Phage strategies facilitate bacterial coexistence under environmental variability.

Bacterial communities are often exposed to temporal variations in resource availability, which exceed bacterial generation times and thereby affect bacterial coexistence. Bacterial population dynamics are also shaped by bacteriophages, which are a main cause of bacterial mortality. Several strategies are proposed in the literature to describe infections by phages, such as "Killing the Winner", "Piggyback the loser" (PtL) or "Piggyback the Winner" (PtW). The two temperate phage strategies PtL and PtW are defined by a change from lytic to lysogenic infection when the host density changes, from high to low or from low to high, respectively. To date, the occurrence of different phage strategies and their response to environmental variability is poorly understood. In our study, we developed a microbial trophic network model using ordinary differential equations (ODEs) and performed 'in silico' experiments. To model the switch from the lysogenic to the lytic cycle, we modified the lysis rate of infected bacteria and their growth was turned on or off using a density-dependent switching point. We addressed whether and how the different phage strategies facilitate bacteria coexistence competing for limiting resources. We also studied the impact of a fluctuating resource inflow to evaluate the response of the different phage strategies to environmental variability. Our results show that the viral shunt (i.e. nutrient release after bacterial lysis) leads to an enrichment of the system. This enrichment enables bacterial coexistence at lower resource concentrations. We were able to show that an established, purely lytic model leads to stable bacterial coexistence despite fluctuating resources. Both temperate phage models differ in their coexistence patterns. The model of PtW yields stable bacterial coexistence at a limited range of resource supply and is most sensitive to resource fluctuations. Interestingly, the purely lytic phage strategy and PtW both result in stable bacteria coexistence at oligotrophic conditions. The PtL model facilitates stable bacterial coexistence over a large range of stable and fluctuating resource inflow. An increase in bacterial growth rate results in a higher resilience to resource variability for the PtL and the lytic infection model. We propose that both temperate phage strategies represent different mechanisms of phages coping with environmental variability. Our study demonstrates how phage strategies can maintain bacterial coexistence in constant and fluctuating environments.

Dual treatment of acute HCV infection in HIV co-infection: influence of HCV genotype upon treatment outcome.

PURPOSE: With DAAs still only being licensed for chronic HCV infection, the ongoing epidemic of acute hepatitis C (AHC) infection among MSM highlights the need to identify factors allowing for optimal HCV treatment outcome. METHODS: 303 HIV-infected patients from 4 European countries with diagnosed acute HCV infection were treated early with pegylated interferon (pegIFN) and ribavirin (RBV) (n = 273) or pegylated interferon alone (n = 30). RESULTS: All patients were male, median age was 39 years. Main routes of transmission were MSM (95%) and IVDU (3%). 69% of patients were infected with HCV GT 1, 4.3% with GT 2, 10.6% with GT 3, 16.1% with GT 4. Overall SVR rate was 69.3% (210/303). RVR (p ≤ 0.001), 48-w treatment duration (p ≤ 0.001) and GT 2/3 (p = 0.024) were significantly associated with SVR. SVR rates were significantly higher in HCV GT 2/3 receiving pegIFN and RBV (33/35) when compared with pegIFN mono-therapy (6/10) (94% vs. 60 % respectively; p = 0.016). In multivariate analysis, pegIFN/RBV combination therapy (p = 0.017) and rapid virological response (RVR) (p = 0.022) were significantly associated with SVR in HCV GT 2/3. In HCV GT 1/4, RVR (p ≤ 0.001) and 48-w treatment duration (p ≤ 0.001) were significantly associated with SVR. CONCLUSIONS: Treatment of AHC GT 2 and 3 infections with pegIFN/RBV is associated with higher SVR rates suggesting different cure rates depending on HCV genotype similar to the genotype effects seen previously in chronic HCV under pegIFN/RBV. With pegIFN/RBV still being the gold standard of AHC treatment and in light of cost issues around DAAs and very limited licensed interferon-free DAA treatment options for chronic HCV GT 3 infection AHC GT 3 patients might benefit most from early interferon-containing treatment.

CD3(+)CD56(+) Natural Killer-Like T Cells Display Anti-HCV Activity but Are Functionally Impaired in HIV(+) Patients With Acute Hepatitis C.

