The MxA protein levels in whole blood lysates of patients with various viral infections

MxA for differentiating viral and bacterial infections in adults: a prospective, exploratory study

PURPOSE

Inappropriate antibiotic prescription in patients with viral infections contributes to the surge of antibiotic resistance. Viral infections induce the expression of the antiviral protein MxA in monocytes, which is a promising biomarker to differentiate between viral and bacterial diseases. In this prospective, exploratory study, we aimed to determine the diagnostic value of monocyte MxA expression in adults with viral, bacterial or co-infections.

METHODS

We measured monocyte MxA expression using flow cytometry in a cohort of 61 adults with various viral, bacterial and co-infections including patients receiving immunosuppressive therapy.

RESULTS

Monocyte MxA expression in virus-infected patients was significantly higher compared to bacterial infections (83.3 [66.8, 109.4] vs. 33.8 [29.3, 47.8] mean fluorescence intensity [MFI]; p < 0.0001) but not co-infections (53.1 [33.9, 88.9] MFI). At a threshold of 62.2 MFI, the area under the ROC curve (AUC) to differentiate between viral and bacterial infections was 0.9, with a sensitivity and specificity of 92.3% and 84.6%, respectively. Immunosuppressive therapy did not affect monocyte MxA expression in virus-infected patients.

CONCLUSION

Our findings corroborate the diagnostic performance of MxA in differentiating viral and bacterial infections but also point to an important caveat of MxA in viral-bacterial co-infections. This study extends previous reports and indicates that MxA is also a useful biomarker in immunocompromised patients.

Considerations for Use of Pharmacodynamic Biomarkers to Support Biosimilar Development - (III) A Randomized Trial with Interferon Beta-1a Products

The US Food and Drug Administration (FDA) has taken steps to bring efficiency to the development of biosimilars, including establishing guidance for the use of pharmacokinetic and pharmacodynamic (PD) similarity study data without a comparative clinical study with efficacy end point(s). To better understand the potential role for PD biomarkers in biosimilar development and inform best practices for biomarker selection and analysis, we conducted a randomized, double-blinded, placebo-controlled, single-dose, parallel-arm clinical study in healthy participants. Eighty-four healthy participants (n = 12 per dose arm) received either placebo or one of three doses of either interferon β-1a (7.5-30 μg) or pegylated interferon β-1a (31.25-125 μg) to evaluate the maximum change from baseline and the baseline-adjusted area under the effect curve for the biomarkers neopterin in serum and myxovirus resistance protein 1 in blood. Both PD biomarkers increased following product administration with clear separation from baseline (neopterin: 3.4-fold and 3.9-fold increase for interferon β-1a and pegylated interferon β-1a, respectively; myxovirus resistance protein 1: 19.0-fold and 47.2-fold increase for interferon β-1a and pegylated interferon β-1a, respectively). The dose-response curves support that therapeutic doses were adequately sensitive to detect differences in both PD biomarkers for consideration in a PD similarity study design. Because baseline levels of both biomarkers are low compared with on-treatment values, there was little difference in using PD measures adjusted to baseline compared with the results without baseline adjustment. This study illustrates potential methodologies for evaluating PD biomarkers and an approach to address information gaps when limited information is publicly available for one or more PD biomarkers.

Diagnostic Accuracy of a Bacterial and Viral Biomarker Point-of-Care Test in the Outpatient Setting

IMPORTANCE

Acute respiratory infections (ARIs) account for most outpatient visits. Discriminating bacterial vs viral etiology is a diagnostic challenge with therapeutic implications.

OBJECTIVE

To investigate whether FebriDx, a rapid, point-of-care immunoassay, can differentiate bacterial- from viral-associated host immune response in ARI through measurement of myxovirus resistance protein A (MxA) and C-reactive protein (CRP) from finger-stick blood.

DESIGN, SETTING, AND PARTICIPANTS

This diagnostic study enrolled adults and children who were symptomatic for ARI and individuals in a control group who were asymptomatic between October 2019 and April 2021. Included participants were a convenience sample of patients in outpatient settings (ie, emergency department, urgent care, and primary care) who were symptomatic, aged 1 year or older, and had suspected ARI and fever within 72 hours. Individuals with immunocompromised state and recent vaccine, antibiotics, stroke, surgery, major burn, or myocardial infarction were excluded. Of 1685 individuals assessed for eligibility, 259 individuals declined participation, 718 individuals were excluded, and 708 individuals were enrolled (520 patients with ARI, 170 patients without ARI, and 18 individuals who dropped out).

EXPOSURES

Bacterial and viral immunoassay testing was performed using finger-stick blood. Results were read at 10 minutes, and treating clinicians and adjudicators were blinded to results.

MAIN OUTCOMES AND MEASURES

Bacterial- or viral-associated systemic host response to an ARI as determined by a predefined comparator algorithm with adjudication classified infection etiology.

RESULTS

Among 520 participants with ARI (230 male patients [44.2%] and 290 female patients [55.8%]; mean [SD] age, 35.3 [17.7] years), 24 participants with missing laboratory information were classified as unknown (4.6%). Among 496 participants with a final diagnosis, 73 individuals (14.7%) were classified as having a bacterial-associated response, 296 individuals (59.7%) as having a viral-associated response, and 127 individuals (25.6%) as negative by the reference standard. The bacterial and viral test correctly classified 68 of 73 bacterial infections, demonstrating a sensitivity of 93.2% (95% CI, 84.9%-97.0%), specificity of 374 of 423 participants (88.4% [95% CI, 85.0%-91.1%]), positive predictive value (PPV) of 68 of 117 participants (58.1% [95% CI, 49.1%-66.7%), and negative predictive value (NPV) of 374 of 379 participants (98.7% [95% CI, 96.9%-99.4%]).The test correctly classified 208 of 296 viral infections, for a sensitivity of 70.3% (95% CI, 64.8%-75.2%), a specificity of 176 of 200 participants (88.0% [95% CI, 82.8%-91.8%]), a PPV of 208 of 232 participants (89.7% [95% CI, 85.1%-92.9%]), and an NPV of 176 of 264 participants (66.7% [95% CI, 60.8%-72.1%]).

CONCLUSIONS AND RELEVANCE

In this study, a rapid diagnostic test demonstrated diagnostic performance that may inform clinicians when assessing for bacterial or viral etiology of ARI symptoms.

Developing a Virus-Binding Bacterium Expressing Mx Protein on the Bacterial Surface to Prevent Grouper Nervous Necrosis Virus Infection

Grouper nervous necrosis virus (GNNV) infection causes mass grouper mortality, leading to substantial economic loss in Taiwan. Traditional methods of controlling GNNV infections involve the challenge of controlling disinfectant doses; low doses are ineffective, whereas high doses may cause environmental damage. Identifying potential methods to safely control GNNV infection to prevent viral outbreaks is essential. We engineered a virus-binding bacterium expressing a myxovirus resistance (Mx) protein on its surface for GNNV removal from phosphate-buffered saline (PBS), thus increasing the survival of grouper fin (GF-1) cells. We fused the grouper Mx protein (which recognizes and binds to the coat protein of GNNV) to the C-terminus of outer membrane lipoprotein A (lpp-Mx) and to the N-terminus of a bacterial autotransporter adhesin (Mx-AIDA); these constructs were expressed on the surfaces of Escherichia coli BL21 (BL21/lpp-Mx and BL21/Mx-AIDA). We examined bacterial surface expression capacity and GNNV binding activity through enzyme-linked immunosorbent assay; we also evaluated the GNNV removal efficacy of the bacteria and viral cytotoxicity after bacterial adsorption treatment. Although both constructs were successfully expressed, only BL21/lpp-Mx exhibited GNNV binding activity; BL21/lpp-Mx cells removed GNNV and protected GF-1 cells from GNNV infection more efficiently. Moreover, salinity affected the GNNV removal efficacy of BL21/lpp-Mx. Thus, our GNNV-binding bacterium is an efficient microparticle for removing GNNV from 10‰ brackish water and for preventing GNNV infection in groupers.

