Publication: Amino acid substitutions in hemagglutinin of the 2009 pandemic influenza A(H1N1) viruses that might affect the viral antigenicity
2
5
Issued Date
2014
Resource Type
Language
eng
Rights
Mahidol University
Rights Holder(s)
BioMed Central
Bibliographic Citation
BMC Research Notes. Vol. 7, (2014), 951
Suggested Citation
Nathamon Kosoltanapiwat, Usa Boonyuen, Phisanu Pooruk, Sopon Iamsirithaworn, Anek Mungaomklang, Kulkanya Chokephaibulkit, Prasert Auewarakul, Pilaipan Puthavathana Amino acid substitutions in hemagglutinin of the 2009 pandemic influenza A(H1N1) viruses that might affect the viral antigenicity. BMC Research Notes. Vol. 7, (2014), 951. doi:10.1186/1756-0500-7-951 Retrieved from: https://repository.li.mahidol.ac.th/handle/123456789/2656
Research Projects
Organizational Units
Authors
Journal Issue
Thesis
Title
Amino acid substitutions in hemagglutinin of the 2009 pandemic influenza A(H1N1) viruses that might affect the viral antigenicity
Other Contributor(s)
Abstract
Background: During 2009 to 2012, Thailand had encountered 4 distinctive waves of the 2009 pandemic influenza
A(H1N1) (H1N1pdm) outbreaks. Considering the RNA nature of the influenza viral genome, a mutation in
hemagglutinin (HA) gene which led to change in antigenicity of the strains circulating during those epidemic
periods is anticipated. It is also uncertain whether the A/California/07/2009 (H1N1) (CA/07) vaccine strain still
confers protective immunity against those evolved viruses, the causative agents of the later epidemic waves.
Methods: HA gene segments of 10 H1N1pdm isolates obtained during 2009 to 2012 were sequenced and
phylogenetically analysed using ClustalW and MEGA5 programs. A total of 124 convalescent serum samples
collected from patients naturally infected during 3 epidemic waves were employed as tools to investigate for
antigenic change in HA of these 10 circulating H1N1pdm viruses by hemagglutination inhibition (HI) assay.
Results: A phylogenetic analysis showed that the 10 virus isolates were grouped into 4 clusters corresponding to
the time of 4 consecutive outbreaks. An accumulation of amino acid substitutions in HA was observed in viruses
derived from the late epidemic waves. Significantly lower antibody titers were observed when CA/07 was tested
against convalescent sera collected from the 3 waves (p < 0.05) compared to most of Thai isolates; and significantly
lower antibody titers were also obtained when virus isolates, retrieved from the third epidemic wave were tested
against convalescent sera collected during the first and second wave. These results were suggestive of change in
antigenicity of the evolved viruses. Our results also showed some mutation position residing outside the previously
reported antigenic site that may involve in an alteration of the viral antigenicity.
Conclusions: Our study demonstrated that convalescent sera collected from individuals naturally infected with
H1N1pdm virus were successfully used to reveal a statistically significant change in antibody titers against the
currently evolved H1N1pdm viruses as determined by HI assay. Nevertheless, the antibody titers of individual serum
against various viruses were less than 4-folded difference as compared to that against the CA/07 vaccine strain.
Therefore, CA/07 is still a potent vaccine strain for those evolved H1N1pdm viruses.