Early diagnosis of human immunodeficiency virus in infants using polymerase chain reaction on dried blood spots in Botswana's national program for prevention of mother-to-child transmission.

BACKGROUND: Botswana has high antenatal human immunodeficiency virus (HIV) prevalence (33.4%). The public health system provides free services for prevention of mother to child transmission of HIV (PMTCT) and antiretroviral therapy, which can reduce vertical HIV transmission from 35% to <5%. Infant HIV diagnosis is challenging in resource-limited settings, and HIV prevalence among HIV-exposed infants in Botswana is unknown. Dried blood spot (DBS) polymerase chain reaction (PCR) provides a feasible method to assess PMTCT programs and identify HIV-infected children. METHODS: We trained staff in 15 clinics and a hospital to obtain DBS on HIV-exposed infants age 6 weeks to 17 months receiving routine care. Samples were sent to the national HIV reference laboratory. Roche Amplicor 1.5 DNA PCR testing was performed. RESULTS: Between June-December 2005, 1931 HIV-exposed infants age 6 weeks to 17 months were tested for HIV, of whom 136 (7.0%) were HIV infected. Among infants

Validation of dilution of plasma samples with phosphate buffered saline to eliminate the problem of small volumes associated with children infected with HIV-1 for viral load testing using Cobas AmpliPrep/COBAS TaqMan HIV-1 test, version 2.0 (CAP CTM HIV v2.0).

The sample requirement of 1 mL for the Roche COBAS AmpliPrep/COBAS TaqMan HIV-1 test, version 2.0 (CAP CTM HIV v2.0) limits its utility in measuring plasma HIV-1 RNA levels for small volume samples from children infected with HIV-1. Viral load monitoring is the standard of care for HIV-1-infected patients on antiretroviral therapy in Botswana. The study aimed to validate the dilution of small volume samples with phosphate buffered saline (1× PBS) when quantifying HIV-1 RNA in patient plasma. HIV RNA concentrations were determined in undiluted and diluted pairs of samples comprising panels of quality assessment standards (n=52) as well as patient samples (n=325). There was strong correlation (R(2)) of 0.98 and 0.95 within the dynamic range of the CAP CTM HIV v2.0 test between undiluted and diluted samples from quality assessment standards and patients, respectively. The difference between viral load measurements of diluted and undiluted pairs of quality assessment standards and patient samples using the Altman-Bland test showed that the 95% limits of agreement were between -0.40 Log 10 and 0.49 Log 10. This difference was within the 0.5 Log 10 which is generally considered as normal assay variation of plasma RNA levels. Dilution of samples with 1× PBS produced comparable viral load measurements to undiluted samples.