The antibody response to HIV-1 occurs in stages, shown here in a clockwise direction starting at the top. A. The initial antibody response to HIV-1 is non-neutralizing and directed at gp41. B. Soon thereafter arise non-neutralizing antibodies directed against gp120. C. After a delay of weeks to months, autologous neutralizing antibodies arise that apply selection pressure on the virus. D. Viral mutation results in neutralization escape by HIV-1, represented here by a change in the shape of gp120. E. In some patients, antibodies that can neutralize a wide range of HIV-1 isolates arise, represented here by a variety of shapes of gp120. Mixing of envelope shapes on a single virus particle is shown for illustrative purposes only.