Increase in plasma viral load after oral cholera immunization of HIV-infected subjects

Constant antigenic stimulation of the large immune cell population contained within gut-associated lymphoid tissue during HIV infection may contribute to patients' total viral load. The aim of this investigation was to evaluate the effect of a mucosal antigenic challenge on HIV replication.

Prospective clinical study.

Twelve HIV-1-infected men (mean age, 42.3 years) from the Casa de Apoio Santo Antonio, Rio de Janeiro, Brazil, were immunized with combined whole cell-toxin B subunit oral cholera vaccine. Blood was collected on days 0, 2, 4, 6, 10 and 15 after immunization and plasma was tested for cholera toxin-specific antibody response (IgG and IgA), beta2-microglobulin, and plasma viral load. CD4 lymphocyte counts were performed within 1 week before immunization. Five HIV-infected non-immunized individuals were studied as controls.

There were no adverse effects following immunization and no deterioration in clinical outcome during 3 months of follow-up. A transient increase in viral load that ranged from twofold to 60-fold was observed in all cases and was statistically significant on days 2, 6 and 10 (P = 0.017, P = 0.025, P = 0.021, respectively). There was no correlation with CD4 cell counts. None of the non-immunized subjects demonstrated the pattern of viraemia observed after immunization (P > 0.10 on all days).

Our data indicate that mucosal immunization with oral cholera vaccine induces a transient increase in HIV viraemia, regardless of clinical stage of infection and CD4 cell counts. These findings suggest that mucosal stimulation of HIV-infected patients enhances HIV replication.