Multi-tiered screening and diagnosis strategy for COVID-19: a model for sustainable testing capacity in response to pandemic

Coronavirus disease 2019 (COVID-19), caused by novel enveloped single stranded RNA coronavirus (SARS-CoV-2), is responsible for an ongoing global pandemic. While other countries deployed widespread testing as an early mitigation strategy, the U.S. experienced delays in development and deployment of organism identification assays. As such, there is uncertainty surrounding disease burden and community spread, severely hampering containment efforts. COVID-19 illuminates the need for a tiered diagnostic approach to rapidly identify clinically significant infections and reduce disease spread. Without the ability to efficiently screen patients, hospitals are overwhelmed, potentially delaying treatment for other emergencies. A multi-tiered, diagnostic strategy incorporating a rapid host immune response assay as a screening test, molecular confirmatory testing and rapid IgM/IgG testing to assess benefit from quarantine/further testing and provide information on population exposure/herd immunity would efficiently evaluate potential COVID-19 patients. Triaging patients within minutes with a fingerstick rather than hours/days after an invasive swab is critical to pandemic response as reliance on the existing strategy is limited by assay accuracy, time to results, and testing capacity. Early screening and triage is achievable from the outset of a pandemic with point-of-care host immune response testing which will improve response time to clinical and public health actions.Key messagesDelayed testing deployment has led to uncertainty surrounding overall disease burden and community spread, severely hampering public health containment and healthcare system preparation efforts.A multi-tiered testing strategy incorporating rapid, host immune point-of-care tests can be used now and for future pandemic planning by effectively identifying patients at risk of disease thereby facilitating quarantine earlier in the progression of the outbreak during the weeks and months it can take for pathogen specific confirmatory tests to be developed, validated and manufactured in sufficient quantities.The ability to triage patients at the point of care and support the guidance of medical and therapeutic decisions, for viral isolation or confirmatory testing or for appropriate treatment of COVID-19 and/or bacterial infections, is a critical component to our national pandemic response and there is an urgent need to implement the proposed strategy to combat the current outbreak.

Detection of resistance protein A (MxA) in paper-based immunoassays with surface enhanced Raman spectroscopy with AuAg nanoshells

Myxovirus protein A (MxA) is a biomarker that can be used to distinguish between viral and bacterial infections. While MxA lateral flow assays (LFAs) have been successfully used for viral vs. bacterial differential diagnosis for children, the clinically relevant level of MxA for adults has been reported to be 100 times lower, which is too low for traditional LFAs. We present results applying the use of surface enhanced Raman spectroscopy (SERS) to detect MxA. AuAg nanoshells (AuAg NSs) were used to enhance the Raman signal of mercaptobenzoic acid (4-MBA), enabling readout by SERS. The AuAg NSs were conjugated to antibodies for the biomarker of interest, resulting in a "nanotag", that could be used in a dipstick immunoassay for detection. We first optimized the nanotag parameters using anti-human IgG/human IgG as a model antibody/antigen system, and then demonstrated detection of MxA using anti-MxA antibodies. We show that SERS readout of immunoassays for MxA can quantify MxA levels at clinically relevant levels for adult viral infection.

Interferon-Inducible Myxovirus Resistance Proteins: Potential Biomarkers for Differentiating Viral from Bacterial Infections

BACKGROUND

In 2015, the 68th World Health Assembly declared that effective, rapid, low-cost diagnostic tools were needed for guiding optimal use of antibiotics in medicine. This review is devoted to interferon-inducible myxovirus resistance proteins as potential biomarkers for differentiating viral from bacterial infections.

CONTENT

After viral infection, a branch of the interferon (IFN)-induced molecular reactions is triggered by the binding of IFNs with their receptors, a process leading to the activation of mx1 and mx2, which produce antiviral Mx proteins (MxA and MxB). We summarize current knowledge of the structures and functions of type I and III IFNs. Antiviral mechanisms of Mx proteins are discussed in reference to their structural and functional data to provide an in-depth picture of protection against viral attacks. Knowing such a mechanism may allow the development of countermeasures and the specific detection of any viral infection. Clinical research data indicate that Mx proteins are biomarkers for many virus infections, with some exceptions, whereas C-reactive protein (CRP) and procalcitonin have established positions as general biomarkers for bacterial infections.

SUMMARY

Mx genes are not directly induced by viruses and are not expressed constitutively; their expression strictly depends on IFN signaling. MxA protein production in peripheral blood cells has been shown to be a clinically sensitive and specific marker for viral infection. Viral infections specifically increase MxA concentrations, whereas viruses have only a modest increase in CRP or procalcitonin concentrations. Therefore, comparison of MxA and CRP and/or procalcitonin values can be used for the differentiation of infectious etiology.

A prospective, multi-centre US clinical trial to determine accuracy of FebriDx point-of-care testing for acute upper respiratory infections with and without a confirmed fever

BACKGROUND

FebriDx is a 10-minute disposable point-of-care test designed to identify clinically significant systemic host immune responses and aid in the differentiation of bacterial and viral respiratory infection by simultaneously detecting C-reactive protein (CRP) and myxovirus resistance protein A (MxA) from a fingerstick blood sample. FebriDx diagnostic accuracy was evaluated in the emergency room and urgent care setting.

METHODS

A prospective, multicentre, observational cohort study of acute upper respiratory tract infections (URIs), with and without a confirmed fever at the time of enrolment, was performed to evaluate the diagnostic accuracy of FebriDx to identify clinically significant bacterial infection with host response and acute pathogenic viral infection. The reference method consisted of an algorithm with physician override that included bacterial cell culture, respiratory PCR panels for viral and atypical pathogens, procalcitonin, and white blood cell count.

RESULTS

Among 220 patients enrolled, 100% reported fever 100.5°F within the last 72 hours while 55% had a measured hyperthermia (T > 100.4) at the time of enrolment. FebriDx demonstrated a sensitivity of 95% (95% CI: 77-100%), specificity of 94% (88-98%), PPV of 76% (59-87%), and a NPV of 99% (93-100%).

CONCLUSION

FebriDx may identify clinically significant bacterial URI's and supports outpatient antibiotic decisions. Key messages FebriDx is an outpatient POC test designed to identify a clinically significant systemic host immune response and aid in the differentiation of viral and bacterial infection through rapid measurement of MxA and CRP from a fingerstick blood sample. FebriDx test was determined to be an accurate test, with a 85% sensitivity, 93% specificity and 97% NPV to rule out bacterial infection for any patient presenting with symptoms and reported fever within the prior 3 days, and when confirming fever (hyperthermia) at the time of testing, the test was even more sensitive (95%) and specific (94%) with a 99% NPV. FebriDx may support antibiotic stewardship by rapidly identifying clinically significant bacterial URIs.

Outpatient Antibiotic Stewardship: A Growing Frontier-Combining Myxovirus Resistance Protein A With Other Biomarkers to Improve Antibiotic Use

Background

The majority of oral antibiotics are prescribed in outpatient primary and urgent care clinics for acute respiratory infections. Effective antibiotic stewardship must include proper prescribing for outpatients as well as for those in a hospital or long-term care facility.

Methods

Major databases, including MEDLINE and the Cochrane Library, were searched for prospective human clinical studies, including children and/or adults published between January 1966 and November 2017 that evaluated Myxovirus resistance protein A (MxA) as a biomarker for diagnosing viral infections as well as both C-reactive protein (CRP) and procalcitonin (PCT) as potential biomarkers for identifying and differentiating true bacterial upper respiratory infection (URI) from colonization.

Results

Ten prospective human studies, totaling 1683 patients, were identified that evaluated MxA as a viral biomarker in children and/or adults. Both systematic review articles, meta-analyses, and randomized controlled clinical trials that examined CRP and/or PCT as a biomarker for identifying clinically significant bacterial infections and supporting antibiotic stewardship were identified.

Conclusions

Quick and accurate differentiation between a viral and bacterial respiratory infection is critical to effectively combat antibiotic misuse. MxA expression in peripheral blood is a highly specific marker for viral infection. Combining MxA with other inflammatory biomarkers to test for respiratory infections offers enhanced sensitivity and specificity, forming an excellent tool for antibiotic stewardship in the outpatient setting.

Characterize a typically Dscam with alternative splicing in mud crab Scylla paramamosain

As a member of the immunoglobulin superfamily, Down syndrome cell adhesion molecule (Dscam) could function in the innate immunity of invertebrates. Recently, it is shown that arthropod Dscams play similar functions as antibodies in the adaptive immune system. Dscam could produce thousands of isoforms by alternative splicing and specifically bind to various pathogens. In the present study, we cloned the first Dscam from mud crab Scylla paramamosain (SpDscam), with full-length cDNA 7363 bp containing an open reading frame (ORF) of 6069bp and encoding 2022 amino acids, which had typical domain architecture as other arthropods, i.e., 10 immunoglobulin domains (Ig), 6 fibronectin type 3 domains (FN III), transmembrane and cytoplasmic tail. Quantitative real-time PCR revealed that SpDscam was highly expressed in brain, skin, muscle, intestine and hepatopancreas, but weakly expressed in hemolymph, heart and gill. SpDscam had three alternative splicing regions, located at the N-terminal of Ig2 and Ig3 as well as on the whole Ig7. In these regions, 32, 41 and 14 exons were detected, together with the two exon types of transmembrane domain, indicating SpDscam could potentially encode at least 36,736 unique isoforms. SpDscam induced by Vibrio parahaemolyticus challenge had strong binding ability to V. parahaemolyticus. Further, SpDscam induced by V. parahaemolyticus possessed a clearance of V. parahaemolyticus in S. paramamosain. Collectively, the results indicated SpDscam was a hypervariable pattern-recognition receptor (PRR) by alternative splicing in innate immunity system of mud crab S. paramamosain.

