The highly pathogenic H5N1 avian influenza virus is one of the greatest influenza pandemic threats since 2003. The association of the receptor binding domain (RBD) with the virulence of influenza virus is rarely addressed, particularly of H5N1 influenza viruses. In this study, BALB/c mice were intranasally infected with A/Vietnam/1194/2004 (VN1194, H5N1). The mouse lung-adapted variants were isolated and the mutation of E190G (H3 numbering) in the RBD was recognized. The recombinant virus, rVN-E190G carrying E190G in hemagglutinin (HA) was designed and rescued using reverse genetics techniques. The receptor binding activity, growth curve and pathogenicity in mice of the rVN-E190G were investigated. Results demonstrated that rVN-E190G virus increased the binding avidity to α2,6 SA (sialic acid) and reduced the affinity to α2,3 SA, meanwhile weakened the viral replication in vitro. Moreover, the virulence assessment demonstrated that rVN-E190G was attenuated in mice. These results indicated that the mutation E190G in HA decreases H5N1 viral replication in vitro and significantly attenuates virulence in vivo. These findings identify one of the determinants in RBD which can be associated with H5N1 virulence in mice.
Experimental infection and replication assays showed that the H5N1 variant with an E190G mutation in hemagglutinin had altered receptor binding and reduced replication, leading to attenuation in mice.
BALB/c mice were intranasally infected with A/Vietnam/1194/2004 (H5N1)... The receptor binding activity, growth curve and pathogenicity in mice of the rVN-E190G were investigated. Results demonstrated that rVN-E190G virus increased the binding avidity to α2,6 SA and reduced the affinity to α2,3 SA, meanwhile weakened the viral replication in vitro.
The E190G mutation in the hemagglutinin of H5N1 influenza virus altered receptor binding specificity and reduced replication and virulence in mice, indicating adaptive attenuation associated with receptor binding domain change.
Results demonstrated that rVN-E190G virus increased the binding avidity to α2,6 SA (sialic acid) and reduced the affinity to α2,3 SA, meanwhile weakened the viral replication in vitro. Moreover, the virulence assessment demonstrated that rVN-E190G was attenuated in mice. These results indicated that the mutation E190G in HA decreases H5N1 viral replication in vitro and significantly attenuates virulence in vivo.
The E190G mutation in hemagglutinin of H5N1 influenza virus increased binding to α2,6-linked sialic acid and reduced affinity for α2,3-linked sialic acid.
Results demonstrated that rVN-E190G virus increased the binding avidity to α2,6 SA (sialic acid) and reduced the affinity to α2,3 SA, meanwhile weakened the viral replication in vitro.
