Unstable pelvic fractures in women: implications on obstetric outcome

PURPOSE

Obstetric outcomes in women following pelvic injuries requiring surgical fixation is not thoroughly known. We aimed to evaluate if radiographic measurements (RMs) can be used to provide information on delivery methods outcome after these injuries, and to evaluate if metal work removal is required prior to delivery.

METHOD

A retrospective study in a level 1 trauma centre of female patients with pelvic fractures treated operatively, aged 16-45 at the time of injury. Participants completed a questionnaire regarding their obstetric history. RM evaluating pelvic symmetry, displacement, and pelvimetry were conducted on postoperative radiographs and CT scans. Patients who gave birth after the injury were divided to two groups according to the delivery method: vaginal delivery (VD) and caesarean section (CS). These two groups RM were compared.

RESULTS

Forty-four patients were included, comparison of the RM of patients who delivered by CS (9) and patients who had only VD (11) showed no significant difference between the groups. Two patients underwent a trial of VD who subsequently underwent urgent CS due to prolonged labour, their RM were below the average and their pelvimetry measurements were above the cut-off for CS recommendation. Eleven patients had uncomplicated VD, all had retained sacroiliac screws at the time of delivery and one patient had an anterior pubic plate.

CONCLUSION

Postoperative RM did not show an effect on delivery method of women after pelvic fracture fixation. A relatively high number of patients who underwent normal vaginal delivery had retained sacroiliac screws. These findings can form the foundation for larger cohort studies.

Choice of treatments of the coronal shear fractures of the humerus. A national survey of Italian AO members

INTRODUCTION

Coronal shear fractures of the distal humerus are uncommon injuries representing 6% of distal humeral fractures. There is no univocal consensus about the correct management of this type of fracture. A national survey was conducted to gain more insight into the current classification, diagnosis and treatment of coronal shear fractures in Italy.

MATERIALS AND METHODS

A postal survey was sent to all AO Italian members including residency orthopaedic surgeons. The survey consisted of general questions about personal experience in the management of these fractures: types of classification systems used, surgical approaches, treatment options and rehabilitation programs.

RESULTS

114 orthopaedic surgeons answered a 13-items questionnaire. The most used classification system was AO/OTA (72,8%). Independent screws and if necessary plates were the most answered regarding surgical treatment (81,6%). The most encountered post-surgical complication was stiffening of the elbow (81,6%).

CONCLUSION

An algorithm of treatment has been proposed. To better classify coronal shear fractures, the authors recommended the integration of two classification systems: AO and Dubberley classifications. In the case of posterior wall comminution, a Kocher extensile approach is recommended, otherwise, if a posterior wall is intact, Kocher or Kaplan approach can be used. The posterior transolecranic approach can be reserved to Dubberley type III or AO 13B3.3. The best treatment choice is represented by independent screws and plates placed according to fracture patterns while arthroplasty is indicated when a stable ORIF is not possible. Mobilization is postponed for about 2 weeks.

Adhesives for treatment of bone fractures: A review of the state-of-the art

Treatment of fractures remains challenging and carries a high economical burden to both patients and society. In order to prevent some of the complications, the use of bone adhesives has been proposed, but up to date, bone adhesives are not part of the current clinical practice. Early results of use of bone cements and bone glues are promising, focusing in the areas of highly fragmented fractures, fixation of long bone fractures, filling bone voids and defects, promoting osseointegration, preventing non-union while maintaining the reduction of fracture fixation. This review aims to describe the state-of-the-art of the development, properties and use of adhesives in fracture treatment.

Forearm segmental bone defect: Successful management using the Masquelet Technique with the aid of 3D printing technology

The management of forearm nonunion is challenging for orthopaedic surgeons because the forearm is a unique anatomical segment in which all the bones and structures involved embody a complex functional unit. Therefore, when treating such a complex condition, the surgeon must focus not only on bone healing but also on the restoration of the native anatomy in order to replicate the normal relationship between the bones and all the surrounding structures and thus the full function of the forearm, the elbow and the wrist.

