Spatial transcriptomics reveal markers of histopathological changes in Duchenne muscular dystrophy mouse models

Duchenne muscular dystrophy is caused by mutations in the DMD gene, leading to lack of dystrophin. Chronic muscle damage eventually leads to histological alterations in skeletal muscles. The identification of genes and cell types driving tissue remodeling is a key step to developing effective therapies. Here we use spatial transcriptomics in two Duchenne muscular dystrophy mouse models differing in disease severity to identify gene expression signatures underlying skeletal muscle pathology and to directly link gene expression to muscle histology. We perform deconvolution analysis to identify cell types contributing to histological alterations. We show increased expression of specific genes in areas of muscle regeneration (Myl4, Sparc, Hspg2), fibrosis (Vim, Fn1, Thbs4) and calcification (Bgn, Ctsk, Spp1). These findings are confirmed by smFISH. Finally, we use differentiation dynamic analysis in the D2-mdx muscle to identify muscle fibers in the present state that are predicted to become affected in the future state.

Impact of Age and Comorbidity on Choice and Outcome of Two Different Treatment Options for Patients with Potentially Curable Esophageal Cancer

Purpose

This study was designed to assess the impact of age and comorbidity on choice and outcome of definitive chemoradiotherapy (dCRT) or neoadjuvant chemoradiotherapy plus surgery.

Methods

In this population-based study, all patients with potentially curable EC (cT1N+/cT2-3, TX, any cN, cM0) diagnosed in the South East of the Netherlands between 2004 and 2014 were included. Kaplan–Meier method with log-rank tests and multivariable Cox regression analysis were used to compare overall survival (OS).

Results

A total of 702 patients was included. Age ≥ 75 years and multiple comorbidities were associated with a higher probability for dCRT (odds ratio [OR] 8.58; 95% confidence interval [CI] 4.72–15.58; and OR 3.09; 95% CI 1.93–4.93). The strongest associations were found for the combination of hypertension plus diabetes (OR 3.80; 95% CI 1.97–7.32) and the combination of cardiovascular with pulmonary comorbidity (OR 3.18; 95% CI 1.57–6.46). Patients with EC who underwent dCRT had a poorer prognosis than those who underwent nCRT plus surgery, irrespective of age, number, and type of comorbidities. In contrast, for patients with squamous cell carcinoma with ≥ 2 comorbidities or age ≥ 75 years, OS was comparable between both groups (hazard ratio [HR] 1.52; 95% CI 0.78–2.97; and HR 0.73; 95% CI 0.13–4.14).

Conclusions

Histological tumor type should be acknowledged in treatment choices for patients with esophageal cancer. Neoadjuvant chemoradiotherapy plus surgery should basically be advised as treatment of choice for operable esophageal adenocarcinoma patients. For patients with esophageal squamous cell carcinoma with ≥ 2 comorbidities or age ≥ 75 years, dCRT may be the preferred strategy.

Recurrence after preoperative chemotherapy and surgery for gastric adenocarcinoma: a multicenter study

BACKGROUND

In most western European countries perioperative chemotherapy is a part of standard curative treatment for gastric cancer. Nevertheless, recurrence rates remain high after multimodality treatment. This study examines patterns of recurrence in patients receiving perioperative chemotherapy with surgery for gastric cancer in a real-world setting.

METHODS

All patients diagnosed with gastric adenocarcinoma between 2010 and 2015 who underwent at least preoperative chemotherapy and a gastrectomy with curative intent (cT1N+/cT2-4a,X; any cN; cM0) in 18 Dutch hospitals were selected from the Netherlands Cancer Registry. Additional data on chemotherapy and recurrence were collected from medical records. Rates, patterns, and timing of recurrence were examined. Multivariable Cox proportional hazard analyses were used to determine prognostic factors for recurrence.

RESULTS

408 patients were identified. After a median follow-up of 27.8 months, 36.8% of the gastric cancer patients had a recurrence of which the majority (88.8%) had distant metastasis. The 1-year recurrence-free survival was 71.8%. The risk of recurrence was higher in patients with an ypN+ stage (HR 4.92, 95% CI 3.35-7.24), partial or no tumor regression (HR 2.63, 95% CI 1.22-5.64), 3 instead of ≥ 6 chemotherapy cycles (HR 3.04, 95% CI 1.99-4.63), R1 resection (HR 1.52, 95% CI 1.02-2.26), and < 15 resected lymph nodes (HR 1.64, 95% CI 1.14-2.37).

