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Updated: Aug 9, 2026
Humanized NOD/SCID/IL2rγnull (hu-NSG) Mouse Model for HIV Replication and Latency Studies
Published on: January 7, 2019
Human immunodeficiency virus type 1 entry into murine cell lines and lymphocytes from transgenic mice expressing a
K J Wieder1, P Chatis, J Boltax
1Division of Immunology, Beth Israel Hospital and Harvard Medical School, Boston, Massachusetts 02215, USA.
Insights
Researchers engineered a mutant mouse CD4 (L3T4) protein to facilitate HIV-1 entry into rodent cells. While viral entry was achieved, high-level viral replication was not observed in these mouse cells.
Area of Science:
- Immunology
- Virology
- Molecular Biology
Background:
- Human CD4 is the primary receptor for HIV-1 entry into CD4+ cells.
- HIV-1 entry into murine cells expressing human CD4 is inefficient, suggesting a need for species-specific cellular factors.
- Murine CD4 (L3T4) alone does not readily mediate HIV-1 entry into rodent cells.
Purpose of the Study:
- To investigate if a modified murine CD4 (L3T4) protein with human CD4 binding residues could facilitate HIV-1 entry into rodent cells.
- To develop and test L3T4 mutants capable of binding HIV-1 gp120.
- To assess viral entry and replication in mouse cells expressing these engineered L3T4 mutants.
Main Methods:
- Construction of murine L3T4 mutants incorporating human CD4 gp120-binding region residues.
- Transfection of HeLa cells and mouse cell lines with L3T4 mutant constructs.
- Infection of engineered cell lines and transgenic mouse leukocytes with HIV-1.
- Detection of viral DNA and spliced RNAs using PCR and in situ PCR.
- Quantification of viral replication markers (p24gag, reverse transcriptase).
Main Results:
- HeLa cells and three mouse cell lines expressing gp120-binding L3T4 mutants were susceptible to HIV-1 infection.
- Transgenic mouse leukocytes showed HIV-1 infection rates comparable to human lymphocytes.
- Despite successful viral entry, high-level viral replication (p24gag and reverse transcriptase activity) was absent in all tested mouse cells.
Conclusions:
- Engineered gp120-binding mutant L3T4 proteins can mediate HIV-1 entry into various mouse cells.
- Murine cellular components may restrict efficient HIV-1 replication even when viral entry is facilitated.
- These findings highlight the complexity of HIV-1 host-cell interactions beyond receptor binding.
Abstract:
Human CD4, the receptor for the gp120 envelope glycoprotein of HIV-1, is the route for viral entry into CD4+ cells; other cellular factors may cooperate with CD4 to facilitate HIV-1 entry into human cells. Human CD4 expressed on murine cells does not readily mediate HIV-1 entry, which may reflect a functional incompatibility of human CD4 with murine cellular components. We postulated that a HIV-1 gp120-binding mutant murine CD4 (L3T4) possessing a minimal number of human amino acid residues could facilitate HIV-1 entry into rodent cells, unlike human CD4. This hypothesis led us to develop a series of murine L3T4 mutants that bear human CD4 gp120-binding region amino acid residues while retaining most L3T4 epitopes. HeLa cell transfectants expressing gp120-binding mutant L3T4 proteins could be infected with HIV-1. Three mouse cell lines expressing these L3T4 mutant proteins could also be infected with HIV-1 as determined by PCR techniques that detect viral DNA and spliced RNAs. Lectin-stimulated polymorphonuclear leukocytes from transgenic mice (SBL mouse) expressing a gp120-binding L3T4 mutant protein were infected with HIV-1 at the same frequency as lectin-stimulated human peripheral blood lymphocytes as determined by in situ PCR analyses. Supernatant p24gag and reverse transcriptase levels in HIV-infected mouse cell cultures, however, were routinely at background levels, unlike HIV-infected human cell cultures. Thus, gp120-binding mutant L3T4 proteins mediate viral entry in all mouse cells that were tested, but high-level viral replication is absent in these cells.
