Seth+Swine

=**HUMAN IMMUNITY TO H1N1 (SWINE) FLU**= (It's not the pigs fault) Seth Ashraf December 8, 2010 Biology 240 Dr. Cannon

=**Abstract**= The H1N1 (Swine) influenza caused roughly 50 million deaths during the pandemic of 1918-1919. A more recent outbreak of the virus occurred during 2009. There have been many theories about the origins of the H1N1 flu and how it became a pandemic in North America, and in particular, the United States. Children are at a much greater risk for contracting the virus, while adults, particular those over the age of 60, are at a much lesser risk.

=**Introduction**= During the Spring of 2009, it was believed that there was a disease on the horizon that was going to cause a great amount of damage. As it turned out, this virus (H1N1) did not quite live up to the catastrophic expectations. During the year 2009, the Centers for Disease Control and Prevention (CDC) estimated that the H1N1 virus infected roughly 22 million Americans; roughly 4,000 of those infections resulted in deaths (Park, 2009).

=**Discussion**= Children are at a much greater risk for contracting the virus, while adults, particular those over the age of 60, are at a much lesser risk. Why is this? What is the role of antibodies in determining these statistics?

--A study conducted by the U.S. Centers for Disease and Prevention (CDC) published in May 2009 found that children under the age of 18 had no preexisting immunity to the H1N1 strain, but that adults, particularly those over 60, had some degree of immunity. Children showed no cross-reactive antibody reaction to the H1N1 strain, adults between the ages of 18 and 64 had 6-9%, and adults over the age of 64 had 33%. (*Serological Tests: **Western Blotting** can be used to determine the presence of specific antibodies)

Does H1N1 have a lytic or lysogenic cycle? Is it an enveloped virus? Does it contain spikes?

--Like the other influenza subtypes, the H1N1 influenza virus exhibits only a lytic cycle. During the lytic cycle, a virus enters the host cell where it begins to replicate its DNA. Then, when the newly synthesized viruses have matured, they are released through lysis of the host cell's wall and plasma membrane. This process ultimately destroys the host cell. (Tortora, 2004).

Like other influenza subtypes, the H1N1 influenza is enveloped and contains spikes, which are carbohydrate-protein complexes that project from the surface of the envelope. Some viruses, such as H1N1, attach to host cells by using these spikes (Tortora, 2004).







The influenza virus genome is composed of eight separate segments. This segmented genome allows the virus genes to mix and create a new influenza virus (Tortora, 2004). In the example below, a pig is infected with both human and avian (bird) influenza at the same time. The viruses can recombine and produce a new virus which can then be transferred back to a human **(Okay, maybe it is the pigs fault)**. In the case of the swine flu outbreak, avian H1N1's non-virulent forms may combine with human strains producing highly pathogenic viruses (Motavalli, 2010).



=Literature Cited:= 1)Motavalli, J//. Lessons From Swine Flu////.// The Environmental Magazine [serial online] 21(3):34-35 (2010). 2) Tortora, Gerard J., Berdell R. Funke, and Christine L. Case. 2004 // Microbiology an Introduction //. San Francisco: Benjamin Cummings, 2010. 371-391 pp. 3)Dudley J. //Public Health and Epidemiological Considerations For Avian Influenza Risk Mapping and Risk Assessment//. Ecology & Society [serial online]13(2):1-23 (2010). 4)Kaiser J. //Facing Down Pandemic Flu, the World's Defenses Are Weak//. Science [serial online] 306(5695):394-397 (2010). 5) Park, A. //Behind the CDC's Soaring H1N1 Death Totals.// Time Magazine: Health and Science. Published online p.1 = =