Viral Dynamics in hepatits B virus infection

Department of Zoology, University of Oxford, United Kingdom
Proceedings of the National Academy of Sciences (Impact Factor: 9.67). 05/1996; 93(9):4398-402. DOI: 10.1073/pnas.93.9.4398
Source: PubMed


Treatment of chronic hepatitis B virus (HBV) infections with the reverse transcriptase inhibitor lamivudine leads to a rapid decline in plasma viremia and provides estimates for crucial kinetic constants of HBV replication. We find that in persistently infected patients, HBV particles are cleared from the plasma with a half-life of approximately 1.0 day, which implies a 50% daily turnover of the free virus population. Total viral release into the periphery is approximately 10(11) virus particles per day. Although we have no direct measurement of the infected cell mass, we can estimate the turnover rate of these cells in two ways: (i) by comparing the rate of viral production before and after therapy or (ii) from the decline of hepatitis B antigen during treatment. These two independent methods give equivalent results: we find a wide distribution of half-lives for virus-producing cells, ranging from 10 to 100 days in different patients, which may reflect differences in rates of lysis of infected cells by immune responses. Our analysis provides a quantitative understanding of HBV replication dynamics in vivo and has implications for the optimal timing of drug treatment and immunotherapy in chronic HBV infection. This study also represents a comparison for recent findings on the dynamics of human immunodeficiency virus (HIV) infection. The total daily production of plasma virus is, on average, higher in chronic HBV carriers than in HIV-infected patients, but the half-life of virus-producing cells is much shorter in HIV. Most strikingly, there is no indication of drug resistance in HBV-infected patients treated for up to 24 weeks.

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    • "Mathematical models have been developed to explore mechanisms and dynamical behaviours of the inhost viral infection process. A basic virus dynamics model consists of the following simple three dimensional system (see [1] [2]): "
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    ABSTRACT: In this paper, we propose a model of virus dynamics that includes diffusion, time delay and a general incidence function. By constructing Liapunov functionals, we show that the model has threshold dynamics: if the basic reproduction number , then the infection-free equilibrium is globally asymptotically stable; whereas if , then there exists an infection equilibrium which is globally asymptotically stable. We pay particular attention to demonstrating that solutions are sufficiently bounded away from that the Liapunov functionals are well-defined. Some applications are listed. Our results improve and generalize some known results.
    Nonlinear Analysis Real World Applications 10/2015; 25:64-78. DOI:10.1016/j.nonrwa.2015.03.002 · 2.52 Impact Factor
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    • "[9] "
    Jian Wu ·
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    ABSTRACT: Cytochrome P450 (CYP) is a super family of phase I enzyme in the biotransformation of xenobiotics and medications. Most medications undergo deactivation by CYP, and then are eliminated through either bile or kidneys from the body. CYP isozymes play a crucial role in drug interactions that may result in enhanced toxicity, reduced efficacy or onset of adverse reactions. On the other hand, many agents affecting CYP expression and activity may alter metabolic rate of different medications co-administrated. Therefore, the molecular basis, regulation by inducers or inhibitors, and pharmacologic reaction of specific CYP isozymes are the key issues of biochemical mechanisms, pharmaceutical development and safe use of various medications. This book is to meet the needs from basic molecular biochemists, pharmacologists, pharmacists, medical students, clinical practitioners and scientists, as well as broad readers who wish to understand how an herbal extract, medication or natural supplement is metabolized or transformed in the liver or other sites for deactivation and elimination. Special focuses are paid to herbal extracts and medications in the treatment of neuro-psychiatric or cardiovascular disorders, diabetes and viral hepatitis. Detailed dissection of drug interactions in a particular field intends to provide rationales for useful guidance of safe drug use in daily practice. The contributing authors are basic scientists, pharmacists, pharmacologists and on-service physicians in cardiovascular, neuro-psychiatric, gastroenterologic and hepatologic fields from Europe (Germany, France, Portugal), Australia, the US and China. Thus, the book is the collection of master pieces by well-known experts from various regions of the world, and represents the current understanding of CYP enzyme reaction and a contemporary coverage of possible drug interactions in involved fields. The featured chapters are scientific elucidation of basic biochemistry, pharmacology and clinical investigations in the interest of drug metabolism, interaction and safe use guidance in the single focus of this microsomal enzyme with multi-facet metabolic function.
    First edited by Jian Wu, 09/2014; Nova Science Publishers, Inc.., ISBN: 978-1-61942-209-4
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    • "A basic viral infection mathematical model (BVIM) introduced by Nowak et al. [10] is widely used for studying the dynamics of infectious agents such as hepatitis B, C virus and HIV: "
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