Question

Describe the microevolution of influenza and its consequences for vaccines.

can u tell me please in detail

Answer 1

Influenza viruses are naturally maintained in aquatic birds, occasionally transfer to mammals to cause individual infections or outerbreak of disease, and sometimes go on to cause epidemics and pandemics in their new hosts.Influenza viruses can also transfer between different mammalian host species,as has recently been observed in the cases of swine- origin pademic H1N1 influenza A virus that emerged in 2009 in human.However ,the determination of host range and of interhost transmission of influenza viruse are often poorly understood . Key question include the nature of any hsot barrier to viral transfer,wheather host-adaptive mutants are required for initial infection of new hosts;and the role,if any,of posttransfer adaptation in determining continued transmission in the new host species.There are also considerable uncertainities about the epidemiological processs involved in host switching , including the role played by unusally dense populastion of suseptible hosts,whwre viruses with lower transmission efficiencies may be maintained after inital transfer.A canine influenza virus is a new pathogene of dogs which resulted from the transfer of an intact A equine influenza virus .and Equine influenza virus A was first recognizad in horses in early 1960.

Vaccination is the principal measure for preventing influenza and for reducing its impat .Almost a century ago after the isolation of the first influenza virus,influenza vaccines have been persistent and have evolved to respond to the evolution of teh influenza viruses evolving in human.Antigenic drift of influenza viruses occurs frequently among circulating strains,which leads to new antigenic variants.However, wheather the drift mechanism occurs with the presence of vaccine presssure is an important question that needs to be addressed at a different level as vaccination is the primary method in the prevention and protection of humands against the influenza virus .Two studies of lee&Hensley have shown that vaccination forces mutations on the HA protein of th influenza virus.These mutations changed the way in which the virus gradually evolved and adapted to a new vaccine-protected environment.