CONCLUSION

A considerable amount of gastric cancer patients who were treated with curative intent developed a recurrence despite surgery and perioperative treatment. The majority developed distant metastases, therefore, multimodality treatment approaches should be focused on the prevention of distant rather than locoregional recurrences to improve survival.

Definitive chemoradiation or surgery in elderly patients with potentially curable esophageal cancer in the Netherlands: a nationwide population-based study on patterns of care and survival

BACKGROUND

The aim of our study was to describe treatment patterns and the impact on overall survival among elderly patients (75 years and older) with potentially curable esophageal cancer.

MATERIAL AND METHODS

Between 2003 and 2013, 13,244 patients from the nationwide population-based Netherlands Cancer Registry (NCR) were diagnosed with potentially curable esophageal cancer (cT2-3, X, any cN, cM0, X) of which 34% were elderly patients (n = 4501).

RESULTS

Surgical treatment with or without neoadjuvant treatment remained stable among elderly patients (around the 16% between 2003 and 2013). However, among younger patients, surgical treatment increased from 60.2 to 67.0%. The use of definitive chemoradiation (dCRT) increased in elderly patients from 1.9 to 19.5% and in younger patients from 5.2 to 17.2%. Due to the increase in dCRT, treatment with curative intent doubled in the elderly from 17 to 37.1%. Multivariable Cox regression revealed that elderly patients with an adenocarcinoma receiving surgery alone or dCRT had a significantly worse overall survival compared to those receiving surgery with neoadjuvant chemo (radio) therapy (nCRT/CT) (HR: 1.7 95% CI 1.4-2.0 and HR: 1.9 95% CI 1.5-2.3). However, among elderly with squamous cell carcinoma overall survival was comparable between dCRT, surgery alone and surgery with nCRT/CT.

CONCLUSIONS

Survival was comparable among elderly patients with squamous cell carcinoma who underwent surgery with nCRT/CT, surgery alone or received dCRT, while elderly patients with an adenocarcinoma who underwent surgery with nCRT/CT had a better overall survival when compared with surgery alone or dCRT. Therefore, dCRT can be considered as a reasonable alternative for surgery among potentially curable elderly patients with esophageal squamous cell carcinoma. However, in elderly patients with esophageal adenocarcinoma surgery with nCRT/CT is still preferable regarding overall survival.

Overall survival before and after centralization of gastric cancer surgery in the Netherlands

BACKGROUND

Centralization of surgery has been shown to improve outcomes for oesophageal and pancreatic cancer, and has been implemented for gastric cancer since 2012 in the Netherlands. This study evaluated the impact of centralizing gastric cancer surgery on outcomes for all patients with gastric cancer.

METHODS

Patients diagnosed with non-cardia gastric adenocarcinoma in the intervals 2009-2011 and 2013-2015 were selected from the Netherlands Cancer Registry. Clinicopathological data, treatment characteristics and mortality were assessed for the periods before (2009-2011) and after (2013-2015) centralization. Cox regression analyses were used to assess differences in overall survival between these intervals.

RESULTS

A total of 7204 patients were included. Resection rates increased slightly from 37·6 per cent before to 39·6 per cent after centralization (P = 0·023). Before centralization, 50·1 per cent of surgically treated patients underwent gastrectomy in hospitals that performed fewer than ten procedures annually, compared with 9·2 per cent after centralization. Patients who had gastrectomy in the second interval were younger and more often underwent total gastrectomy (29·3 per cent before versus 41·2 per cent after centralization). Thirty-day postoperative mortality rates dropped from 6·5 to 4·1 per cent (P = 0·004), and 90-day mortality rates decreased from 10·6 to 7·2 per cent (P = 0·002). Two-year overall survival rates increased from 55·4 to 58·5 per cent among patients who had gastrectomy (P = 0·031) and from 27·1 to 29·6 per cent for all patients (P = 0·003). Improvements remained after adjustment for case mix; however, adjustment for hospital volume attenuated this association for surgically treated patients.

CONCLUSION

Centralization of gastric cancer surgery was associated with reduced postoperative mortality and improved survival.

