Influenza viruses and their ion channels

Influenza is an ancient disease that has infected humans in irregular intervals throughout recorded history. The most infamous pandemic was "Spanish Flu" which affected large parts of the world population and killed in 1918-1919, at a rough estimate, at least 50 million people. More recently, two influenza A pandemics occurred in 1957 ("Asian influenza") and 1968 ("Hong Kong influenza") and caused significant morbidity and mortality globally. Most recently, in 1997 and 2003, limited outbreaks caused by a new influenza A virus subtype H5N1 that was directly transmitted from birds to humans, occurred in the Hong Kong Special Administrative Region of China. Since 2003, the avian H5N1 strain has infected more then 130 persons in Vietnam, Thailand, and Cambodia and has killed more than half of them. To prevent the human and economical losses caused by human and avian influenza viruses, it is necessary to prepare safe universal influenza vaccines. In order to develop a broad-spectrum protection against different influenza virus strains or variants, some recent studies have were aimed at the M2 protein of Influenza A virus. This review compares the influenza A, B, and C viruses by focusing on their ion channels.