Prolonged disturbances of in vitro cytokine production in patients with severe acute respiratory syndrome (SARS) treated with ribavirin and steroids

Cytokines, chemokines, and cells growth factors in patients with mild to moderate SARS-CoV-2 infection: A case-control study

Several biomarkers have been evaluated as predictors of severity or in directing the treatment of COVID-19, however there are no conclusive results. In this study, we evaluated serum levels of cytokines, chemokines, and cell growth factors in association with the pathobiology of mild to moderate SARS-CoV-2 infection. Serum levels of SARS-CoV-2 infected patients (n = 113) and flu symptoms individuals negative for SARS-CoV-2 (n = 58), tested by the RT-qPCR test-nasal swab were compared to healthy controls (n = 53). Results showed that the proinflammatory cytokines IL-1β, MCP-3, TNF-α, and G-CSF were increased in symptomatic patients and the cytokines IL-6 and IL-10 were associated with patients positive for SARS-CoV-2 when compared to healthy controls. Symptoms associated with COVID-19 were fever, anosmia, ageusia, and myalgia. For patients without SARS-CoV-2 infection, their major symptom was sore throat. The pathobiology of mild to moderate SARS-CoV-2 infection was associated with increasing proinflammatory cytokines and a pleiotropic IL-6 and anti-inflammatory IL-10 cytokines compared to healthy controls. Thus, knowledge about the pathophysiology and the involvement of biomarkers in the mild to moderate profile of the disease should be evaluated. Monitoring these biomarkers in patients with mild to moderate disease can help establish adequate treatment and prevention strategies for long-term COVID-19.

The role of IL-6 in coronavirus, especially in COVID-19

Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) infects both people and animals and may cause significant respiratory problems, including lung illness: Corona Virus Disease 2019 (COVID-19). Swabs taken from the throat and nose of people who have the illness or are suspected of having it have shown this pathogenic virus. When SARS-CoV-2 infects the upper and lower respiratory tracts, it may induce moderate to severe respiratory symptoms, as well as the release of pro-inflammatory cytokines including interleukin 6 (IL-6). COVID-19-induced reduction of IL-6 in an inflammatory state may have a hitherto undiscovered therapeutic impact. Many inflammatory disorders, including viral infections, has been found to be regulated by IL-6. In individuals with COVID-19, one of the primary inflammatory agents that causes inflammatory storm is IL-6. It promotes the inflammatory response of virus infection, including the virus infection caused by SARS-CoV-2, and provides a new diagnostic and therapeutic strategy. In this review article, we highlighted the functions of IL-6 in the coronavirus, especially in COVID-19, showing that IL-6 activation plays an important function in the progression of coronavirus and is a rational therapeutic goal for inflammation aimed at coronavirus.

Plant Molecular Pharming and Plant-Derived Compounds towards Generation of Vaccines and Therapeutics against Coronaviruses

The current century has witnessed infections of pandemic proportions caused by Coronaviruses (CoV) including severe acute respiratory syndrome-related CoV (SARS-CoV), Middle East respiratory syndrome-related CoV (MERS-CoV) and the recently identified SARS-CoV2. Significantly, the SARS-CoV2 outbreak, declared a pandemic in early 2020, has wreaked devastation and imposed intense pressure on medical establishments world-wide in a short time period by spreading at a rapid pace, resulting in high morbidity and mortality. Therefore, there is a compelling need to combat and contain the CoV infections. The current review addresses the unique features of the molecular virology of major Coronaviruses that may be tractable towards antiviral targeting and design of novel preventative and therapeutic intervention strategies. Plant-derived vaccines, in particular oral vaccines, afford safer, effectual and low-cost avenues to develop antivirals and fast response vaccines, requiring minimal infrastructure and trained personnel for vaccine administration in developing countries. This review article discusses recent developments in the generation of plant-based vaccines, therapeutic/drug molecules, monoclonal antibodies and phytochemicals to preclude and combat infections caused by SARS-CoV, MERS-CoV and SARS-CoV-2 viruses. Efficacious plant-derived antivirals could contribute significantly to combating emerging and re-emerging pathogenic CoV infections and help stem the tide of any future pandemics.

Immune Profiling of COVID-19 in Correlation with SARS and MERS

Acute respiratory distress syndrome (ARDS) is a major complication of the respiratory illness coronavirus disease 2019, with a death rate reaching up to 40%. The main underlying cause of ARDS is a cytokine storm that results in a dysregulated immune response. This review discusses the role of cytokines and chemokines in SARS-CoV-2 and its predecessors SARS-CoV and MERS-CoV, with particular emphasis on the elevated levels of inflammatory mediators that are shown to be correlated with disease severity. For this purpose, we reviewed and analyzed clinical studies, research articles, and reviews published on PubMed, EMBASE, and Web of Science. This review illustrates the role of the innate and adaptive immune responses in SARS, MERS, and COVID-19 and identifies the general cytokine and chemokine profile in each of the three infections, focusing on the most prominent inflammatory mediators primarily responsible for the COVID-19 pathogenesis. The current treatment protocols or medications in clinical trials were reviewed while focusing on those targeting cytokines and chemokines. Altogether, the identified cytokines and chemokines profiles in SARS-CoV, MERS-CoV, and SARS-CoV-2 provide important information to better understand SARS-CoV-2 pathogenesis and highlight the importance of using prominent inflammatory mediators as markers for disease diagnosis and management. Our findings recommend that the use of immunosuppression cocktails provided to patients should be closely monitored and continuously assessed to maintain the desirable effects of cytokines and chemokines needed to fight the SARS, MERS, and COVID-19. The current gap in evidence is the lack of large clinical trials to determine the optimal and effective dosage and timing for a therapeutic regimen.