Diagnostic Accuracy of FebriDx: A Rapid Test to Detect Immune Responses to Viral and Bacterial Upper Respiratory Infections

C-reactive protein (CRP) and myxovirus resistance protein A (MxA) are associated with bacterial and viral infections, respectively. We conducted a prospective, multicenter, cross-sectional study of adults and children with febrile upper respiratory tract infections (URIs) to evaluate the diagnostic accuracy of a rapid CRP/MxA immunoassay to identify clinically significant bacterial infection with host response and acute pathogenic viral infection. The reference standard for classifying URI etiology was an algorithm that included throat bacterial culture, upper respiratory PCR for viral and atypical pathogens, procalcitonin, white blood cell count, and bandemia. The algorithm also allowed for physician override. Among 205 patients, 25 (12.2%) were classified as bacterial, 53 (25.9%) as viral, and 127 (62.0%) negative by the reference standard. For bacterial detection, agreement between FebriDx and the reference standard was 91.7%, with FebriDx having a sensitivity of 80% (95% CI: 59–93%), specificity of 93% (89–97%), positive predictive value (PPV) of 63% (45–79%), and a negative predictive value (NPV) of 97% (94–99%). For viral detection, agreement was 84%, with a sensitivity of 87% (75–95%), specificity of 83% (76–89%), PPV of 64% (63–75%), and NPV of 95% (90–98%). FebriDx may help to identify clinically significant immune responses associated with bacterial and viral URIs that are more likely to require clinical management or therapeutic intervention, and has potential to assist with antibiotic stewardship.

Immunohistochemical Evaluation of Mx Protein Expression in Canine Encephalitides

Mx proteins are a group of interferon-induced GTPases whose expression has been demonstrated in a number of human viral infections and in some idiopathic inflammatory diseases. In this study, the expression of Mx protein was evaluated in known viral, nonviral, and idiopathic encephalitides in the dog via immunohistochemistry using an antibody against human MxA. All 12 cases of confirmed viral encephalitis, including 7 cases of canine distemper, 4 cases of canine herpesvirus, and 1 case of rabies, were Mx positive. In canine distemper cases, staining was particularly strong and a variety of cell types were positive, including astrocytes, macrophages/microglia, and neurons. Immunoreactivity for Mx protein was evident in a few cases of nonviral infectious encephalitis, including neosporosis (1/1), Chagas disease (2/3), aspergillosis (1/2), and encephalitozoonosis (1/1). Consistent staining was observed in most cases of idiopathic encephalitis, including granulomatous meningoencephalomyelitis (7/7), necrotizing meningoencephalitis of pug dogs (6/7), and necrotizing encephalitis of the Yorkshire Terrier (3/3) and Maltese (1/1) breeds. Mx staining was negative in 5 normal dog brains; 3 cases of cryptococcosis; and single cases of blastomycosis, protothecosis, and bacterial meningitis.

Evaluation of a combined MxA and CRP point-of-care immunoassay to identify viral and/or bacterial immune response in patients with acute febrile respiratory infection

Background

Challenges in the clinical differentiation of viral and/or bacterial respiratory infection lead to the misappropriation of antibiotics and increased healthcare costs. A tool to facilitate rapid and accurate point-of-care (POC) differentiation is needed.

Methods and findings

A prospective, single center, blinded, observational clinical trial was conducted at Beth Israel Deaconess Medical Center from December 2012 to August 2013 to determine the accuracy of a POC immunoassay to identify a clinically significant immune response to viral and/or bacterial infection. Sixty patients with acute febrile respiratory infection (19 pharyngitis and 41 lower respiratory tract infection [LRTI]) were enrolled. Participants provided fingerstick blood for immunoassay testing (myxovirus A [MxA] and c-reactive protein [CRP]) and four oropharyngeal samples for viral PCR and routine bacterial cell culture. A venous blood sample was collected. An ELISA was used to measure CRP and MxA. Paired serological testing was used to confirm atypical bacteria. A urine sample was provided for Streptococcus and Legionella antigen testing. Patients with suspected LRTI had sputum and blood cultures, chest X-ray, and WBC count measured. Viral infection was confirmed if oropharyngeal PCR was positive for viral pathogens. Bacterial infection was confirmed in positive throat or sputum cultures. Elevated immunoglobulin M antibodies or twofold increase in IgG antibodies between acute and convalescent phase indicated atypical bacteria. Positive Streptococcus or Legionella urine antigen assays also confirmed bacterial infection. The immunoassay correctly categorized subjects as 92% (22/24) negative, 80% (16/20) with bacterial infection, and 70% (7/10) with viral infection.

Conclusions

The interplay between an MxA value and a semi-quantitative CRP value can aid in the differentiation of infectious etiology. In isolation, neither MxA nor CRP alone is sensitive or specific. However, the pattern of results in a rapid immunoassay provides a sensitive and specific method to differentiate acute febrile respiratory infections. This diagnostic information may help reduce antibiotic misuse and resistance and lower healthcare costs.

Diagnosis of viral infections using myxovirus resistance protein A (MxA)

BACKGROUND

Myxoma resistance protein 1 (MxA) is induced during viral infections. MxA testing could be helpful to differentiate between viral and bacterial infections.

METHODS

A prospective multicenter cohort study was performed in pediatric emergency departments. MxA blood values were measured in children with confirmed viral or bacterial infections, uninfected controls, and infections of unknown origin. First patients were used to determine MxA threshold for viral infection. The diagnostic performance of MxA was determined by using receiver operating characteristic (ROC) analysis. Sensitivities (Se), specificities (Sp), and positive and negative likelihood ratios (LR+, LR-) were calculated.

RESULTS

The study included 553 children; 44 uninfected controls and 77 confirmed viral infections (mainly respiratory syncytial virus and rotavirus) were used to determine an MxA threshold at 200 ng/mL. In the 193 other patients with confirmed infections and uninfected controls (validation group), MxA was significantly higher in patients with viral than in those with bacterial infections and uninfected controls (P < .0001). The area under the ROC curve (AUC) were 0.98, with 96.4% Se and 85.4% Sp, for differentiating uninfected from virus-infected patients and 0.89, with 96.4% Se and 66.7% Sp, for differentiating bacterial and viral infections. MxA levels were significantly higher in patients with clinically diagnosed viral versus clinically diagnosed bacterial infections (P < .001). Some patients with Streptococcus pneumonia infections had high MxA levels. Additional studies are required to elucidate whether this was due to undiagnosed viral coinfections.

CONCLUSIONS

MxA is viral infection marker in children, at least with RSV and rotavirus. MxA could improve the management of children with signs of infection.

Methamphetamine inhibits Toll-like receptor 9-mediated anti-HIV activity in macrophages

Toll-like receptor 9 (TLR9) is one of the key sensors that recognize viral infection/replication in the host cells. Studies have demonstrated that methamphetamine (METH) dysregulated host cell innate immunity and facilitated HIV infection of macrophages. In this study, we present new evidence that METH suppressed TLR9-mediated anti-HIV activity in macrophages. Activation of TLR9 by its agonist CpG-ODN 2216 inhibits HIV replication, which was demonstrated by increased expression of TLR9, interferon (IFN)-α, IFN regulatory factor-7 (IRF-7), myeloid differentiation factor 88 (MyD88), and myxovirus resistance gene A (MxA) in macrophages. However, METH treatment of macrophages greatly compromised the TLR9 signaling-mediated anti-HIV effect and inhibited the expression of TLR9 downstream signaling factors. Dopamine D1 receptor (D1R) antagonists (SCH23390) could block METH-mediated inhibition of anti-HIV activity of TLR9 signaling. Investigation of the underlying mechanisms of the METH action showed that METH treatment selectively down-regulated the expression of TLR9 on macrophages, whereas it had little effect on the expression of other TLRs. Collectively, our results provide further evidence that METH suppresses host cell innate immunity against HIV infection by down-regulating TLR9 expression and its signaling-mediated antiviral effect in macrophages.

