Rapid quantification of hepatitis B virus DNA by real-time PCR using fluorescent hybridization probes.

A highly sensitive and rapid assay has been developed to quantify hepatitis B virus (HBV) DNA, based on the fluorescence resonance energy transfer principle and real-time PCR, using the LightCycler and a pair of specific fluorescent hybridization probes. This LightCycler real-time PCR assay (LC-PCR) detected HBV DNA in a linear range from 10(1) to 10(8) copies per reaction (250-2.5 x 10(9) copies ml(-1)), with a rapid PCR cycling time of 35 min. The assay was validated with two EUROHEP HBV DNA standards (ad and ay subtypes) and exhibited low intra-assay (< 6 %) and inter-assay (< 16 %) variation for both subtypes over the complete range of 7 orders of magnitude. The assay was evaluated clinically using serum samples from 120 HBsAg(+) individuals and 45 healthy controls who were negative for both HBsAg and anti-HBc. Levels of HBV DNA were measured in these samples using both the LC-PCR and Digene Hybrid Capture II HBV DNA (HCII) assays. The prevalence rates for HBV DNA in the HBsAg(+) serum samples were respectively 95 % (114/120) and 56 % (67/120) by LC-PCR and HCII (P < 0.01). All 67 HCII-positive samples tested positive with LC-PCR, while the 47 discordant samples showed low levels of HBV DNA (down to 265 copies ml(-1)), detectable only by the more sensitive LC-PCR assay. Levels of HBV DNA as measured by the two assays showed good correlation (r = 0.902; P < 0.001). The level of HBV DNA was significantly higher in HBeAg(+) than anti-HBe(+) samples (median 1.5 x 10(7) vs 4.6 x 10(4) copies ml(-1); P < 0.01). It is concluded that this LC-PCR assay is clinically useful for the rapid, sensitive and accurate measurement of HBV DNA.

Effect of human anti-DNA antibodies on proximal renal tubular epithelial cell cytokine expression: implications on tubulointerstitial inflammation in lupus nephritis.

This study aimed to investigate the effects of human anti-DNA antibodies (Ab) from patients with lupus on renal proximal tubular epithelial cells (PTEC), focusing on alterations in cell morphology and proinflammatory cytokine synthesis. Immunohistochemistry showed increased tubulointerstitial IL-6 expression and IgG deposition in renal biopsies from patients with diffuse proliferative lupus nephritis, not observed in controls or membranous lupus nephritis, which correlated with the severity of inflammatory cell infiltration. Sera from patients with lupus nephritis contained IgG that bound to cultured PTEC. Such binding increased with disease activity and correlated with the level of anti-DNA Ab. Incubation of PTEC with anti-DNA Ab that were isolated during active (active Ab) or inactive (inactive Ab) disease induced IL-6 synthesis, both apically and from the basolateral aspect. This was accompanied by altered cell morphology, increased cell proliferation (P < 0.05), and lactate dehydrogenase release (P < 0.05). The binding of inactive Ab and active Ab to PTEC resulted in differential and sequential upregulation of TNF-alpha, IL-1beta, and IL-6 secretion (P < 0.05). Early induction of TNF-alpha was observed with active Ab; the two then acted synergistically to induce IL-6 secretion. Exposure of PTEC to inactive Ab was associated with modest induction of TNF-alpha, which was not involved in downstream induction of other proinflammatory peptides. These data suggest distinct immunopathogenetic mechanisms during disease flare or remission. Conditioned media from human mesangial cells acted synergistically with anti-DNA Ab to induce cytokine secretion in PTEC. Results from these studies underscore the pivotal role of PTEC in the pathogenesis of tubulointerstitial inflammation and fibrosis in lupus nephritis.