Post-treatment LSM rather than change during treatment predicts decompensation in patients with cACLD after HCV cure.

BACKGROUND & AIMS: Baveno VII has defined a clinically significant (i.e., prognostically meaningful) decrease in liver stiffness measurement (LSM) in cACLD as a decrease of ≥20% associated with a final LSM <20 kPa or any decrease to <10 kPa. However, these rules have not yet been validated against direct clinical endpoints. METHODS: We retrospectively analysed patients with cACLD (LSM ≥10 kPa) with paired liver stiffness measurement (LSM) before (BL) and after (FU) HCV cure by interferon-free therapies from 15 European centres. The cumulative incidence of hepatic decompensation was compared according to these criteria, considering hepatocellular carcinoma and non-liver-related death as competing risks. RESULTS: A total of 2,335 patients followed for a median of 6 years were analysed. Median BL-LSM was 16.6 kPa with 37.1% having ≥20 kPa. After HCV cure, FU-LSM decreased to a median of 10.9 kPa (<10 kPa: 1,002 [42.9%], ≥20 kPa: 465 [19.9%]) translating into a median LSM change of -5.3 (-8.8 to -2.4) kPa corresponding to -33.9 (-48.0 to -15.9) %. Patients achieving a clinically significant decrease (65.4%) had a significantly lower risk of hepatic decompensation (subdistribution hazard ratio: 0.12, 95% CI 0.04-0.35, p <0.001). However, these risk differences were primarily driven by a negligible risk in patients with FU-LSM <10 kPa (5-year cumulative incidence: 0.3%) compared to a high risk in patients with FU-LSM ≥20 kPa (16.6%). Patients with FU-LSM 10-19.9 kPa (37.4%) also had a low risk of hepatic decompensation (5-year cumulative incidence: 1.7%), and importantly, the risk of hepatic decompensation did not differ between those with/without an LSM decrease of ≥20% (p = 0.550). CONCLUSIONS: FU-LSM is key for risk stratification after HCV cure and should guide clinical decision making. LSM dynamics do not hold significant prognostic information in patients with FU-LSM 10-19.9 kPa, and thus, their consideration is not of sufficient incremental value in the specific context of HCV cure. IMPACT AND IMPLICATIONS: Liver stiffness measurement (LSM) is increasingly applied as a prognostic biomarker and commonly decreases in patients with compensated advanced chronic liver disease achieving HCV cure. Although Baveno VII proposed criteria for a clinically significant decrease, little is known about the prognostic utility of LSM dynamics (changes through antiviral therapy). Interestingly, in those with a post-treatment LSM of 10-19.9 kPa, LSM dynamics did not provide incremental information, arguing against the consideration of LSM dynamics as prognostic criteria. Thus, post-treatment LSM should guide the management of patients with compensated advanced chronic liver disease achieving HCV cure.

Clinical profile of Spanish hepatitisC virus-infected treatment-naïve patients with compensated cirrhosis in the CREST study. / Perfil clínico de los pacientes españoles con hepatitisC naïve con cirrosis compensada tratados en el estudio CREST.

BACKGROUND AND AIM OF THE STUDY: There are still patients with hepatitisC in Spain who have yet to be diagnosed, but their clinical profile is unclear. In 2021, 21.93% of patients diagnosed had cirrhosis and were mostly treatment-naïve. METHODS: This sub-analysis describes the clinical profile of the 60Spanish treatment-naïve patients with compensated cirrhosis who were included in the CREST study. MAJOR RESULTS: Sixty percent of patients were male, median age 56years, and 33% had a history of drug use. Almost three-quarters (71.3%) had more than one comorbidity and 78.3% took concomitant medication. At treatment initiation, median platelet count was 139×103/µL and FibroScan® 17kPa. No virological failure was observed and no patient discontinued treatment due to adverse events. No clinically significant changes were noted during or after treatment in the median platelet, albumin, bilirubin, and transaminase levels. CONCLUSIONS: Treatment with glecaprevir/pibrentasvir for 8weeks in this cohort of treatment-naïve patients with compensated cirrhosis in Spain was safe and effective. This information reinforces the use of this short antiviral regimen even when there is compensated cirrhosis, simplifying the approach to hepatitisC among those patients still to be diagnosed and treated in Spain.

