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Syncytium induction by fresh HIV isolates: quantitative analysis using a transactivation beta-gal assay
D Emilie1, M C Maillot, C Bonnerot
1INSERM U131, Clamart, France.
AIDS (London, England)
|August 1, 1990
Summary
A new beta-gal assay rapidly detects syncytium-inducing HIV strains in patient samples. This quantitative bioassay identifies infectious HIV isolates, aiding in faster diagnosis and understanding of HIV disease progression.
Area of Science:
- Virology
- Immunology
- Molecular Biology
Background:
- Syncytium formation is a hallmark of productive human immunodeficiency virus (HIV) infection.
- Quantifying syncytium-inducing HIV isolates is crucial for understanding viral pathogenesis and disease progression.
- Existing methods for detecting syncytium-inducing strains can be time-consuming and labor-intensive.
Purpose of the Study:
- To develop and validate a rapid, quantitative bioassay for detecting syncytium-inducing HIV isolates.
- To assess the prevalence of syncytium-inducing HIV strains in different stages of HIV infection.
- To correlate syncytium-inducing properties with HIV replication rates and clinical parameters.
Main Methods:
- A quantitative bioassay (beta-gal assay) was developed using a chimeric HIV-1 long terminal repeat (LTR)-lacZ gene.
- The assay measures beta-galactosidase activity, which is transactivated by the HIV tat protein, leading to nuclear translocation and enzymatic staining of syncytia.
- Fresh HIV isolates from patient lymphocytes were co-cultured with normal lymphocytes for 4 days, followed by enzymatic staining.
Main Results:
- The beta-gal assay unequivocally detected syncytium-inducing HIV isolates in 11 out of 40 (27.5%) seropositive patients.
- Syncytium-inducing strains were predominantly isolated from patients with advanced HIV disease (8/17 Grade IV patients).
- Three patients with lower disease severity (Grade II/III) also harbored syncytium-inducing strains, exhibiting high CD4+ counts and no detectable p24 antigenemia.
- HIV isolates that induced syncytia showed the highest in vitro replication rates.
Conclusions:
- The beta-gal assay provides a rapid and reliable method for detecting syncytium-inducing HIV strains.
- This assay can be routinely used for early identification of infectious HIV isolates.
- The findings highlight the presence of syncytium-inducing HIV in various disease stages and suggest a correlation with viral replication capacity.