Figure 2
From: Genetic characterisation of influenza B viruses detected in Singapore, 2004 to 2009
Phylogenetic tree of the NA gene segment of Singaporean specimens isolated from 2004 to 2009. The NA sequences of these specimens were aligned together with the NA gene segments of B/Lee/40, B/Yamagata/16/88, B/Victoria/2/87, the vaccine strains from 2004–2013 (Table 1) and the NA gene segments of Singaporean strains isolated in 1979, 1991, 1994, 1998, 2010 and 2011. Representative strains of influenza B from countries within SEA, such as Hong Kong, Philippines, Taiwan, Thailand, Malaysia and Myanmar, isolated post 2000 available from GenBank were included in this alignment as well. Lineages were marked by the labelled brackets.