TABLE 1.
Properties of HA mutants
| HA | Amino acid at position:
|
Cell surface expressiona | Adsorptionb of erythrocytes from:
|
Rescued by reverse geneticsc | Ability to support viral replication in duck intestined | |||
|---|---|---|---|---|---|---|---|---|
| 226 | 228 | Chickens | Humans | Horses | ||||
| Wild type | Leu | Ser | ++ | ++ | ++ | + | + | − |
| LN | Leu | Asn | − | NT | NT | NT | NT | NA |
| LC | Leu | Cys | ++ | − | − | − | NT | NA |
| LV | Leu | Val | ++ | ++ | ++ | − | − | NA |
| LK | Leu | Lys | ++ | + | ++ | − | − | NA |
| LT | Leu | Thr | ++ | ++ | ++ | − | − | NA |
| LA | Leu | Ala | + | +++ | +++ | + | − | NA |
| LR | Leu | Arg | ++ | + | ++ | − | − | NA |
| LG | Leu | Gly | ++ | ++ | ++ | + | NT | NA |
| LD | Leu | Asp | +++ | − | − | − | NT | NA |
| QS (R4) | Gln | Ser | ++ | ++ | ++ | +++ | + | − |
| QN | Gln | Asn | +++ | + | + | − | NT | NA |
| QC | Gln | Cys | + | + | + | − | − | NA |
| QV | Gln | Val | ++ | +++ | +++ | +++ | − | NA |
| QK | Gln | Lys | +++ | − | + | + | NT | NA |
| QT | Gln | Thr | + | − | − | − | NT | NA |
| QA | Gln | Ala | ++ | + | + | + | + | − |
| QR | Gln | Arg | ++ | + | ++ | ++ | + | − |
| QG (R2) | Gln | Gly | ++ | +++ | +++ | +++ | + | + |
| QD | Gln | Asp | ++ | − | − | + | NT | NA |
a
Relative cell surface expression was determined by FACS analysis, using a pool of HA monoclonal antibodies as described in the legend to Fig. 1. Symbols: +, 1 to 50%; ++, 50 to 150%; +++, more than 150% of the wild-type expression. QS and QG mutants are identical to the HAs of R4 and R2 viruses (11), respectively.
b
Symbols: +, 1 to 100 hemadsorption-positive cells; ++, 100 to 300 hemadsorption-positive cells; +++, over 300 hemadsorption-positive cells/1,000 cells examined. NT, not tested.
c
+, rescued by reverse genetics; NT, not tested; −, not rescued by reverse genetics.
d
−, not able to support viral replication; NA, not applicable; +, able to support viral replication.