Differences in reverse transcriptase activity versus p24 antigen detection in cell culture, when comparing a homogeneous group of HIV type 1 subtype B viruses with a heterogeneous group of divergent strains.
Failure to detect infection with HIV-1 non-B subtypes in some antibody screening assays has been shown. To date, however, no studies have been published evaluating the capacity of standard tests to quantify replication of divergent HIV-1 in cell culture. Reverse transcriptase (RT) activity and p24 antigen assays are the two methods most commonly used for this purpose. A homogeneous panel of HIV-1 subtype B viruses from northern Italy and a heterogeneous panel of diverse genetic subtypes (A to F and O) from different regions of the world were cultured under identical conditions. A new nonradioactive RT assay was used as a basis for comparison to evaluate the capacity of two p24 assays to quantify viral growth in both panels. Comparison of the p24 amount/RT activity (p24/RT) ratios showed that ratios in the subtype B panel tended to be markedly higher than in the diverse subtype panel. Greatest variation was seen with one of the subtype O isolates, where up to a 400 times lower ratio was obtained compared with the average ratio for the subtype B panel. In addition, one Thai subtype B virus also gave a markedly reduced ratio. Furthermore, comparison between the two p24 assays showed different abilities to detect p24 from different HIV-1 isolates. We discuss limitations for the use of anti-HIV-1 p24 antibodies produced by immunization with subtype B p24 in p24 assays.
Corrigan
G E
GE
Cavidi Tech AB, Uppsala Science Park, Staben, Sweden.
Al-Khalili
L
L
Malmsten
A
A
Thorstensson
R
R
Fenyö
E M
EM
Källander
C F
CF
Gronowitz
J S
JS
D015492:AIDS Serodiagnosis; D005814:Genes, Viral; D014644:Genetic Variation; D015483:HIV Antibodies; D016655:HIV Core Protein p24 / Q000032:analysis*; D015658:HIV Infections / Q000175:diagnosis / Q000276:immunology / Q000821:virology; D054303:HIV Reverse Transcriptase / Q000032:analysis*; D015497:HIV-1 / Q000145:classification* / Q000201:enzymology / Q000276:immunology; D006801:Humans; D007558:Italy
D015483:HIV Antibodies; D016655:HIV Core Protein p24; D054303:HIV Reverse Transcriptase