Children may be particularly susceptible to avian influenza, according to the online journal Respiratory Research.

John Nicholls, MD, PhD, 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.

The technique is based on lectins (molecules that bind to sugars) as a method for differentiating 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.

The researchers found that a particular form of MAA (MAA1) displayed widespread binding throughout the respiratory tract, but was particularly good at binding to children’s cells in the lower respiratory tract as well as the upper respiratory tract of adults.

Although this MAA1 binding is not unique for avian influenza receptors, these findings could explain how avian influenza infects children more readily than it does adults.