Identification and expression analysis of a CC chemokine from cobia (Rachycentron canadum)

Chemokines are small, secreted cytokine peptides known principally for their ability to induce migration and activation of leukocyte populations and regulate the immune response mechanisms. The cobia (Rachycentron canadum), a marine finfish species, has a great potential for net cage aquaculture in the South China Sea. We isolated and characterized a CC chemokine cDNA from cobia-designated RcCC2. Its cDNA is 783 bp in length and encodes a putative protein of 110 amino acids. Homology and phylogenetic analysis revealed that the RcCC2 gene, which contains four conserved cysteine residues, shares a high degree of similarity with other known CC chemokine sequences and is closest to the CCL19/21 clade. The mRNA of RcCC2 is expressed constitutively in all tested tissues, including gill, liver, muscle, spleen, kidney, head kidney, skin, brain, stomach, intestine and heart, but not blood, with the highest level of expression in gill and liver. The reverse transcription quantitative polymerase chain reaction was used to examine the expression of the RcCC2 gene in immune-related tissues, including head kidney, spleen and liver, following intraperitoneal injection of the viral mimic polyriboinosinic polyribocytidylic acid, formalin-killed Vibrio carchariae (bacterial vaccine) and phosphate-buffered saline as a control. RcCC2 gene expression was up-regulated differentially in head kidney, spleen and liver during 12 h after challenge. These results indicate that the RcCC2 gene is inducible and is involved in immune responses, suggesting RcCC2 has an important role in the early stage of viral and bacterial infections.

Immune modulatory effects of Aloe arborescens extract on the piscine SAF-1 cell line

The pharmacological potential of Aloe arborescens Miller leaf components was investigated, with special attention deserved to immune modulatory effects on the Sparus aurata fibroblast cell line SAF-1. The cells were treated with Aloe extract at different concentrations (1.2-4.8 mg ml(-1)) for various times (24-72 h). The lowest concentration did not provoke any cellular damage observable by SEM and did not affect ATP amounts after 24 and 48 h, while even induced a significant increase over controls after 72 h. We next examined the transcription kinetics of different immune-related genes (IL-1β, TGF-β, TNF-α, COX-2, IFN-I, Mx and MHCI-α) in SAF-1 cells stimulated with LPS or poly I:C. The Aloe extract (1.2 mg ml(-1)) acted as a powerful immune stimulant in LPS- or poly I:C-activated SAF-1 cells, inducing a synergic effect on interconnected genes that are expected to be involved in different aspects of the immune responses. These reports provide a new perspective for the use of A. arborescens to prevent or oppose bacterial and viral fish diseases and to face, as an alternative strategy based on natural plant extracts, the growing unwillingness to rely upon standard solutions involving antibiotics or antimicrobial chemicals.

New sandwich-type enzyme-linked immunosorbent assay for human MxA protein in a whole blood using monoclonal antibodies against GTP-binding domain for recognition of viral infection

OBJECTIVES

To develop a clinically significant and practical enzyme-linked immunosorbent assay (ELISA) for the detection of MxA protein in human whole blood, a biological marker of viral infection.

DESIGN AND METHODS

A sandwich ELISA suitable for the measurement of human MxA protein in whole blood was developed using mouse monoclonal antibodies (mAbs) raised against the GTP-binding domain of human MxA protein. Prior to the assay, the whole blood sample was treated with special buffer to extract the MxA protein, improve its stability, and avoid interference from hemoglobin.

RESULTS

This ELISA meets all the requirements for use in routine clinical assays, especially in terms of sensitivity (detection limit: 1.3 ng/ml whole blood), accuracy (recovery: 93.0-100.0%), and rapidity (<1.5 h). The present ELISA had a sensitivity of 100% and a specificity of 100% for viral infection when compared to samples from healthy control and 87.1% and 90.9% when compared to samples from the bacterial infection group.

CONCLUSION

We have developed a new ELISA for measuring MxA protein in human whole blood using mAbs specific for the GTP-binding domain of MxA. This ELISA has analytical performance enough for routine clinical assay and can be used in detecting the possibility of viral infection.

Receptor characterization and susceptibility of cotton rats to avian and 2009 pandemic influenza virus strains

Animal influenza viruses (AIVs) are a major threat to human health and the source of pandemic influenza. A reliable small-mammal model to study the pathogenesis of infection and for testing vaccines and therapeutics against multiple strains of influenza virus is highly desirable. We show that cotton rats (Sigmodon hispidus) are susceptible to avian and swine influenza viruses. Cotton rats express α2,3-linked sialic acid (SA) and α2,6-linked SA residues in the trachea and α2,6-linked SA residues in the lung parenchyma. Prototypic avian influenza viruses (H3N2, H9N2, and H5N1) and swine-origin 2009 pandemic H1N1 viruses replicated in the nose and in the respiratory tract of cotton rats without prior adaptation and produced strong lung pathology that was characterized by early lung neutrophilia, followed by subsequent pneumonia. Consistent with other natural and animal models of influenza, only the H5N1 virus was lethal for cotton rats. More importantly, we show that the different avian and pandemic H1N1 strains tested are strong activators of the type I interferon (IFN)-inducible MX-1 gene both locally and systemically. Our data indicate that the cotton rat is a suitable small-mammal model to study the infection of animal influenza viruses and for validation of vaccines and therapeutics against these viruses.

Molecular cloning and expression profiles of nitric oxide synthase (NOS) in mud crab Scylla paramamosain

The importance of the nitric oxide synthase (NOS) gene family is demonstrated by many studies in vertebrates and invertebrates in recent years. However, it keeps unknown of nitric oxide (NO) system and NOS gene family in mud crab Scylla paramamosain, an important cultured commercial crustacean in China and Pacific area. In this report, the cDNA of NOS containing full-length ORF was cloned from mud crab, S. paramamosain. It was of 4424 bp, including a 5'-terminal untranslated region (UTR) of 239 bp, a 3'-terminal UTR of 540 bp, which contained two ATTTA motifs, and an open reading frame (ORF) of 3645 bp encoding a polypeptide of 1214 amino acids. Structural analysis indicated that NOS contained a typical NO synthase domain at the N-terminal, next to a flavodoxin 1 domain, a flavin adenine dinucleotide (FAD) binding domain, respectively, and a conservative nicotinamide adenine dinucleotide (NAD) binding domain structure at the C-terminal. Quantitative real-time PCR analysis revealed S. paramamosain NOS (SpNOS) to be expressed in all tissues examined, with the highest expression in midintestine and the weakest level in heart and eyestalk. The expression profiles of SpNOS indicated that the NOS expression levels were significantly induced in midintestine, hepatopancrease and hemocytes after challenged with Vibrio Parahaemolyticus, the synthetic double-stranded RNA polyinosinic polycytidylic acid (poly I:C) and lipopolysaccharides (LPS). The NOS activity in hemocytes showed significant increase during at 24 h-48 h time period after immune challenges with V. Parahaemolyticus, poly I:C and LPS. Results here may suggest that the inducible NOS play an important role in mud crab's defense against pathogenic infection.

IFN-α is constitutively expressed in the human thymus, but not in peripheral lymphoid organs

Type I interferons have been typically studied for their effects in the context of bacterial or viral infections. However in this report, we provide evidence that Interferon-alpha (IFN-α) expressing cells are present in the thymus in the absence of infection. We show that pDC express the highest level of IFN-α and that MxA, which is exclusively expressed after engagement of the type I IFN receptor by IFN-α/β, is expressed in normal fetal and post-natal thymus, but not in the periphery. The highest level of MxA is expressed in mature thymocytes and pDC located in the medulla and at the cortico-medullary junction. The anti-microbial peptide LL-37, which is expressed in the thymus, when complexed with eukaryotic nucleic acids, induces the secretion of IFN-α by thymic pDC. This results in the upregulation of MxA expression in responsive thymocytes. We propose that the secretion of IFN-α in the thymus may function to regulate the rate of T cell development and modulate the requirements for the selection of developing T cells.