HCC risk stratification after cure of hepatitis C in patients with compensated advanced chronic liver disease.

BACKGROUND & AIMS: Hepatocellular carcinoma (HCC) is a major cause of morbidity and mortality in patients with advanced chronic liver disease (ACLD) caused by chronic hepatitis C who have achieved sustained virologic response (SVR). We developed risk stratification algorithms for de novo HCC development after SVR and validated them in an independent cohort. METHODS: We evaluated the occurrence of de novo HCC in a derivation cohort of 527 patients with pre-treatment ACLD and SVR to interferon-free therapy, in whom alpha-fetoprotein (AFP) and non-invasive surrogates of portal hypertension including liver stiffness measurement (LSM) were assessed pre-/post-treatment. We validated our results in 1,500 patients with compensated ACLD (cACLD) from other European centers. RESULTS: During a median follow-up (FU) of 41 months, 22/475 patients with cACLD (4.6%, 1.45/100 patient-years) vs. 12/52 decompensated patients (23.1%, 7.00/100 patient-years, p <0.001) developed de novo HCC. Since decompensated patients were at substantial HCC risk, we focused on cACLD for all further analyses. In cACLD, post-treatment-values showed a higher discriminative ability for patients with/without de novo HCC development during FU than pre-treatment values or absolute/relative changes. Models based on post-treatment AFP, alcohol consumption (optional), age, LSM, and albumin, accurately predicted de novo HCC development (bootstrapped Harrel's C with/without considering alcohol: 0.893/0.836). Importantly, these parameters also provided independent prognostic information in competing risk analysis and accurately stratified patients into low- (~2/3 of patients) and high-risk (~1/3 of patients) groups in the derivation (algorithm with alcohol consumption; 4-year HCC-risk: 0% vs. 16.5%) and validation (3.3% vs. 17.5%) cohorts. An alternative approach based on alcohol consumption (optional), age, LSM, and albumin (i.e., without AFP) also showed a robust performance. CONCLUSIONS: Simple algorithms based on post-treatment age/albumin/LSM, and optionally, AFP and alcohol consumption, accurately stratified patients with cACLD based on their risk of de novo HCC after SVR. Approximately two-thirds were identified as having an HCC risk <1%/year in both the derivation and validation cohort, thereby clearly falling below the cost-effectiveness threshold for HCC surveillance. LAY SUMMARY: Simple algorithms based on age, alcohol consumption, results of blood tests (albumin and α-fetoprotein), as well as liver stiffness measurement after the end of hepatitis C treatment identify a large proportion (approximately two-thirds) of patients with advanced but still asymptomatic liver disease who are at very low risk (<1%/year) of liver cancer development, and thus, might not need to undergo 6-monthly liver ultrasound.

International multicenter validation of GES score for HCC risk stratification in chronic hepatitis C patients.

We have recently demonstrated the ability of a simple predictive model (GES) score to determine the risk of hepatocellular carcinoma (HCC) after using direct-acting antivirals. However, our results were restricted to Egyptian patients with hepatitis C virus (HCV) genotype 4. Therefore, we studied a large, independent cohort of multiethnic populations through our international collaborative activity. Depending on their GES scores, patients are stratified into low risk (≤ 6/12.5), intermediate risk (> 6-7.5/12.5), and high risk (> 7.5/12.5) for HCC. A total of 12,038 patients with chronic HCV were analyzed in this study, of whom 11,202 were recruited from 54 centers in France, Japan, India, the U.S., and Spain, and the remaining 836 were selected from the Gilead-sponsored randomized controlled trial conducted across the U.S., Europe, Canada, and Australia. Descriptive statistics and log-rank tests. The performance of the GES score was evaluated using Harrell's C-index (HCI). The GES score proved successful at stratifying all patients into 3 risk groups, namely low-risk, intermediate-risk, and high-risk. It also displayed significant predictive value for HCC development in all participants (p < .0001), with HCI ranging from 0.55 to 0.76 among all cohorts after adjusting for HCV genotypes and patient ethnicities. The GES score can be used to stratify HCV patients into 3 categories of risk for HCC, namely low-risk, intermediate-risk, and high-risk, irrespective of their ethnicities or HCV genotypes. This international multicenter validation may allow the use of GES score in individualized HCC risk-based surveillance programs.

