Differing Epidemiological Dynamics of Influenza B Virus Lineages in Guangzhou, Southern China, 2009-2010

Abstract

The epidemiological and evolutionary dynamics of the two cocirculating lineages of influenza B virus, Victoria and Yamagata, are poorly understood, especially in tropical or subtropical areas of Southeast Asia. We performed a phylogenetic analysis of the hemagglutinin (HA) and neuraminidase (NA) sequences of influenza B viruses isolated in Guangzhou, a southern Chinese city, during 2009 to 2010 and compared the demographic and clinical features of infected patients. We identified multiple viral introductions of Victoria strains from both Chinese and international sources, which formed two phylogenetically and antigenically distinct clades (Victoria 1 and 2), some of which persisted between seasons. We identified one dominant Yamagata introduction from outside China during 2009. Our phylogenetic analysis reveals the occurrence of reassortment events among the Victoria and Yamagata lineages and also within the Victoria lineage. We found no significant difference in clinical severity by influenza B lineage, with the exceptions that (i) the Yamagata lineage infected older people than either Victoria lineage and (ii) fewer upper respiratory tract infections were caused by the Victoria 2 than the Victoria 1 clade. Overall, our study reveals the complex epidemiological dynamics of different influenza B lineages within a single geographic locality and has implications for vaccination policy in southern China.

Molecular epidemiology and evolution of influenza A and B viruses during winter 2013-2014 in Beijing, China

“…Our phylogenetic results showed that the influenza B virus strains circulating in Beijing during the 2013-2014 influenza season were dominated by reassortants with the Yamagata lineage of hemagglutinin and the Victoria lineage of neuraminidase. This new finding is clearly different from those of previous studies [4,32,33]. McCullers et al [23] demonstrated that influenza B viruses adopt reassortment as a means to acquire genetic variability, and that this strategy has shaped the natural evolution of influenza B viruses.…”

Literature review of the epidemiology of influenza B disease in 15 countries in the Asia‐Pacific region

“…Evidence suggests differences in the age distribution of patients infected with the B/Yamagata or B/Victoria lineages, with the latter appearing to be more frequently identified in younger age groups . Although the lineage seems to have generally no impact on the clinical outcome of the infection, recent data from Hong Kong suggested that B/Victoria viruses may be associated with more influenza B hospitalization in children compared with B/Yamagata viruses .…”

Human Co-Infection with Avian and Seasonal Influenza Viruses, China

“…Some amino acid features within the HA and NA of these 2 viruses were the same as those in the A/Shanghai/2/2013(H7N9) strain: L226 and G228 in HA, believed to control host receptor specificity; the cleavage site in HA, relevant for virulence; a deletion in NA stalk (position 69–73), associated with the adaption to gallinaceous hosts; and R294 in NA, related to virus sensitivity to oseltamivir ( 5 ). The HA and NA sequences of A/Hangzhou/10–2/2014(H1N1)pdm09 and B/Hangzhou/17–2/2014 were very close to those of A(H1N1)pdm09 virus and B/Yamagata-lineage viruses that had recently circulated in China ( 6 , 7 ). …”