Effects of the polymorphisms of Mx1, BAT2 and CXCL12 genes on immunological traits in pigs

It is necessary that genetic markers or biomarkers can be used to predict resistance towards a wide range of infectious diseases. In the present study, we estimated the potential markers and measured their relationship with heritabilities of a wide range of immune traits. Polymorphisms in exon 13 of Mx1, intron 25 of BAT2 and intron 3 of CXCL12 were identified by sequencing, and the genotypes were analyzed by PCR-RFLP in a resource population composed of 352 pure breed Landrace piglets at days 0, 17 and 32 after birth. Associations of single-nucleotide polymorphisms (SNPs) in these genes with a variety of immunological traits and antibody levels for pig reproduction and porcine respiratory syndrome virus (PRRSV), pseudorabies virus (PRV) and classical swine fever virus (CSFV) were performed. The performance of GG genotype of BAT2 on hemoglobin concentration (HBG) and hematocrit (HCT) of piglets at day 0 was significantly higher than that of the AA and AG individuals. For Mx1, compared with CT genotype, the pigs with TT or CC generated more PRRS antibody at day 0. The piglets with CT genotype had highly significant difference of PRV antibody from those with CC and TT genotypes at day 0. And the piglets with CC genotype had higher level red blood cell count (RBC), hemoglobin concentration (HBG) and hematocrit (HCT) than those with CT and TT genotypes at day 17. For the C7462G SNP in the intron 3 of CXCL12, the PRV antibody level of piglets with the CG genotype were higher than that of piglets with CC and GG genotypes at day 17, and the mean corpuscular volume (MCV) of GG piglets were larger than that of CC and CG individuals at day 0. At the locus 7331 bp in the intron 3 of CXCL12, there were significantly differences of mean corpuscular hemoglobin concentrations (MCHC) at day 0 and white blood cell count (WBC) at day 32, which showed the trend GG or AG>AA, AA>AG or GG, respectively. The pigs with AA or GG genotype had more platelet distribution width (PDW), mean platelet volume (MPV) and platelet-large cell ratio (PLR) at day 17 than those with AG. The results of this study indicated that polymorphisms in Mx1, BAT2 and CXCL12 genes were significantly associated with the immunological traits in Landrace piglets and had potential application value for marker-assisted selection of pig breeding with disease resistance.

Transcriptional response of MxA, PKR and SOCS3 to interferon-based therapy in HCV genotype 4-infected patients and contribution of p53 to host antiviral response

AIMS

To investigate the myxovirus-resistance protein A (MxA) and double-stranded RNA-activated protein kinase (PKR) genetic response to interferon (IFN) therapy in hepatitis C virus (HCV) genotype 4-infected patients. Moreover, we studied the association between suppressor of cytokine signaling 3 (SOCS3) gene expression and therapy resistance in genotype 4. Finally, we investigated the novel link between p53 and IFN-stimulated genes (ISGs) in humans.

METHODS

Gene expression analyses were performed in peripheral blood using TaqMan real-time PCR. Virologic response was assessed with a branched-DNA assay. Genotyping was confirmed.

RESULTS

Early virologic responders (EVRs, n = 23) but not non-EVRs (n = 7) showed strong upregulation of PKR at week 12 of therapy compared to baseline. Both EVRs and non-EVRs showed MxA upregulation at week 12 compared to baseline. Baseline SOCS3 expression did not distinguish EVRs from non-EVRs in genotype 4. An association was found between p53 and MxA and PKR gene expression.

CONCLUSION

Measurement of MxA and PKR transcriptional induction during treatment may distinguish EVRs from non-EVRs in genotype 4. SOCS3 gene does not seem to be implicated in therapy resistance in genotype 4. An association between p53 and ISGs expression was shown for the first time in HCV-infected patients, further supporting the contribution of p53 to host antiviral response.

Preparation of polyclonal antibody against human MxA protein and its specificity to diversified myxovirus resistant protein A

OBJECTIVE

To study the human myxovirus resistant protein A (MxA), a specifically induced peptide by interferon I, and to use its level as a diagnostic criterion for viral infections.

METHODS

Anti-MxA antisera from immunized mice were prepared with the expressed MxA protein of pET32a-MxA in E. coli BL-21(DE3). To confirm the antiserum activity and specificity, the expression product of BL21, wild type MxA pEGFP-C1-wMxA and site-directed mutant MxA pEGFP-C1-mMxA(N589S) stably transfected 3T3 cells and induced A549 cells were detected by Western blot with the antisera using non-MxA transfected or non-IFN-beta induced cells, intact A549, NIH 3T3 cells transfected with pEGFP-C1 and pET32a (+)-transformed BL-21 as controls.

RESULTS

The antisera had specific positive immunoreactivity to the NIH3T3 cells transformed with pEGFP-C1-wMxA and pEGFP-C1-mMxA, INF-beta induced A549 cells and BL21 proteins expressed with pET32a (+)-MxA. The hybridization signals from IFN-beta induced A549 cells depended on the IFN-beta inducing concentrations. Meanwhile, immunohistochemical assay showed that NIH 3T3 cells with pEGFP-C1-wMxA and pEGFP-C1-mMxA had > 98% of positive cells at 1:50 dilution of the serum and A549 cells induced by 20 ng/mL IFN-beta for 48 h showed 95% positive cells. pEGFP-C1-transfected NIH 3T3 cells were all negative.

CONCLUSION

Anti-sera are highly specific to diversified MxAs. The antibody is detectable by Western blot, immunocytochemistry and immunofluorescence assay.

Incidence of hepatotropic viruses in biliary atresia

Biliary atresia (BA) is the most frequent indication for paediatric liver transplantation. We tested the hypothesis of a viral aetiology of this disease by screening liver samples of a large number of BA patients for the common human hepatotropic viruses. Moreover, we correlated our findings to the expression of Mx protein, which has been shown to be significantly up-regulated during viral infections. Seventy-four liver biopsies (taken during Kasai portoenterostomy) were tested by polymerase chain reaction (PCR) for DNA viruses (herpes simplex virus [HSV], Epstein-Barr virus [EBV], varicella zoster virus [VZV], cytomegalovirus [CMV], adenovirus, parvovirus B19 and polyoma BK) and RNA viruses (enteroviruses, rotavirus and reovirus 3). Mx protein expression was assessed by immunohistochemistry. Virus DNA/RNA was found in less than half of the biopsies (8/74 CMV, 1/74 adenovirus; 21/64 reovirus, 1/64 enterovirus). A limited number presented with double infection. Patients that had detectable viral RNA/DNA in their liver biopsies were significantly older than virus-free patients (P = 0.037). The majority (54/59) of the liver biopsies showed expression of Mx proteins in hepatocytes, bile ducts and epithelium. Our data suggest that the known hepatotropic viruses do not play a major role in the aetiology and progression of BA. Their incidence appears to be, rather, a secondary phenomenon. Nonetheless, the inflammatory response in the livers of BA patients mimics that observed during viral infections.

Type I interferon-dependent gene MxA in perinatal HIV-infected patients under antiretroviral therapy as marker for therapy failure and blood plasmacytoid dendritic cells depletion

Background

To determine the role of interferon-alpha in controlling HIV infection we phenotypically and functionally analyzed circulating plasmacytoid dendritic cells (pDC), which are known to be the highest interferon-alpha producing cells, in 33 perinatally infected HIV⁺ patients undergoing standard antiretroviral therapy.

Methods

Circulating pDC were identified by flow cytometry using anti-BDCA-2 monoclonal antibody and by measuring BDCA-2 mRNA by real-time PCR, while tissue-resident pDC were identified by immunohistochemistry. mRNA for interferon-alpha and MxA, a gene that is specifically induced by interferon-alpha, was quantified in peripheral blood cells by real-time PCR, while serum interferon-alpha protein was measured by ELISA.

Results

While median values of pDC, both in terms of percentage and absolute number, were not statistically different from age-matched controls, interferon-alpha mRNA was increased in HIV-infected patients. However, in a group of patients with long disease duration, having a low number of both pDC and CD4⁺ lymphocytes and a significant increase of serum interferon-alpha, MxA mRNA was produced at high level and its expression directly correlated with HIV RNA copy numbers. Furthermore in patients displaying a low CD4⁺ blood cell count, a severe depletion of pDC in the tonsils could be documented.

Conclusion

HIV replication unresponsive to antiretroviral treatment in perinatal-infected patients with advanced disease and pDC depletion may lead to interferon-alpha expression and subsequent induction of MxA mRNA. Thus, the latter measurement may represent a valuable marker to monitor the clinical response to therapy in HIV patients.