Timing of postoperative chemotherapy in patients undergoing perioperative chemotherapy and gastrectomy for gastric cancer

BACKGROUND

For patients who qualify for perioperative chemotherapy and gastrectomy for gastric cancer, the optimal timing of the postoperative chemotherapy (PC) seems equivocal. The aim of this study was to evaluate the influence of timing of PC on overall survival (OS) in patients receiving perioperative chemotherapy.

METHODS

Patients undergoing perioperative chemotherapy and gastrectomy with curative intent (2010-2014) were extracted from the nationwide population-based Netherlands Cancer Registry. Timing of PC was analyzed as a linear and categorical variable (<6 weeks, 6-8 weeks, and >8 weeks). Risk factors for a late start of PC (≥6 weeks), and the association between timing of PC and OS were assessed by multivariable regression analyses.

RESULTS

Among 1066 patients who underwent perioperative chemotherapy and gastrectomy, 463 (43%) patients started PC. PC was administered within 6 weeks in 208 (45%) patients, within 6-8 weeks in 155 (33%) patients, and after 8 weeks in 100 (22%) patients. A total of 419 (91%) and 351 (76%) patients finished all cycles of preoperative and PC, respectively. A late start of PC was associated with a longer hospital stay (+1 hospital day: OR 1.15, 95% CI [1.08-1.23], p < 0.001). Timing of PC was not associated with OS (6-8 weeks vs. <6 weeks, HR 1.14, 95% CI [0.79-1.65], p = 0.471; >8 weeks vs. <6 weeks, HR 1.04, 95% CI [0.79-1.65], p = 0.872).

CONCLUSION

Timing of postoperative chemotherapy does not influence survival in patients receiving perioperative chemotherapy for gastric cancer. The results suggest that the early postoperative period may be safely used for recovery and optimizing patients for the start of PC.

Natural disease history of the dy2J mouse model of laminin α2 (merosin)-deficient congenital muscular dystrophy

Merosin deficient congenital muscular dystrophy 1A (MDC1A) is a very rare autosomal recessive disorder caused by mutations in the LAMA2 gene leading to severe and progressive muscle weakness and atrophy. Although over 350 causative mutations have been identified for MDC1A, no treatment is yet available. There are many therapeutic approaches in development, but the lack of natural history data of the mouse model and standardized outcome measures makes it difficult to transit these pre-clinical findings to clinical trials. Therefore, in the present study, we collected natural history data and assessed pre-clinical outcome measures for the dy^2J/dy^2J mouse model using standardized operating procedures available from the TREAT-NMD Alliance. Wild type and dy^2J/dy^2J mice were subjected to five different functional tests from the age of four to 32 weeks. Non-tested control groups were taken along to assess whether the functional test regime interfered with muscle pathology. Respiratory function, body weights and creatine kinase levels were recorded. Lastly, skeletal muscles were collected for further histopathological and gene expression analyses. Muscle function of dy^2J/dy^2J mice was severely impaired at four weeks of age and all mice lost the ability to use their hind limbs. Moreover, respiratory function was altered in dy^2J/dy^2J mice. Interestingly, the respiration rate was decreased and declined with age, whereas the respiration amplitude was increased in dy^2J/dy^2J mice when compared to wild type mice. Creatine kinase levels were comparable to wild type mice. Muscle histopathology and gene expression analysis revealed that there was a specific regional distribution pattern of muscle damage in dy^2J/dy^2J mice. Gastrocnemius appeared to be the most severely affected muscle with a high proportion of atrophic fibers, increased fibrosis and inflammation. By contrast, triceps was affected moderately and diaphragm only mildly. Our study presents a complete natural history dataset which can be used in setting up standardized studies in dy^2J/dy^2J mice.

[Hospital of diagnosis influences the probability of receiving curative treatment for oesophageal and gastric cancer]

OBJECTIVE

The aim of these studies was to examine the influence of hospital of diagnosis on the probability of receiving curative treatment and its impact on survival among oesophageal and gastric cancer.

DESIGN

Although oesophageal and gastric cancer surgery is centralised in the Netherlands, the disease is often diagnosed in hospitals that do not perform this procedure.

METHOD

Patients with potentially curable oesophageal or gastric cancer tumours diagnosed between 2005 and 2013 were selected from the Netherlands Cancer Registry. The probability to undergo curative treatment was examined for each hospital of diagnosis after adjustment for case-mix. Effects of variation in probability of undergoing curative treatment among these hospitals on survival were investigated Cox regression.