Hepatitis C eradication improves cognitive function in patients with or without cirrhosis: A prospective real-life study.

BACKGROUND AND PURPOSE: Hepatitis C virus (HCV) infection is associated with neuropsychiatric disturbances that impact on functioning and health-related quality of life (HRQoL). Reversibility at different liver disease stages is unknown, particularly in cirrhosis. We aimed to evaluate cognition, functioning, and HRQoL following HCV eradication at different liver disease stages. METHODS: A random sample (n = 152) of consecutive patients treated with direct-acting antiviral agents (DAAs) between April 2015 and March 2017 were included. A comprehensive neuropsychological assessment, functioning and HRQoL questionnaires were applied at baseline, and 12 and 48 weeks after the end of antivirals. RESULTS: One-hundred thirty-five patients who achieved virological response completed the follow-up, of whom 44 had cirrhosis (27% decompensated). Twenty-one percent had cognitive impairment before starting DAAs (34.1% cirrhotic vs. 14.4% noncirrhotic, p < 0.011). Viral eradication was associated with a decrease in cognitive impairment to 23% of cirrhotic and 6% of noncirrhotic patients (p < 0.05). Interestingly, older patients (B = 0.11, 95% confidence interval [CI] = 0.03-0.19) with baseline cognitive impairment (B = 3.58, 95% CI = 1.54-5.62) were those with higher cognitive benefit, regardless of liver disease. Persistent cognitive impairment was associated with having higher cardiovascular risk, cirrhosis, lower education, and higher anxiety and depression scores. Functioning and HRQoL also improved after eradication but remained worse in the cirrhotic group. CONCLUSIONS: Viral eradication decreases the prevalence of cognitive impairment and improves functioning and HRQoL. Patients with lower brain reserve (older patients) and baseline cognitive impairment may benefit the most. Identification and treatment of HCV patients through screening programs may reduce the burden of cognitive disturbances beyond the prevention of liver disease progression.

A Model Based on Noninvasive Markers Predicts Very Low Hepatocellular Carcinoma Risk After Viral Response in Hepatitis C Virus-Advanced Fibrosis.

BACKGROUND AND AIMS: Patients with hepatitis C virus (HCV) and advanced fibrosis remain at risk of hepatocellular carcinoma (HCC) after sustained viral response (SVR) and need lifelong surveillance. Because HCC risk is not homogenous and may decrease with fibrosis regression, we aimed to identify patients with low HCC risk based on the prediction of noninvasive markers and its changes after SVR. APPROACH AND RESULTS: This is a multicenter cohort study, including patients with HCV and compensated advanced fibrosis that achieved SVR after direct antivirals. Clinical and transient elastography (TE) data were registered at baseline, 1 year, and 3 years after the end of treatment (EOT). All patients underwent liver ultrasound scan every 6 months. Patients with clinical evaluation 1 year after EOT were eligible. Univariate and multivariate Cox regression analysis were performed, and predictive models were constructed. HCC occurrence rates were evaluated by Kaplan-Meier. Nine hundred and ninety-three patients were eligible (56% male; 44% female; median age 62 years), 35 developed HCC (3.9%), and the median follow-up was 45 months (range 13-53). Baseline liver stiffness measurement (LSM) (HR 1.040; 95% CI 1.017-1.064), serum albumin (HR 0.400; 95% CI 0.174-0.923), 1-year DeltaLSM (HR 0.993; 95% CI 0.987-0.998), and 1-year FIB-4 score (HR 1.095; 95% CI 1.046-1.146) were independent factors associated with HCC. The TE-based HCC risk model predicted 0% of HCC occurrence at 3 years in patients with score 0 (baseline LSM ≤ 17.3 kPa, albumin >4.2 g/dL, and 1-year DeltaLSM > 25.5%) versus 5.2% in patients with score 1-3 (Harrell's C 0.779; log-rank 0.002). An alternative model with FIB-4 similarly predicted HCC risk. CONCLUSIONS: A combination of baseline and dynamic changes in noninvasive markers may help to identify patients with a very low risk of HCC development after SVR.

