Glycan receptor binding determinants of Influenza A virus hemagglutinin
Massachusetts Institute of Technology. Dept. of Biological Engineering.
Ram Sasisekharan and Jianzhu Chen.
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An understanding of the factors involved in the human adaptation of influenza A viruses is critical for various aspects of influenza preparedness, including the development of appropriate surveillance measures, preventive strategies and effective treatments. A key step in influenza human adaptation is the acquisition of mutations in the viral coat glycoprotein, hemagglutinin (HA), which changes its binding specificity towards glycan receptors in the human upper respiratory epithelia (referred to as human receptors). In this thesis, determinants that mediate changes in HA-glycan receptor binding specificity are investigated, with focus on the molecular environments within and surrounding the glycan receptor binding site (RBS) of HA. The glycan receptor binding properties of HA from different influenza subtypes (H1N1, H2N2, H3N2 and H5N1) are studied using a combination of approaches including dose-dependent glycan binding, human tissue staining and structural modeling. Using these complementary analyses, it is shown in this thesis that the molecular interactions between amino acids in and proximal to the RBS (referred to as amino acid interaction networks), including those between the RBS and glycosylation at sites proximal to the RBS, and interactions between the RBS and the glycan receptor together govern the high affinity binding of HA to human receptors. The thesis is divided into three sections. First, the evolution of glycan receptor binding specificity of recent human-adapted H3 strains such as A/Fujian/411/02 and A/Panama/2007/99 is investigated, with implications on vaccine production in chicken eggs. Second, the determinants of glycan receptor binding affinity of potentially pandemic avian viruses is studied in the context of the recently circulating H2 A/Chicken/Pennsylvania/2004 and the highly pathogenic H5 A/Vietnam/1203/2004. Here it is shown that mutations which cause human adaptation of H2 do not increase human receptor binding affinity in H5, and the importance of amino acid interaction networks is implicated. Third, determinants that govern the high affinity human receptor binding of pandemic influenza HAs is investigated using the prototypic 1918 H1N1 HA as a model system. The roles of amino acid interaction networks and the molecular interactions between the RBS and glycosylation at sites proximal to the RBS in contributing to the high affinity human receptor binding of 1918 H1N HA are investigated. The approaches presented in this thesis to systematically investigate molecular interactions between HA and glycan receptors that impinge on quantitative HA-glycan receptor binding affinity offer a new angle towards studying determinants of human receptor binding specificity and affinity of influenza A virus HAs.
Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Biological Engineering, 2010.Cataloged from PDF version of thesis.Includes bibliographical references.
DepartmentMassachusetts Institute of Technology. Dept. of Biological Engineering.
Massachusetts Institute of Technology