Lack of isolate-specific neutralizing activity is correlated with an increased viral burden in rapidly progressing HIV-1-infected patients.

OBJECTIVE

To delineate the interaction between in vivo HIV replication and host antiviral immunity during disease progression in order to elucidate the pathogenesis of AIDS.

DESIGN

In a cohort of HIV-seropositive patients, the serum concentration of viral particles, the blood concentration of mononuclear cells harbouring infectious virus and the serum titre of isolate-specific neutralizing antibodies were correlated with the rates of CD4+ T-cell depletion and disease progression.

METHODS

Using a quantitative reverse-transcriptase linked polymerase chain reaction assay, the concentration of viral particles was measured in blood samples from 103 initially symptom-free subjects who were followed up for > or = 24 months. The concentration of infectious virus and the neutralizing antibodies to autologous HIV isolates were assessed in 37 out of the 103 subjects. The rate of decrease in CD4 cells over the 24 months was calculated for each subject.

RESULTS

Rapidly progressing patients (rate of decrease in CD4 cells > or = 60%) had a high concentration of viral particles and a high concentration of infectious virus associated with an undetectable serum titre of isolate-specific neutralizing antibodies. Stable patients (rate of decrease in CD4 cells < 30%) had a low concentration of infectious virus and either a low concentration of viral particles with the absence of isolate-specific neutralizing antibodies or a high concentration of viral particles with the presence of isolate-specific neutralizing antibodies. Slowly progressing patients (rate of decrease in CD4 cells > or = 30 and < 60%) showed an intermediate profile.

CONCLUSIONS

Progression to AIDS is associated with a shift in the balance between viral replication and host immunity that increases the concentration of infected cells and destroys the CD4+ T-lymphocyte population.