Resistance to HIV-1 infection among highly exposed sex workers in Nairobi: what mediates protection and why does it develop?

Variability in susceptibility to infection and disease caused by infectious agents is a characteristic of all populations. Among susceptible individuals exposed to an infection, not all become infected and among infected individuals, not all develop disease. It seems logical that variability in susceptibility to infection and disease would apply to infection and disease with human immunodeficiency viruses. However, until recently, it has been generally held that there is no natural immunity to HIV-1 and that once infected, all individuals would ultimately succumb to AIDS.