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Indeterminate human immunodeficiency virus type 1 western blots: seroconversion risk, specificity of supplemental
C L Celum1, R W Coombs, W Lafferty
1Department of Medicine, University of Washington, Seattle.
Insights
Indeterminate human immunodeficiency virus type 1 (HIV-1) Western blots require careful follow-up. High-risk individuals, particularly those with p24 bands, have a significant risk of seroconversion.
Area of Science:
- Virology
- Immunology
- Infectious Diseases
Background:
- Enzyme immunoassays (EIA) can yield false-positive results for human immunodeficiency virus type 1 (HIV-1).
- Indeterminate HIV-1 Western blots occur in 10%-20% of reactive EIA sera, necessitating further investigation.
Observation:
- Eighty-nine individuals with repeatedly reactive EIA and indeterminate Western blots were prospectively studied.
- Four high-risk individuals seroconverted within 10 months, indicating a 4.5% seroconversion risk.
- A higher seroconversion rate (18.2%) was observed in high-risk individuals with initial p24 bands compared to low-risk cases (0%).
Findings:
- Supplemental HIV-1 testing demonstrated high specificity: HIV-1 culture (100%), serum p24 antigen (100%), polymerase chain reaction (98.6%), and recombinant ENV 9 EIA (94.4%).
- Low-risk individuals with negative repeat EIAs did not require further follow-up.
- High-risk individuals, especially those with p24 bands on Western blot, warrant at least 6 months of serological monitoring.
Implications:
- An expedited evaluation protocol for indeterminate HIV-1 results is proposed.
- Risk stratification is crucial for managing indeterminate HIV-1 Western blot results.
- This study informs clinical guidelines for HIV-1 testing and patient management.
Abstract:
The human immunodeficiency virus type 1 (HIV-1) Western blot is indeterminate in 10%-20% of sera reactive by EIA. Eighty-nine individuals with prior repeatedly reactive EIA and indeterminate Western blots were followed prospectively to study the risk of seroconversion and specificity of supplemental tests. Four high-risk cases seroconverted within 10 months after enrollment (seroconversion risk, 4.5%, 95% confidence interval, 1.2%-11.1%). Among cases with p24 bands initially, 4 (18.2%) of 22 high-risk individuals seroconverted compared with 0 of 33 low-risk cases (P = .03). Specificities of HIV-1 culture, serum p24 antigen, polymerase chain reaction, and recombinant ENV 9 EIA were 100%, 100%, 98.6%, and 94.4%, respectively. An expedited evaluation protocol is proposed. Low-risk individuals with nonreactive EIAs upon repeat testing do not need further follow-up; high-risk individuals should be followed serologically for at least 6 months, especially those with p24 bands on Western blot.