Receptor proteins on newborn Balb/c mouse brain cells for coxsackievirus B3 are immunologically distinct from those on HeLa cells

Newborn Balb/c mice are highly susceptible to infection by the six coxsackievirus serotypes of group B (CVB) and it is known that receptors for these viruses are in highest concentration in the brain as compared to other tissues. Therefore, proteins from the brain tissues of these animals were solubilized (Brain-Ext) and characterized for the identification of mouse brain receptor (MBR) proteins. Virus-blot analyses of Brain-Ext suggested that each of three virus variants of CVB3-(N, W and RD) recognized four receptor proteins designated p46, p44, p36 and p33 according to their molecular size. Similar analyses of cultured neurons from newborn Balb/c mice revealed the presence of the same four receptor proteins, while astrocytes appeared to posses only p46 and/or p44. Isoelectric focusing of Brain-Ext, focused MBR proteins in the pH range 4.0–8.5, with a peak around pH 5.7. P46 was found to be neuraminidase sensitive. A polyclonal rat antiserum (anti-MBR) protected cultured neurons and astrocytes against infection by CVB3, inhibited virus binding to these cells and recognized the same four receptor proteins on western-blots as detected on virus-blots by CVB3. However, a rabbit polyclonal anti-HeLa cell antiserum, which strongly binds to HeLa cells and protects them from CVB3 infection, neither recognized any of the receptor proteins in western-blot analyses of Brain-Ext nor inhibited CVB3 infection on cultured neurons and astrocytes. Conversely, anti-MBR did not recognize any of the receptor proteins by western-blot analysis of HeLa cell extracts nor did it inhibit CVB3 infection of HeLa cells. These results indicate that the mouse brain cell receptor proteins for CVB3 are immunologically distinct from those of HeLa cells. Further immunologic analysis of the MBR proteins, using rat antisera to p46, p36 and p33, respectively, revealed that they are related.