Here we report the case of a 53-year-old patient with a left forearm deformity due to an atrophic nonunion of the ulna and a malunion of the radius, which was successfully managed with the use of the Masquelet technique associated with a corrective osteotomy of the radius, performed with the aid of a 3D model.

Prevalence of transthyretin amyloid cardiomyopathy in male patients who underwent bilateral carpal tunnel surgery: The ACTUAL study

INTRODUCTION

Bilateral carpal tunnel syndrome (CTS), particularly in male individuals with left ventricular hypertrophy (LVH), has been recognized as a red flag for transthyretin cardiac amyloidosis (TTR-CA). Nonetheless, the opportunity of screening CTS patients for TTR has yet to be determined.

METHODS

Medical records of 1689 CTS surgeries performed at our institution between 2008 and 2018 were reviewed. Eighty-three males who underwent bilateral CTS surgery were considered eligible for the study, and offered a screening examination including electrocardiography and echocardiography. Individuals with LVH (diastolic septal wall thickness > 12 mm) were offered second-line diagnostic testing including blood testing and bone scintigraphy.

RESULTS

Study population consisted of 53 bilateral CTS male patients, with median age of 73 years. LVH was found in 6 (11%) individuals. None of them had monoclonal gammopathy or reported CTS occupational risk factors. Two declined to undergo further testing, whereas 2 had negative and 2 had positive bone scintigraphy (both Perugini 2 uptake) and tested negative for TTR gene mutations (wild-type TTR-CA).

CONCLUSIONS

Prevalence of TTR-CA in the entire study population was 4%, but among bilateral CTS patients with LVH peaked at 33%. In this latter population, screening for TTR-CA appeared feasible and effective.

Plate osteosynthesis for mid-shaft clavicle fractures: An update

INTRODUCTION

Over the last few years, treatment of mid-shaft clavicle fractures seems to have shifted from conservative to surgical. Our study reports the results of plate osteosynthesis of mid-shaft clavicle fractures and compares them with literature.

MATERIALS AND METHODS

A retrospective cohort study was conducted on 32 patients with mid-shaft clavicle fractures treated with plate and screws between January 2009 and December 2014. All the patients followed the same post-operative rehabilitation program with radiographic and clinical evaluation (DASH score and Constant score) at a minimum follow-up of 24 months.

RESULTS

All the patients healed clinically and radiographically, without deformities or non-unions, with complete and early functional recovery and return to their pre-injury sport activities. At one year follow-up the mean Constant Score was 93.8 (SD 4.8) and the mean DASH score was 42 (SD 5.0).

CONCLUSIONS

Osteosynthesis with plate and screws of mid-shaft clavicle fractures allows not only restoration of the anatomy, but also early recovery of shoulder function. For this reason, such surgical treatment should always be considered when facing this particular fracture group, also in accordance with recent literature.

Optimum timing of conversion from DCO to definitive fixation in closed fractures of the lower limb: When and how?

INTRODUCTION

In damage control orthopaedics (DCO), fractures are initially stabilised with external fixation followed by delayed conversion to definitive internal fixation. The aim of this study is to determine whether the timing of the conversion influences the development of deep infection and fracture healing in a cohort of patients treated by DCO after a closed fracture of the lower limb. Furthermore, we wanted to evaluate whether the one-stage conversion procedure is always safe.

MATERIALS AND METHODS

A retrospective cohort study was conducted at a single level 1 trauma centre. Ninety-four cases of closed fractures of lower limb treated by DCO subsequently converted to internal fixation from 2012 to 2019 were included. Development of deep infection, superficial infection, non-union and time to union were recorded. Patients were then divided into three groups according to the timing of conversion: Group A (<7 days), Group B (7-13 days), Group C (> 14 days). Comparison between groups was performed to assess intergroup variabilty.

