Viruses Jumping Species: Influenza virus and the SARS coronavirus.

Recent research has focused on mechanisms whereby two different viruses, the avian influenza virus and the SARS coronavirus, have acquired the ability for cross‐species infection. As a high school SMART Team (Students Modeling A Research Topic) we have designed physical models of the influenza virus hemagglutinin protein and the SARS spike protein, highlighting the amino acids that have been mutated to allow these viruses to infect human cells. The flu pandemic of 1918 resulted from the ability of the avian influenza virus to jump from birds to humans through mutations in the hemagglutinin protein. This protein binds to sialic acid, located on host cells, thus allowing the virus to infect the host. The different strains of flu that infect humans each year result from the mutations of this protein. As we continue to combat the flu with vaccines and other treatments, more mutations may arise, thus possibly causing another pandemic similar to what was seen in 1918. Like the flu virus, the SARS coronavirus from palm civets has mutated, resulting in human infection. In the case of the SARS spike protein, just four amino acid substitutions allowed the SARS virus to spread from palm civets to humans. In light of recent avian flu transmissions to humans, understanding how a virus mutates, thus enabling cross‐species infections, is imperative for vaccine research. The hemagglutinin protein model was based on the work of Skehel et. al. (Science 303, pp1838, 2004) as reported in 1RUZ.pdb and the SARS spike protein model was based on the work of Harrison et. al. (Science 309, pp1864, 2005) as reported in 2AJF.pdb. The models were built in a spacefilled format, with color coding to highlight the amino acids that were critical in the binding of the proteins to the human receptor proteins.