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Cytomegalovirus Strain AD169 Binds β
2 Microglobulin in Vitro after Release from Cells
Abstract
Summary
We previously reported that a host protein, β 2 microglobulin (β 2 m) inhibited the detection of human cytomegalovirus (CMV) in urine specimens by enzyme immunoassay and postulated that β 2 m bound to the virus particle and masked the viral antigenic determinants. We report here that CMV strain AD169 grown in cell culture bound human β 2 m when this protein was added to cell culture fluids or when the virus was added to urine. Such binding was not seen with herpes simplex virus. CMV could also bind bovine β 2 m from foet al calf serum in cell culture fluids. The use of radiolabelled β 2 m in other experiments showed that CMV bound β 2 m after release from cells and that the bound β 2 m did not represent acquisition of class I HLA molecules during budding from host cell membranes. Immunoprecipitation studies showed that β 2 m was bound by two viral envelope proteins β 2 m BP1 (β 2 m-binding protein 1) and β 2 m BP2 of molecular masses 36000 and 65000 daltons respectively. β 2 m could not bind to separated viral proteins under reducing or non-reducing conditions. We propose that interaction of these two proteins on the viral surface is required to enable CMV to bind β 2 m.
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© The Journal of General Virology 1987