RESULTS

The mean number of days between DCO and conversion was 6.7±4.52 (range 1-22). We observed one case of deep infection (1.1%), one case of non-union (1.1%), four cases of superficial infection (4.3%) and mean time to union was ±1.38 months. Comparison between groups demonstrated no significant correlation between timing of conversion and development of superficial or deep infection and non-union, while it highlighted that complexity of the fracture and longer surgical time of conversion procedure were significantly higher in Group C.

CONCLUSIONS

One-stage conversion to definitive internal fixation within 22 days from DCO is a safe and feasible procedure, which does not influence the incidence of infection or non-union.

Sacral fractures: issues, challenges, solutions

Sacral fractures are a heterogeneous group of fractures occurring in young people following road traffic accidents and falls from height, or in the elderly with osteoporosis following trivial trauma.This heterogeneity, combined with the low incidence of sacral fractures, determines a lack of experience amongst physicians, often leading to misdiagnosis, underestimation and inadequate treatment. The diagnosis should be made by assessing specific features during the clinical presentation, while computed tomography (CT) scan continues to be the choice of investigation.Sacral fractures can be treated non-operatively or surgically. Non-operative treatment is based on rest, pain relief therapy and early mobilization as tolerated. Surgical techniques can be split into two main groups: posterior pelvic fixation techniques and lumbopelvic fixation techniques. Anterior pelvic fixation techniques should be considered when sacral fractures are associated with anterior pelvic ring injuries, in order to increase stability and reduce the risk of posterior implant failure. To improve fracture reduction, different solutions could be adopted, including special positioning of the patient, manipulation techniques and use of specific reduction tools. Patients suffering from spinopelvic dissociation with associated neurologic lesions hardly ever recover completely, with residual lower-limb neurologic sequelae, urinary problems and sexual disfunction.Herein, we present issues, challenges and solutions related to the management of sacral fractures. Cite this article: EFORT Open Rev 2020;5:299-311. DOI: 10.1302/2058-5241.5.190064.

Femoral non-union above a fused knee: Successful treatment with exchange nailing and intramedullary delivery of bone morphogenetic protein

Bone healing is a complex and well-orchestrated physiological process, in which bone repairs and regenerates regaining its original biomechanical and biochemical properties. It is estimated that 5 to 10% of all fractures are complicated by delayed union or non-union. Progression to non-union is thought to be multifactorial, even though the exact biological sequence remains obscure. Treatment should aim to addressing deficiencies in both the mechanical and biological components, along with eliminating co-factors that could negatively affect the locally induced fracture healing response. We report a case of a 78-year-old patient who presented with a distal femoral non-union above a previously fused knee, which was successfully managed with exchange nailing and intramedullary delivery of recombinant human bone morphogenetic protein-7 (rhBMP-7).

Leeds-Genoa Non-Union Index: a clinical tool for asessing the need for early intervention after long bone fracture fixation

AIM OF THE STUDY

The aim of this case-control study was to develop a clinical decision rule to support assessment of the risk of long-bone non-union and plan for appropriate early intervention.

METHODS

Two hundred patients (100 cases and 100 controls) were recruited. Risk factors identified to contribute to the development of non-union were recorded and analysed with a multivariable logistic regression model. Tabulation of the outcome (non-union/union) against each risk factor in turn (univariable analysis) was carried out. Odds ratios and confidence intervals were derived using Wald's method. A receiver-operator curve was calculated and the area under the curve was computed. Having established the eight most important risk factors, a non-union risk index was developed as the count of the risk factors present in each patient.

RESULTS

The five risk factors for non-union with greater effect size were post-surgical fracture gap > 4 mm (odds ratio (OR) = 11.97 95% CI (4.27, 33.53)), infection superficial/deep (OR 10.16 (2.44, 42.36)), not optimum mechanical stability (OR 10.06 (3.75, 26.97)), displacement > 75% of shaft width (OR 6.81 (2.21, 20.95)), and site of fracture-tibia (OR 4.33 (1.32, 14.14)). The ROC curve for the non-union index was 0.924, sensitivity 91%, specificity 77%.

