CD4 and infection: Early immunosuppressive signals and upregulation of T-regulatory cells within 24 hours of infection are characteristic of nonpathogenic infections, despite subsequent intense viral replication and initial depletion of CD4 in blood and lymphoid tissue in both pathogenic and nonpathogenic infections, while CSW who resist HIV infection entirely for long periods appear to have reduced levels of T cell activation and increased anti-inflammatory molecules in vaginal secretions.