RESULTS

All 13,017 patients with potentially curable oesophageal and 5,620 patients with potentially curable gastric cancer, diagnosed in 91 hospitals, were included. After adjustment, the proportion of oesophageal cancer patients receiving curative treatment ranged from 50% to 82% and from 48% to 78% for patients with gastric cancer in 2010-2013, depending on hospital of diagnosis (both P < 0.001). Furthermore, patients diagnosed in hospitals with a low probability of undergoing curative treatment had a worse overall survival in the period 2010-2013 (oesophageal cancer hazard ratio (HR): 1,15; 95%-CI: 1,07-1,24; gastric cancer HR: 1,21; 95%-CI: 1,04-1,41).

CONCLUSION

The variation in probability of undergoing potentially curative treatment for oesophageal and gastric cancer between hospitals of diagnosis and its impact on survival indicates that treatment decision-making for these patients may be improved. Regional expert multidisciplinary team meetings in this field may improve the selection of patients for curative treatment.

Effect of age on rates of palliative surgery and chemotherapy use in patients with locally advanced or metastatic gastric cancer

BACKGROUND

This study assessed trends in the treatment and survival of palliatively treated patients with gastric cancer, with a focus on age-related differences.

METHODS

For this retrospective, population-based, nationwide cohort study, all patients diagnosed between 1989 and 2013 with non-cardia gastric cancer with metastasized disease or invasion into adjacent structures were selected from the Netherlands Cancer Registry. Trends in treatment and 2-year overall survival were analysed and compared between younger (age less than 70 years) and older (aged 70 years or more) patients. Analyses were done for five consecutive periods of 5 years, from 1989-1993 to 2009-2013. Multivariable logistic regression analysis was used to examine the probability of undergoing surgery. Multivariable Cox regression analysis was used to identify independent risk factors for death.

RESULTS

Palliative resection rates decreased significantly in both younger and older patients, from 24·5 and 26·2 per cent to 3·0 and 5·0 per cent respectively. Compared with patients who received chemotherapy alone, both younger (21·6 versus 6·3 per cent respectively; P < 0·001) and older (14·7 versus 4·6 per cent; P < 0·001) patients who underwent surgery had better 2-year overall survival rates. Multivariable analysis demonstrated that younger and older patients who received chemotherapy alone had worse overall survival than patients who had surgery only (younger: hazard ratio (HR) 1·22, 95 per cent c.i. 1·12 to 1·33; older: HR 1·12, 1·01 to 1·24). After 2003 there was no association between period of diagnosis and overall survival in younger or older patients.

CONCLUSION

Despite changes in the use of resection and chemotherapy as palliative treatment, overall survival rates of patients with advanced and metastatic gastric cancer did not improve.

Cognitive flexibility deficits in a mouse model for the absence of full-length dystrophin

Duchenne muscular dystrophy (DMD) is a progressive muscle-wasting disorder, caused by mutations in the DMD gene and the resulting lack of dystrophin. The DMD gene has seven promoters, giving rise to multiple full-length and shorter isoforms. Besides the expression of dystrophin in muscles, the majority of dystrophin isoforms is expressed in brain and dystrophinopathy can lead to cognitive deficits, including intellectual impairments and deficits in executive function. In contrast to the muscle pathology, the impact of the lack of dystrophin on the brain is not very well studied. Here, we study the behavioral consequences of a lack of full-length dystrophin isoforms in mdx mice, particularly with regard to domains of executive functions and anxiety. We observed a deficit in cognitive flexibility in mdx mice in the absence of motor dysfunction or general learning impairments using two independent behavioral tests. In addition, increased anxiety was observed, but its expression depended on the context. Overall, these results suggest that the absence of full-length dystrophin in mice has specific behavioral effects that compare well to deficits observed in DMD patients.

Volume-outcome relation in palliative systemic treatment of metastatic oesophagogastric cancer

INTRODUCTION

Palliative systemic therapy has been shown to improve survival in metastatic oesophagogastric cancer. Administration of palliative systemic therapy in metastatic oesophagogastric cancer varies between hospitals. We aimed to explore the association between the annual hospital volume of oesophagogastric cancer patients and survival.