CONCLUSIONS

The non-union index derived from counting risk factors predicts union for 0-4 risk factors and non-union for 5-8 risk factors. It can be readily applied and can guide clinicians about the risk of development of long-bone non-union. It can become a powerful aid for assessing fracture fixation outcome and to support early intervention.

Aetiology of trauma-related acute compartment syndrome of the leg: A systematic review

BACKGROUND

Acute compartment syndrome (ACS) is characterised by abnormal pressure inside a compartment, resulting in ischemia of muscles and nerves. Most orthopaedic surgeons, especially those who work in major trauma centres, have been or will be facing a case of ACS in their clinical activity. Fortunately, complications related to untreated compartment syndrome have become less frequent thanks to a better understanding of pathogenesis and to early recognition and prompt surgical treatment. The aim of this study is to identify the existing evidence regarding aetiology of trauma-related ACS of the leg.

METHODS

A systematic review of the literature was undertaken using PubMed Medline, Ovid Medline and the Cochrane library, extended by a manual search of bibliographies. Retrieved articles were eligible for inclusion if they reported data about aetiology of trauma-related compartment syndrome of the tibia.

RESULTS

Ninety-five studies that fulfilled the inclusion criteria were identified. By dividing the studies into three groups according to the traumatic aetiology, we were able to classify traumatic ACS as fracture related, soft tissue injury related and vascular injury related. Fracture related was the most represented group, comprising 58 papers, followed by the soft tissue injury related group which includes 44 articles and vascular injury related group with 24 papers.

CONCLUSIONS

Although traditionally ACS has been associated mainly with fractures of tibial diaphysis, literature demonstrates that other localisations, in particular in the proximal tibia, are associated with an increased incidence of this serious condition. The forms of ACS secondary to soft tissues injuries represent an extremely variable spectrum of lesions with an insidious tendency for late diagnosis and consequently negative outcomes. In the case of vascular injury, ACS should always be carefully considered as a priority, given the high incidence reported in the literature, as a result of primitive vascular damage or as a result of revascularisation of the limb. Knowledge of aetiology of this serious condition allows us to stratify the risk by identifying a population of patients most at risk, together with the most frequently associated traumatic injuries.

Treatment of distal clavicle nonunion with and without bone grafting

The management of distal clavicle nonunion represents a challenging task for orthopaedic trauma surgeon. Both the choice of the implant and whether a bone graft is needed are controversial points which must be addressed. Particularly, in the case of a hypertrophic nonunion, grafting may not necessarily be needed, but given a poor underlying biological environment, a bone graft becomes necessary in order to enhance fracture healing. We report the case of a 62-year-old patient who came to us with a hypertrophic nonunion of the left distal clavicle. She was initially treated with a hook plate without bone grafting. After an early peri-implant fracture she was treated again with anatomical S-shaped locking plate associated with autologous cancellous bone graft.

Masquelet technique to treat a septic nonunion after nailing of a femoral open fracture

Septic nonunion is one of the most serious complications after an open fracture because both the infection and the bone defect need to be dealt with. Treatment is always protracted and expensive, and the result is uncertain. In the 1980s, Masquelet first described the technique of the induced membrane and autologous bone grafting to manage critical size bone defects. In septic nonunions, the described approach, characterised by two different surgical steps, allows a radical approach to manage the infection, and gives a significant biological stimulus to bone healing. In this case, we present a 35-year-old male patient with an open grade II femoral shaft fracture (AO / OTA 32C3). The patient was initially treated with an intramedullary nail and the resulting septic nonunion was subsequently managed with the induced membrane technique and a double-plate osteosynthesis to protect the biological chamber.

