New findings, reported in in the online open access journal Respiratory Research, about how the virus binds to the respiratory tract and lung suggest children may be particularly susceptible to avian influenza.
The results also mean that previous receptor distribution studies may have to be re-evaluated.
John Nicholls and colleagues at the University of Hong Kong and Adelaide Women and Children's Hospital, in Australia, describe a modified technique to visualize the putative receptors for influenza viruses in the upper and lower respiratory tract, including the lung.
Sialic acid molecules on the cell surface act as chemical beacons for the influenza virus. Once the virus finds sialic acid, it can attach and infect the cell, although the precise distribution of sialic acid molecules affects how easily the virus can find host cells to infect.
The team has turned to lectins- molecules which bind sugars, to help them differentiate receptors for human and avian influenza viruses. The researchers used an improved staining technique to see how well two lectins, Sambucus nigra agglutinin (SNA) and Maackia amurensis agglutinin (MAA), bind to different forms of sialic acid on respiratory tract cells in healthy adults and children. SNA is particularly good at identifying the receptor for human influenza viruses while MAA identifies the receptor for avian viruses - including H5N1.