OBJECTIVE: To analyze the role of CD3(+)CD56(+) natural killer (NK)-like T cells in HIV(+) patients with acute hepatitis C. DESIGN: Frequency, phenotype, and anti-hepatitis C virus (HCV) activity of CD3(+)CD56(+) NK-like T cells were studied in 36 HIV(+) patients with acute hepatitis C. As controls, 12 patients with chronic HCV/HIV coinfection, 8 HIV monoinfected patients, and 12 healthy donors were enrolled in this study. METHODS: CD3(+)CD56(+) NK-like T-cell-mediated inhibition of HCV replication was analyzed using the HuH7A2HCVreplicon model. The CD3(+)CD56(+) NK-like T-cell phenotype and interferon (IFN)-γ secretion were studied by flow cytometry. RESULTS: Interleukin 12/interleukin 15 stimulated CD3(+)CD56(+) NK-like T cells from healthy donors effectively block HCV replication in vitro in an IFN-γ dependent manner. Accordingly, we found that blocking of IFN-γ with a specific antibody significantly reduced the antiviral activity of CD3(+)CD56(+) NK-like T cells. However, when CD3(+)CD56(+) NK-like T cells from HIV(+) patients were studied, we found HIV infection to be associated with a significantly impaired IFN-γ production, irrespective of HCV coinfection. Accordingly, CD3(+)CD56(+) NK-like T cells from HIV(+) patients were significantly less effective in blocking HCV replication in vitro than cells from healthy individuals. CONCLUSIONS: Taken together, our data indicate that HIV infection is associated with an impaired anti-HCV activity of CD3(+)CD56(+) NK-like T cells, which might represent a novel mechanism of dysregulated immune response in HIV/HCV-coinfected patients.

An effective interferon-gamma-mediated inhibition of hepatitis C virus replication by natural killer cells is associated with spontaneous clearance of acute hepatitis C in human immunodeficiency virus-positive patients.

UNLABELLED: Hepatitis C virus (HCV) coinfection is an increasing health problem in human immunodeficiency virus-positive (HIV(+) ) individuals. However, a considerable proportion of HIV(+) patients manage to overcome acute hepatitis C (AHC) spontaneously. In the present study, we analyzed the role of natural killer (NK) cells in modulating the course of AHC in HIV(+) patients. Twenty-seven HIV(+) patients with AHC (self-limited course: n = 10; chronic course: n = 17), 12 HIV(+) patients with chronic hepatitis C (CHC), 8 HIV monoinfected individuals, and 12 healthy controls were studied. NK cells were phenotypically analyzed by flow cytometry. Interferon-gamma (IFN-γ) secretion, degranulation (CD107a), and anti-HCV (= inhibition of HCV replication) activity of NK subpopulations were analyzed using the HuH7A2 HCVreplicon cell system. NK cell frequency did not differ significantly between HIV(+) patients with chronic and self-limited course of AHC. However, we found NK cells from patients with self-limiting infection to be significantly more effective in inhibiting HCV replication in vitro than NK cells from patients developing CHC. Of note, antiviral NK cell activity showed no significant correlation with NK cell degranulation, but was positively correlated with IFN-γ secretion, and blocking experiments confirmed an important role for IFN-γ in NK cell-mediated inhibition of HCV replication. Accordingly, NK cells from patients that spontaneously cleared the virus displayed a stronger IFN-γ secretion than those developing chronic infection. Finally, we observed high expression of NKG2D and NKp46, respectively, to be associated with self-limiting course of aHCV. Accordingly, we found that blocking of these NK cell receptors significantly impaired antiviral NK cell activity. CONCLUSION: Our data suggest a strong IFN-γ-mediated antiviral NK cell response to be associated with a self-limited course of AHC in HIV(+) patients.

Variation in IFNL4 genotype and response to interferon-based therapy of hepatitis C in HIV-positive patients with acute and chronic hepatitis C.

The IFNL4 ss469415590 polymorphism has recently be shown to better predict treatment response in chronic hepatitis than the IL28B rs12979860 variant. However, no data exist in patients with HIV/hepatitis C virus (HCV) coinfection. Analysing 206 HCV(+)/HIV(+) and 162 HCV(+)/HIV(-) patients, we found that compared with IL28B rs12979860, IFNL4 ss469415590 was strongly associated with response to interferon/ribavirin therapy in HCV(+)/HIV(-) individuals but not in HIV(+)/HCV(+) patients. Thus, effects of the IFNL4 variant may differ in HIV(+) and HIV(-) patients.

Nevirapine pharmacokinetics in HIV-infected and HIV/HCV-coinfected individuals.

OBJECTIVES: An increased risk of drug-related liver injury has been repeatedly reported in individuals infected with hepatitis C virus (HCV) receiving the antiretroviral drug nevirapine. This study was undertaken to assess the differences in the pharmacokinetics of nevirapine between patients with HIV/HCV coinfection and HIV infection that could explain higher rates of hepatotoxicity. METHODS: A 12 h pharmacokinetic analysis was performed in 18 patients: 7 HIV/HCV-coinfected and 11 HIV-monoinfected. Advanced liver disease was an exclusion criterion in order to assess the impact of chronic HCV infection alone. RESULTS: Comparing the two groups, no difference was observed between minimum and maximum drug levels or total drug exposure in terms of area under the curve. CONCLUSIONS: Hepatitis C coinfection does not alter the pharmacokinetics of nevirapine in patients with preserved liver function.

