Association between Haemagglutination inhibiting antibodies and protection against clade 6B viruses in 2013 and 2015
Related Experiment Video
Updated: Dec 28, 2025
Use of an Influenza Antigen Microarray to Measure the Breadth of Serum Antibodies Across Virus Subtypes
Published on: July 26, 2019
Sophia Ng1, Saira Saborio2, Guillermina Kuan3
1Department of Epidemiology, School of Public Health, University of Michigan, Ann Arbor, MI 48109, USA.
Background:
The epidemiology of the pandemic A(H1N1) virus has been changing as population immunity continues to co-evolve with the virus. The impact of genetic changes in the virus on human's susceptibility is an outstanding important question in vaccine design. In a community-based study, we aim to (1) determine the genetic characteristics of 2009-2015 pandemic H1N1 viruses, (2) assess antibody response following natural infections and (3) assess the correlation of A/California/07/09 antibody titers to protection in the 2013 and 2015 epidemics.
Methods:
In a household transmission study, serum specimens from 253 individuals in Managua, Nicaragua were analyzed. Combined nose and throat swabs were collected to detect RT-PCR confirmed influenza infection and virus sequencing. Hemagglutination inhibition assays were performed and the protective titer for circulating H1N1pdm was determined.
Results:
Clade 6B pandemic H1N1 viruses predominated in Nicaragua during the 2013 and 2015 seasons. Our household transmission study detected a household secondary attack rate of 17% in 2013 and 33% in 2015. Infected individuals, including vaccinees, showed an apparent antibody response to A/California/07/09. Baseline titers of A/California/07/09 antibodies were found to associate with protection in both seasons. A titer of ≥1:40 correlated to a 44% protection in children, a 29% protection in adults 15-49years old and a 51% protection in adults 50-85years old.
Conclusion:
In 2013 and 2015, antibody titers to A/California/07/09 associated with an infection risk reduction amongst exposed household contacts. This is consistent with a detectable vaccine effectiveness reported in a number of studies. Genetic changes in clade 6B viruses might have led to a reduced immunity in some whereas others might have been less affected. The use of human serologic data is important in virus characterization and if performed in a timely manner, could assist in vaccine strain selection.
Related Concept Videos
00:42Cross-reactivity
01:51Vaccinations
01:29Immune Response Against Viral Pathogens
NK Cells
NK cells are a crucial part of our innate immune system, acting as the first line of defense against viral infections. These cells can recognize and kill infected cells without prior exposure to the virus, effectively slowing down the spread of infection. Additionally, NK cells produce proinflammatory...