Influenza is a highly contagious respiratory illness caused by influenza viruses with resultant symptoms which include malaise, fever, headache, tiredness, cough, sore throat, runny or stuffy nose, diarrhea, vomiting and body aches. Diarrhea and vomiting are more common among children than adults. Although most healthy people recover from the influenza without complication, young children, pregnant women, adults over 65 years, people with chronic medical conditions (such as asthma, diabetes, or heart disease), are at a high risk to develop serious complications which include bacterial pneumonia, sinus problems, ear infections, dehydration, and worsening of chronic medical conditions. Disease presentation can vary from mild to severe illness and at times can lead to death. Historically, influenza pandemics have proved difficult to manage, clearly highlighting the gravity of a potential influenza pandemic. The three influenza pandemics of 1918 to 1919 (Spanish flu), 1957 to 1958 (Asian flu) 1968 to 1969 (Hong Kong flu) were caused by three different strains of influenza A and resulted in human death tolls of about 100 million, 1 million and 750,000, respectively. The spread of seasonal influenza is usually from person to person when respiratory droplets from infected people are spread through a cough or sneeze. The highly pathogenic avian influenza (HPAI) strain H5N1 has emerged as a new global health threat of great socioeconomic importance. It has jumped the species barrier to infect humans with grave consequences and has decimated large flocks of poultry. The avian influenza is spread through human contact with infected poultry. However, there is the looming threat of human to human transmission of avian influenza which could be devastating. Taken together, the development of platforms to study the pathogenicity of influenza A, immune response and to assess the efficacy of vaccines and treatment interventions against influenza A is of utmost importance. © 2009.