How does a virus that originally infected animals change in such a way that it can infect humans? Topic: Topic: H1N1 (Swine Flu) Rationale:  H1N1 or swine flu, is a respiratory disease originating from pigs caused by a type A influenza virus.  Three categories of swine flu: swine triple reassortant (tr) H1N1 influenza virus, trH3N2v virus, and trH1N2v virus.  Swine flu viruses do not normally infect humans, due to various mutations in the DNA of the virus, it became able to do so.  It is a zoonotic disease; a virus that once originated in an animal is able to infect humans. Causes and Effects:  The person to person mechanism is the cause for spreading of the virus.  The virus induces proinflammatory responses in human cells. Increases plasma levels may be markers of critical illness including interleukin-15.  Fatal cases have caused alveolar hemmorrhaging and vascular congestion.  Antigenic shift is one way that flu viruses move from animals to humans.  There are three general types of antigenic shift.  Pigs can be infected by flu strains from other organisms like humans and birds. Prevention and Treatments:  To prevent spreading of the swine flu, protection against the H1N1 virus was included into the seasonal flu vaccine.  Follow simple hygiene rules: to wash your hands regularly, avoid close contact with sick people, etc.  Treatment consists of bed rest, increased fluid consumption, cough suppressants, and antipyretics and analgesics for fever.  Some of the same antiviral drugs that are used. Oseltamivir (Tamiflu) and zanamivir (Relenza) seem to work best, although some kinds of swine flu are resistant to Tamiflu. Conclusions:  Antigenic shift is most likely how the virus can transmit from pigs to humans.  Generally, the pig will be infected from variant viruses from other species such as humans or birds.  These infect the same cell and when the cells divide, the genes from the strains will cross over and create a virus that still needs a host; but it is still capable of using humans as a viable host.  Once the virus gets into circulation, it continues to spread and reassort itself. The antigenic shift causes the number of variations of the virus to grow, making it even more difficult to find a vaccination. References: "2009 H1N1 Flu ("Swine Flu") and You." CDC. Centers for Disease Control and Prevention. 10 Feb Web. 26 Mar ( m) "Clinical Aspects of Pandemic 2009 Influenza A (H1N1) Virus Infection." The New England Journal of Medicine. Massachusetts Medical Society. 6 May Web. 14 Apr ( 6/NEJMra ) Michael Stuart Bronze, MD. "H1N1 Influenza (Swine Flu) Treatment & Management." Medscape. WebMD LLC. 1 Oct Web. 15 Apr ( om/article/ treatment) "How the Flu Virus Changes." Flu.gov. U.S. Department of Health & Human Services. n.d. Web. 15 Apr ( rus_changes/index.html) mhttp:// 6/NEJMra http://emedicine.medscape.c om/article/ treatmenthttp:// rus_changes/index.html Further Questions To Consider:  There are major gaps in the understanding of viral transmission, what causes the mutations of viruses to allow them to transmit to other species?  Other than vaccination, what preventative tactics can be researched using viral cells? Bechen J., Bithoney B., Cange C., Dorion F., Patel B., and Soloviev A.