Antiviral therapy for hepatitis C virus recurrence after liver transplantation in HIV-infected patients: outcome in the Bonn cohort.

Recurrent hepatitis C is a major cause of mortality in HIV/hepatitis C virus (HCV)-co-infected patients after orthotopic liver transplantation. We report sustained viral clearance in all four transplanted HIV/HCV-positive patients treated with pegylated interferon/ribavirin. Early therapy after HCV recurrence, tailoring treatment duration to the individual decline in HCV-RNA and the management of side effects are key factors for improved efficacy. At experienced centres interferon treatment is a valuable option for recurrent hepatitis C in HIV-positive patients.

Pegylated interferon alpha-2b plus ribavirin for the treatment of chronic hepatitis C in HIV-coinfected patients.

OBJECTIVES: HIV-coinfection accelerates the course of HCV-related liver disease. Since, highly active anti-retroviral therapy significantly improved survival of HIV-patients more coinfected patients develop end stage liver disease. Therefore, treatment options for chronic hepatitis C in HIV-coinfected patients need to be evaluated. METHODS: Efficacy and safety of pegylated interferon alpha-2b (peg IFN) plus ribavirin (RBV) was examined within this prospective, uncontrolled, multicentre trial. Patients received peg IFN (1.5 microg/kg) once weekly plus RBV 800 mg daily for 48 weeks for HCV genotypes (GT) 1/4 and 24 weeks for GT 2/3. RESULTS: One hundred and twenty-two patients were enrolled. Patients were predominantly male (68%) and former i.v. drug users (61%). Baseline characteristics (median) were as follows: age 39 years (range 23-58), CD4 count 494 cells/microl (range 150-1578/microl), HIV-RNA 2.3log copies/ml (range <1.7-5.4log copies/ml). 61% currently received anti-retroviral treatment. Fifty-six percent had HCV GT 1. EOT response was achieved by 52%. However, only 25% achieved sustained response (SR) due to a high relapse rate. SR rates were significantly higher among patients with GT 2/3 compared to those with GT 1/4 (44 vs. 18%). SR was observed in only one patient without early response (ER). Discontinuation rate was 30%, 21% discontinued due to adverse events. CONCLUSION: Peg IFN/RBV appears safe and effective in HIV/HCV-coinfected patients. GT 2/3 is associated with better SR. Lack of ER strongly predicts non-response. High relapse rates substantially reduce treatment success. In terms of toxicity neuro-psychiatric side effects frequently required treatment discontinuation.

Orthotopic liver transplantation in human immunodeficiency virus (HIV)-positive patients: outcome of 7 patients from the Bonn cohort.

The outcome and clinical features of 7 HIV-positive patients who were liver transplanted at Bonn University in the era of highly active antiretroviral therapy (HAART) between 1997 and 2004, analyzed by retrospective chart review, are reported. Reasons for orthotopic liver transplantation (OLT) were end-stage liver disease due to chronic hepatitis C (n = 4) or hepatitis B (n = 1) or acute liver failure due to fulminant hepatitis B (n = 2). Immunosuppression was based on cyclosporine A and prednisone. HAART was reinitiated 1 month after transplantation, and immunosuppression was carefully adapted to account for drug-drug interactions between cyclosporine A and protease inihibitors. Prednisone was withdrawn 5 months (median) after OLT when immunosuppression had been reliably established in the presence of HAART. One patient died 95 days after OLT due intrathoracic hemorrhage, whereas 6 patients were alive at a median of 24 months. A single episode of acute rejection was observed. The spectrum of postoperative complications was no different from HIV-negative patients apart from Kaposi's sarcoma and multicentric Castleman's disease in a single patient. Recurrent hepatitis B infection was efficiently prevented, whereas hepatitis C reinfection occurred in all 4 patients who had preexisting hepatitis C. Earlier reports on fatal courses of recurrent hepatitis C infection, high rates of organ rejection, and HAART-related liver toxicity were not observed in our patients. In conclusion, even though preliminary, our data suggest that outcomes after liver transplantation of HIV-infected patients can be improved.

Detection of HPV 52, 58 and 87 in cervicovaginal intraepithelial lesions of HIV infected women.

