In vivo pathogenic properties of two clonal human immunodeficiency virus type 1 isolates

Abstract

We have investigated the in vivo pathogenic properties of two molecularly cloned strains of human immunodeficiency virus type 1 (HIV-1), HIV-1 NL4-3 and HIV-1 JR-CSF , in human fetal thymus/liver implants in severe combined immunodeficient mice. Studies comparing their in vivo replication kinetics and abilities to induce CD4 ؉ thymocyte depletion were performed. HIV-1 NL4-3 replicated in vivo with faster kinetics and induced greater levels of CD4 ؉ thymocyte depletion than did HIV-1 JR-CSF. These results demonstrate that different viral isolates have different pathogenic properties in this system. In the SCID-hu model, this pathogenesis most likely occurs in the absence of an immune response. Therefore, we investigated whether the absence of immune selection resulted in extensive genetic variation and the generation of viral quasispecies. To this end, DNA corresponding to the fourth variable domain region of the viral envelope gp120 protein recovered from biopsy samples at 6 weeks postinfection was sequenced. Little genetic variation was noted in either HIV-1 JR-CSF-or HIV-1 NL4-3-infected implants. The mutation levels demonstrated in both viral strains were more reflective of the acute rather than the chronic phase of HIV-1 infection in humans. These results suggest that the SCID-hu mouse model can be used to study the in vivo pathogenicity of different HIV-1 isolates in the absence of host immune selective pressures.

Mechanism of human immunodeficiency virus type 1 localization in CD4-negative thymocytes: differentiation from a CD4-positive precursor allows productive infection

“…Thymocytes infected with HIV-1 JR-CSF demonstrated a less severe depletion of CD4bearing cells; depletion of cells with low levels of surface expression of CD4 and CD8 (CD4CD8 DP dim) was most ap-parent. Analysis of replication kinetics by ELISA for viral p24 antigen production in the supernatant revealed that the replication rate of HIV-1 NL4-3 was slightly greater than that of HIV-1 JR-CSF (data not shown), as has been observed in infected Thy/Liv implants in SCID-hu mice (20).…”

“…SCID-hu mice. CB-17 mice homozygous for the SCID defect were bred at the University of California at Los Angeles and housed as described previously (20). Construction of the SCID-hu (Thy/Liv) mouse, using fetal tissue between 18 and 23 weeks of gestational age, has been described previously (2,30,32).…”

“…Construction of the SCID-hu (Thy/Liv) mouse, using fetal tissue between 18 and 23 weeks of gestational age, has been described previously (2,30,32). Four to six months following implantation of the human fetal liver and thymus, mice were injected with 100 tissue culture infectious units of HIV-1 NL4-3 in 50 l of medium (2,20). Mock-infected mice were injected with 50 l of mock-electroporated COS or CEM cell supernatant, as appropriate.…”

“…Flow cytometry and fluorescence-activated cell sorting (FACS). HIV-1-infected and mock-infected Thy/Liv implants from SCID-hu mice were subjected to biopsy, teased into single-cell suspensions, and stained with monoclonal antibodies specific for CD4 (Leu3a or v4) and CD8 (Leu2a) conjugated with phycoerythrin (PE) and fluorescein isothiocyanate (FITC) (Becton Dickinson, San Jose, Calif.), respectively (20). Staining with Leu3a or v4 yielded similar results with respect to both staining and quantitative PCR for viral distribution, indicating that epitope masking of the Leu3a antibody was not occurring (data not shown).…”

Chemokine Receptor‐Usage of Clinical HIV‐1 Isolates Obtained from Patients with HIV‐1 Infection in Late Clinical Stages Using PHA‐Blast

“…The cloning of single HIV-1 from the clinical isolate is a useful method for analysis of the properties of the isolate. Infectious molecular clones have been prepared from clinical isolates and their properties have been investigated (13).…”