Evaluation of Patients Who Have Not Had Success With Zidovudine

To determine the relationship of viral susceptibility to zidovudine (AZT) and baseline viral load (as determined by plasma viremia and quantitative endpoint dilution). To determine the relationship between viral load and susceptibility during different antiretroviral therapy strategies. To correlate measures of viral load and short term clinical and laboratory markers (such as weight, CD4 count, p24 antigenemia, and beta2 microglobulin) on the different therapy arms. High-grade resistance to AZT has been detected in HIV isolates from approximately 25 percent of individuals with AIDS who received AZT for at least 1 year. To elucidate the clinical significance of in vitro AZT resistance, it is necessary to distinguish between clinical failure caused by AZT resistance and clinical decompensation caused by other factors.