Polymorphism of the major envelope glycoprotein (gp70) of murine C-type viruses: virion associated and differentiation antigens encoded by a multi-gene family.

Structural comparison of the major envelope glycoproteins (gp70) from 35 different murine type C viruses and free gp70 expressed at various anatomical sites in the mouse showed that the gp70s are polymorphic products of a large multi-gene family encoding viral and differentiation antigens. Different proviruses are expressed in cells following distinct pathways of differentiation. When the various gp70s are grouped according to primary structure they fall naturally into viral host range classes, confirming the suspicion that C-type viral tropism is largely determined by the nature of the gp70 product expressed.