Volume 25, Number 1—January 2019
Research
Association of Increased Receptor-Binding Avidity of Influenza A(H9N2) Viruses with Escape from Antibody-Based Immunity and Enhanced Zoonotic Potential
Table 1
Change in HI titers of influenza A(H9N2) viruses from Pakistan during 2014–2016 viruses compared to UDL-01/08 virus*
HA backbone and substitution | Fold change in HI titer (titer)† |
---|---|
SKP-827/16 | |
I116L | – (2,048) |
P118S | – (2,048) |
S134L | – (2,048) |
N135D | – (2,048) |
N148S | – (2,048) |
A156V | 1‡ (4,096) |
R162Q + D262N | – (2,048) |
G163E | – (2,048) |
K164N | 1‡ (4,096) |
180T | 4 (128) |
A180T + K164N | 4 (128) |
A180V | 4 (128) |
N198D | (2,048) |
D262N | (2,048) |
S265I |
1‡ (4,096) |
UDL-01/08 | |
A180T | 4 (128) |
A180V | 4 (128) |
*Postinfection polyclonal antiserum raised in a single chicken inoculated with UDL-01/08 was used in all HI assays. Amino acid substitutions were introduced into a contemporary virus HA backbone (SKP-827/16 with A180) or the UDL-01/08 HA backbone and rescued by reverse genetics. HI titers between contemporary viruses and UDL-01/08 virus were compared. HA, hemagglutinin; HI, hemagglutination inhibition; –, no change.
†The homologous HI titer for UDL-01/08 antiserum was 2,048.
‡Indicates fold decrease compared with UDL-01/08.
1Current affiliation: Imperial College London, London, UK.
2Current affiliation: Chinese Academy of Agricultural Sciences, Beijing, China.