Risk factors for long bone fracture non-union: a stratification approach based on the level of the existing scientific evidence

Non-union continues to be the most devastating complication after fracture fixation. Its treatment can be prolonged and often unpredictable. The burden to the patient, surgeon and health care system can be immense. Strategies to prevent it and or identify early its development are desirable in order to improve the clinical course of the affected patients and their outcomes. We undertook a systematic review of the literature in order to identify the most common and important risk factors based on the hierarchy of level of evidence. Accordingly, a stratification scale was formed which highlighted 10 risk factors including; an open method of fracture reduction, open fracture, presence of post-surgical fracture gap, smoking, infection, wedge or comminuted types of fracture, high degree of initial fracture displacement, lack of adequate mechanical stability provided by the implant used, fracture location in the poor zone of vascularity of the affected bone, and the presence of the fracture in the tibia. Clinicians should take in to account these findings when managing patients with long bone fractures, particularly the femur and tibia in order to minimise the risk of non-union.

Late recurrent peripheral upper limb ischemia after non-union of a clavicle fracture

A 74-year-old woman was referred to our hospital due to recurrent episodes of upper limb ischemia. Her past medical history included a clavicle non-union developed after a clavicle midshaft fracture that had occurred 30 years previously. After a long asymptomatic period, she started showing symptoms of chronic ischemia to the left arm that were misdiagnosed. Thoracic outlet syndrome (TOS) is a rare but possible complication of mal-union and non-union of clavicle fractures; symptoms related to arterial involvement (ATOS) amount to less than 1% of all existing forms of thoracic outlet syndrome. In case of clavicle non-union, local instability plays a key role in determining the initial injury to the vessels and the recurrence of symptoms. Restoration of local bone stability and anatomy, obtained by compression plating and autologous bone grafting, combined with an appropriate vascular surgery, is essential to achieve a clinical resolution of symptoms and to avoid the recurrence of symptomatology as seen in the herein case.

Differential patterns of expression of Eps15 and Eps15R during mouse embryogenesis

Eps15 and Eps15R are related tyrosine kinase substrates, which have been implicated in endocytosis and synaptic vesicle recycling. Through the protein:protein interaction abilities of their EH domains, they establish a complex network of interactions with several proteins, including Numb, a protein necessary for neuronal cell fate specification. We analyzed the expression of Eps15 and Eps15R during murine development, at the time of active neurogenesis. The most striking difference was at the level of subcellular localization, with Eps15 present in the cytosol and on the plasma membrane, while Eps15R exhibited mainly a nuclear localization. Interesting topographical differences also emerged. In the 12.5 days post coitum neuroepithelium, Eps15 was expressed in the ventricular zone, which contains proliferating neuroblasts, whereas Eps15R was found only in postmitotic neurons. Conversely, both proteins were expressed in sensory and cranial ganglia. At later times, the expression of Eps15 and Eps15R was widely maintained in neuronal structures. In other tissues, Eps15 was first seen in the liver primordium and at low levels in choroid plexus, lung, kidney and intestine; later on the expression was maintained at high levels in epithelia. Nuclear staining of Eps15R was present in kidney, intestine, lung and liver, as well as in heart and pancreas.

The EH network

The EH domain is an evolutionary conserved protein-protein interaction domain present in a growing number of proteins from yeast to mammals. Even though the domain was discovered just 5 years ago, a great deal has been learned regarding its three-dimensional structure and binding specificities. Moreover, a number of cellular ligands of the domain have been identified and demonstrated to define a complex network of protein-protein interactions in the eukaryotic cell. Interestingly, many of the EH-containing and EH-binding proteins display characteristics of endocytic "accessory" proteins, suggesting that the principal function of the EH network is to regulate various steps in endocytosis. In addition, recent evidence suggests that the EH network might work as an "integrator" of signals controlling cellular pathways as diverse as endocytosis, nucleocytosolic export, and ultimately cell proliferation.

