Early dynamics of hepatitis C virus in the circulation of chimpanzees with experimental infection

Incidence rates of hepatitis C virus infection among blood donors in Japan: a nationwide retrospective cohort study

BACKGROUND

The classification of many new cases of hepatitis virus infection as overt hepatitis does not reflect the true incidence of infection because the disease takes an asymptomatic course in some cases. In this retrospective cohort study, we aimed to estimate the incidence rates of new hepatitis C virus (HCV) infections among the blood donors.

STUDY DESIGN AND METHOD

A 5-year retrospective cohort study was conducted to estimate the incidence rates by using the medical records of the blood donors between 2008 and 2013 for HCV infection. HCV seroconversions were investigated using a chemiluminescent enzyme immunoassay and then confirmed by nucleic acid amplification tests.

RESULTS

The incidence rate of HCV infection was 0.40 per 100,000 person-years (95% confidence interval, 0.27-0.57) for HCV RNA seroconversion only and 7.32 per 100,000 person-years (95% confidence interval, 6.73-7.95) if either HCV RNA or anti-HCV seroconversion were taken into consideration. No significant difference of new HCV infections was found between the sexes.

CONCLUSION

The incidence rate of HCV infection of this study was lower than that detected in a previous 1994-2004 study in which HCV incidence was 1.86 per 100,000 person-year, which reflects the presence of an effective blood screening system and health strategies targeting hepatitis control and prevention.

Usefulness of nucleic acid testing to reduce risk of hepatitis B virus transfusion-transmitted infection in Argentina: high rate of recent infections

BACKGROUND

Results from 10-year experience using nucleic acid test (NAT) screening in a blood bank of Córdoba are presented, showing the first data on prevalence of recent hepatitis B virus (HBV) infections and occult HBV infections (OBIs) in Argentina.

STUDY DESIGN AND METHODS

Molecular screening was performed by COBAS AmpliScreen human immunodeficiency virus Type 1 (HIV-1) test Version 1.5 and COBAS AmpliScreen hepatitis C virus (HCV) test Version 2.0 and COBAS TaqScreen MPX and MPX Version 2.0 test (Roche Molecular Systems). To characterize OBI, additional molecular and serologic assays were performed.

RESULTS

As results of NAT, 0.075% of the donors (155/205,388) tested positive for HIV, 0.05% (106/205,388) for HCV, and 0.045% (76/168,215) for HBV. Donors who tested positive for HIV or HCV by NAT were also positive by serology. There was one of 33,643 donors recently infected with HBV. At time of donation, six of 76 (7.9%) donors with confirmed HBV infection presented virologic and serologic profiles consistent with OBI. By additional studies three were OBI, two were window period infections, and one remained unclassified.

CONCLUSION

NAT contributed significantly to the reduction of the potential risk of HBV transmission with a frequency of one in 56,072, detecting three in 168,215 donors without serologic evidence of infection. NAT also detected three in 168,215 OBIs. The finding of high frequency of recent infections (1/33,643), unexpected for this country, highlights the need of promoting unified effective regulations that enforce the use of NAT in all blood banks in Argentina and points out the importance of assessing the risk of HBV transmission in blood banks of other countries considered to be low-endemic.

Interferon alone or combined with ribavirin for acute prolonged infection with hepatitis C virus in chimpanzees

Infection with hepatitis C virus (HCV) persisted for longer than 29 weeks in 2 chimpanzees after they had been inoculated with it experimentally. One of them (C-210) received short-term subcutaneous interferon-α (IFN-α) 6 million units (MU) daily for 7 days at week 29. He cleared HCV RNA from the serum and remained negative for it during 25 weeks after the withdrawal of IFN. The other (C-224) did not respond to 2 courses of a short-term IFN monotherapy at weeks 20 and 23. Twelve weeks thereafter, he received IFN-α 3 MU daily for 2 weeks and then 3 times a week for 14 weeks combined with oral ribavirin 600 mg daily during 16 weeks. HCV RNA disappeared from the serum and stayed negative until the last follow-up 24 weeks after the completion of combination therapy.

Chimpanzees in hepatitis C virus research: 1998-2007

BACKGROUND

Chimpanzees have been widely used in hepatitis C virus (HCV) research, but their endangered status and high financial and ethical costs have prompted a closer review.

METHODS

One hundred and nine articles published in 1998-2007 were analyzed for the number of chimpanzees involved, experimental procedures, objectives and other relevant issues.

RESULTS

The articles described the use of 852 chimpanzees, but accounting for likely multiple uses, the number of individual chimpanzees involved here is estimated to be approximately 500. Most articles addressed immunology and inoculation studies. A significant portion of studies lasted for several months or years. Approximately one half of the individual chimpanzees were each used in 2-10 studies.

