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Functional significance of the hemadsorption activity of influenza virus neuraminidase and its alteration in pandemic viruses.

Uhlendorff J, Matrosovich T, Klenk HD, Matrosovich M - Arch. Virol. (2009)

Bottom Line: Each substitution abolished hemadsorption activity.Although, there was no correlation between hemadsorption activity of the NA variants and their enzymatic activity with respect to monovalent substrates, all four hemadsorption-negative NAs desialylated macromolecular substrates significantly slower than did the hemadsorption-positive counterpart.Our data indicate that the hemadsorption site serves to enhance the catalytic efficiency of NA and they suggest that, in addition to changes in the receptor-binding specificity of the hemagglutinin, alterations of the NA are needed for the emergence of pandemic influenza viruses.

View Article: PubMed Central - PubMed

Affiliation: Institute of Virology, Philipps University, Hans-Meerwein-Str.2, 35043, Marburg, Germany.

ABSTRACT
Human influenza viruses derive their genes from avian viruses. The neuraminidase (NA) of the avian viruses has, in addition to the catalytic site, a separate sialic acid binding site (hemadsorption site) that is not present in human viruses. The biological significance of the NA hemadsorption activity in avian influenza viruses remained elusive. A sequence database analysis revealed that the NAs of the majority of human H2N2 viruses isolated during the influenza pandemic of 1957 differ from their putative avian precursor by amino acid substitutions in the hemadsorption site. We found that the NA of a representative pandemic virus A/Singapore/1/57 (H2N2) lacks hemadsorption activity and that a single reversion to the avian-virus-like sequence (N367S) restores hemadsorption. Using this hemadsorption-positive NA, we generated three NA variants with substitutions S370L, N400S and W403R that have been found in the hemadsorption site of human H2N2 viruses. Each substitution abolished hemadsorption activity. Although, there was no correlation between hemadsorption activity of the NA variants and their enzymatic activity with respect to monovalent substrates, all four hemadsorption-negative NAs desialylated macromolecular substrates significantly slower than did the hemadsorption-positive counterpart. The NA of the 1918 pandemic virus A/Brevig Mission/1/18 (H1N1) also differed from avian N1 NAs by reduced hemadsorption activity and less efficient hydrolysis of macromolecular substrates. Our data indicate that the hemadsorption site serves to enhance the catalytic efficiency of NA and they suggest that, in addition to changes in the receptor-binding specificity of the hemagglutinin, alterations of the NA are needed for the emergence of pandemic influenza viruses.

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NA hemadsorption to native and modified erythrocytes. Cos-7 cells expressing the hemadsorption-positive NA variant N367S were probed with native human erythrocytes, erythrocytes desialylated with V. cholerae sialidase, and erythrocytes resialylated using α2-3- and α2-6-sialyltransferases. Data show mean numbers of red blood cells attached per ten Cos-7 cells and are representative of three independent experiments
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Fig4: NA hemadsorption to native and modified erythrocytes. Cos-7 cells expressing the hemadsorption-positive NA variant N367S were probed with native human erythrocytes, erythrocytes desialylated with V. cholerae sialidase, and erythrocytes resialylated using α2-3- and α2-6-sialyltransferases. Data show mean numbers of red blood cells attached per ten Cos-7 cells and are representative of three independent experiments

Mentions: To characterize binding specificity of the hemadsorption site with respect to two major natural sialic acid determinants (Neu5Acα2-3Gal and Neu5Acα2-6Gal), we employed human erythrocytes that were desialylated using V. cholerae sialidase and then resialylated using either α2-3- or α2-6-sialyltransferases. As expected, desialylated erythrocytes lost their ability to bind to Cos-7 cells expressing hemadsorption-positive NA variant N367S (Fig. 4). Resialylation of erythrocytes partially restored their binding although modified erythrocytes bound less efficiently than native red blood cells. It seems likely, that reduced hemadsorption activity of resialylated cells was at least partially determined by reduced levels of incorporation of sialic acid as compared to that of native erythrocytes [36]. However, as both α2-3- and α2-6-resialylated erythrocytes showed substantial hemadsorption activity, we conclude that the hemadsorption site of the NA can bind to sialic acids attached to the penultimate sugar chain by either linkage type.Fig. 4


Functional significance of the hemadsorption activity of influenza virus neuraminidase and its alteration in pandemic viruses.

