The composition of human immunodeficiency virus type 1 (HIV-1) clonal populations at different stages of infection and in different compartments was analyzed. Biological HIV-1 clones were obtained by primary isolation from patient peripheral blood mononuclear cells under limiting dilution conditions, with either blood donor peripheral blood lymphocytes or monocyte-derived macrophages (MDM) as target cells, and the biological phenotype of the clones was analyzed. In asymptomatic individuals, low frequencies of HIV-1 clones were observed. These clones were non-syncytium inducing and preferentially monocytotropic. In individuals progressing to disease, a 100-fold increase in frequencies of productively HIV-1-infected cells was observed as a result of a selective expansion of nonmonocytotropic clones. In a person progressing to AIDS within 19 months after infection, only syncytium-inducing clones were detected, shifting from MDM-tropic to non-MDMtropic over time. From his virus donor, a patient with wasting syndrome, only syncytium-inducing clones, mostly non-MDM-tropic, were recovered. Parallel clonal analysis of HIV-1 populations in cells present in bronchoalveolar lavage fluid and peripheral blood from an AIDS patient revealed a qualitatively and quantitatively more monocytotropic virus population in the lung compartment than in peripheral blood at the same time point. These findings indicate that monocytotropic HIV-1 clones, probably generated in the tissues, are responsible for the persistence of HIV-1 infection and that progression of HIV-1 infection is associated with a selective increase of T-cell-tropic, nonmonocytotropic HIV-1 variants in peripheral blood.

Human immunodeficiency virus isolates were studied with respect to syncytium-inducing capacity, replicative properties, and host range. Five of 10 isolates from patients with acquired immunodeficiency syndrome (AIDS) and AIDS-related complex were able to induce syncytia in cultures of peripheral blood mononuclear cells (MNC). In contrast, only 2 of 12 isolates from asymptomatic individuals had syncytium-inducing capacity. Syncytium-induciiig isolates were reproducibly obtained from the same MNC sample in over 90% of the cases, independent of the donor MNC used for propagation. Syncytium-inducing capacity was shown to be a stable property of an isolate, independent of viral replication rates. Evidence was obtained that the high replication rate of syncytium-inducing isolates observed during primary isolation may be due to higher infectivity of these isolates. The finding that only syncytium-inducing isolates could be transmitted to the H9 cell line is compatible with this higher infectivity. The frequent isolation of syncytium-inducing isolates from individuals with AIDS-related complex or AIDS and the apparent higher in vitro infectivity of these isolates suggest that syncytium-inducing isolates may unfavorably influence the course of human immunodeficiency virus infection.

No abstract

We studied the relative importance of class I and class II major histocompatibility complex (MHC) immunoregulation in the control of Tand B-cell lymphomas induced by murine leukemia virus. Previously, we have described a mink cell focus-inducing (MCF) murine leukemia virus, MCF 1233, which induces not only lymphoblastic T-cell lymphomas but also follicle center cell or lymphoblastic B-cell lymphomas. We now report that the outcome of neonatal infection with MCF 1233 in H-2-congenic C57BL/10 and C57BL/6 mice is decisively influenced by the H-2 I-A locus. A total of 64% of H-2 I-Ak, d mice [B1O.BR, B10.D2, B10.A(2R), B10.A(4R), and B10.MBR] developed T-cell lymphomas after MCF 1233 infection (mean latency, 37 weeks). In contrast, H-2 I-Ab [B10, B10.A(5R), B6], H-2 I_Ab/k [(B10.A x B10)F1 and (BlO x B10.A)F1], and H-2 * Corresponding author.