Yerly S.; Kaiser, L.; Baumberger, C.; Hirschel, B.; Perrin, L. H.Journal of Acquired Immune Deficiency Syndromes & Human Retrovirology: April 1995 Original Articles: PDF Only Free Abstract Fourteen patients previously treated with zidovudine were monitored for laboratory parameters and clinical events during 1 year after introduction of didanosine (ddl) monotherapy. Proviral human immunodeficiency virus type 1 (HIV-1) copy numbers (cell-associated DNA) and concentration of free virions (viremia) were determined using a semiquantitative polymerase chain reaction (PCR). High levels of circulating virus were detected in all patients (range, 17 to 5,934 ± 103/ml of serum). Within 4 weeks of therapy, a decrease of viremia (60 to 98%) was observed in nine patients. After 1 year of treatment, eight of these nine patients still had decreased viremia when proviral HIV DNA was decreased or stable, and CD4+ lymphocytes were stable or higher in seven of these eight patients. Antiviral effect was more pronounced in the six patients with CD4+ >100/mm3 at entry, five of them belonging to the subgroup of the seven responding patients as compared to two of eight patients with CD4+ >100/mm3. Clinical events in this small group were not statistically correlated with virologic parameters; however, responding patients had a tendency to stabilize or gain weight. This study suggests that measurement of viremia deserves further study as a marker of antiviral efficacy and might predict, even at 4 weeks, the beneficial potential of ddl. © Lippincott-Raven Publishers.