CONCLUSIONS

Significant financial and scientific resources have been expended in these chimpanzee HCV studies. Discussion addresses troublesome questions presented by some of the reviewed articles, including statistical validity, repeatability, and biological relevance of this model. These concerns merit attention as future approaches to HCV research and research priorities are considered.

Minimum infectious dose of hepatitis B virus in chimpanzees and difference in the dynamics of viremia between genotype A and genotype C

BACKGROUND

In planning optimal hepatitis B virus (HBV) blood screening strategies, the minimum infectious dose and early dynamics of HBV need to be determined for defining the window period for HBV DNA as well as for hepatitis B surface antigen (HBsAg).

STUDY DESIGN AND METHODS

Pairs of chimpanzees were inoculated with preacute-phase inocula containing HBV of genotype A or genotype C to determine the minimum infectious dose, and two pairs of chimps infected with the lowest infectious dose of genotypes A and C were followed for HBV markers.

RESULTS

The minimum 50 percent chimpanzee infectious dose (CID50) was estimated to be approximately 10 copies for genotype A and for genotype C. In the two chimps inoculated with the lowest infectious dose, the HBV DNA window was 55 to 76 days for genotype A and 35 to 50 days for genotype C, respectively. The HBsAg window was 69 to 97 days for genotype A and 50 to 64 days for genotype C, respectively. The doubling times of HBV DNA were 3.4 days (95% confidence interval [CI], 2.6-4.9 days) for genotype A and 1.9 days (95% CI, 1.6-2.3 days) for genotype C. When comparing the replication velocity of HBV DNA between the two genotypes, the doubling time of genotype C was significantly shorter than that of HBV genotype A (p < 0.01).

CONCLUSION

Although the CID50 of approximately 10 copies was similar for the two HBV genotypes, the doubling time and pre-HBV nucleic acid amplification technology (<100 copies/mL) window period in chimps infected with the lowest infectious dose seemed to be shorter for genotype C than for genotype A.

Kinetics of hepatitis C virus reinfection after liver transplantation

Improved understanding of hepatitis C virus (HCV) dynamics during and after liver transplantation can be useful in optimizing antiviral therapy in transplant recipients. We analyzed serum HCV ribonucleic acid (RNA) levels during and after cadaveric liver transplantation in 6 HCV patients. After removal of the liver and before the new liver started producing virions, HCV RNA levels dropped with an average half-life (t(1/2)) of 0.8 hours. Viral loads then continued to drop up to 23 hours postimplantation (t(1/2) = 3.4 hours), and began to rise (doubling-time = 2.0 days) as soon as 15 hours after the anhepatic phase. In 3 patients the viral load reached a plateau before rising, suggesting that a nonhepatic source supplied virions and balanced their intrinsic clearance. However, from the decline in viral load over the first 24 hours of the postanhepatic phase, we estimate that nonhepatic sources can at most correspond to 4% of total viral production, 96% of which occurs in the liver, even after we corrected for fluid exchanges during surgery. As the new liver was reinfected, production increased and viral load rose to a new steady state. Using nonlinear regression, we were able to fit the patients' HCV RNA data to a viral dynamic model and estimate the de novo infection rate (mean 1.5 x 10(-6) mL/virion/day), as well as the average percentage of hepatocytes infected at the posttransplantation steady state (19%). In conclusion, we have quantified liver reinfection dynamics in the absence of posttransplantation antiviral therapy. Our findings support the notion that early antiviral therapy may delay or prevent reinfection.

Robust hepatitis C virus infection in vitro

The absence of a robust cell culture model of hepatitis C virus (HCV) infection has severely limited analysis of the HCV life cycle and the development of effective antivirals and vaccines. Here we report the establishment of a simple yet robust HCV cell culture infection system based on the HCV JFH-1 molecular clone and Huh-7-derived cell lines that allows the production of virus that can be efficiently propagated in tissue culture. This system provides a powerful tool for the analysis of host-virus interactions that should facilitate the discovery of antiviral drugs and vaccines for this important human pathogen.

Robust hepatitis C virus infection in vitro

The absence of a robust cell culture model of hepatitis C virus (HCV) infection has severely limited analysis of the HCV life cycle and the development of effective antivirals and vaccines. Here we report the establishment of a simple yet robust HCV cell culture infection system based on the HCV JFH-1 molecular clone and Huh-7-derived cell lines that allows the production of virus that can be efficiently propagated in tissue culture. This system provides a powerful tool for the analysis of host-virus interactions that should facilitate the discovery of antiviral drugs and vaccines for this important human pathogen.