To describe the magnitude and duration of changes in HIV-1 RNA levels during and after an acute febrile illness. To identify factors associated with increases, i.e., type of illness ultimately diagnosed (bacterial, viral, fungal), CD4 cell count, and antiretroviral treatment regimen. To describe changes in phenotypic markers of immune activation/dysregulation of CD4 and CD8 lymphocyte subsets and their relationship to intercurrent illness. To describe changes in plasma cytokines and soluble activation markers and their relationship to plasma HIV-1 viremia during and after the onset of intercurrent illness. To characterize the viral biologic phenotype and the viral drug susceptibility genotype before, during, and after the onset of an acute febrile illness. To characterize the expression of HIV-1 co-receptors before, during, and after the onset of an acute febrile illness Repeated episodes of intercurrent infections have been postulated to be an important stimulus for progression of HIV infection. The study of intercurrent illness in patients with initially undetectable viral load removes viral load as a possible cause for virologic and immunologic changes and allows for a more direct association of the intercurrent illness with changes in viral load, viral HIV-1 phenotypes, viral HIV-1 genotypes, and T cell phenotypes.

Studying intercurrent illness and viral load provides an opportunity to characterize the potentially dynamic changes not only in viral load but also in phenotypic markers of T cell activation, plasma cytokine levels, phenotypic and genotypic changes in circulating virus, and HIV-1 tropisms.

Repeated episodes of intercurrent infections have been postulated to be an important stimulus for progression of HIV infection. The study of intercurrent illness in patients with initially undetectable viral load removes viral load as a possible cause for virologic and immunologic changes and allows for a more direct association of the intercurrent illness with changes in viral load, viral HIV-1 phenotypes, viral HIV-1 genotypes, and T cell phenotypes.

Studying intercurrent illness and viral load provides an opportunity to characterize the potentially dynamic changes not only in viral load but also in phenotypic markers of T cell activation, plasma cytokine levels, phenotypic and genotypic changes in circulating virus, and HIV-1 tropisms.

This is a study to determine whether patients exhibit a temporary burst of viral replication or other changes in response to intercurrent febrile illness. Although there is no study treatment, patients on this study must be co-enrolled in at least 1 other ACTG antiretroviral treatment study.

Plasma HIV-1 RNA and other variables are measured at the time of presentation, on Day 3, and at Weeks 1, 2, 4, 8, 16, and 24.

Inclusion Criteria

Patients must have:

• HIV-1 infection documented by any licensed ELISA test kit and confirmed by either Western blot, HIV-1 culture, HIV-1 antigen, plasma HIV-1 RNA or a second antibody test by a method other than ELISA at any time prior to study entry.
• Undetectable plasma HIV-1 RNA (by Roche Amplicor Assay) within 8 weeks prior to study entry.
• Documented temperature above 101degrees F during at least 1 of the 2 days prior to the day of screening and present on the day of screening, or documented temperature above 101 F on the day of the screening but no fever on 1 of the 2 days prior to screening.

[AS PER AMENDMENT 7/7/98:

• Documented temperature above 101degrees F on the day of the screening.]
• Co-enrollment in at least 1 other ACTG antiretroviral treatment study (NOTE:
• Co-enrollment is approved and encouraged with the following ACTG studies:
• 343, 347, 359, 368, 370, and 372). [AS PER AMENDMENT 7/7/98: Must be enrolled in either an ACTG antiretroviral therapy study or a pharmaceutical company-sponsored antiretroviral therapy study prior to entry. Co-enrolled in a non-ACTG pharmaceutical company-based study must have a baseline viral isolate accessible for use in this study.]
• Written informed consent of a parent or guardian if under 18 years of age.

Exclusion Criteria

Co-existing Condition:

Patients with the following symptoms or conditions are excluded:

• Interruption of current antiretroviral therapy due to the onset of acute intercurrent illness.

Concurrent Medication:

Excluded:

• Patients receiving IL-2.

Patients with the following prior conditions are excluded:

• Change in antiretroviral therapy combination within 8 weeks prior to study entry.

Required:

• Concurrent enrollment in an ACTG antiretroviral therapy study [or, AS PER AMENDMENT 7/7/98, in a non-ACTG pharmaceutical company-sponsored antiretroviral treatment study].
• Stable antiretroviral and/or nucleoside analog therapy for 8 weeks prior to study entry.