The Epstein-Barr virus (EBV), also called human herpesvirus 4 (HHV-4), is one of eight known viruses in the herpes family, and is one of the most common viruses in humans. EBV infects B cells of the immune system and epithelial cells. Once EBV's initial lytic infection is brought under control, EBV latency persists in the individual's B cells for the rest of the individual's life. BLLF1 encoded envelope glycoprotein gp350 initiates virion attachment to host B-lymphocyte cell, leading to virus entry. Acts by binding to host CR2 at the surface of B-lymphocytes, facilitating the binding of viral glycoprotein gp42 to HLA class II molecules. Attachment triggers virion-host membrane fusion and invasion of the host cell.