METHODS

Patients diagnosed in the Netherlands between 2005 and 2013 with metastatic oesophagogastric cancer were identified in the Netherlands Cancer Registry. Patients were attributed according to three definitions of high volume: (1) high-volume incidence centre, (2) high-volume treatment centre and (3) high-volume surgical centre. Independent predictors for administration of palliative chemotherapy were evaluated by means of multivariable logistic regression analysis, and multivariable Cox proportional hazard regression analysis was performed to assess the impact of high-volume centres on survival.

RESULTS

Our data set comprised 4078 patients with metastatic oesophageal cancer, and 5425 patients with metastatic gastric cancer, with a median overall survival of 20 weeks (95% confidence interval [CI] 19-21 weeks) and 16 weeks (95% CI 15-17 weeks), respectively. Patients with oesophageal cancer treated in a high-volume surgical centre (adjusted hazard ratio [HR] 0.80, 95% CI 0.70-0.91) and a high-volume treatment centre (adjusted HR 0.88, 95% CI 0.78-0.99) exhibited a decreased risk of death. For gastric cancer, patients treated in a high-volume surgical centre (adjusted HR 0.83, 95% CI 0.74-0.92) had a superior outcome.

CONCLUSION

Improved survival in patients undergoing palliative systemic therapy for oesophagogastric cancer was associated with treatment in high-volume treatment and surgical centres. Further research should be implemented to explore which specific factors of high-volume centres are associated with improved outcomes.

Hospital of diagnosis and probability of having surgical treatment for resectable gastric cancer

Background

Gastric cancer surgery is increasingly being centralized in the Netherlands, whereas the diagnosis is often made in hospitals where gastric cancer surgery is not performed. The aim of this study was to assess whether hospital of diagnosis affects the probability of undergoing surgery and its impact on overall survival.

Methods

All patients with potentially curable gastric cancer according to stage (cT1/1b–4a, cN0–2, cM0) diagnosed between 2005 and 2013 were selected from the Netherlands Cancer Registry. Multilevel logistic regression was used to examine the probability of undergoing surgery according to hospital of diagnosis. The effect of variation in probability of undergoing surgery among hospitals of diagnosis on overall survival during the intervals 2005–2009 and 2010–2013 was examined by using Cox regression analysis.

Results

A total of 5620 patients with potentially curable gastric cancer, diagnosed in 91 hospitals, were included. The proportion of patients who underwent surgery ranged from 53·1 to 83·9 per cent according to hospital of diagnosis (P &lt; 0·001); after multivariable adjustment for patient and tumour characteristics it ranged from 57·0 to 78·2 per cent (P &lt; 0·001). Multivariable Cox regression showed that patients diagnosed between 2010 and 2013 in hospitals with a low probability of patients undergoing curative treatment had worse overall survival (hazard ratio 1·21; P &lt; 0·001).

Conclusion

The large variation in probability of receiving surgery for gastric cancer between hospitals of diagnosis and its impact on overall survival indicates that gastric cancer decision-making is suboptimal.

Upper limits on a stochastic background of gravitational waves

The Laser Interferometer Gravitational-Wave Observatory has performed a third science run with much improved sensitivities of all three interferometers. We present an analysis of approximately 200 hours of data acquired during this run, used to search for a stochastic background of gravitational radiation. We place upper bounds on the energy density stored as gravitational radiation for three different spectral power laws. For the flat spectrum, our limit of omega0 < 8.4 x 10(-4) in the 69-156 Hz band is approximately 10(5) times lower than the previous result in this frequency range.

Limits on gravitational-wave emission from selected pulsars using LIGO data

We place direct upper limits on the amplitude of gravitational waves from 28 isolated radio pulsars by a coherent multidetector analysis of the data collected during the second science run of the LIGO interferometric detectors. These are the first direct upper limits for 26 of the 28 pulsars. We use coordinated radio observations for the first time to build radio-guided phase templates for the expected gravitational-wave signals. The unprecedented sensitivity of the detectors allows us to set strain upper limits as low as a few times 10(-24). These strain limits translate into limits on the equatorial ellipticities of the pulsars, which are smaller than 10(-5) for the four closest pulsars.

