Myron Elmer "Max" Essex is the Mary Woodard Lasker Professor of Health Sciences, emeritus in the department of immunology and infectious diseases at Harvard University, chair of the Harvard T.H. Chan School of Public Health AIDS Initiative (HAI) in the department of immunology and infectious diseases, and chair of the Botswana–Harvard AIDS Institute in Gaborone, Botswana. Essex was one of the first to link animal and human retroviruses to immunosuppressive disease, to suspect that a retrovirus was the cause of AIDS, and to determine that HIV could be transmitted through blood and blood products to hemophiliacs and recipients of blood transfusions. With collaborators, Essex also provided the first evidence that HIV could be transmitted by heterosexual intercourse.

Envelope glycoprotein GP120 is a glycoprotein exposed on the surface of the HIV envelope. It was discovered by Professors Tun-Hou Lee and Myron "Max" Essex of the Harvard School of Public Health in 1984. The 120 in its name comes from its molecular weight of 120 kDa. Gp120 is essential for virus entry into cells as it plays a vital role in attachment to specific cell surface receptors. These receptors are DC-SIGN, Heparan Sulfate Proteoglycan and a specific interaction with the CD4 receptor, particularly on helper T-cells. Binding to CD4 induces the start of a cascade of conformational changes in gp120 and gp41 that lead to the fusion of the viral membrane with the host cell membrane. Binding to CD4 is mainly electrostatic although there are van der Waals interactions and hydrogen bonds.