Evaluation of a prototype Amplicor PCR assay for detection of human immunodeficiency virus type 1 DNA in blood samples from Tanzanian adults infected with HIV-1 subtypes A, C and D.

BACKGROUND: In previous evaluations, the standard Amplicor HIV-1 DNA PCR test (Roche Diagnostic Systems) has been reported to have low sensitivity for the detection of some non-B HIV-1 subtypes. It has therefore become necessary to determine the performance of commercially available as well as prototype HIV-1 PCR assays for HIV-1 DNA detection in samples from various geographical settings, in order to assess their ability to detect the different HIV-1 genotypes. OBJECTIVES: To determine the performance of the prototype Roche Amplicor version 1.5 PCR test in comparison to that of the standard Roche Amplicor PCR test for the detection of HIV-1 DNA in blood samples from HIV-1 seropositive pregnant Tanzanian women infected with various HIV-1 subtypes. STUDY DESIGN: This was a cross-sectional study done on 161 blood samples collected from 106 HIV-1 seropositive and 55 seronegative asymptomatic pregnant women attending antenatal clinic in Dar es Salaam, Tanzania. METHODS: Cell pellets for PCR were prepared from EDTA blood by the Amplicor whole blood PCR sample preparation method. Plasma was used for HIV serology by enzyme linked immunosorbent assays. Subtyping was done by the heteroduplex mobility assay (HMA) using cell pellets and/or plasma. RESULTS: The sensitivities of the prototype PCR and the standard assays were 99.1% (105/106) and 97% (99/102), respectively. All samples from 55 HIV-1 seronegative women were negative by both PCR assays. Among the 101 samples subtyped by HMA, 48 (47%) were subtype A, 30 (30%) subtype C, 20 (20%) subtype D and 3 (3%) were indeterminate. In the standard DNA PCR assay, a statistically significantly higher proportion of subtype A samples had a low level of reactivity as measured as optical density compared with the subtypes C and D samples while in the prototype assay all three subtypes showed a high level of reactivity. CONCLUSIONS: The Amplicor version 1.5 DNA PCR test has a high sensitivity for the detection of HIV-1 DNA in blood samples from Tanzanian adults. Since performance of this assay does not appear to be influenced by differences in HIV-1 subtypes A, C and D, it has the potential for use in the detection of HIV-1 DNA in samples from geographic areas where these subtypes are prevalent.

Immunological and virological interactions in patients receiving passive immunotherapy with HIV-1 neutralizing monoclonal antibodies.

Mouse monoclonal antibodies with high human immunodeficiency virus type 1 (HIV-1) neutralizing titers were used for passive immunotherapy of eleven late-state HIV-infected patients. In five patients the serum level of the core protein p24 decreased, while in five cases it remained unchanged. The level of viral RNA in plasma as measured by quantitative polymerase chain reaction (PCR) decreased in four cases, was stable in another four, and increased in three cases. An anti-mouse (HAMA) response developed in eight patients and anti-idiotypic antibodies appeared in six. Immune complexes that formed in patient sera during the treatment were shown to contain mostly envelope glycoprotein gp120 which decreased in nine of the eleven treated patients toward the end of treatment. Antibodies inhibiting gp120 binding to CD4 became detectable or increased in six patients during immunotherapy. Serology of the HIV-1 V3 region was studied for both the HIV-1 IIIB and MN strains with no or very small changes in titer or avidity after treatment. No change in neutralizing titers to strain HTLVIIIB was observed in serum samples collected before and after treatment was terminated. In nine of the eleven patients stimulation of the T lymphocytes to proliferate in vitro when activated by phytohemagglutinin (PHA) was shown to be increased compared to before treatment. Increased T-cell proliferation was also noted with several antigens such as HIV-1 recombinant antigens, cytomegalovirus (CMV), tetanus toxoid (TT), and purified protein derivate of mycobacterium tuberculosis (PPD). These findings indicate a decreased total gp120 content in serum, permitting better T-cell activation.