BACKGROUND: Occult viremia occurring before the appearance of HBsAg or after the disappearance of HBsAg is detectable by gene amplification technologies whose efficiency depends on nucleic acid preparation. STUDY DESI...
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BACKGROUND: Occult viremia occurring before the appearance of HBsAg or after the disappearance of HBsAg is detectable by gene amplification technologies whose efficiency depends on nucleic acid preparation. STUDY DESIGN AND METHODS: To isolate HBV DNA from viremic plasma, immunoaffinity capture (IAC) of intact HBV with biotinylated pre-S1 antibodies coupled to streptavidin-coated magnetic beads was evaluated. IAC was compared with a silica-gel method (Qiagen [QSG]) and its two modifications wherein the samples were heated with lysis buffer at 60 degrees C for 10 minutes (QSG-60) or at 58 degrees C for 60 minutes with proteinase-K (QSG-PK). Each HBV DNA sample was tested by heminested PCR amplification of the HBV gene sequences. A total of 36 coded serum samples were tested, including three HBsAg-positive controls and 33 former chronic HBV carriers who had seroconverted (developed antibody to HBsAg [anti-HBs]). Commercially available seroconversion panels (PHM 907, 911, and 922) were similarly tested for window-period viremia. RESULTS: In the 33 former chronic HBV carriers who had seroconverted, IAC revealed HBV DNA in 17 samples, whereas it was revealed in only 11 samples by QSG-PK (p = 0.031), 10 by QSG-60 (p = 0.016), and 9 by QSG (p = 0.0078). However, HBV DNA was not amplified from the 17 samples at 1-in-10 dilutions;thus, they were considered to have low-level viremia. IAC revealed HBV DNA as early as or earlier than the other methods in PHM 907, 911, and 922 panels. CONCLUSION: IAC is apparently an optimal method of sample preparation for amplification of HBV DNA in patients in the pre-HBsAg window period, and for detecting low-level viremia persistent in several individuals who were former chronic HBV carriers who had seroconverted (developed anti-HBs).
Chemokine homologs are encoded by many large DNA viruses, suggesting that they contribute to control of host leukocyte transmigration and trafficking during viral infection. Murine cytomegalovirus carries a CC (beta) ...
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Chemokine homologs are encoded by many large DNA viruses, suggesting that they contribute to control of host leukocyte transmigration and trafficking during viral infection. Murine cytomegalovirus carries a CC (beta) chemokine homolog gene giving rise to two related proteins, murine cytomegalovirus chemokine 1 and 2 (MCK-1 and MCK-2). MCK-1 peptide was found to induce calcium signaling and adherence in murine peritoneal macrophages. Cells bearing human chemokine receptor CCR3 and the human macrophage THP1 cell line were responsive to MCK-1. This pattern suggested that MCK-1 might act as an agonist, promoting leukocyte trafficking during viral infection. Consistent with this prediction, MCK-1/MCK-2 mutant viruses exhibit dramatically reduced peak levels of monocyte-associated viremia in experimentally infected mice. Thus, MCK-1/MCK-2 appears to promote host leukocyte migration to initial sites of infection and may be responsible for attracting monocytes or macrophages that efficiently disseminate virus in the host.
Mononuclear cells can be infected in vitro by hepatitis C virus and the viral RNA can be detected in mononuclear cells of chronically infected patients. It was suggested that the virus could persist in the mononuclear...
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Mononuclear cells can be infected in vitro by hepatitis C virus and the viral RNA can be detected in mononuclear cells of chronically infected patients. It was suggested that the virus could persist in the mononuclear cells of some patients treated by interferon. The aim of this study was to follow the presence of viral RNA in the plasma and peripheral bleed mononuclear cells of 16 chronically infected patients treated by alpha2b interferon for 1 year. The RNA was detected by reverse transcription followed by nested PCR and quantified using the branched DNA method at regular intervals for at least one year. Before PCR, the mononuclear cells were treated by RNase and trypsin in order to eliminate the viral particles that could be stuck at the cell surface. Six patients were non responders and had persistent plasmatic viral RNA during the treatment. Two patients were good responders and had persistantly negative PCR in both plasma and mononuclear cells. Eight patients had initial negativation of plasmatic hepatitis C virus RNA but showed a relapse characterized by positive plasmatic PCR. Positive PCR in mononuclear cells despite negativity of plasmatic PCR was noted 18 times in 8 patients. Persistently positive PCR in mononuclear cells in absence of detectable viraemia was followed by a virological relapse in 5 of these patients. This study confirms that hepatitis C virus RNA can be detected in mononuclear cells despite negative plasmatic PCR in patients treated by interferon. Moreover, the persistence of viral RNA in peripheral mononuclear cells could be a predictive factor of treatment failure. Our data also suggest that detection of viral RNA in mononuclear cells is probably not only due to passive virus adsorption from plasma.
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