The aim of this Concerted Action was the evaluation and comparison of different approaches for the detection of HIV-1 and HIV-2 infections in seronegative individuals (e.g. during the few weeks following infection and preceding seroconversion, or in children born to infected mothers). It was decided that the Polymerase Chain Reaction (PCR) was the most promising technique for this purpose and that all efforts within this Concerted Action would be focused on studying the possibility of using it as a standard diagnostic tool in human retroviral infections.
The aim of this concerted action was the evaluation and comparison of different approaches for the detection of human immunodeficiency virus-1 (HIV-1) and HIV-2 infections in seronegative individuals. It was decided that the polymerase chain reaction (PCR) was the most promising technique for this purpose and that all efforts would be focused on studying the possibility of using it as a standard diagnostic tool in human retroviral infections. 3 Workshops, were organized with the aim of collecting and spreading information on the procedures used and results obtained in laboratories that had pioneered the use of PCR for the detection of HIV, and setting up a collaborative programme of standardization. A reference panel was established in eary 1990, consisting of serial dilutions of deoxyribonucleic acid (DNA) from a cell line with a stable single copy of HIV-1 provirus, as well as a control uninfected cell DNA, and primer pairs and probes located in different regions of the viral genome.
The first results of this standardization programme showed that: even laboratories with a good experience in PCR may have contamination problems; it is possible to define an average level of sensitivity which should be consistently obtained in every laboratory and that PCR, at its present stage of development, should be limited to a defined range of applications. It was recognized that PCR was useful for HIV detection in newborns; resolution of indeterminate Western blot results; measurement of virus load; monitoring of antiviral drugs and vaccines; typing of HIV infection and studies on the genetic variability of HIV. At the same time, it was recommended that PCR, as its present stage of development should not be used as a confirmatory assay for serological methods such as enzyme linked immunosorbent assay (ELISA) and Western Blot for routine diagnosis or for mass screening of HIV infection. Further work on the use of PCR is in progress.
A major problem was the occurrence of false positive results due to artefactual contamination. Moreover, duplicate testing of the same samples in different laboratories showed wide differences in sensitivity and specificity.
To address these problems, our Concerted Action has sponsored two programs:
a Since October 1988, a workshop on the Standardization of PCR for the Diagnosis of HIV and HTLV Infections has been organized every year in Paris by Dr. C. Brechot (Hopital Necker and Institut Pasteur), under the co-sponsoring of the EEC and WHO, with the aim of collecting information on the procedures and results of PCR studies in different laboratories, and setting up a collaborative program of PCR standardization. The meetings were intended as informal exchanges of results and technical experience, and no abstracts were printed. The main data presented at these meetings and conclusions of ensuring discussion will be summarized in this report.
b During the October 1989 workshop, it was decided that a reference panel would be established, consisting of DNA samples from uninfected and HIV-infected cell lines. The panel would be distributed to participating laboratories to serve as a standard for specificity and sensitivity. The results obtained with this panel were presented at the October 1990 and June 1992 workshops and will be discussed below.