US28 is a receptor for a C-C type chemokine. Binds to MIP-1 alpha, RANTES, and MCP-1 and subsequently transduces a signal by increasing the intracellular calcium ions level. May regulate viral latency or reactivation; potential pathway for virally transformed cell proliferation. Nb7 is a sdAb that recognizes CMV US28. US28Nb7 is a fusion protein of US28 and Nb7.