November 30, 2011
N50 RNA - Hemagglutinin
Nucleic Acid Aptamer Selection Against Hemagglutinin for the Inhibition of Influenza Binding Capabilities to Human Cells
The H1N1 Influenza virus, along with many other flu strains, is very easily transmissible and presents a range of symptoms that includes fever, mild respiratory infections, and some severe respiratory complications such as pneumonia that can lead to death (3). Along with seasonal epidemics in several countries, a few of the strains have created pandemics such as that of the H1N1, killing some 20 million people in 1918 (1). This RNA virus replicates itself in the human body by first binding to sialic acid sites on erythrocytes and epithelial cells, causing the host cells to agglutinate (4).
The Hemagglutinin (HA) Influenza protein is the surface-binding protein that the virus uses in attaching to host cells, and is dubbed after its mechanism in agglutinating red blood cells into visible clumps (1/2). HA is made up of two different types of chains, one that detects sialic acid on human cell-surface glycoproteins, and another that facilitates in the attack and agglutination of cells. The severity of each strain of influenza is based on the slightly different structures of the HA protein, however in general, the HA protein is the only method by which the flu virus can bind to host cells and begin replication and agglutination (4).
The HA binding protein is essential for the influenza virus, and without it, there is no host cell for which the virus can tether itself to for mass RNA replication (1). By understanding the binding properties of Hemagglutinin proteins, a nucleic aptamer can be developed in order to inhibit the HA protein from binding to host cells. Such a therapeutic aptamer can be used to contain seasonal epidemics and worldwide pandemics, thereby lifting public health standards and possibly pave the way for the inhibition of future mutated strains of HA.
Specific Aim 1: Selection of RNA Aptamers against Hemagglutinin.
As stated, HA is a crucial surface-binding protein for the influenza virus to attack the cells of the human body and propagate the replication of the virus throughout. The protein has sequences that make up the head, which fits into sialic acid sequences of human cells like a lock and key (2). In this case, an aptamer can be selected in order to alter the confirmation of the HA protein, or attach to the fusion peptides of HA, thereby preventing sailic acid from binding to the protein (1). As displayed in Figure 1, once the virus enters the body, its hemagglutinin proteins will bind to human cells via sialic acid sites. The specific aim is to inhibit the function of the protein, thereby impeding the virus’s ability to use the host cell for infection and mass replication.
The H1 strain of the hemagglutinin protein can be purchased through Immune Tech Corp (http://immune-tech.com/) for the price of $349 per 100 ug. The catalog number for the order is IT-003-00101∆TMp.-------------------