Decreased type I interferon receptor-soluble isoform in antiretroviral-treated HIV-positive children

We developed a real-time PCR assay to simultaneously measure the mRNA level of type I interferon (IFN) receptor (IFNAR) components in peripheral blood cells of children with chronic immune stimulation due to HIV infection. All patients were undergoing antiretroviral therapy and were divided into two groups on the basis of the induction of MxA mRNA, a marker of type I IFN bioactivity. We found that IFNAR-2 subunit mRNA was higher than that of the IFNAR-1 subunit, that the mRNA for the IFNAR-2.2 functional isoform was more expressed than that for the truncated IFNAR-2.1 isoform, and both were much more represented than that of the IFNAR-2.3 soluble isoform. We also demonstrated that soluble isoform mRNA was significantly diminished in the subgroup of patients with MxA mRNA below the cutoff value (determined as the 99th percentile of MxA measured in healthy controls). These results suggest that downregulation of the soluble receptor isoform, which would not compete with the functional isoform for binding to the target cytokine, would give type I IFN, eventually induced in these patients in the case of viral reactivation, the opportunity to promptly exert its antiviral activity.

MxA protein assay for optimal monitoring of IFN-beta bioactivity in the treatment of MS patients

OBJECTIVES

Myxovirus resistance protein A (MxA) can be used as a marker of the bioactivity of interferon-beta (IFN-beta) therapy. Two to forty per cent of IFN-beta-treated multiple sclerosis (MS) patients develop IFN-beta-neutralizing antibodies (NAb) with subsequent attenuation of MxA protein induction. The aim of this study was to set up a simple MxA enzyme immunoassay (EIA) for the measurement of MxA protein and to evaluate the EIA test by comparing the results with flow cytometric analysis and the measurement of NAb.

METHODS

total of 51 IFN-beta-treated relapsing-remitting MS (RRMS) patients were tested for MxA protein expression by using both MxA EIA assay and flow cytometric analysis. Thirteen patients were confirmed to be NAb-positive.

RESULTS

The correlation between EIA and flow cytometric analysis was significant with a wider range of measured levels in the EIA. Patients with NAb had low MxA levels, but in some patients, remaining MxA induction could be detected despite NAb.

CONCLUSIONS

The MxA EIA assay seems to be a practical method for large-scale analysis of the bioactivity of IFN-beta treatment.

Incidence of hepatotropic viruses in biliary atresia

Biliary atresia (BA) is the most frequent indication for paediatric liver transplantation. We tested the hypothesis of a viral aetiology of this disease by screening liver samples of a large number of BA patients for the common human hepatotropic viruses. Moreover, we correlated our findings to the expression of Mx protein, which has been shown to be significantly up-regulated during viral infections. Seventy-four liver biopsies (taken during Kasai portoenterostomy) were tested by polymerase chain reaction (PCR) for DNA viruses (herpes simplex virus [HSV], Epstein-Barr virus [EBV], varicella zoster virus [VZV], cytomegalovirus [CMV], adenovirus, parvovirus B19 and polyoma BK) and RNA viruses (enteroviruses, rotavirus and reovirus 3). Mx protein expression was assessed by immunohistochemistry. Virus DNA/RNA was found in less than half of the biopsies (8/74 CMV, 1/74 adenovirus; 21/64 reovirus, 1/64 enterovirus). A limited number presented with double infection. Patients that had detectable viral RNA/DNA in their liver biopsies were significantly older than virus-free patients (P = 0.037). The majority (54/59) of the liver biopsies showed expression of Mx proteins in hepatocytes, bile ducts and epithelium. Our data suggest that the known hepatotropic viruses do not play a major role in the aetiology and progression of BA. Their incidence appears to be, rather, a secondary phenomenon. Nonetheless, the inflammatory response in the livers of BA patients mimics that observed during viral infections.

Modulation of IFNAR1 mRNA expression in multiple sclerosis patients

Interferon-beta receptor (IFNAR) is composed of 2 subunits, IFNAR1 and IFNAR2, the latter of which is expressed as functional (IFNAR2.2), non-functional (IFNAR2.1) and soluble (IFNAR2.3) isoform. Real-Time PCR analysis of mRNA for all IFNAR components in multiple sclerosis patients naïve for therapy and undergoing long-term treatment with interferon-beta shows that IFNAR1 mRNA level is lower than in healthy controls. If long-term treated patients are divided according to the production of mRNA for Myxovirus protein-A, a marker of interferon-beta bioactivity, IFNAR1 mRNA reaches the values observed in controls only in Myxovirus protein-A-induced patients. Since chronic cell stimulation by interferon-beta induces IFNAR protein down-regulation, we suggest that the increase of IFNAR1 mRNA might serve as a mechanism for counterbalancing the loss of protein receptor, enhancing, at least in this sub-group of patients, cell responsiveness to interferon-beta.

Grouper Mx confers resistance to nodavirus and interacts with coat protein

Over-expression of grouper Mx negatively regulated nodavirus activity through direct interaction, likely via the binding and perturbation of the intracellular localization of nodavirus coat protein. Deletion analysis of grouper Mx indicated that the coat protein binds to the effector domain of Mx. The presence of grouper Mx in a poly [I:C] interferon system inhibited nodavirus infection, demonstrating that grouper Mx over-expression has an inhibitory effect on both coat protein and RNA-dependent RNA polymerase of nodavirus antigens, which results in reduced viral yields. We conclude that grouper Mx has a key role in cellular resistance to nodavirus infection.

Interferon-Induced Effector Proteins and Hepatitis C Virus Replication

Hepatitis C virus (HCV) is a small, enveloped RNA virus that is often capable of establishing a persistent infection, which may lead to chronic liver disease, cirrhosis, hepatocellular carcinoma, and eventually death. For more than 20 years, hepatitis C patients have been treated with interferon-alpha (IFN-α). Current treatment usually consists of polyethylene glycol-conjugated IFN-α that is combined with ribavirin, but even the most advanced IFN-based therapies are still ineffective in eliminating the virus from a large proportion of individuals. Therefore, a better understanding of the IFN-induced innate immune response is urgently needed. By using selectable self-replicating RNAs (replicons) and, more recently, recombinant full-length genomes, many groups have tried to elucidate the mechanism(s) by which IFNs inhibit HCV replication. This chapter attempts to summarize the current state of knowledge in this interesting field of HCV research.

Expression analysis of Mx protein and evaluation of its antiviral activity against sole aquabirnavirus in SAF-1 and TV-1 cell lines

The transcription of Mx mRNA after poly I:C induction and sole aquabirnavirus infection has been analysed in SAF-1 and TV-1 cells (derived from gilt-head seabream and turbot, respectively). Both cell lines were stimulated with 10 microg ml(-1) poly I:C and Mx mRNA was analysed by a specific RT-PCR at several times post-induction. The results showed a high level of Mx expression from 12 to 120 h after induction in SAF-1 cells, whereas in TV-1 cells Mx mRNA was only detected at 12 and 24h. The treatment with different concentrations of poly I:C showed that TV-1 cells are less sensitive to this inductor than the SAF-1 cell line. The antiviral activity derived from poly I:C induction has been clearly demonstrated against sole aquabirnavirus on both cell lines. The inoculation of sole aquabirnavirus resulted in the Mx mRNA transcription at 48, 72, and 96 h post-infection (p.i.) in SAF-1 cells. On the contrary, inoculated TV-1 cells only showed a faint Mx mRNA band at 24 and 48 h p.i. This study has established different patterns of Mx expression in both cells under study as a consequence of the poly I:C induction and sole aquabirnavirus infection, and it shows that gilt-head seabream and turbot Mx inhibit sole aquabirnavirus replication.

Expression of biomarkers of interferon type I in patients suffering from chronic diseases

Interferons (IFNs) are used widely in the treatment of viral infections, tumours and neurological disorders. The aim of this study was to evaluate the endogenous expressions of various IFN-induced compounds [specifically: neopterin (NPT), beta2microglobulin (beta2mg) and 2-5 oligoadenylate synthetase (2-5 OAS)] in patients with various chronic diseases requiring treatment with IFN type I. The results showed that patients with such chronic diseases as hepatitis C virus-associated type II mixed cryoglobulinaemia (MC), chronic hepatitis C (CHC) and relapsing-remitting multiple sclerosis (RRMS) are characterized by different activations of the IFN system. Furthermore, the interindividual variability in baseline levels of IFN-induced biomarkers was higher in patients with chronic diseases than in healthy individuals. When levels of the above biomarkers were measured 24 h after the first injection of IFN in patients with CHC or RRMS, significant increases in expression levels of IFN-induced compounds were recorded but, again, there is a broad range of variability in the degree of increase. Further, a significant inverse correlation between baseline levels of NPT, beta2mg and 2-5 OAS activity and their relative increases after IFN administration was found in patients with CHC or RRMS. Together, the results are consistent with the observation that there is considerable interindividual heterogeneity in the clinical response to IFNs, which suggests that host factors other than disease markers must be taken into account in order to manage and optimize the IFN therapy.

