There Are Two Different Species B Adenovirus Receptors: sBAR, Common to Species B1 and B2 Adenoviruses, and sB2AR, Exclusively Used by Species B2 Adenoviruses

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Abstract
Unlike most adenovirus (Ad) serotypes, the species B Ads do not use the coxsackie-adenovirus receptor as an attachment receptor. The species B attachment receptor(s) has not yet been identified and is also poorly characterized. Species B Ads can be further divided into species B1 and B2 Ads, and these display different organ tropisms, suggesting a difference in receptor usage. We have studied the receptor interactions of the species B1 serotypes 3p and 7p and the species B2 serotypes 11p and 35 and characterized the properties of the species B receptor(s). Reciprocal blocking experiments using unlabeled Ad11p or Ad3p virions to block the binding to A549 cells of (35)S-labeled 3p, 7p, 11p, and 35 showed that only Ad11p virions efficiently blocked the binding of all the species B Ads studied (> or =70%). Thus, there is apparently a common species B Ad receptor (sBAR). However, Ad3p virions only partially (< or =30%) blocked the binding of Ad11p and Ad35 to A549 cells. Binding experiments after trypsin treatment of the cells confirmed that the species B2 serotypes address at least two different receptors on A549 and J82 cells, since sBAR is trypsin sensitive but the species B2 Ad receptor (sB2AR) is not. Both receptors are proteins or glycoproteins, since binding of all species B serotypes was abolished after proteinase K or subtilisin treatment of A549 or J82 cells. Furthermore, binding of the species B serotypes to sBAR was abolished with EDTA and restored with Ca(2+), whereas the binding of Ad11p and Ad35 to SB2AR was independent of divalent cations.