HIV positive or otherwise immunosuppressed patients are susceptible to cervicovaginal infections with a wide spectrum of HPV types. The aim of our study was to investigate the distribution of HPV in squamous intraepithelial lesions (SIL) with regard to HIV infection. We evaluated the HPV status in 20 HIV positive women with cytologically assessed SIL (11 high grade, 9 low grade) in relation to clinical and histological/cytological findings. Twenty HIV negative patients (15 high grade, 5 low grade SIL) served as a control. HPV typing was performed by polymerase chain reaction followed by PCR-ELISA (HPV 6/11, 16/18, 31/33, 40, 45, 52, 58) or sequence analysis of the amplicon (HPV 73, 87). HPV 52 was the most common type in the HIV positive group (8 HIV positive cases vs. 1 HIV negative case). HPV 16/18 was found in 6 HIV positive and 11 HIV negative patients. Further types detected in HIV positive patients were HPV 40, 58, 73 and 87 (one case each). No correlation was found between the HPV status and the CD4+ count or the grading of SIL. Persisting HPV infection with recurrence of SIL was documented in 5 cases after initial therapy of HPV positive lesions (HPV 87, 73, 58, 31/33, 16/18). HIV infected patients reveal a wider spectrum of HPV types in cervicovaginal SIL than HIV negative women. Especially HPV 87 and its relation with HIV infection and development and persistence of SIL needs further investigation. Our results indicate the inclusion of otherwise rare HPV types in screening programs for HIV positive and immunosuppressed patients.

Switching to atazanavir improves metabolic disorders in antiretroviral-experienced patients with severe hyperlipidemia.

OBJECTIVE: To describe the efficacy and change in lipid profile in patients with severe hyperlipidemia after switch to an atazanavir-containing highly active antiretroviral therapy regimen. DESIGN AND METHODS: Open-field, 24-week, prospective observational cohort study including 33 HIV-infected, antiretroviral-experienced patients with hyperlipidemia. Changes in lipid profiles were evaluated by analyses of triglycerides, total cholesterol, high- and low-density lipoprotein (HDL and LDL) cholesterol, and efficacy by HIV RNA and CD4 cell changes, both from baseline to week 24. RESULTS: A rapid and significant decrease of 46% (5.81 +/- 4 mmol/L vs. 3.16 +/- 2.6 mmol/L, P = 0.002) in triglyceride levels was shown. Similarly, a sustained improvement of 18% was observed in total cholesterol levels during the first 24 weeks after switching to atazanavir (6.45 +/- 1.9 mmol/L vs. 5.3 +/- 1.3 mmol/L, P = 0.001). After 24 weeks of treatment there was a significant decrease of 22% in non-HDL cholesterol (5.76 +/- 1.9 mmol/L at baseline vs. 4.5 +/- 1.3 mmol/L at 24 weeks; P = 0.003). HDL and LDL cholesterol profiles did not change significantly as did the viral load or CD4 cell count. CONCLUSIONS: Switching to atazanavir results in a significant improvement in HIV therapy-induced hyperlipidemia. A switch to atazanavir is proposed as a valuable option to improve atherogenic lipid profiles while maintaining virologic control.

Management of drug-to-drug interactions between cyclosporine A and the protease-inhibitor lopinavir/ritonavir in liver-transplanted HIV-infected patients.

Highly active antiretroviral therapy (HAART) has improved the life expectancy of HIV-infected patients, allowing orthotopic liver transplantation as a reasonable treatment option for selected patients with terminal liver disease. Both non-nucleoside reverse transcriptase inhibitors and protease inhibitors, key elements of HAART, give rise to substantial drug-to-drug interactions with immunosuppressive drugs such as tacrolimus and cyclosporine A. After studying 12-hour pharmacokinetic profiles in 3 HIV-positive patients after liver transplantation, we describe how dosing of cyclosporine A can be adjusted to maintain effective immunosuppressive drug levels on a daily dosing schedule when ritonavir-boosted indinavir or lopinavir-based antiretroviral therapy is given. To avoid toxic drug levels, we used an orally available cyclosporine A formulation prepared from the commercial available intravenous solution, which enabled dose adjustments in 1-mg increments. Under ritonavir-boosted HAART, cyclosporine A levels showed markedly altered absorption/elimination characteristics with more or less constant blood-levels throughout the dosing interval and prolonged elimination half-lives up to 38 hours. To obtain equivalent areas under the curve of cyclosporine A, daily doses were reduced to 5-20% of the individual standard doses given before initiation of ritonavir-boosted HAART. Because of the flat absorption/elimination profiles under ritonavir-boosted HAART cyclosporine A, dosing could be reliably monitored long term by measuring cyclosporine A trough-levels.