Quality of life in patients with hepatitis C. Importance of treatment. / Calidad de vida en los pacientes con hepatitis C. Importancia del tratamiento.

Chronic hepatitis C virus infection is a systemic disease that impairs the quality of life of affected individuals. The impairment is not only due to physiological factors, such as the non-hepatic manifestations of the disease or certain symptoms such as fatigue, weakness and nausea, but is also due to the substantial psychological impact of the infection. Treatment with direct-acting antivirals (DAA) has been demonstrated to substantially improve patient's quality of life, starting in the initial phases. Supplement information: This article is part of a supplement entitled "The value of simplicity in hepatitis C treatment", which is sponsored by Gilead. © 2019 Elsevier España, S.L.U. All rights reserved.

Updated Results from the Retrospective CREST Study on the Safety and Effectiveness of 8-Week Glecaprevir/Pibrentasvir in HCV-Infected Treatment-Naïve Patients with Compensated Cirrhosis.

INTRODUCTION: This brief report presents updated findings from the previously published CREST study evaluating the safety and effectiveness of 8-week glecaprevir/pibrentasvir (GLE/PIB) in treatment-naïve patients with chronic hepatitis C virus (HCV) infection and compensated cirrhosis. The current study includes an additional 51 patients, presents effectiveness data stratified by additional comorbidities and comedications, and offers insights into healthcare resource utilization. METHODS: Analysis of treatment-naïve patients with HCV infection and compensated cirrhosis enrolled in the CREST study, a real-world, observational multicenter study. All enrolled patients were included in the full analysis set (FAS); the modified analysis set (MAS) excluded patients with missing SVR12 data, or who discontinued GLE/PIB for nonvirologic failure. The primary endpoint was sustained virologic response at posttreatment week 12 (SVR12) in the MAS. Safety and healthcare resource utilization were also assessed. RESULTS: The FAS included 437 patients, and the MAS 375. Overall, the results were consistent with the previously published study, with 98.9% of patients in the MAS achieving SVR12. Patients with comorbidities such as alcoholism, diabetes, and hyperlipidemia achieved SVR12 rates > 94%. High SVR12 rates were also achieved by patients receiving comedications such as anxiolytics, antidepressants, and opioid agonists. Of the 26.8% of patients with an adverse event, 1.1% had a serious adverse event, none of which were deemed related to GLE/PIB. Healthcare resource utilization varied by employment status and history of drug use. Active drug users had more physician and nurse visits than specialist visits compared with former drug users. CONCLUSION: This study provides further evidence on the safety and effectiveness of 8-week GLE/PIB, supporting the use of shorter treatment in treatment-naïve patients with Child-Pugh A cirrhosis including subgroups of interest, regardless of comorbidities and comedications observed in this population. The variable healthcare resource utilization in different patient types can help plan and resource linkage to care better, thus supporting HCV elimination efforts.

Safety and Effectiveness Using 8 Weeks of Glecaprevir/Pibrentasvir in HCV-Infected Treatment-Naïve Patients with Compensated Cirrhosis: The CREST Study.

