Researchers at The Wistar Institute have identified the specific mutations that rendered the 2014-2015 influenza vaccine ineffective. Scott Hensley, PhD, assistant professor at The Wistar Institute, led the study in which researchers identified 10 different viral mutations that circulated from 2014 to 2015 and were different from the viral strain that was utilized to create the vaccine. The researchers then examined sera, the clear part of the blood that contains viral antibodies, from humans, ferrets, and sheep exposed to the current H3N2 vaccine strain.

The researchers in Hensley’s lab began to investigate antigenic drift of the 2014-2015 seasonal influenza viruses in December 2014 while the virus was still circulating. According to a Science Newsline report, the mutations were studied using reverse engineering and allowed the researchers to modify the ineffective H3N2 vaccine strain so that it matched the H3N2 strain with mutations caused by antigenic drift.

Hensley states, “Our studies show that flu viruses recently acquired mutations in critical regions that are recognized by our immune system. These new mutations likely contributed to the ineffectiveness of flu vaccines during the 2014-2015 flu season.” He adds, “I have a really talented team of researchers who are very good at quickly dissecting the specificity of flu antibody responses.”

Benjamin Chambers, a graduate student in Hensley’s laboratory, says, “We identified mutations that were common in flu isolates in December of 2014 and we engineered viruses that allowed us to characterize these mutations the following month.”

The Science Newsline report notes that the World Health Organization (WHO) recommends that the seasonal flu vaccine be properly updated for the 2015-2016 flu season to account for the recent case of antigenic drift. The authors write that their data strongly supports this recommendation and are presently completing studies to determine if antibodies elicited by the new vaccine strain recognize the types of H3N2 strains that may circulate in 2016.

Source: Science Newsline