Study On B-cell Epitopic Biology Of Viral Antigenic Protein

The immune system has been shaped by the types of microbes that challenge it. Roles of immune functions during viral infections have been characterized by nonspecific responses and specific humoral and cell-mediated responses to the virus. For the later, the two different lymphocytes, B cell and T cell, have evolved to control infection. Unlike T cells, which mainly lyse the infected cells by recognition of MHC/peptide complex, B cells play the versatile roles in virus-host cell interaction besides producing the antibodies to neutralize the target in the course. The functions exerted by B cells are primordially to recognize the epitopes distributed on the proteins of virus in their native form. Depending on the epitope recognized, the outcome of humoral response to viral infections will in turn be changed. These epitopes therefore can be subdivided into several distinctive groups, including protective vs non-protective epitope, immunodominant vs sub-immunodominant epitope, suppressive vs toxic epitope, and so on, according to the beneficial or detrimental immune response. Characterizing the structure and function of these epitope in depth, which is termed as B-cell epitopic biology in this study, will undoubtedly get insight into the pathogenicity of viral antigenic proteins as well as maximize the B-cell immunological advantages during viral infections. For this purpose, we select two viral models to study, which described as follows.One is SARS-CoV. Being a positive-stranded RNA viruses, its dominant feature during viral infection is that nucleocapsid (N) protein-specific antibodies in the serum of SARS patients have higher sensitivity and longer persistence than those of other structural proteins of SARS-CoV. This raised the questions: what's the role of NP in SARS-CoV infection, and, which epitope should correspond to that? To answer these questions, we first produced a panel of 14 NP-specific monoclonal antibodies (mAbs) to map the antigenic sites located on intact NP. For better mapping the structural vs linear epitope, yeast surface displaying system is employed to express the protein fragments. And then, we prepared the monospecific antisera of NP to differentiate the immunodominant epitopes from the...