INTRODUCTION: In clinical trials with hepatitis C virus-infected treatment-naïve (TN) patients with compensated cirrhosis (CC), glecaprevir/pibrentasvir (G/P), a fixed-dose, once-daily, pangenotypic regimen, has demonstrated sustained virologic response at posttreatment Week 12 (SVR12) > 95%. We evaluated the real-world safety and effectiveness of 8-week G/P therapy in TN patients with CC, including certain subgroups of interest. METHODS: The CREST study is a real-world, noninterventional, multicenter study retrospectively assessing data from Canada, Germany, Israel, Italy, and Spain. The full analysis set (FAS) designated all patients in the study; the modified analysis set (MAS) excluded patients who discontinued G/P for nonvirologic failure or who had missing SVR12 data. The primary endpoint was SVR12; safety endpoints were also assessed. RESULTS: A total of 386 patients were included in the FAS, 375 patients completed the study, and 325 patients were included in the MAS; 51 patients had missing SVR12 data. Overall, in the MAS and FAS, SVR12 was achieved in 99.1% and 84.2% of patients, respectively. In subgroups of interest, the percentage of patients achieving SVR12 in the MAS (and FAS) was: genotype (GT)3: 97.5% (80.6%); FibroScan® ≥ 12.5 kPa: 98.9% (89.3%); platelet count < 100 × 109/l: 100% (88.2%); both platelets < 150 × 109/l and FibroScan® > 20 kPa: 100% (88.9%); aspartate aminotransferase-to-platelet ratio index > 1.09: 98.7% (83.1%); fibrosis-4 index > 3.25: 98.6% (84.0%); albumin < 3 g/dl: 100% (91.7%); people who use drugs: 97.7% (84.3%); psychiatric disorders: 96.6% (84.8%); and human immunodeficiency virus coinfection: 100% (95.0%). Overall, 26.9% (104/386) of patients experienced an adverse event, none of which were classed as serious. CONCLUSION: In this real-world cohort, 8 weeks of G/P therapy was well tolerated in TN patients with CC. SVR12 rates were similar to clinical trials, supporting 8-week treatment in TN patients with CC, including those with signs of advanced liver disease and GT3 infection.

Hepatocellular carcinoma risk after viral response in hepatitis C virus-advanced fibrosis: Who to screen and for how long?

Hepatitis C virus (HCV) chronic infection is associated with fibrosis progression, end-stage liver complications and HCC. Not surprisingly, HCV infection is a leading cause of liver-related morbidity and mortality worldwide. After sustained virological response (SVR), the risk of developing hepatocellular carcinoma is not completely eliminated in patients with established cirrhosis or with advanced fibrosis. Therefore, lifelong surveillance is currently recommended. This strategy is likely not universally cost-effective and harmless, considering that not all patients with advanced fibrosis have the same risk of developing HCC. Factors related to the severity of liver disease and its potential to improve after SVR, the molecular and epigenetic changes that occur during infection and other associated comorbidities might account for different risk levels and are likely essential for identifying patients who would benefit from screening programs after SVR. Efforts to develop predictive models and risk calculators, biomarkers and genetic panels and even deep learning models to estimate the individual risk of HCC have been made in the direct-acting antiviral agents era, when thousands of patients with advanced fibrosis and cirrhosis have reached SVR. These tools could help to identify patients with very low HCC risk in whom surveillance might not be justified. In this review, factors affecting the probability of HCC development after SVR, the benefits and risks of surveillance, suggested strategies to estimate individualized HCC risk and the current evidence to recommend lifelong surveillance are discussed.

Development of a metabolically active, non-replicating sporozoite vaccine to prevent Plasmodium falciparum malaria.

Immunization of volunteers by the bite of mosquitoes carrying radiation-attenuated Plasmodium falciparum sporozoites protects greater than 90% of such volunteers against malaria, if adequate numbers of immunizing biting sessions and sporozoite-infected mosquitoes are used. Nonetheless, until recently it was considered impossible to develop, license and commercialize a live, whole parasite P. falciparum sporozoite (PfSPZ) vaccine. In 2003 Sanaria scientists reappraised the potential impact of a metabolically active, non-replicating PfSPZ vaccine, and outlined the challenges to producing such a vaccine. Six years later, significant progress has been made in overcoming these challenges. This progress has enabled the manufacture and release of multiple clinical lots of a 1(st) generation metabolically active, non-replicating PfSPZ vaccine, the Sanaria PfSPZ Vaccine, submission of a successful Investigational New Drug application to the US Food and Drug Administration, and initiation of safety, immunogenicity and protective efficacy studies in volunteers in MD, US. Efforts are now focused on how best to achieve submission of a successful Biologics License Application and introduce the vaccine to the primary target population of African children in the shortest possible period of time. This will require implementation of a systematic, efficient clinical development plan. Short term challenges include optimizing the (1) efficiency and scale up of the manufacturing process and quality control assays, (2) dosage regimen and method of administration, (3) potency of the vaccine, and (4) logistics of delivering the vaccine to those who need it most, and finalizing the methods for vaccine stabilization and attenuation. A medium term goal is to design and build a facility for manufacturing highly potent and stable vaccine for pivotal Phase 3 studies and commercial launch.

