Detection of expression of influenza virus receptors in tissues of BALB/c mice by histochemistry.

Infection of host cells with the influenza virus is mediated by specific interactions between the viral hemagglutinin and its cell receptor, oligosaccharides containing sialic acid (SA) residues. Avian and human influenza viruses preferentially bind to α-2, 3-linked and α-2, 6-linked sialic acids, respectively. Therefore, differential expression of these receptors may be crucial to influenza virus infection. To date, the distribution of these two receptors has never been investigated in the tissues of BALB/c mice, which is the routine animal model for influenza research. Here, the expression pattern of alpha-2,3 and alpha-2,6 sialic acid-linked receptors in various organs (respiratory tract, gastrointestinal tract, brain, cerebellum, spleen, liver, kidney and heart) of BALB/c mice were determined. Histochemical staining of mouse tissue sections was performed by using biotinylated Maackia amurensis lectin II (MAAII), and Sambucus nigra agglutinin (SNA) were performed to detect the alpha-2,3 and alpha-2,6 sialic acid-linked receptors, respectively. The results showed that the alpha-2,3 and alpha-2,6 sialic acid-linked receptors were both expressed on trachea, lung, cerebellum, spleen, liver and kidney. Only the epithelial cells of cecum, rectum and blood vessels in the heart express the alpha-2,6 sialic acid-linked receptors. The distribution patterns of the two receptors may explain why this model animal can be infected by the AIV and HuIV and the pathological changes when infection occurred. These data can account for the multiple organ involvement observed in influenza infection and should assist investigators in interpreting results obtained when analyzing AIV or HuIV in the mouse model of disease.