Table 2.
Surveillance samples of influenza B virus with NA mutations resulting in decreased susceptibility to FDA-approved NAIs.
| NA mutation and function a |
Method of testing b |
Susceptibility to NAIs (range of fold-difference) c |
Reference | |
|---|---|---|---|---|
| Oseltamivir | Zanamivir | |||
| Catalytic mutation | ||||
| R371K | CL | 407 | 29 | Sheu et al., 2008 |
| Framework mutation | ||||
| D198E | on FL | 8.4 - 14 | 6.4 - 9 | Hurt et al., 2004b, 2006 |
| CL | 14.2 | 2.2 | ||
| D198E | CL | 4.0 | 3.1 | Sheu et al., 2010, Okomo-Adhiambo et al., 2010 |
| D198N | CL | 5 | 7 | Wang et al., 2013 |
| D198N | CL | > 10 | > 10 | WHO, 2007, Tashiro et al., 2009 |
| D198Y | FL | 14.5 | 14.31 | Escuret et al., 2008 |
| I222T | CL | 3.2 | 2.1 | Sheu et al., 2008 |
| I222T d | FL | 5 - 8 | S | Wang et al., 2013 |
| CL | 9 | S | ||
| I222T | CL | 7.3 - 13.4 | 2.3 - 6.5 | Monto et al., 2006 |
| I222V e | FL | 5.5 - 6.9 | 2.5 - 3.3 | Sleeman et al., 2011 |
| CL | 2.6 - 4.8 | 1.2 - 2.2 | ||
| H274Y | CL | 3.3 | 0.4 | Sheu et al., 2008 |
| Other mutation | ||||
| T325I | CL | 2.7 | 0.9 | Sheu et al., 2008 |
| G142R+N146K | FL | 6 | 10 | Okomo-Adhiambo et al., 2013 |
a
The function of NA mutation is based on Colman et al. (1989), N2 numbering.
b
Fold difference in mean IC50 values derived from FL, fluorescence-based or CL, chemiluminescence-based assay.
c
Fold difference as compared to mean IC50 value of susceptible isolates.
d
Cluster of 4 isolates (3 from Chongqing, China and 1 from Shanghai, China).
e
Cluster of 14 isolates (North Carolina, United States).
Abbreviations: S, susceptible