Hepatitis B virus viral dynamics: effects of drug dose and baseline alanine aminotransferase

Modeling the dynamics of hepatitis B infection, immunity, and drug therapy

Hepatitis B virus infection is the cause of liver diseases such as cirrhosis and liver cancer. Understanding the host-virus mechanisms that mediate virus pathogenesis can help design better preventive measures for disease control. Mathematical models have been used alongside experimental data to provide insight into the role of immune responses during the acute and chronic hepatitis B infections as well as virus dynamics following administration of combined drug therapy. In this paper, we review several modeling studies on virus-host interactions during acute infection, the virus-host characteristics responsible for transition to chronic disease, and the efficacy and optimal control measures of drug therapy. We conclude by presenting our opinion on the future directions of the field.

Early HIV RNA decay during raltegravir-containing regimens exhibits two distinct subphases (1a and 1b)

BACKGROUND

We analyzed the early kinetics with integrase inhibitor treatment to gain new insights into viral dynamics.

METHODOLOGY

We analyzed data from 39 HIV-1 infected, treatment-naive, participants: 28 treated with raltegravir (RAL; multiple doses) monotherapy for 9 days, and 11 with RAL 400 mg twice daily and emtricitabine (200 mg daily)/tenofovir disoproxil fumarate (300 mg daily). Plasma HIV-1 RNA was measured frequently; the data was fitted using a mathematical model of viral dynamics distinguishing between infected cells with unintegrated HIV DNA and productively infected cells. Parameters were estimated using mixed-effect models.

RESULTS

RAL treatment led to a biphasic viral decline with a rapid first phase (1a) lasting approximately 5 days followed by a slower phase (1b). Phase 1a is attributed to the rapid elimination of productively infected cells. Phase 1b reflects the loss of infected cells with nonintegrated provirus due to cell loss and integration of HIV DNA. The half-lives of productively infected cells and of infected cells that had completed reverse transcription but had not yet integrated HIV DNA were approximately 19 h and between 3.6 and 5.8 days, respectively. The effectiveness of RAL in preventing proviral integration was 94% and 99.7%, for the combination therapy and monotherapy groups, respectively.

CONCLUSION

We found that the first phase of viral decay with RAL therapy was composed of two subphases corresponding to the half-lives of infected cells with integrated proviruses and with unintegrated HIV-DNA.

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