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| The Flu Virus |The Flu and Global Health | The Epitope-based Approach | The Immune System | Links | Publications | | |||||
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The Flu Disease The flu disease is an acute respiratory tract infection characterized by fever, rhinitis, coughing, headaches and malaise. The incubation period ranges from 1-5 days, with an average of 2 days. Flu patients are more vulnerable to other infections, with the most common complication being pneumonia. During an epidemic, the virus may infect 5%-20% of the entire population. The influenza A viruses are responsible for about 80% of influenza illnesses, resulting in many millions of infected individuals worldwide. The WHO reports 250 to 500 thousands of deaths annually due to the flu, the majority due to pulmonary and cardiovascular complications. An annual economic burden of over $25 Billion USD is associated with the flu in the US alone. It is therefore a high priority target for primary prevention by national health organizations. The Flu Pandemic The Influenza pandemic is becoming one of the major concerns among health authorities due to increasing international travel, as well as over-population associated with poor sanitary conditions for humans and livestock living together in some developing countries. As a result, there is a heightened risk for emergence of new and more violent and resistant influenza virus strains as well as increased human infection by animal virus strains, as observed since 1997 with the Avian Flu. The H5N1 virus has raised concerns about a potential human pandemic because it is highly virulent; it is spreading by migrating birds and can be transmitted from bird to human. A further change of this virus could potentially result in a human-to-human transmission of the disease and lead to a worldwide pandemic. The Flu Vaccine Despite the improvement in antiviral therapy during the last decade, vaccination is still the most effective method of prophylaxis. However, effective vaccines must be of the same type that is likely to be common in the following influenza season. Rapid changes in the viral surface antigens render the current strain-specific vaccines only partially effective. Commercial vaccines consist of whole, live-attenuated or killed virus or fragments of their envelope (surface proteins). Due to the ever changing nature of the influenza viruses, and the inability to predict the new strains to come, vaccine makers prepare the flu vaccine according to WHO expert’s recommendation, using three different strains every year (two influenza A and one influenza B strains). This “educated guess” process based on circulating strains from previous season is not always accurate, resulting in reduced efficacy of commercial vaccines. A New Approach New strategies for influenza vaccination include the development of vaccines based on short immunogenic peptides, called epitopes that elicit protective immunity. The key factor for the success of this approach is the exact identification of those epitopes common to the vast majority of influenza strains and capable of eliciting a broad range and long lasting immune (both humoral and cellular) response. |
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