Association between Haemagglutination inhibiting antibodies and protection against clade 6B viruses in 2013 and 2015. Issue 45 (27th October 2017)

• Record Type: Journal Article
• Authors: Ng, Sophia; Saborio, Saira; Kuan, Guillermina; Gresh, Lionel; Sanchez, Nery; Ojeda, Sergio; Harris, Eva; Balmaseda, Angel; Gordon, Aubree
• Is Part Of: Vaccine. Volume 35:Issue 45(2017)
• Page Start: 6202
• Page End: 6207
• Publication Date: 2017-10-27
• Subjects: Cal09 Influenza A/California/07/2009 virus -- C.I. Confidence interval -- H1N1pdm Pandemic influenza A(H1N1) virus -- HAI Haemagglutination inhibition assay -- HCSFV Health Center Sócrates Flores Vivas -- MN Microneutralization assay -- NA Neuraminidase -- NAI Neuraminidase inhibition assay -- rRT-PCR Real-time RT-PCR; H1N1pdm virus -- Influenza -- Immune correlates -- Antibody titer -- Clade 6b; Vaccines -- Periodicals; 615.372
• DOI: 10.1016/j.vaccine.2017.09.036
• Languages: English
• ISSNs: 0264-410X

Abstract

Highlights: H1N1pdm transitioned from 97D to clade 6 and 6b genotypes between 2009 and 2015. Cal09 HI antibodies associated with protection against clade 6b virus in 2013 and 2015. Strong antibody response to Cal09 after 6b virus infection. Abstract: 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 15–49 years old and a 51% protection in adults 50–85 years 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.