Please use this identifier to cite or link to this item: http://scholarbank.nus.edu.sg/handle/10635/47723
Title: MURINE MODELS TO STUDY IMMUNITY AND IMMUNISATION AGAINST RESPIRATORY VIRAL PATHOGENS
Authors: POH WEE PENG
Keywords: SARS, Influenza, host immune responses, DNA vaccine, IRF-4, transcriptional factor
Issue Date: 13-Jul-2010
Source: POH WEE PENG (2010-07-13). MURINE MODELS TO STUDY IMMUNITY AND IMMUNISATION AGAINST RESPIRATORY VIRAL PATHOGENS. ScholarBank@NUS Repository.
Abstract: This thesis investigates two key concepts (vaccination and elicitation of host immune responses) in prevention of respiratory virus infections, focusing on SARS coronavirus (SARS-CoV) and influenza virus (InfV). A novel approach to increasing DNA vaccine efficacy was investigated. The integrin-binding motif, Arg-Gly-Asp (RGD) was incorporated into a mammalian expression vector expressing codon-optimized extra-cellular domain of SARS-CoV spike protein, and tested by immunizing C57BL/6 mice. Immune responses were characterized by 51Cr-release assay and IFN-gamma secretion ELISPOT assay against RMA/S target lines presenting predicted MHC class I H2-Kb epitopes (including residues 884-891 and 116-1123 within the S2 subunit). Immunization with the Spike-RGD/His DNA vaccine generated robust cell-mediated immune responses. The role of interferon regulatory factor-4 (IRF-4) as a direct transducer of influenza virus-mediated signaling is unclear. IRF-4 -/- mice in C57BL/6 background infected with a lethal dose of InfV A/Puerto Rico/8/1934 H1N1 had the highest lung viral titres and were unable to mount a detectable antibody response in virus neutralization test. Lung homogenates revealed a dysregulation of pro-inflammatory cytokines (IL-1ß and IL-6 levels: suppressed; GM-CSF and TNF-a levels: augmented). Th-1 cytokines (IL-2, IFN-¿) levels decreased, whereas Th2 cytokines (IL-4, IL-10) were increased. Chemokine CXCL1 indicated a dysfunction in neutrophil attractant activity. IFN-a and -ß mRNA levels remained unchanged. However, IFN-¿ mRNA levels were undetectable due to dysfunctional T lymphocytes. Microarray analysis revealed that besides being involved in signaling pathways of both innate and adaptive immune responses, the IRF-4 gene also played multiple roles in other previously unknown pathways. The absence of IRF-4 which has critical function in the development of lymphoid and myeloid cells appears to be detrimental to InfV-infected mice, resulting in the failure to arm the mice with the necessary protective immunity to mount an efficient adaptive immune response.
URI: http://scholarbank.nus.edu.sg/handle/10635/47723
Appears in Collections:Master's Theses (Open)

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