Effectiveness, safety/tolerability of OBV/PTV/r ± DSV in patients with HCV genotype 1 or 4 with/without HIV-1 co-infection, chronic kidney disease (CKD) stage IIIb-V and dialysis in Spanish clinical practice - Vie-KinD study.

BACKGROUND AND AIMS: Limited data are available on the effectiveness and tolerability of direct-acting antivirals (DAAs) therapies in the real world for HCV-infected patients with comorbidities. This study aimed to describe the effectiveness of OBV/PTV/r ± DSV (3D/2D regimen) with or without ribavirin (RBV) in HCV or HCV/HIV co-infected patients with GT1/GT4 and CKD (IIIb-V stages), including those under hemodialysis and peritoneal dialysis in routine clinical practice in Spain in 2015. MATERIAL AND METHODS: Non-interventional, retrospective, multicenter data collection study in 31 Spanish sites. Socio-demographic, clinical variables, study treatment characteristics, effectiveness and tolerability data were collected from medical records. RESULTS: Data from 135 patients with a mean age (SD) of 58.3 (11.4) years were analyzed: 92.6% GT1 (81.6% GT1b and 17.6% GT1a) and 7.4% GT4, 14 (10.4%) HIV/HCV co-infected, 19.0% with fibrosis F3 and 28.1% F4 by FibroScan®, 52.6% were previously treated with pegIFN and RBV. 11.1%, 14.8% and 74.1% of patients had CKD stage IIIb, IV and V respectively. 68.9% of patients were on hemodialysis; 8.9% on peritoneal dialysis and 38.5% had history of renal transplant. A total of 125 (96.2%) of 135 patients were treated with 3D, 10 (7.4%) with 2D and 30.4% received RBV. The overall intention-to-treat (ITT) sustained virologic response at week 12 (SVR12) was 92.6% (125/135) and the overall modified-ITT (mITT) SVR12 was 99.2% (125/126). The SVR12 rates (ITT) per sub-groups were: HCV mono-infected (91.7%), HCV/HIV co-infected (100%), GT1 (92.0%), GT4 (100%), CKD stage IIIb (86.7%), stage IV (95%) and stage V (93%). Among the 10 non-SVR there was only 1 virologic failure (0.7%); 4 patients had missing data due lost to follow up (3.0%) and 5 patients discontinued 3D/2D regimen (3.7%): 4 due to severe adverse events (including 3 deaths) and 1 patient´s decision. CONCLUSIONS: These results have shown that 3D/2D regimens are effective and tolerable in patients with advanced CKD including those in dialysis with GT 1 or 4 chronic HCV mono-infection and HIV/HCV coinfection in a real-life cohort. The overall SVR12 rates were 92.6% (ITT) and 99.2% (mITT) without clinically relevant changes in eGFR until 12 weeks post-treatment. These results are consistent with those reported in clinical trials.

Similar effectiveness of direct-acting antiviral against hepatitis C virus in patients with and without HIV infection.