Uhlendorff J, Matrosovich T, Klenk HD, Matrosovich M - Arch. Virol. (2009)

NA hemadsorption to native and modified erythrocytes. Cos-7 cells expressing the hemadsorption-positive NA variant N367S were probed with native human erythrocytes, erythrocytes desialylated with V. cholerae sialidase, and erythrocytes resialylated using α2-3- and α2-6-sialyltransferases. Data show mean numbers of red blood cells attached per ten Cos-7 cells and are representative of three independent experiments
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC2691527&req=5

Fig4: NA hemadsorption to native and modified erythrocytes. Cos-7 cells expressing the hemadsorption-positive NA variant N367S were probed with native human erythrocytes, erythrocytes desialylated with V. cholerae sialidase, and erythrocytes resialylated using α2-3- and α2-6-sialyltransferases. Data show mean numbers of red blood cells attached per ten Cos-7 cells and are representative of three independent experiments
Mentions: To characterize binding specificity of the hemadsorption site with respect to two major natural sialic acid determinants (Neu5Acα2-3Gal and Neu5Acα2-6Gal), we employed human erythrocytes that were desialylated using V. cholerae sialidase and then resialylated using either α2-3- or α2-6-sialyltransferases. As expected, desialylated erythrocytes lost their ability to bind to Cos-7 cells expressing hemadsorption-positive NA variant N367S (Fig. 4). Resialylation of erythrocytes partially restored their binding although modified erythrocytes bound less efficiently than native red blood cells. It seems likely, that reduced hemadsorption activity of resialylated cells was at least partially determined by reduced levels of incorporation of sialic acid as compared to that of native erythrocytes [36]. However, as both α2-3- and α2-6-resialylated erythrocytes showed substantial hemadsorption activity, we conclude that the hemadsorption site of the NA can bind to sialic acids attached to the penultimate sugar chain by either linkage type.Fig. 4

Bottom Line: Each substitution abolished hemadsorption activity.Although, there was no correlation between hemadsorption activity of the NA variants and their enzymatic activity with respect to monovalent substrates, all four hemadsorption-negative NAs desialylated macromolecular substrates significantly slower than did the hemadsorption-positive counterpart.Our data indicate that the hemadsorption site serves to enhance the catalytic efficiency of NA and they suggest that, in addition to changes in the receptor-binding specificity of the hemagglutinin, alterations of the NA are needed for the emergence of pandemic influenza viruses.

View Article: PubMed Central - PubMed

Affiliation: Institute of Virology, Philipps University, Hans-Meerwein-Str.2, 35043, Marburg, Germany.

ABSTRACT
Human influenza viruses derive their genes from avian viruses. The neuraminidase (NA) of the avian viruses has, in addition to the catalytic site, a separate sialic acid binding site (hemadsorption site) that is not present in human viruses. The biological significance of the NA hemadsorption activity in avian influenza viruses remained elusive. A sequence database analysis revealed that the NAs of the majority of human H2N2 viruses isolated during the influenza pandemic of 1957 differ from their putative avian precursor by amino acid substitutions in the hemadsorption site. We found that the NA of a representative pandemic virus A/Singapore/1/57 (H2N2) lacks hemadsorption activity and that a single reversion to the avian-virus-like sequence (N367S) restores hemadsorption. Using this hemadsorption-positive NA, we generated three NA variants with substitutions S370L, N400S and W403R that have been found in the hemadsorption site of human H2N2 viruses. Each substitution abolished hemadsorption activity. Although, there was no correlation between hemadsorption activity of the NA variants and their enzymatic activity with respect to monovalent substrates, all four hemadsorption-negative NAs desialylated macromolecular substrates significantly slower than did the hemadsorption-positive counterpart. The NA of the 1918 pandemic virus A/Brevig Mission/1/18 (H1N1) also differed from avian N1 NAs by reduced hemadsorption activity and less efficient hydrolysis of macromolecular substrates. Our data indicate that the hemadsorption site serves to enhance the catalytic efficiency of NA and they suggest that, in addition to changes in the receptor-binding specificity of the hemagglutinin, alterations of the NA are needed for the emergence of pandemic influenza viruses.

Show MeSH
Related in: MedlinePlus