Question

How far has the H1N1 virus become resistant to neuraminidase inhibitors?

Answer 1

Two neuraminidase inhibitors have been widely used in the prophylaxis or treatment of pandemic (H1N1) influenza: oseltamivir (marketed as Tamiflu) and, to a lesser extent, zanamivir (Relenza). Oseltamivir-resistant pandemic strains have been detected, often associated with prolonged treatment of severe cases, but to date there is little evidence of sustained spread of these strains among untreated individuals. As the most common oseltamivir resistance mutation (an H to Y change at position 275) is close to the substrate-binding site of the neuraminidase protein, it was expected from earlier animal studies that such mutants would be less transmissible than their wild-type counterparts. There are conflicting data on this issue. For example, the H275Y oseltamivir resistance mutation emerged in seasonal (H1N1) viruses in late 2007 and spread globally during 2008 in the absence of widespread usage of the drug, suggesting that the mutation had not impaired viral transmissibility. Subsequent work has identified 'permissive' mutations that restored the fitness of these viruses . There are contradicting reports on the impact of oseltamivir resistance on transmission of pandemic influenza strains in ferret models, with one demonstrating lower transmission, and the other showing no impact . The reason for this difference is still unclear, so there is plainly a need to monitor the behavior of such drug-resistant viruses in humans carefully.   

Answer 2

H1N1 or Influenza A is a subtype of Influenza A virus, which is the most common cause of human flu (influenza), established in the year 2009. It is an Orthomyxovirus and that is why these are described as HINI, H1N2, depend upon the H or N antigen types they express. Hemagglutinin causes red blood cells to clump together and attaches the virus to the infected cell. Neuraminidase are a type of hydrolase enzyme that help to move the virus particles through the infected cell and help in budding from the host cells. Flu viruses are constantly changing. Changes that occur in circulating flu viruses typically involve the structures of the viruses