In vitro study of the NS2-3 protease of hepatitis C virus

Processing at the C terminus of the NS2 protein of hepatitis C virus (HCV) is mediated by a virus-encoded protease which spans most of the NS2 protein and part of the NS3 polypeptide. In vitro cotranslational cleavage at the 2-3 junction is stimulated by the presence of microsomal membranes and ultimately results in the membrane insertion of the NS2 polypeptide. To characterize the biochemical properties of this viral protease, we have established an in vitro assay whereby the NS2-3 protease of HCV BK can be activated posttranslationally by the addition of detergents. The cleavage proficiency of several deletion and single point mutants was the same as that observed with microsomal membranes, indicating that the overall sequence requirements for proper cleavage at this site are maintained even under these artificial conditions. The processing efficiency of the NS2-3 protease varied according to the type of detergent used and its concentration. Also, the incubation temperature affected the cleavage at the 2-3 junction. The autoproteolytic activity of the NS2-3 protease could be inhibited by alkylating agents such as iodoacetamide and N-ethylmaleimide. Metal chelators such as EDTA and phenanthroline also inhibited the viral enzyme. The EDTA inhibition of NS2-3 cleavage could be reversed, at least in part, by the addition of ZnCl2 and CdCl2. Among the common protease inhibitors tested, tosyl phenylalanyl chloromethyl ketone and soybean trypsin inhibitor inactivated the NS2-3 protease. By means of gel filtration analysis, it was observed that the redox state of the reaction mixture greatly influenced the processing efficiency at the 2-3 site and that factors present in the rabbit reticulocyte lysate, wheat germ extract, and HeLa cell extract were required for efficient processing at this site. Thus, the in vitro assay should allow further characterization of the biochemical properties of the NS2-3 protease of HCV and the identification of host components that contribute to the efficient processing at the 2-3 junction.

Binding specificity and in vivo targets of the EH domain, a novel protein-protein interaction module

EH is a recently identified protein-protein interaction domain found in the signal transducers Eps15 and Eps15R and several other proteins of yeast nematode. We show that EH domains from Eps15 and Eps15R bind in vitro to peptides containing an asparagine-proline-phenylalanine (NPF) motif. Direct screening of expression libraries with EH domains yielded a number of putative EH interactors, all of which possessed NPF motifs that were shown to be responsible for the interaction. Among these interactors were the human homolog of NUMB, a developmentally reguated gene of Drosophila, and RAB, the cellular cofactor of the HIV REV protein. We demonstrated coimmunoprecipitation of Eps15 with NUMB and RAB. Finally, in vitro binding of NPF-containing peptides to cellular proteins and EST database screening established the existence of a family of EH-containing proteins in mammals. Based on the characteristics of EH-containing and EH-binding proteins, we propose that EH domains are involved in processes connected with the transport and sorting of molecules within the cell.

The NS2 protein of hepatitis C virus is a transmembrane polypeptide

The NS2 protein of hepatitis C virus (HCV) is released from its polyprotein precursor by two proteolytic cleavages. The N terminus of this protein is separated from the E2/p7 polypeptide by a cleavage thought to be mediated by signal peptidase, whereas the NS2-3 junction located at the C terminus is processed by a viral protease. To characterize the biogenesis of NS2 encoded by the BK strain of HCV, we have defined the minimal region of the polyprotein required for efficient cleavage at the NS2-3 site and analyzed the interaction of the mature polypeptide with the membrane of the endoplasmic reticulum (ER). We have observed that although cleavage can occur in vitro in the absence of microsomal membranes, synthesis of the polyprotein precursor in the presence of membranes greatly increases processing at this site. Furthermore, we show that the membrane dependency for efficient in vitro processing varies among different HCV strains and that host proteins located on the ER membrane, and in particular the signal recognition particle receptor, are required to sustain efficient proteolysis. By means of sedimentation analysis, protease protection assay, and site-directed mutagenesis, we also demonstrate that the NS2 protein derived from processing at the NS2-3 site is a transmembrane polypeptide, with the C terminus translocated in the lumen of the ER and the N terminus located in the cytosol.