OBJECTIVE: We compared the baseline characteristics, effectiveness, and tolerance of direct-acting antiviral drug (DAA)-based regimens taken by hepatitis C virus (HCV)-monoinfected and HCV/HIV-coinfected individuals in clinical practice. DESIGN: We performed a prospective observational study in two tertiary centres in Madrid, Spain, which included all HCV-monoinfected and HCV/HIV-coinfected patients undergoing HCV treatment with all-oral DAA regimens in a routine clinical setting, from April 2015 to November 2015. We evaluated sustained virological response 12 weeks after the end of therapy (SVR12), adverse events, and baseline and treatment characteristics. RESULTS: The study population comprised 1634 patients: 1152 HCV-monoinfected patients (70%) and 482 HCV/HIV-coinfected patients (30%). Fifty percent had cirrhosis, and 47% were peginterferon/ribavirin-experienced. HCV/HIV-coinfected patients were younger [median age (interquartile range) 51 (48-54) years vs. 59 (50-68) years; P < 0.001), more frequently male (76 vs. 54%; P < 0.001), and infected with genotypes 1a (37 vs. 17%; P < 0.001), 3 (15 vs. 7%; P < 0.001), and 4 (23 vs. 4%; P < 0.001). One of every three patients took ribavirin. SVR12 was 94% (95% confidence interval 91.7-96%) and 97% (95% confidence interval 95.7-99.4%) in coinfected and monoinfected patients, respectively, with no significant differences between the groups after adjustment for cirrhosis, genotype, and DAA combination. DAA-based regimens were well tolerated, and only 1% of patients had severe adverse events, with no differences between the populations. CONCLUSIONS: HCV/HIV-infected patients treated with all-oral DAA combinations achieved high rates of SVR12 that were similar to those of HCV-monoinfected patients under real-life conditions. Safety and tolerance were excellent, even in patients with end-stage liver disease.

The role of the Zn(II) binding domain in the mechanism of E. coli DNA topoisomerase I.

BACKGROUND: Escherichia coli DNA topoisomerase I binds three Zn(II) with three tetracysteine motifs which, together with the 14 kDa C-terminal region, form a 30 kDa DNA binding domain (ZD domain). The 67 kDa N-terminal domain (Top67) has the active site tyrosine for DNA cleavage but cannot relax negatively supercoiled DNA. We analyzed the role of the ZD domain in the enzyme mechanism. RESULTS: Addition of purified ZD domain to Top67 partially restored the relaxation activity, demonstrating that covalent linkage between the two domains is not necessary for removal of negative supercoils from DNA. The two domains had similar affinities to ssDNA. However, only Top67 could bind dsDNA with high affinity. DNA cleavage assays showed that the Top67 had the same sequence and structure selectivity for DNA cleavage as the intact enzyme. DNA rejoining also did not require the presence of the ZD domain. CONCLUSIONS: We propose that during relaxation of negatively supercoiled DNA, Top67 by itself can position the active site tyrosine near the junction of double-stranded and single-stranded DNA for cleavage. However, the interaction of the ZD domain with the passing single-strand of DNA, coupled with enzyme conformational change, is needed for removal of negative supercoils.

Delineation of stage specific expression of Plasmodium falciparum EBA-175 by biologically functional region II monoclonal antibodies.

BACKGROUND: The malaria parasite Plasmodium falciparum EBA-175 binds its receptor sialic acids on glycophorin A when invading erythrocytes. The receptor-binding region (RII) contains two cysteine-rich domains with similar cysteine motifs (F1 and F2). Functional relationships between F1 and F2 domains and characterization of EBA-175 were studied using specific monoclonal antibodies (mAbs) against these domains. METHODS AND FINDINGS: Five mAbs specific for F1 or F2 were generated. Three mAbs specific for F2 potently blocked binding of EBA-175 to erythrocytes, and merozoite invasion of erythrocytes (IC(50) 10 to 100 µg/ml IgG in growth inhibition assays). A mAb specific for F1 blocked EBA-175 binding and merozoite invasion less effectively. The difference observed between the IC(50) of F1 and F2 mAbs was not due to differing association and disassociation rates as determined by surface plasmon resonance. Four of the mAbs recognized conformation-dependent epitopes within F1 or F2. Used in combination, F1 and F2 mAbs blocked the binding of native EBA-175 to erythrocytes and inhibited parasite invasion synergistically in vitro. MAb R217, the most potent, did not recognize sporozoites, 3-day hepatocyte stage parasites, nor rings, trophozoites, gametocytes, retorts, ookinetes, and oocysts but recognized 6-day hepatocyte stage parasites, and schizonts. Even though efficient at blocking binding to erythrocytes and inhibiting invasion into erythrocytes, MAb R217 did not inhibit sporozoite invasion and development in hepatocytes in vitro. CONCLUSIONS: The role of the F1 and F2 domains in erythrocyte invasion and binding was elucidated with mAbs. These mAbs interfere with native EBA-175 binding to erythrocyte in a synergistic fashion. The stage specific expression of EBA-175 showed that the primary focus of activity was the merozoite stage. A recombinant RII protein vaccine consisting of both F1 and F2 domains that could induce synergistic activity should be optimal for induction of antibody responses that interfere with merozoite invasion of erythrocytes.

