This article is more than 5 years old. Information may no longer be current.
Middle-aged adults show cross-neutralizing antibodies to some flu strains
Click Here to Manage Email Alerts
Annual seasonal influenza vaccination may play a role in the production of cross-neutralizing antibodies to some potentially pandemic influenza viruses among middle-aged adults, particularly H2N2, according to government researchers.
“The extent to which broadly cross-neutralizing antibodies can be found in sera of persons who have received seasonal influenza vaccines for multiple years remains unknown,” Carol D. Weiss, MD, PhD, from the NIAID’s Laboratory of Immunoregulation in Silver Spring, Maryland, and colleagues wrote in The Journal of Infectious Diseases. “The degree to which different strains within potential pandemic subtypes vary in their susceptibilities to these cross-neutralizing antibodies is also unclear.”
Weiss and colleagues analyzed serum samples collected from September through December 2009 from 45 participants aged 48 to 64 years. The study population had no self-reported history of influenza symptoms, exposures or previous vaccinations that year. Participants had received all seasonal vaccines during the 2004-2005 to 2008-2009 seasons, and 23 additionally received the A/New Jersey/1976 swine influenza vaccine. They used 65 pre-vaccination blood samples from A/New Jersey/1976 swine influenza vaccine trials conducted in 1976 as controls.
The researchers incubated heat-inactivated serum samples with pseudoviruses containing various hemagglutinins to identify cross-neutralizing antibodies to potential pandemic strains.
Results of their analysis suggested that 100% of sera taken from the participants had high neutralization titers ( ≥ 160) to A/Japan/305/1957 (H2N2); 53% had high neutralization titers to A/Hong Kong/1073/99 (H9N2); 56% to the H3N2 variant A/Indiana/08/11 (H3N2v); 11% to A/Hong Kong/G9/97 (H9N2); and 36% to A/chicken/Hong Kong/SF41/01 (H6N1). None had titers greater than 160 to A/Shanghai/2/13 (H7N9) or A/Netherlands/219/03 (H7N7).
Neutralization titers to various H5N1 strains were found in 36% to 0% of samples. While titers to H9, H6 and H5 hemagglutinins were found to correlate with each other, no association was found between these and H3N2v, indicating group-specific cross-neutralization.
“Although it has been nearly a half century since the H2N2 influenza viruses have circulated, the threat of a pandemic from an H2 subtype influenza remains because those born after 1968 likely have little immunity to such viruses,” Weiss and colleagues wrote. “Our data show that 100% of sera in our cohort … still have very high neutralization titers to H2N2, consistent with a previous report, but younger individuals were not studied.” – by Jen Byrne
Disclosure: The researchers report no relevant financial disclosures.
Click Here to Manage Email Alerts