Bone morphogenetic protein-7 and interferon-alpha synergistically suppress hepatitis C virus replicon

Various cytokines contribute to control hepatitis C virus (HCV) viral replication. HCV subgenomic replicon systems have been developed, and cell-cycle-dependent replication has been reported. But the molecules involved in this processes is not totally elucidated. The aim of this study is to investigate the involvement of the bone morphogenetic protein (BMP)-7, a member of TGF-beta superfamily, to the in vitro HCV replication. BMP-7 dose-dependently suppressed the replication and protein expression from the HCV replicon in Huh7/Rep-Feo cells and was associated with cell-cycle arrest at the G1 phase. These results were consistent with the effect of TGF-beta in a previous study. Combination of BMP-7 and interferon-alpha showed a synergic decrease of HCV replication, and was more effective compared to the treatment with interferon-alpha alone. This synergistic effect was also present in HCV-JFH1 virus cell culture. While BMP-7 alone did not stimulate expression of the interferon-stimulated genes (ISGs), it augmented interferon-induced expression of the ISGs independently of the interferon-induced Jak/STAT pathway. Taken together, BMP-7 may constitute a novel molecule to suppress HCV replication.

Expression of toll-like receptors and type 1 interferon specific protein MxA in biliary atresia

Viral infection and type I interferon have been implicated in the pathogenesis of biliary atresia (BA), but the expression of toll-like receptors (TLRs) that recognize viruses, as well as of type 1 interferon specific signaling molecules are still unknown in BA. Fresh liver tissues were obtained from patients in early and late stage of BA and from patients with choledochal cyst (CC), as well as from normal controls receiving liver resection for benign lesion other than cholestasis or fibrosis. Archived liver tissues from patients with neonatal hepatitis (NH) were obtained for immunohistochemical studies. TLR2, 3, 4, 7 and 9 that recognized Gram-positive bacteria, double-stranded RNA virus, lipopolysaccharide, single-stranded RNA virus and DNA virus, respectively, were studied. Real-time quantitative reverse transcription polymerase chain reaction (QRT-PCR) was used to quantitate TLR, type I interferon specific molecule MxA, interleukin-6 (IL-6) and IL-8 mRNA expression and immunohistochemistry for TLR 7 and MxA protein staining. These results show that there were significantly higher TLR7 and lower TLR3 and TLR9 mRNA expression in early stage of BA than in CC. MxA mRNA expression was also significantly higher in early stage of BA and in CC than in late stage of BA. Immunoreactive TLR7 and MxA staining was higher in early stage of BA than in late stage of BA, NH and CC, which was associated with significantly higher IL-8 mRNA expression in BA than in CC. The results implicate involvement of TLRs, particularly TLR7, and type 1 specific interferon signaling in the pathogenesis of BA, especially in early stage, which is associated with upregulation of inflammatory cytokines IL-8.

MxA-based recognition of viral illness in febrile children by a whole blood assay

Febrile children are often given antibiotics empirically and unnecessarily. MxA is a protein induced in peripheral lymphoid cells by type 1 interferons during active viral infection. The ability of a whole blood ELISA assay for MxA to identify children with viral illness was studied in 122 children who presented with acute onset fever and 52 age-matched healthy controls. The febrile children were divided into three groups according to their final diagnoses: etiologically diagnosed viral infection, clinically diagnosed viral infection, and bacterial infection. MxA levels in the bacterial infection group and controls were similar and low (90.9 +/- 69.7 and 76.9 +/- 63.2 ng/mL, respectively). In contrast, mean MxA levels in the two viral infection groups were higher than in both the bacterial and control groups (719.2 +/- 386.4 and 827.0 +/- 651.1, respectively). A receiver operating characteristic analysis showed that the area under the curve of the MxA level was greater than under the curves of both the white blood cell count and the C-reactive protein concentration. Whole blood assay of MxA is a clinically useful tool for diagnosing viral illness in febrile children and should help reduce use of unnecessary antibiotics.

Expression of MxA protein in blood lymphocytes of children receiving anticancer chemotherapy

The aim of the study was to evaluate whether IFN-alpha/beta-inducible MxA protein expression in children receiving anticancer treatment can be used as an indicator for virus infections during the febrile episodes. Twenty-six children with mainly hematological malignancies entered the study. Children with laboratory-confirmed virus infections had clearly elevated MxA protein levels compared to their counterparts with bacterial or unknown etiology. MxA protein expression increased moderately following the administration of cytostatic agents, even though these children had no clinical signs of infection.

Correlation between the anti-virus-induced cytopathic effect activity of interferon-alpha subtypes and induction of MxA protein in vitro

There are several interferon-alpha (IFN-alpha) subtypes. Mechanism of disparity in biological effects among members of IFN-alpha subtypes remains unexplained. Biological activity of IFN-alpha is mediated in part by induction of intracellular antiviral proteins. We studied whether differences in biologic effects of IFN-alpha subtypes may rely on their antiviral protein inducing effect. Intracellular induction of MxA protein and anti-virus-induced cytopathic effect (CPE) activity of 11 IFN-alpha subtypes in human amnion WISH cells have been studied. MxA protein quantitation in cell lysates was performed by immunochemiluminescence assay and anti-virus-induced CPE activity was assessed by protection against vesicular stomatitis virus (VSV)-induced CPE. Range of MxA values was high when cells were treated with 10 and 100 IU/ml of each IFN-alpha subtype. Levels of MxA correlated with anti-VSV-induced CPE obtained with 10 IU/ml IFN-alpha subtype. Together our data show a disparity in MxA-inducing activity of IFN-alpha subtypes and suggest that differences in anti-VSV-induced CPE of IFN-alpha subtypes in WISH cells can be related to their different ability to induce MxA.

Scarring skin lesions of discoid lupus erythematosus are characterized by high numbers of skin-homing cytotoxic lymphocytes associated with strong expression of the type I interferon-induced protein MxA

BACKGROUND

Infiltrating T lymphocytes are considered to play a major pathological role in skin lesions of cutaneous lupus erythematosus (CLE), a cutaneous autoimmune disease of unknown aetiology. Earlier histological studies revealed that the inflammatory infiltrate in CLE skin lesions is predominantly composed of T lymphocytes, with a slight predominance of CD4+ over CD8+ T cells, but failed to explain the development of scarring skin lesions, characteristic for chronic discoid lupus erythematosus (CDLE). Because recent investigations have highlighted the relevance of cytotoxic lymphocytes in autoimmune tissue destruction, we hypothesized that the scarring CDLE lesions might be caused by cytotoxic T lymphocytes.

OBJECTIVES

To analyse skin biopsies of 15 patients with CLE [10 female, five male; localized CDLE (lCDLE), n = 5; disseminated CDLE (dCDLE), n = 5, subacute CLE (SCLE), n = 5] and five control biopsies taken from healthy controls and to characterize the inflammatory infiltrate. Methods We used immunohistochemistry, including staining for the cytotoxic molecule granzyme B, the skin-homing molecule cutaneous lymphocyte antigen (CLA) and the protein MxA, which is specifically induced by type I interferons (IFNs).

RESULTS

We found a strong coexpression of granzyme B and CLA on lesional lymphocytes of patients with scarring lCDLE and dCDLE, which was significantly enhanced when compared with nonscarring SCLE and healthy controls. The increased expression of granzyme B was closely associated with the lesional expression of the type I IFN-induced protein MxA.

CONCLUSIONS

Our results provide evidence that type I IFNs and potentially autoreactive cytotoxic lymphocytes targeting adnexal structures are highly associated with scarring lupus erythematosus lesions and might be responsible for their scarring character.

Association of amino acid substitution pattern in core protein of hepatitis C virus genotype 1b high viral load and non-virological response to interferon-ribavirin combination therapy

OBJECTIVE

Patients with high titer (>/=100 kIU/ml) of hepatitis C virus (HCV) genotype 1b do not achieve highly sustained virological response rates to combination therapy with interferon plus ribavirin. Non-virological responders (NVRs, namely ultimate resistant cases) who do not achieve HCV-RNA negativity during treatment are also encountered. We investigated the pretreatment virological features of NVRs.

METHODS

We evaluated 50 consecutive Japanese adults with high titer of HCV genotype 1b who received combination therapy for 48 weeks. We investigated the pretreatment substitution patterns in amino acids 1-191 of the core region and amino acids 2209-2248 of NS5A, and early viral kinetics.