Biosynthesis and biochemical properties of the hepatitis C virus core protein

The biosynthesis and biochemical properties of the putative nucleocapsid protein of hepatitis C virus (HCV) were investigated. RNA transcripts for cell-free translation were prepared from truncated form of the cDNA construct encoding the structural proteins of HCV. Processing of the translation products was dependent on microsomal membranes and signal recognition particle, suggesting that release of the 21-kDa core protein from the polyprotein precursor is mediated solely by the signal peptidase of the endoplasmic reticulum (ER) and is achieved by the removal of a putative signal sequence of approximately 18 residues located at its C terminus. The core protein was found to bind membranes in vitro and in transfected cells, as shown by centrifugation analysis of in vitro translation products and transfected-cell lysates. Immunofluorescence of transfected cells showed that the core protein colocalized with the E2 glycoprotein as well as with a cellular ER membrane marker. The nucleocapsid protein expressed by in vitro translation in rabbit reticulocyte lysates cosedimented with the large ribosomal subunit in sucrose gradients. The ribosome binding domain was mapped to the N-terminal region of the core protein. Moreover, the same region was shown to bind RNA in vitro, suggesting that cosedimentation of core protein with ribosomes may be mediated by the RNA binding of the nucleocapsid protein of HCV. These studies indicate that the HCV core protein is a cytoplasmic protein associated with the ER membranes and possesses RNA binding activity.

NS3 is a serine protease required for processing of hepatitis C virus polyprotein

Hepatitis C virus (HCV) possesses a positive-sense RNA genome which encodes a large polyprotein of 3,010 amino acids. Previous data and sequence analysis have indicated that this polyprotein is processed by cellular proteases and possibly by a virally encoded serine protease localized in the N-terminal domain of nonstructural protein NS3. To characterize the molecular aspects of HCV protein biogenesis and to clearly identify the protein products derived from the HCV genome, we have examined HCV polyprotein expression by using the vaccinia virus T7 transient expression system in transfected cells and by cell-free translation studies. HCV proteins were identified by immunoprecipitation with region-specific antisera. Here we show that the amino-terminal region of the HCV polyprotein is processed in vitro by cellular proteases releasing three structural proteins: p21 (core), gp37 (E1), and gp61 (E2). Processing of the nonstructural region of HCV was evident in transfected cells. Two proteins of 24 and 68 kDa were immunoprecipitated with anti-NS2 and NS3 antisera, respectively. Antiserum against NS4 recognized three proteins of 6, 26, and 31 kDa, while antisera specific for NS5 immunoprecipitated two polypeptides of 56 and 65 kDa, indicating that each of these two genes encodes at least two different proteins. When the NS3 protease domain was inactivated by replacing the proposed catalytic Ser-1165 with Ala, processing at several sites was abolished. When Ser-1164 was mutated to Ala, no effect on the processing was observed. Cleavage activities at three of the four sites affected by NS3 were shown to occur in trans, while processing at the carboxy terminus of NS3 could not be mediated in trans. These results provide a detailed description of the protein products obtained from the processing of the HCV polyprotein. Furthermore, the data obtained implicate NS3 as a serine protease and demonstrate that a catalytically active NS3 is necessary for cleavage of the nonstructural region of HCV.

Epstein-Barr virus DNA recombines via latent origin of replication with the human genome in the lymphoblastoid cell line RGN1

We show here that in a lymphoblastoid cell line Epstein-Barr virus DNA recombines with the human genome. The genetic exchange involves the oriP region of the virus. A junction between viral and human DNA from this line has been cloned and sequenced. The results indicate that the integration of Epstein-Barr virus DNA involves a region of the human genome which contains internal short repetition. An 800-bp probe has been isolated from the human part of the junction. This probe has been used to show that the human region exists as a duplication in normal cells.