruited in this study. By using intracellular IFN-staining and flow cytometry, we examined their pandemic H1N1 virus and seasonal influenza H1N1-specific CD4+ and CD8+ T cell responses. Healthy contacts did have measurable but low frequencies of cross-reactive influenza-specific CD4+ and CD8+ T cells, though the frequencies of these T cells specific to pandemic H1N1 virus were slightly lower than that specific to seasonal H1N1 virus. Furthermore, when compared the pandemic H1N1-specific T cell responses between healthy contacts and patients with pandemic H1N1 infection, we can found that the healthy contacts have higher pandemic H1N1 specific-T cell responses than patients, suggesting these pre-existing pandemic H1N1 specific-T cells may have protection from pandemic influenza virus infection. In addition, we conducted a prospective T cell immunity and influenza surveillance study in a cohort of more than 200 healthy volunteers before the influenza season and investigated whether the pre-existing T cell immunity is related to the protection from influenza infection in the next coming influenza season. Using intracellular IFN-staining assay, we examined their pre-existing seasonal influenza H1N1, H3N2, seasonal influenza B virus-specific CD4+ and CD8+ T cell responses. Due to the small number of cases of influenza infection in the coming influenza season, the results only showed a trend that the subjects who have higher frequency of influenza virus strain-specific T cells may have lower chance to suffer from same strain of influenza infection, which to some extent, reflect the pre-exist memory T cells have association with the protection in the coming influenza season. In conclusion, T cells play an important role in defensing against influenza infection. The higher influenza virus specific-T cells response activity in healthy adults may have a protection against influenza virus infection.-
dc.languageeng-
dc.publisherThe University of Hong Kong (Pokfulam, Hong Kong)-
dc.relation.ispartofHKU Theses Online (HKUTO)-
dc.rightsThe author retains all proprietary rights, (such as patent rights) and the right to use in future works.-
dc.rightsCreative Commons: Attribution 3.0 Hong Kong License-
dc.subject.lcshInfluenza A virus-
dc.subject.lcshT-cells-
dc.titleThe role of virus-specific human T cells in influenza A virus infection-
dc.typePG_Thesis-
dc.identifier.hkulb4729546-
dc.description.thesisnameMaster of Philosophy-
dc.description.thesislevelMaster-
dc.description.thesisdisciplinePaediatrics and Adolescent Medicine-
dc.description.naturepublished_or_final_version-
dc.identifier.doi10.5353/th_b4729546-
dc.date.hkucongregation2011-

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