Laboratory-Based Surveillance and Molecular Epidemiology of Influenza Virus in Taiwan

Abstract

A laboratory-based surveillance network of 11 clinical virological laboratories for influenza viruses was established in Taiwan under the coordination of the Center for Disease Control and Prevention (CDC), Taiwan. From October 2000 to March 2004, 3,244 influenza viruses were isolated, including 1,969 influenza A and 1,275 influenza B viruses. The influenza infections usually occurred frequently in winter in the northern hemisphere. However, the influenza seasonality in Taiwan was not clear during the four seasons under investigation. For example, the influenza A viruses peaked during the winters of 2001, 2002, and 2003. However, some isolated peaks were also found in the summer and fall (June to November) of 2001 and 2002. An unusual peak of influenza B also occurred in the summer of 2002 (June to August). Phylogenetic analysis shows that influenza A isolates from the same year were often grouped together. However, influenza B isolates from the year 2002 clustered into different groups, and the data indicate that both B/Victoria/2/87-like and B/Yamagata/16/88-like lineages of influenza B viruses were cocirculating. Sequence comparison of epidemic strains versus vaccine strains shows that many vaccine-like Taiwanese strains were circulating at least 2 years before the vaccine strains were introduced. No clear seasonality of influenza reports in Taiwan occurred in contrast to other more continental regions

Shaping the phylogenetic tree of influenza by cross-immunity

“…Specific strains appear to be well suited for the low-transmission period (Gog et al, 2003) and in addition genetic and antigenic variation is always present at least at the global and regional scales (Plotkin et al, 2002;Holmes et al, 2005). Still within a single epidemic, variation appears to be 6 limited (Schweiger et al, 2002;Shih et al, 2005). We shall return to these issues in the discussion but for now we ignore such complications and assume the strains arrive to the host population sequentially as described.…”

Genetic and Epidemiological Analysis of Influenza Virus Epidemics in Taiwan during 2003 to 2006

“…Details about the virology laboratories and the specimen collection, virus isolation, RNA extraction, reverse transcription-PCR, and nucleotide sequencing methods used can be found in a previous report (18). In summary, 12 virology laboratories throughout the island of Taiwan collected clinical samples and sent them to the core sequencing laboratory at the CDC of Taiwan for reverse transcription-PCR and nucleotide sequencing.…”

Molecular characterization of influenza B viruses isolated in east-central China in 2009–2010

“…Each of these two types has achieved predominance at different times and in different geographic regions. Since the 1990s, the strains derived from the Yamagata lineage have circulated globally [8,10,11]. Viruses of the Victoria lineage were found primarily in the 1980s and sporadically found in the 1990s [6].…”