QUANTITATIVE MOLECULAR MONITORING OF HIV-1 RNA DURING ANTIRETROVIRAL THERAPY

Plasma HIV-I RNA testing was used to monitor 43 HIV-1 infected patient s newly placed on antiretroviral therapy or whose therapy had been rec ently changed, A polymerase chain reaction kit was used to measure HIV -1 RNA in clinical samples or frozen plasma, The cutoff of this test w as 200 RNA copies/ml. The first group ill patients was stable on long- term zidovudine monotherapy when switched to stavudine. The HIV-1 RNA of three patients who had a regular decline in CD4(+) T cell count did not change despite this switch, with a mean follow-up of 630 days, Th e HIV-1 RNA copy numbers of eight patients whose CD4(+) T cell counts were stable declined an average of 8.53 log(10) between days 90 and 65 0, The second group (14 patients) was on long-term zidovudine monother apy and had declining CD4(+) T cell counts over the past (6 months, La mivudine was added to this regimen on day 14, HIV-1 RNA copy number de creased rapidly within 30 d, reaching -0.85 log(10) on day 90, and thi s effect was maintained thereafter, with a mean follow-up of 161 days, There was a concomitant wean gain of +33 CD4(+) T cells on day 90. Th e third group (nine patients) had never received anti-retroviral thera py and was given zidovudine + didanosine, HIV-1 RNA copy number decrea sed in all cases but one, reaching -1.31 log(10) on day 150. This decr ease was transient in three cases, The last group (nine patients) had also not had previous anti-retroviral therapy and was given zidovudine + didanosine + lamivudine in combination. HIV-1 RNA copy numbers decl ined rapidly in all eases, to below the cutoff in eight cases within a mean period of 50.5 days, The CD4(+) cell counts increased by 164 cel ls/mu l on day 14 and by 201 cells/mu l on day 180, The response to th erapy of the total population of 43 patients varied according to cases , The relative changes in p24 antigen compared to HIV-1 RNA also diffe red between patients, Measurement of HIV-1 viremia appears to be a val uable tool in current practice for individualizing therapy.