Immune activation and virologic response to immunization in recent HIV type 1 seroconverters

Antigenic stimulation from invasive bacterial infections, and the vaccines designed to prevent them, may promote T cell activation and enhancement of HIV-1 replication. Changes in viral load have been correlated with antigen- specific responses. We prospectively determined the impact of immunization with 23-valent pneumococcal vaccine (PVAX) and Haemophilus influenzae type b (Hib)-modified diphtheria toroid CRM197 (DT) vaccine on HIV-1 replication in recent HIV-1 seroconverters (n = 14; median, 5.5 months from infection; median CD4(+) T cells, 535 mu l), and correlated results with vaccine-rela ted immune activation. Specific antibody responses, markers of CD4(+) T cel l activation (transferrin and interleukin 2 receptors), and viral burden we re measured at weeks -2 (pre), 0, 1, 2, 6, and 12 after immunization. By we ek 2, levels of IgG had increased significantly over baseline in both HIV-1 -infected patients and HIV-1-seronegative control subjects (n = 9) for each antigen (geometric mean fold rise: PVAX, 10.1 versus 5.3; Dib, 16.0 versus 11.7; and DT, 26.2 versus 24.5, respectively). Despite these vigorous resp onses to both polysaccharide and protein antigens, HIV-1-infected patients showed limited evidence of CD4(+) T cell activation at 1 week, no consisten t rise in HIV-1 burden at any point, and no decline in CD4(+) T cell number over time. We conclude that recent HIV-1 seroconverters show vigorous humo ral responses to vaccine antigens and limited early evidence of T cell acti vation, but no substantial or sustained increase in viral replication or de cline in CD4(+) T cell number. Thus, respiratory bacterial vaccines appear immunogenic and safe early in HIV-1 infection.