RESULTS

Overall, a non-virological response was noted in 12 (24%) patients. Multivariate analysis identified serum albumin <3.9 g/dl, substitutions of amino acid 70 in the core region, and substitutions of amino acid 91 as independent and significant factors associated with a non-virological response. Especially, substitutions of arginine (R) by glutamine (Q) at amino acid 70, and/or leucine (L) by methionine (M) at amino acid 91 were significantly more common in NVRs. The falls in HCV-RNA levels during treatment in patients with specific substitutions in the core region were significantly less than in those without such substitutions.

CONCLUSIONS

Our results suggest that serum albumin and amino acid substitution patterns in the core region in patients with high titers of HCV genotype 1b may have an effect on combination therapy in NVRs. Further large-scale studies are required to examine the role of amino acid substitutions specific to a non-virological response to combination therapy.

Endogenous IFN-alpha production by plasmacytoid dendritic cells exerts an antiviral effect on thymic HIV-1 infection

Plasmacytoid dendritic cells (pDC) are the principal producers of IFN-alpha in response to viral infection. Because pDC are present in the thymus, we investigated the consequences of HIV-1-induced IFN-alpha production by thymic pDC. We observed that thymic pDC as well as thymocytes express intracellular IFN-alpha upon infection with HIV-1. However, only the pDC could suppress HIV-1 replication, because depletion of pDC resulted in enhancement of HIV-1 replication in thymocytes. Thymic pDC could also produce IFN-alpha in response to CpG oligonucleotides, consistent with the observations of others that peripheral pDC produce IFN-alpha upon engagement of TLR-9. Importantly, CpG considerably increased IFN-alpha production induced by HIV-1, and addition of CpG during HIV-1 infection enhanced expression of the IFN response protein MxA in thymocytes and strongly reduced HIV-replication. Our data indicate that thymic pDC modulate HIV-1 replication through secretion of IFN-alpha. The degree of inhibition depends on the level of IFN-alpha produced by the thymic pDC.

Rapid and simple detection of IFN-neutralizing antibodies in chronic hepatitis C non-responsive to IFN-α

Different mechanisms have been proposed for the failure of interferon (IFN) therapy in patients with chronic hepatitis C and multiple sclerosis, for example, the presence of IFN-neutralizing antibodies. In this study, a novel assay system based on the IFN-inducible Mx-promoter was used to detect IFN-neutralizing antibodies in sera of patients with chronic hepatitis C. To monitor IFN bioactivity in IFN-treated patients, a real-time RT-PCR for MxA gene expression in PBMCs was established. Using these two methods, patients with chronic hepatitis C virus (HCV) infection receiving IFN therapy and patients with treatment induced HCV clearance were monitored. Importantly, neutralizing anti-IFN antibodies were detected in the sera of 3 of 38 chronically HCV-infected patients who failed to respond to therapy but none in sera of patients who cleared HCV after IFN therapy. Interestingly, the presence of these antibodies correlated with the lack of MxA induction in PBMCs after initiation of IFN-alpha therapy. Retrospective analysis of one patient's sera revealed that the anti-IFN-alpha antibodies had already developed after the first of four unsuccessful IFN therapies, suggesting that neutralizing antibodies may have contributed to the failure of previous IFN treatments. In summary, a novel screening assay was established that may be helpful for testing IFN non-responders for the presence of clinically relevant anti-IFN-alpha antibodies and for selecting alternative IFN preparations not neutralized by these antibodies.

Immunoanalysis of antiviral Mx protein expression in Japanese flounder (Paralichthys olivaceus) cells

Mx proteins are interferon-inducible GTPases that possess antiviral properties in vertebrates. Japanese flounder (Paralichthys olivaceus) Mx protein has previously been shown to possess some antiviral activity against rhabdoviruses. A polyclonal antibody was generated against a purified peptide fragment of Japanese flounder Mx protein that had been produced in an Escherichia coli expression system. The PAb detected the approximately 71 kDa Mx protein from Japanese flounder (hirame) natural embryo (HINAE) cells that had been cultured with poly I:C, an interferon inducer, but not in unstimulated cells. The polyclonal antibody did not cross react with Mx protein from carp epithelial, grouper fin and zebrafish embryo cell lines that had been similarly induced or transfected with poly I:C. By immunofluorescence cytochemistry, Japanese flounder Mx protein was localized to the cell cytoplasm. Hirame rhabdovirus stimulated expression of Mx protein in the infected and surrounding HINAE cells. Within virus-infected cells, there was some indication of Mx protein colocalizing with viral proteins. Poly I:C stimulation of HINAE cells induced an early increase in Mx protein mRNA transcripts, but maximum Mx mRNA transcript and protein expression was reached after 48 h. Both Mx mRNA transcripts and protein levels were maintained till at least 72 h.

Differential transcriptional expresión of the polymorphic myxovirus resistance protein A in response to interferon-alpha treatment

Levels of myxovirus resistance protein A (MxA) mRNA were studied for a single nucleotide polymorphism in the promoter region at nucleotide position -88 of the gene to identify individual-specific responses to interferon (IFN)-alpha2 that might predict responsiveness to IFN-alpha therapy. We quantified MxA expression by reverse transcription and real-time polymerase chain reaction in peripheral blood mononuclear cells (PBMC) in vitro, induced by IFN-alpha2, from 22 healthy donors, in relation with G/T polymorphism located in the promoter of the MxA. MxA mRNA was significantly upregulated in all subjects (mean of 53-fold) in response to IFN-alpha2 in vitro (P < 0.01). Comparison of the inducibility of MxA mRNA expression in relation with G/T polymorphism showed a 4.26-fold higher induction of MxA mRNA levels in PBMC from carriers of the mutant allele (GT or TT) than homozygotes with the wild-type allele (GG) (P < 0.001). We propose that expression of the IFN-inducible MxA is affected by a single nucleotide polymorphism in the MxA promoter which can identify an individual response to IFN-alpha2.

Viral Infections in Juvenile Myelomonocytic Leukemia: Prevalence and Clinical Implications

OBJECTIVES

Viral infections may complicate the diagnosis of juvenile myelomonocytic leukemia (JMML) in a substantial proportion of patients, but this possibility has not been tested in a prospective study. The authors therefore measured the cellular expression of the MxA protein, a reliable marker of viral infection, at diagnosis in children with JMML to estimate the prevalence of such infections.

METHODS

Eighteen children, aged 1 to 69 months, who met the diagnostic criteria of the International JMML Working Group were prospectively studied. MxA expression was assessed by flow cytometric analysis of peripheral blood mononuclear cells stained with an antihuman MxA antibody. All data were obtained through the MDS Committee of the Japanese Society of Pediatric Hematology.

RESULTS

Twelve patients (67%) had elevated levels of the MxA protein, with rotavirus, RS virus, or CMV infection documented in three of these patients. Although none of the patients had primary Epstein-Barr virus (EBV) infection, reactivation of the virus was strongly suspected in four children, including two with monosomy 7, each having increased levels of MxA. Southern blot analysis revealed monoclonal integration of the EBV genome into bone marrow mononuclear cells from one of these patients. There was no discernible correlation between increases in the marker protein and the presenting features or course of the disease.

CONCLUSIONS

Viral infection may be present in two thirds of children with newly diagnosed JMML, but it does not constitute a basis for revising clinical management. The possibility that EBV or other viruses contribute to JMML pathogenesis by stimulating pre-exiting malignant clones warrants further investigation.

Characterization of Atlantic halibut (Hippoglossus hippoglossus) Mx protein expression

Mx proteins are antiviral GTPases that are induced by type I interferons in vertebrates. An Atlantic halibut Mx cDNA (HHMx) was recently cloned. In this work, a polyclonal antiserum against HHMx protein was generated that detected a 71 kDa protein in the nuclei of Chinook salmon embryo cells transfected with the HHMx cDNA. Mx protein expression in organs of halibut was studied by immunoblot analysis after injection with the double-stranded RNA poly I:C or infectious pancreatic necrosis virus. Poly I:C stimulated increased Mx protein expression in liver, kidney, heart, spleen, gills and intestine. The Mx protein level in liver reached a maximum after 3 days and remained elevated for 14 days after treatment. IPNV infection resulted in increased Mx protein in liver from 4 to at least 35 days. Immunocytochemical detection of Mx proteins in blood smears from poly I:C treated halibut indicated that a cytoplasmic Mx form might exist in this species. Detection of Mx proteins in blood leukocytes could thus work as an early non-lethal test for viral infections.