BST2 takes part in the growth and development of B-cells. The human cellular protein BST2 inhibits retrovirus infection by maintaining the diffusion of virus particles after budding from infected cells. BST2 was originally discovered as an inhibitor to HIV-1 infection in the absence of Vpu， but it is also known to inhibit the release of other viruses such as the Lassa and Marburg virions. In addition， BST2 has a part in B-cell activation in rheumatoid arthritis.
