Antigenic drift and variability of influenza viruses

Abstract

Annual influenza epidemics are caused by rapid evolution of the viral genome. Continuous and extensive antigenic variation has been shown for hemagglutinin (HA), the principal immunizing antigen of the virus. Monitoring of the antigenicity of circulating influenza viruses is necessary for selection of the most suitable vaccine strains. In this study, characterization of influenza A/H3N2 and influenza B viruses recently circulating in Germany was performed by molecular and antigenic analysis. Sequencing and phylogenetic analysis of the HA1 gene revealed that two distinct groups of H3N2 viruses co-circulated during 1997/1998. The majority of isolates clustered with the new drift variant A/Sydney/5/97, as was also shown by antigenic characterization. A noteworthy genetic drift of H3N2 viruses was evident during the winter 1998/1999. However, serological characterization using hemagglutinin inhibition tests did not result in detection of viruses belonging to different groups as confirmed by molecular analysis. Influenza B viruses isolated during 1996/1997 were antigenically closely related to the prototype vaccine strains B/Beijing/184/93 or B/Harbin/7/94. Molecular analysis demonstrated that our German 1996/1997 isolates differed by nine amino acids from B/Harbin/7/94 and represented a group of viruses that was completely different from the Harbin strain. Retrospective studies revealed the circulation of B/Yamanshi/166/98-like viruses in Germany already during the 1996/1997 season. Our results suggest that molecular analysis of the HA gene is important to complement the antigenic characterization for a better selection of appropriate vaccine strains.

Epidemic dynamics and antigenic evolution in a single season of influenza A

“…This result may help explain a phenomenon described by Schweiger et al (2002), namely, that 'comparable major antigenic differences may result in a severe Table 2. Partial correlations between a parameter and a dynamic quantity, when the other four model parameters are held constant.…”

“…Techniques for the accurate estimation of mutation rates could be applied to detailed, localized influenza datasets such as the one described by Schweiger et al (2002). A precise estimate of influenza's mutation rate would be a significant step towards accurate predictions of near-term antigenic drift.…”

Genetic mutations in influenza H3N2 viruses from a 2012 epidemic in Southern China

“…Influenza virus undergoes rapid evolution by both antigenic shift and antigenic drift and this presents a significant challenge for vaccine design to best match with viruses likely to circulate in the coming influenza season [1,2]. Since their emergence in 1968, influenza H3N2 viruses tend to be highly prevalent most years.…”

Sustained oscillations in an evolutionary epidemiological model of influenza A drift

“…Influenza A and B are currently associated with human diseases, while influenza C has only subclinical importance (Schweiger et al 2002). Influenza A viruses are further classified into subtypes based on two different spike-like protein components, haemagglutinin (HA) and neuraminidase (NA), called antigens, on the surface of the virus (WHO 2009).…”

“…Influenza type A viruses undergo two kinds of changes. Antigenic drift is a major process that accumulates point mutations at the antibody sites in the HA protein, leading to the emergence of immunologically distinct strains and enabling the viruses to evade recognition by hosts' antibodies (Schweiger et al 2002;Treanor 2004;Shih et al 2007). The immunologically distinct influenza virus strains can reinfect hosts that are immune to the progenitor influenza strain and reinvade the communities that recently suffered an epidemic of the progenitor strain (Pease 1987).…”