Performance of the Amplicor human immunodeficiency virus type 1 PCR and analysis of specimens with false-negative results

Abstract

Over a 4-year period, the Roche Amplicor kit was used in a United Kingdom reference laboratory for the detection or confirmation of human immunodeficiency virus (HIV) type 1 infection, particularly in infants born to HIV-infected mothers. Of 408 specimens from adults and older children tested, the 122 seronegative specimens were all Amplicor negative. Of the 286 seropositive specimens, 268 were Amplicor positive. On the basis of these results, the Amplicor assay has a specificity of 100% and a sensitivity of 93.7%. In addition, for 247 specimens from infants and young children, serological results may not have been diagnostic because of placental transfer of maternal antibodies. Forty-eight were Amplicor positive, and of the 199 Amplicor-negative specimens, 19 were assumed to be false negative on the basis of clinical data, serological markers (including p24 antigen), and/or results for previous or follow-up specimens. This represents a sensitivity of 75% for the Amplicor test for specimens from patients under 2 years of age. Of these 37 false-negative specimens plus 2 specimens from other laboratories, 31 could be characterized by amplifying extracted material from them by an in-house nested gag PCR spanning the Amplicor target region. The amplicons were sequenced and found to represent subtypes A (35.5%), B (22.6%), C (22.6%), D (16.1%), and G (3.2%). False-negative results by the Amplicor assay may be ascribed to low-target copy number, the physical behavior of one primer (SK462), and sequence variation in the target region of the other primer (SK431).

Evaluation of a transcription‐mediated amplification‐based HCV and HIV‐1 RNA duplex assay for screening individual blood donations: a comparison with a minipool testing system

“…Consequently, the detection of viral variants is a concern for NAT. 21 In this study, the TMA duplex assay detected with similar efficiency the calibrated reference strains of HIV-1 subtype B and HCV genotype 1, in addition to clinical samples of HIV-1 subtypes A-E and HCV subtypes 1a-4a of various geographical origins ( Table 1).…”

Molecular Colony Diagnostics: Detection and Quantitation of Viral Nucleic Acids by In-Gel PCR

“…At low virus amounts, the background may completely hide the signal generated by the target. If that happens, then assays produce false-negative results (3,27). Of course, the MCT format cannot eliminate background synthesis; however, because of the high resolving power of the MCT gel, it could negate that effect by spatially separating background colonies from those produced by the target.…”

Comparison of an Amplified Enzyme-Linked Immunosorbent Assay with Procedures Based on Molecular Biology for Assessing Human Immunodeficiency Virus Type 1 Viral Load

“…To enhance the level of detection, we performed kinetic studies with samples with ODs higher than the average of the negative control ODs but lower than the threshold (average negative control ODs ϩ standard deviations). We carried out these studies with different incubation times (4,8,16,24,36, and 48 h). More than 50% of the samples became positive when the incubation period reached 16 h (plateau at 16 h).…”