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Real-time quantitative polymerase chain reaction (PCR) on the LightCycler instrument (LC-PCR) was developed to measure the Epstein-Barr virus (EBV) load in clinical samples. LC-PCR detected two copies of the EBV genome per 500 ng of DNA. Its specificity was confirmed by assays in EBV-negative cell lines, other human herpesviruses and EBV-seronegative individuals. Excellent inter-assay reproducibility of LC-PCR was obtained in 43 samples (r = 0.983). LC-PCR results were compared with a routinely used ELISA-PCR of 150 samples and a good correlation was found (r = 0.956). A total of 88 individuals were studied, including healthy EBV-seropositive adults (n = 32), patients with EBV-associated disease (n = 34), and HIV-infected patients (n = 22); 37.5% of PBMC samples from healthy individuals contained EBV DNA, while no serum sample was positive. The viral load was significantly higher in PBMCS and saliva specimens in patients recently infected with HIV (19 and 39,400 copies/microg DNA, respectively), as well as in AIDS patients (122 and 331,130 copies/microg DNA) than in the control population (0 and 35 copies/microg DNA). This study confirmed that EBV load measurement with LC-PCR is helpful in the management of EBV-related post-transplantation lymphoproliferative disorders and probably of EBV-associated primary central nervous system B-cell lymphoma.

The genotypic inhibitory quotient (GIQ) has been proposed as a way to integrate drug exposure and genotypic resistance to protease inhibitors and can be useful to enhance the predictivity of virologic response for boosted protease inhibitors. The aim of this study was to evaluate the predictivity of the GIQ in 116 protease inhibitor-experienced patients treated with lopinavir-ritonavir. The overall decrease in human immunodeficiency virus type 1 (HIV-1) RNA from baseline to month 6 was a median of ؊1.50 log 10 copies/ml and 40% of patients had plasma HIV-1 RNA below 400 copies/ml at month 6. The overall median lopinavir study-state C min concentration was 5,856 ng/ml. Using univariate linear regression analyses, both lopinavir GIQ and the number of baseline lopinavir mutations were highly associated with virologic response through 6 months. In the multivariate analysis, only lopinavir GIQ, baseline HIV RNA, and the number of prior protease inhibitors were significantly associated with response. When the analysis was limited to patients with more highly mutant viruses (three or more lopinavir mutations), only lopinavir GIQ remained significantly associated with virologic response. This study suggests that GIQ could be a better predictor of the virologic response than virological (genotype) or pharmacological (minimal plasma concentration) approaches used separately, especially among patients with at least three protease inhibitor resistance mutations. Therapeutic drug monitoring for patients treated by lopinavir-ritonavir would likely be most useful in patients with substantially resistant viruses.The development of human immunodeficiency virus (HIV) drug resistance during antiretroviral therapy can compromise the efficacy of subsequent regimens following virologic failure. Several studies have shown that changes in baseline viral genotype, compared to that of wild-type virus, adversely affect the virologic response of antiretroviral-experienced subjects with a subsequent regimen (3,4,19). However, the efficacy of antiretroviral treatment can be impaired by several factors, including poor adherence to treatment regimens, suboptimal antiviral potency and/or drug concentrations, and of course selection of antiretrovirus agent-resistant HIV quasispecies.More information on the effect of these parameters should be beneficial for optimizing the use of protease inhibitors in salvage therapy. The inhibitory quotient, mainly used for the protease inhibitors, has been proposed as a way to integrate drug exposure and viral susceptibility. Defined as the ratio between the trough concentration of a drug in a patient and the susceptibility of the virus in that patient to that drug, the inhibitory quotient has been associated with virologic response to protease inhibitor-based antiretroviral therapy in several studies (6, 17;

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