Lab studies of flu mutations

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   Lab studies of flu mutations may help in picking vaccine strains

Flu viruses that underwent random mutations in a laboratory setting became antigenically similar to wild circulating viruses, suggesting that in vitro observation of antigenic behavior may more effectively guide selection of flu vaccine strains than current methods, according to a study today in Nature Microbiology.

Researchers with the Centers of Excellence for Influenza Research and Surveillance (CEIRS) created hemagglutinin libraries from naturally occurring H1N1 and H3N2 viruses isolated during the 2009-10 and 2012-13 flu seasons, respectively, mixed them with convalescent  sera from humans and/or ferrets, and observed which isolates escaped the antibody response.

H1N1 mutants had amino acid changes at key antigenic positions on the hemagglutinin head, resulting in reduced reactivity with antiserum against naturally occurring viruses, the authors said. When immunized mice were challenged with a wild-type and a mutant virus, 12 of 13 mutated strains evaded immune system response and replicated efficiently, while none of the naturally occurring strains replicated. Four mutants replicated in immunized ferrets, suggesting that mutand versions of H1N1 still have pandemic potential, the authors said.

An analysis of 2,555 wild-type H1N1 viruses that circulated between 2009 and 2013 revealed that they differed from vaccine strains by more than 6%, the authors said. Antigenic changes in these naturally occurring viruses were identical to the effects observed in the lab with mutations causing formation of antigenically distinct clusters on the hemagglutinin head.

Amino acid changes at antigenically important sites were also observed in the mutated H3N2 viruses, suggesting that in vitro studies of mutated viruses can help predict patterns in how flu viruses evolve in humans. "Antigenic cartography," the authors said, can simulate and predict flu mutations before they occur and inform the development of effective flu vaccines.

http://www.cidrap.umn.edu/news-perspective/2016/05/news-scan-may-23-2016

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arirish Members Profile Send Private Message Find Members Posts Add to Buddy List Admin Group Joined: June 19 2013 Location: Arkansas Status: Offline Points: 39215	Post Options Post Reply Quote arirish Report Post Thanks(0) Quote Reply Topic: Lab studies of flu mutations Posted: May 23 2016 at 3:45pm
	Lab studies of flu mutations may help in picking vaccine strains Flu viruses that underwent random mutations in a laboratory setting became antigenically similar to wild circulating viruses, suggesting that in vitro observation of antigenic behavior may more effectively guide selection of flu vaccine strains than current methods, according to a study today in Nature Microbiology. Researchers with the Centers of Excellence for Influenza Research and Surveillance (CEIRS) created hemagglutinin libraries from naturally occurring H1N1 and H3N2 viruses isolated during the 2009-10 and 2012-13 flu seasons, respectively, mixed them with convalescent sera from humans and/or ferrets, and observed which isolates escaped the antibody response. H1N1 mutants had amino acid changes at key antigenic positions on the hemagglutinin head, resulting in reduced reactivity with antiserum against naturally occurring viruses, the authors said. When immunized mice were challenged with a wild-type and a mutant virus, 12 of 13 mutated strains evaded immune system response and replicated efficiently, while none of the naturally occurring strains replicated. Four mutants replicated in immunized ferrets, suggesting that mutand versions of H1N1 still have pandemic potential, the authors said. An analysis of 2,555 wild-type H1N1 viruses that circulated between 2009 and 2013 revealed that they differed from vaccine strains by more than 6%, the authors said. Antigenic changes in these naturally occurring viruses were identical to the effects observed in the lab with mutations causing formation of antigenically distinct clusters on the hemagglutinin head. Amino acid changes at antigenically important sites were also observed in the mutated H3N2 viruses, suggesting that in vitro studies of mutated viruses can help predict patterns in how flu viruses evolve in humans. "Antigenic cartography," the authors said, can simulate and predict flu mutations before they occur and inform the development of effective flu vaccines. http://www.cidrap.umn.edu/news-perspective/2016/05/news-scan-may-23-2016
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