We used a new real-time polymerase chain reaction (PCR)-based assay that is sensitive, has a wide dynamic linear range, and is highly reproducible to quantify hepatitis B virus (HBV) DNA in the serum of infected individuals undergoing potent antiviral therapy. In addition, we made frequent measurements of viral load after initiation of treatment and maintained follow-up to about 12 weeks. To analyze the data we used a new model of HBV decay, which takes into account that existing drug treatments do not completely block de novo infection and the possibility of noncytolytic loss of infected cells. On initiation of therapy, there was a mean delay of 1.6 days followed by a biphasic or muliphasic decay of plasma HBV DNA. Analysis of viral dynamics during antiviral therapy has been critical to the understanding of the pathogenesis of several blood-borne viruses including human immunodeficiency virus (HIV), hepatitis C virus (HCV), and hepatitis B virus (HBV). 1-7 Pathogenesis of each of these viruses is characterized by a dynamic equilibrium between virus production and clearance. By disturbing this equilibrium with antiviral therapy and by mathematically analyzing the resulting decline in plasma viral load, insight has been gained into viral dynamics in vivo. In the case of HIV, the virion clearance rate and the rate of loss of infected cells derived from these analyses have been minimal estimates because they were based on the assumption that drug penetration is complete and that antiviral therapy is 100% effective. In the case of HCV and HBV it has not been necessary to assume that therapy is 100% effective, yet it has been possible to estimate the virion clearance rate, the infected cell loss rate, and the effectiveness of the therapy in blocking virion production. In the case of HIV and HCV, parameter estimates obtained by using viral dynamic theory have been independently confirmed by methods such as quantitative image analysis of tissue samples 8,9 and plasma apheresis. 10 However, the application of viral dynamic theory to HBV viral load measurements made in individuals on antiviral therapy is still in its early stages, and the conclusions drawn from these kinetic analyses still await experimental confirmation.A number of nucleoside analogues such as lamivudine (LMV), 11 famciclovir (FCV), 12,13 and adefovir dipivoxil 7,14 have been shown to be effective in suppressing HBV replication in vivo. A recent study of antiviral therapy for HBV showed enhanced efficacy of combination therapy with LMV and FCV as compared with LMV alone. 15 We performed a viral dynamic analysis on these same individuals, but used a molecular beacon assay 16,17 that accurately quantifies viral load over a wide dynamic range to further characterize the half-life of free virions and infected cells for each individual. Our analysis shows a heterogeneous and complex pattern of HBV viral decay.After treatment of HBV with antiviral agents, a biphasic decline in viral load has been reported, with an initial rapid decline representing decay of H...

Plasma ACE2 activity is elevated in human AF. Both AF and vascular disease predict elevated plasma ACE2 activity, and elevated plasma ACE2 is significantly associated with more advanced LA structural remodelling.

The introduction of lamivudine (LMV) for the treatment of chronic hepatitis B infection has been an important advance in the management of this disease. However, the long-term efficacy of LMV may become limited by the emergence of antiviral-resistant hepatitis B virus (HBV) mutants. The two most common LMV-resistant mutants produce changes in the viral polymerase protein (rt) of rtM204I and rtL180M/M204V (previously rtM550I and rtL526M/M550V). A number of studies have demonstrated that these HBV mutants appear to be replication impaired, both in vitro and in vivo. The detection and selection of compensatory mutations in the polymerase protein that restore the replication phenotype of these HBV mutants have been poorly described to date. The effects of mutations in the fingers subdomain of the viral polymerase protein arising as a consequence of vaccine and hepatitis B immune globulin (HBIg) selected changes in the overlapping envelope gene (S), and a determinant of the hepatitis Bs antigen (HBsAg) were analyzed in vitro. The LMV-resistant HBV mutants rtM204I and rtL180M/M204V produced substantially weaker HBV DNA replicative intermediate signals by Southern blot analysis and less total intracellular HBV DNA by real-time PCR compared to wild-type virus. The viral polymerase protein of these mutants produced little detectable radiolabeled HBV DNA in an endogenous polymerase assay. In contrast, the HBV a determinant HBIg/vaccine escape mutants sP120T, sT123N, sG145R, and sD144E/G145R (that produce rtT128N, Q130P, rtW153Q, and rtG153E respectively) yielded as much virus as wild-type HBV while the sM133L (rtY141S) mutant was replication impaired. Two of these mutants, rtT128N and rtW153Q, when introduced into a replication-competent HBV vector containing the rtL180M/M204V polymerase mutation restored the replication phenotype of this LMV-resistant mutant. These viruses produced levels of intracellular HBV DNA as determined by Southern blot and real-time PCR that were comparable to those of wild-type HBV, indicating that the changes in the fingers subdomain were able to compensate for the reduced replication of the LMV-resistant mutations. Since these viruses carry mutations in the a determinant of HBsAg that may potentially decrease the ability of anti-HBs antibody to neutralize these viruses, these HBV mutants also have the potential to behave as vaccine escape mutants.

No abstract