HIV1 p24 Antibody, C-91
Description
Enhanced Sensitivity in HIV Detection
C-91 has been utilized in combination with technologies like PSAM (Peptide-Mediated Signal Amplification) to improve ELISA sensitivity. For example:
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Clinical Sensitivity: In viral loads <3,000 RNA copies/mL, conventional ELISA detects 0% of HIV-positive samples, whereas PSAM-coupled assays (using antibodies like C-91) achieve 52.63% sensitivity .
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Early Infection Detection: p24 antigen appears within 2 weeks of infection, making C-91 critical for reducing the diagnostic window period .
Monitoring Antiretroviral Therapy (ART)
Ultrasensitive p24 assays incorporating C-91 can detect residual viral protein in patients on combined ART (cART), even when RNA viral loads are undetectable . For instance:
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Post-cART, 19% of patients showed detectable p24 levels despite suppressed RNA, correlating with lower baseline HIV DNA and higher CD4<sup>+</sup> T-cell counts .
Comparative Performance in Assays
C-91-based assays outperform conventional methods:
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Limit of Detection (LOD): PSAM-enhanced ELISA detects p24 at levels 40-fold lower than standard ELISA .
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Viral Load Correlation: p24 levels measured by C-91 antibodies strongly correlate with RNA viral loads (r = 0.42–0.90) .
Table 1: Clinical Performance of p24 Detection Assays
Research Implications
Product Specs
The antibody appears as a sterile-filtered, white powder that has been freeze-dried (lyophilized).
The antibody has been freeze-dried in a solution containing phosphate-buffered saline (PBS).
The antibody is shipped at ambient temperature in its lyophilized (freeze-dried) form.
For long-term storage, keep the lyophilized antibody at 4°C in a dry environment. After reconstituting the antibody, it can be stored at -20°C for up to a month. If not intended for use within a month, it's recommended to divide the reconstituted antibody into smaller portions (aliquots) before freezing.
To reconstitute the lyophilized antibody, add 1 ml of 1x PBS (phosphate-buffered saline) to the vial. Mix gently by swirling, ensuring the solution makes contact with the sides of the vial. Allow 30-60 seconds for the antibody to dissolve completely before use.
Protein A / S-Sepharose.
Mouse Monoclonal antibodies against HIV-1 full length recombinant p24. Captures the p24 antigen. May be paired with mAbs catalog numbers ant-748.
91.
r.HIV-1p24 Core.
mouse IgG1.
Q&A
What is HIV-1 p24 and why is it valuable as a research biomarker?
Ultrasensitive p24 quantification provides several advantages for research:
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Detects viral protein production even when RNA may be undetectable
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Serves as a complementary biomarker to standard HIV RNA testing
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Potentially identifies viral replication events that may be missed by other assays
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Allows monitoring throughout infection stages and during antiretroviral treatment
What are the primary challenges in detecting p24 in chronic HIV infection?
The formation of immune complexes with anti-p24 antibodies makes quantification difficult beyond acute HIV-1 infection. In chronically infected individuals, circulating antibodies bind to p24, masking epitopes required for detection in conventional immunoassays . This explains why p24 detection has historically been most useful during acute infection before seroconversion or in advanced disease when antibody production wanes.
Research demonstrates that immune complex dissociation (ICD) methods can overcome this limitation, particularly when combined with ultrasensitive detection platforms . Among different ICD methods tested, acid-mediated dissociation proved most compatible with ultrasensitive digital ELISA methods, strongly enhancing p24 detection across different stages of HIV-1 infection .
What technological advances enable ultrasensitive detection of HIV-1 p24?
Single-molecule array (Simoa) technology combined with digital enzyme-linked immunosorbent assay (ELISA) represents a breakthrough in p24 detection. This approach achieves ultrasensitive protein detection that can overcome previous limitations . Key methodological elements include:
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Immune complex dissociation (ICD) - Acid-mediated dissociation protocols that are compatible with digital ELISA systems
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Digital ELISA platform - Single-molecule detection capabilities that dramatically lower the limit of detection
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Optimized antibody combinations - Selection of antibodies that recognize conserved epitopes after ICD
This methodology achieves sensitivity levels at least 1 log higher than conventional ELISA methods, with detection limits in the femtogram/mL range . The ultrasensitive approach allows p24 detection in approximately 78% of samples from people with primary HIV infection and 72% of samples from those with chronic infection prior to antiretroviral treatment .
How should researchers interpret correlations between ultrasensitive p24 and other HIV biomarkers?
Research demonstrates significant correlations between ultrasensitive p24 (usp24) levels and other established HIV biomarkers:
| Biomarker | Correlation with usp24 in Primary Infection | Correlation with usp24 in Chronic Infection |
|---|---|---|
| HIV RNA | r = 0.78, P < 0.0001 | r = 0.42, P < 0.0001 |
| HIV DNA | r = 0.64, P < 0.0001 | r = 0.32, P = 0.0004 |
| CD4+ T cells | r = -0.22, P = 0.03 | r = -0.15, P = 0.07 |
| D-dimers | Not reported | r = 0.24, P = 0.006 |
| IFN-α | Not reported | r = 0.38, P < 0.001 |
These correlations indicate that usp24 detection effectively aligns with viral replication markers (RNA, DNA) while also showing relationships with immune status (CD4+ counts) and inflammation (D-dimers, IFN-α) . The stronger correlations in primary infection suggest p24 may be particularly valuable as a biomarker during early infection stages.
When designing studies, researchers should consider that these correlations exist but are not perfect, suggesting usp24 provides complementary rather than redundant information to existing biomarkers .
What sample processing protocols are essential for reliable ultrasensitive p24 detection?