Two-body wear resistance and degree of conversion of laboratory-processed composite materials

PURPOSE

The purpose of this investigation was to evaluate the relative 2-body abrasive wear and degree of conversion of 4 laboratory-processed composites (Targis, Concept, belleGlass, and Artglass) and 2 direct placement composites (Herculite and Heliomolar) after 7 days of storage.

MATERIALS AND METHODS

Human enamel was used as a positive control for 2-body abrasive wear, and 10 cylindric specimens (3.5-mm diameter, 8-mm height) of each material were prepared and stored in distilled water at 37 +/- 2 degrees C for wear testing. Relative 2-body abrasive wear rates were determined using a 30-micron diamond disk and a 2-body pin-on-disk apparatus. Subsequently, 3 polymerized specimens that had been stored in sealed polyethylene vials for 7 days were prepared for degree of conversion testing. The degree of conversion was determined on an infrared spectrometer using standard baseline techniques and various internal standards.

RESULTS

Statistical analysis using analysis of variance and the Tukey-Kramer multiple range test indicated significant differences between several of the materials tested for both 2-body abrasive wear and degree of conversion.

CONCLUSION

Concept exhibited significantly less 2-body abrasive wear compared to the direct and indirect composites (P < 0.01). Concept and belleGlass exhibited a mean degree of conversion that was significantly higher than any of the other composites tested (P < 0.01).

Low levels of hepatitis C virus RNA in serum, plasma, and peripheral blood mononuclear cells of injecting drug users during long antibody-undetectable periods before seroconversion

Screening of antibodies to hepatitis C virus (HCV) is widely used for monitoring the prevalence of HCV infections and to assess HCV infectivity. Among HCV-infected individuals in the general population, the interval between the detection of HCV RNA and the development of HCV antibodies is usually 5 to 6 weeks, but in rare cases, seroconversion may be prolonged up to 6 to 9 months. In this study, we tested for the presence of HCV RNA during the antibody-undetectable period of 19 drug-injecting HCV seroconverters to gain insight into the antibody-negative carrier status in this population. HCV seroconversion status was determined by testing the first and last serum samples obtained from each subject, using third-generation antibody screening and confirmation assays. Serial samples were tested for HCV-specific antibodies to establish the moment of seroconversion and HCV RNA by single reverse transcriptase-polymerase chain reaction (RT-PCR) and branched DNA assay (bDNA) in serum. Plasma and peripheral blood mononuclear cells (PBMCs) were independently collected and tested for HCV RNA. HCV RNA-positivity was confirmed by Southern blot hybridization and sequencing of serial samples. The 19 HCV seroconverters had a mean follow-up of 5 years (range, 1 to 8 years). Of the 19, 4 were human immunodeficiency virus (HIV)-infected before HCV seroconversion. HCV RNA was detected in serum before seroconversion in 12 (63.2%) of the 19 HCV seroconverters, independent of HIV status. In 7 of these 12, the antibody-undetectable period was relatively short (2 to 10 months). The other 5, who were all HIV-negative before HCV seroconversion, had intermittent low levels of HCV RNA before seroconversion for a period of more than 12 months, with a mean of 40.8 months (range, 13 to 94 months). In all 5 individuals, independent repeats of the experiments confirmed the presence of HCV RNA in serum, and in 3 of these individuals, HCV-positivity was confirmed in independently collected plasma and PBMC samples. Low levels of HCV RNA may be present during prolonged antibody-undetectable periods before seroconversion in a number of injecting drug users. Independent of HIV status, their immune system appears to be unable to respond to these low HCV RNA levels and was sometimes only activated after reinfections with distinct HCV genotypes. These results indicate that primary HCV infection may not always elicit the rapid emergence of HCV antibodies and suggests that persistent low levels of HCV RNA (regardless of the genotype) may not elicit at all or delay antibody responses for prolonged periods of time.

