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Viral mutations rendered 2014-2015 influenza vaccine ineffective
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Observed mutations within hemagglutinin site B of influenza A (H3N2) may explain the shortcomings of last winter’s influenza vaccine, according to data recently published in Cell Reports.
“Our study shows that flu viruses recently acquired mutations in critical regions that are recognized by our immune system,” Scott E. Hensley, PhD, assistant professor at the Wistar Institute in Philadelphia, said in a press release. “These new mutations likely contributed to the ineffectiveness of flu vaccines during the 2014-2015 flu season.”
Researchers in the Hensley lab began studying antigenic drift in December using reverse genetics methodology. By analyzing sera isolated from vaccinated humans, as well as infected ferrets and sheep, Hensley and colleagues were able to observe reduced hemagglutination inhibition and in vitro neutralization titers against viruses with mutations in the hemagglutinin site B. The researchers identified 10 viral mutations that presented a mismatch for the 2014-15 influenza vaccine H3N2 strain, according to the release, and engineered an appropriate virus to ward off the mutated influenza strains as well.
Scott E. Hensley
“We identified mutations that were common in flu isolates in December 2014 and we engineered viruses that allowed us to characterize these mutations the following month,” Benjamin Chambers, a graduate student and researcher, said in the release.
WHO has recommended that the 2015-2016 influenza vaccine be altered to account for these mutations – a wise move, according to Hensley and colleagues.
“Our data suggest that mutations in antigenic site B of 2014-2015 H3N2 strains have led to a major antigenic change. Our studies support the World Health Organization’s decision to update the H3N2 component of the 2015-2016 influenza vaccine,” the researchers wrote. – by David Jwanier
Disclosure: The researchers report no relevant financial disclosures.
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