Effective immune complex dissociation is critical for detecting p24 in samples from chronically infected individuals. Research demonstrates that acid-mediated dissociation is most compatible with ultrasensitive digital ELISA platforms .
Key methodological considerations include:
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Sample handling to prevent protein degradation
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Optimized acid dissociation protocols compatible with downstream assay platforms
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Appropriate controls including p24 standards and antibody-spiked samples
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Validation with samples of known HIV status and viral load
Researchers should establish experimental cutoffs based on negative controls and validate the specific ICD protocol with their detection platform to ensure reliability .
How can ultrasensitive p24 detection enhance monitoring during antiretroviral treatment?
Ultrasensitive p24 measurement provides unique insights during antiretroviral treatment. Studies show p24 levels sharply decrease after cART initiation, generally becoming undetectable, similar to the pattern observed with HIV RNA .
When designing longitudinal treatment studies, researchers should consider:
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Baseline measurements before treatment initiation
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Strategic timepoints after treatment (e.g., 24 and 48 weeks)
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Correlation with other clinical and virological parameters
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Potential to identify subjects with unique virological or immunological profiles
How can researchers use ultrasensitive p24 to identify subjects with distinct immunovirological profiles?
Research demonstrated that individuals who maintained detectable p24 after 48 weeks of cART exhibited different baseline characteristics compared to those whose p24 became undetectable:
| Parameter | Subjects with Detectable p24 at W48 | Subjects with Undetectable p24 at W48 | Significance |
|---|---|---|---|
| Baseline HIV RNA/p24 ratio | Lower trend | Higher | Not specified |
| Baseline HIV DNA | Lower | Higher | Significant |
| Baseline CD4+ T cells | Higher | Lower | Significant |
| Baseline IFN-α | Lower | Higher | Significant |
| Baseline CRP | Higher | Lower | Significant |
| Baseline D-dimers | Higher trend | Lower | Not specified |
| Baseline IL-6 | Higher trend | Lower | Not specified |
| Detectable viral load at W48 | 31.6% | 9.0% | P = 0.0078 |
These findings suggest that ultrasensitive p24 detection can identify a subset of individuals with distinct characteristics that may reflect differences in viral pathogenesis, immune control, or reservoir dynamics . This application could be valuable for stratifying research participants in cure-oriented studies.
What is the relationship between ultrasensitive p24 and inflammatory markers?
Research demonstrates correlations between ultrasensitive p24 and certain inflammatory markers before treatment initiation:
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D-dimers: r = 0.24, P = 0.006
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IFN-α: r = 0.38, P < 0.001
Interestingly, individuals who maintained detectable p24 after treatment showed different inflammatory profiles at baseline compared to those who achieved undetectable p24:
These relationships suggest ultrasensitive p24 detection may provide insights into the inflammatory aspects of HIV pathogenesis beyond viral replication alone. Researchers should consider incorporating inflammatory marker assessment alongside p24 measurements in comprehensive studies.
What controls and standards are essential for implementing ultrasensitive p24 detection?
When establishing ultrasensitive p24 detection protocols, researchers should implement:
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Experimental cutoff determination using HIV-negative plasma samples
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Standard curves with recombinant p24 protein at known concentrations
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Internal quality controls including:
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HIV-negative plasma samples
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HIV-positive samples with known viral loads
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Spiked samples to assess recovery after immune complex dissociation
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Assessment of inter-assay and intra-assay variability
Studies demonstrated the importance of establishing specific cutoffs for different cohorts and validating the immune complex dissociation protocol against known standards .
How do researchers resolve discordant results between ultrasensitive p24 and HIV RNA measurements?
Discordances between p24 detection and HIV RNA may reflect important biological phenomena rather than technical issues. Research identified individuals with detectable p24 despite undetectable viral RNA after treatment . Potential explanations include:
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Production of viral proteins without complete virion assembly
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Different half-lives of viral RNA versus p24 protein
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Compartmentalized viral replication with differential release of RNA versus protein
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Technical differences in assay sensitivity or sampling variation
When encountering discordant results, researchers should:
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Verify results with repeat testing
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Consider longitudinal monitoring to detect patterns
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Incorporate additional biomarkers (HIV DNA, inflammatory markers)
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Evaluate for potential causes of false positivity or negativity
Product Science Overview
HIV-1 p24 is a capsid protein that constitutes the core of the Human Immunodeficiency Virus type 1 (HIV-1). It is produced by the digestion of its precursor, Gag p55, by HIV-1 protease . The p24 protein is indispensable for the reproduction of the AIDS virus and is an essential element for the construction of the virus particle .
HIV-1 p24 is detectable from the early stages of HIV infection and is used as a marker for monitoring the progression of the disease and the effectiveness of treatment . The presence of p24 in the blood indicates the amount of virus present, making it a crucial target for diagnostic and therapeutic research .
Mouse antibodies against HIV-1 p24, such as Clone-91, are monoclonal antibodies specifically developed to target the p24 protein. These antibodies are produced by immunizing mice with the HIV-1 p24 antigen and then isolating the specific antibody-producing cells. The cells are fused with myeloma cells to create hybridomas, which can be cultured to produce large quantities of the monoclonal antibody.
The HIV-1 p24 (Mouse Antibody, Clone-91) can be used in various scientific applications, including:
- Western Blotting (WB): To detect the presence of HIV-1 p24 protein in samples.
- Enzyme-Linked Immunosorbent Assay (ELISA): For quantifying the amount of p24 protein.
- Immunocytochemistry (ICC): To visualize the localization of p24 protein within cells.
- Immunohistochemistry (IHC): To detect p24 protein in tissue samples.
These applications are essential for research in understanding the biology of HIV-1, developing diagnostic tools, and evaluating the efficacy of potential treatments.