Quantitative antibody responses to structural (Core) and nonstructural (NS3, NS4, and NS5) hepatitis C virus proteins among seroconverting injecting drug users: impact of epitope variation and relationship to detection of HCV RNA in blood

To gain insight into the natural history of hepatitis C virus (HCV), 13 human immunodeficiency virus (HIV)-seronegative injecting drug users were studied who seroconverted for HCV as determined by third-generation enzyme-linked immunosorbent assay, showed an ensuing antibody response to HCV, and were not treated with any antiviral drugs during follow-up. Subjects included 13 untreated HIV-negative individuals, of whom 5 (38.5%) apparently cleared HCV and were polymerase chain reaction (PCR)-negative in at least 3 consecutive samples, 3 (23.1%) showed transient viremia and were PCR-negative in 1 sample during the study period, and the other 5 (38.5%) showed persistent viremia. Viremia was determined longitudinally by reverse-transcription PCR (RT-PCR) and quantified by branched DNA (bDNA). HCV genotypes were determined on serial samples during follow-up. Quantitative antibody levels to core, NS3, NS4, and NS5 were determined using the Chiron RIBA HCV-titering Strip Immunoblot Assay, which is based on HCV genotype 1. The antibody responses to core, NS3, NS4, and NS5 were erratic. In individuals infected with HCV genotype 1, significantly higher median antibody responses to core (P =.02) and to NS4 (P =.04) were found as compared with those infected with other genotypes, showing a significant impact of HCV genotype specificity of the assay. In groups infected with HCV genotype 1, significantly higher median NS3 antibody titers (2.61 relative intensity [RI] vs. 0.38 RI; P =.003) were found in the individuals with persistent viremia than in those with apparent resolution of HCV RNA in blood. In groups infected with genotypes other than genotype 1, significantly higher median NS3 antibody titers (0.89 RI vs. 0.03 RI; P =.0004) and NS5 antibody titers (1.86 RI vs. 0.01 RI; P =.006) were found in the individuals with persistent viremia than in those with apparent resolution of HCV RNA in blood. Individuals with viral persistence had higher HCV-RNA loads with higher antibody responses as compared with individuals with apparent viral clearance from blood. Apparent viral clearance from blood was observed in an unexpectedly high percentage (38.5%), associated with a significant decrease of antibodies to NS3, independent of HCV genotype, as compared with individuals with persistent viremia (P <.005). Apparent viral clearance from blood with gradual loss of antibodies to various HCV proteins, independent of HCV genotype, was observed in 4 of the 5 individuals within approximately 1 year after HCV seroconversion, whereas 1 of these individuals apparently cleared the virus from blood, with complete seroreversion.

Hepatitis C virus serotype-specific core and NS4 antibodies in injecting drug users participating in the Amsterdam cohort studies

In the present study, the RIBA HCV serotyping SIA was evaluated with a cohort of injecting drug users. Serotyping may be a rapid and cost-effective method of determining genotypes in cohort studies. In this study, hepatitis C virus (HCV) antibody-positive sera from a cohort of 331 chronically infected injecting drug users, of which 167 were coinfected with human immunodeficiency virus (HIV), were serotyped by the RIBA HCV Serotyping SIA. Among the 331 specimens, serotype-specific antibodies were detected in 250 (sensitivity, 75. 5%), in which serotype 1 was predominant (57.2%), followed by serotype 3 (26.8%). Among the 331 specimens, 164 were HIV negative, and serotype-specific antibodies were detected in 151 (sensitivity, 92.1%), in which serotype 1 was predominant (59.6%), followed by serotype 3 (33.8%). For a subset of 58 samples taken from 19 chronically infected HCV seroconverters with a mean follow-up of 5 years, serotypes were compared with genotypes, which were determined by a line probe assay (HCV LiPa) and by direct sequencing of the products obtained by nested PCR of the 5' untranslated region. Among the 58 samples with known genotypes, serotype-specific antibodies were detected in 38 (total sensitivity, 65.5%), with a specificity of 78.9%. Thirty of these serotypeable samples revealed a serotype that corresponded to the genotype in the 58 samples (total positive predictive value, 51.7%). Of the 58 samples, 23 were coinfected with HIV, and when these were excluded, the total sensitivity increased to 76.5%, with a total specificity of 80.8% and a total positive predictive value of 61.8%. The serotyping assay showed a high total sensitivity (96.3%) for samples positive by HCV RIBA, version 3.0, with four bands. We conclude that the sensitivity of the RIBA HCV serotyping SIA is limited by the immunocompetence of the HCV-infected host. In general, samples from HIV-negative individuals containing genotype 1a had higher sensitivity, specificity, and concordance in the serotyping assay compared with genotyping, whereas samples containing genotype 3a were found to be more cross-reactive and untypeable. Therefore, the prevalence of genotypes other than genotype 1 could be underestimated if they are determined by serotyping, and improvements in specificity are recommended.