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Abstract

Plaque assay under Avicel-containing overlay media is easier, faster and more sensitive than assays under agar- and methylcellulose overlays. The assay can be readily performed in a 96-well plate format and seems particularly suitable for high-throughput virus titrations, serological studies and experiments on viral drug sensitivity. It may also facilitate work with highly pathogenic agents performed under hampered conditions of bio-safety labs.

Structural basis for receptor specificity of influenza B virus hemagglutinin

“…The HA molecules of influenza A viruses isolated from different hosts differ in their ability to recognize different cellular receptors in which the linkage between sialic acid and galactose of the carbohydrate chain is either ␣(2,3) or ␣ (2,6). HA molecules of human viruses preferentially bind to ␣(2,6)-linked receptors, those of avian and equine viruses bind to ␣(2,3)-linked, and those of swine viruses bind to both (1)(2)(3)(4)(5)(6)(7)(8)(9). Thus, ␣(2,3)-linked and ␣(2,6)-linked receptors are also referred to as avian and human receptors, respectively.…”

“…We now have a detailed understanding of the molecular determinants for the different receptor specificity of different subtypes of influenza A virus HAs, in particular for H1, H2, and H3 subtypes that infect humans (1)(2)(3)(10)(11)(12)(13)(14)(15)(16)(17)(18)(19)(20)(21)(22)(23)(24)(25)(26)(27)(28). For H2 and H3 HAs, it is predominantly determined by residues at 226 and 228 (Leu-226 and Ser-228 in human HAs and Gln-226 and Gly-228 in avian HAs, following the numbering convention for H3 HA) (5,7,11,21,(29)(30)(31). However, H1 HAs are different in this regard: although human and avian H1 HAs recognize ␣(2,6)-linked or ␣(2,3)-linked receptors, respectively, they both have Gln-226 and Gly-228.…”

Sialobiology of Influenza: Molecular Mechanism of Host Range Variation of Influenza Viruses

“…58) However, if the avian H5N1 virus acquires a mutation in receptor binding properties from avian type to human type (SA2-3Gal→SA2-6Gal) by the reverse mechanism of only two sets of amino acid exchange described above (Gln222→Leu; Gly 224→Ser, shown as a numbering of H5; Gln226→Leu; Gly228→Ser, shown as H3 subtype numbering), which allows human-to-human transmission, this highly pathogenic virus will spread quickly cause a pandemic. We have already observed that receptor binding specificity of hemagglutinin has changed during circulation in humans since its introduction from avian viruses.…”

Outbreaks of avian influenza H6N2 viruses in chickens arose by a reassortment of H6N8 and H9N2 ostrich viruses

“…NA stalk deletions have been shown to reduce the enzymatic activity of the protein [14] and, presumably, adversely affect the spread of the virus to uninfected cells. Secondly, changes in the HA gene that compensate for a shortened N stalk have been described, including increased glycosylation near the receptor binding site thereby decreasing receptor binding affinity [15,16]. Sub-lineage I displayed this hyperglycosylation, with five predicted N-glycosylations sites in the HA gene compared to only three in sub-lineage II, which did not contain the Nstalk deletion.…”