Poly(I:C) is an effective adjuvant for antibody and multi-functional CD4+ T cell responses to Plasmodium falciparum circumsporozoite protein (CSP) and αDEC-CSP in non human primates.

Development of a fully effective vaccine against the pre-erythrocytic stage of malaria infection will likely require induction of both humoral and cellular immune responses. Protein based vaccines can elicit such broad-based immunity depending on the adjuvant and how the protein is formulated. Here to assess these variables, non human primates (NHP) were immunized three times with Plasmodium falciparum (Pf) circumsporozoite protein (CSP) or CSP cloned into MG38, a monoclonal antibody that targets DEC-205 (αDEC-CSP), an endocytic receptor on dendritic cells (DCs). Both vaccines were administered with or without poly(I:C) as adjuvant. Following three immunizations, the magnitude and quality of cytokine secreting CD4+ T cells were comparable between CSP+poly(I:C) and αDEC-CSP+poly(I:C) groups with both regimens eliciting multi-functional cytokine responses. However, NHP immunized with CSP+poly(I:C) had significantly higher serum titers of CSP-specific IgG antibodies and indirect immunofluorescent antibody (IFA) titers against Pf sporozoites. Furthermore, sera from both CSP or αDEC-CSP+poly(I:C) immunized animals limited sporozoite invasion of a hepatocyte cell line (HC04) in vitro. To determine whether CSP-specific responses could be enhanced, all NHP primed with CSP or αDEC-CSP+poly(I:C) were boosted with a single dose of 150,000 irradiated Pf sporozoites (PfSPZ) intravenously. Remarkably, boosting had no effect on the CSP-specific immunity. Finally, immunization with CSP+poly-ICLC reduced malaria parasite burden in the liver in an experimental mouse model. Taken together, these data showing that poly(I:C) is an effective adjuvant for inducing potent antibody and Th1 immunity with CSP based vaccines offers a potential alternative to the existing protein based pre-erythrocytic vaccines.

Multistrain genetic comparisons reveal CCR5 as a receptor involved in airway hyperresponsiveness.

Asthma is a ubiquitous disease with a broad range of clinical phenotypes. To better understand the complex genetic and environmental interactions underlying asthma, we compared the gene-gene interactions of four genetically distinct mouse strains that demonstrate biologically distinct responses to allergen. Using DNA microarrays and knock-out mouse studies, we showed that CCR5 plays a definitive role in the development of ovalbumin-induced allergic airway inflammatory disease. In addition, gene expression profiling data have revealed other potential novel targets for therapeutics-based research and has enhanced the understanding of the molecular mechanisms underlying the etiology of "asthma."

Direct interaction between Escherichia coli RNA polymerase and the zinc ribbon domains of DNA topoisomerase I.

Escherichia coli DNA topoisomerase I (encoded by the topA gene) is important for maintaining steady-state DNA supercoiling and has been shown to influence vital cellular processes including transcription. Topoisomerase I activity is also needed to remove hypernegative supercoiling generated on the DNA template by the progressing RNA polymerase complex during transcription elongation. The accumulation of hypernegative supercoiling in the absence of topoisomerase I can lead to R-loop formation by the nascent transcript and template strand, leading to suppression of transcription elongation. Here we show by affinity chromatography and overlay blotting that E. coli DNA topoisomerase I interacts directly with the RNA polymerase complex. The protein-protein interaction involves the beta' subunit of RNA polymerase and the C-terminal domains of E. coli DNA topoisomerase I, which are homologous to the zinc ribbon domains in a number of transcription factors. This direct interaction can bring the topoisomerase I relaxing activity to the site of transcription where its activity is needed. The zinc ribbon C-terminal domains of other type IA topoisomerases, including mammalian topoisomerase III, may also help link the enzyme activities to their physiological functions, potentially including replication, transcription, recombination, and repair.