The controversial therapeutic journey of chloroquine and hydroxychloroquine in the battle against SARS-CoV-2: A comprehensive review

Recently, the pandemic outbreak of a novel coronavirus, officially termed as severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2), indicated by a pulmonary infection in humans, has become one of the most significant challenges for public health. In the current fight against coronavirus disease-2019, the medical and health authorities across the world focused on quick diagnosis and isolation of patients; meanwhile, researchers worldwide are exploring the possibility of developing vaccines and novel therapeutic options to combat this deadly disease. Recently, based on various small clinical observations, uncontrolled case studies and previously reported antiviral activity against SARS-CoV-1 chloroquine (CQ) and hydroxychloroquine (HCQ) have attracted exceptional consideration as possible therapeutic agents against SARS-CoV-2. However, there are reports on little to no effect of CQ or HCQ against SARS-CoV-2, and many reports have raised concerns about their cardiac toxicity. Here, in this review, we examine the chemistry, molecular mechanism, and pharmacology, including the current scenario and future prospects of CQ or HCQ in the treatment of SARS-CoV-2.

COVID-19 Impacts, Diagnosis and Possible Therapeutic Techniques: A Comprehensive Review

BACKGROUND

The spread of COVID-19 has become a growing cause of mortalities over the globe since its major outbreak in December 2019. The scientific and medical communities are rallying to study different strains and probable mutations to develop more rapid and reliable molecular diagnostic tests and possible therapeutic approaches for SARS-CoV-2.

INTRODUCTION

In the first section, following the introductory part, we shed light on structural and pathogenic features of SARS-CoV-2 and risk factors related to age, gender, neonatal and comorbidities. The next section summarizes the current diagnostic tests for COVID-19, such as nucleic acid and computed tomography (CT) techniques, with further emphasis on emerging diagnostic approaches for COVID-19.

METHODS

Further, we also review the ongoing therapeutic practices which can block virus-host interaction, cease viral proliferation or inhibit hyperbolic host immune response with subsections on drug therapy, cell therapy, immunotherapy and herbal medicines that are being used for the possible treatment of patients.

RESULTS AND CONCLUSION

Among the different promising drugs, remdesivir, by inhibiting the RNA-dependent RNA-Polymerase activity, gives much better results, including declined viral load and quick lung tissue recovery. The long-lasting repercussions of COVID-19 have also been discussed at the end. In this review, we have also critically discussed the progress in several vaccines that are under development.

Imaging features of COVID-19: What we can learn from SARS and MERS (Review)

Coronavirus disease 2019 (COVID-19) is a highly infectious type of pneumonia caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) that has rapidly become a global pandemic. COVID-19, SARS and Middle East respiratory syndrome (MERS) are all caused by members of the Coronaviridae family. As expected, emerging genetic and clinical evidence from patients with COVID-19 has indicated that the pathway of infection is similar to that of SARS and MERS. Additionally, much like SARS and MERS, chest imaging serves an important role in the diagnosis, management and follow-up of patients with COVID-19. Although these related viruses present a similar pneumonic pathogenesis, the imaging results have distinguishable features. The current review evaluated the imaging results of patients with SARS and MERS and explored the potential similarities and differences among patients with COVID-19, SARS and MERS at early, progressive, severe and recovery stages, with the aim of improving our understanding of SARS-CoV-2 infections by comparing the features of COVID-19 images with those of SARS and MERS. The current review assessed whether imaging results had implications for the administration of corticosteroids as treatment for COVID-19. Whether corticosteroids can inhibit inflammatory cytokine storms and reduce the mortality of patients with viral pneumonia remains controversial. However, his review may help radiologists and clinicians to identify viral pneumonia and guide appropriate COVID-19 treatment.

Convalescent Blood: Current Perspective on the Efficacy of a Legacy Approach in COVID-19 Treatment

Since early 2020, COVID-19 has wreaked havoc in many societies around the world. As of the present, the SARS-CoV-2-borne disease is propagating in almost all countries, affecting hundreds of thousands of people in an unprecedented way. As the name suggests, the novel coronavirus, widely known as SARS-CoV-2, is a new emerging human pathogen. A novel disease of relatively unknown origin, COVID-19 does not seem to be amenable to the currently available medicines since there is no specific cure for the disease. In the absence of any vaccine or effective antiviral medication, we have no tools at our disposal, but the method of quarantine, be it domestic or institutional, to hinder any further progression of this outbreak. However, there is a record of physicians in the past who practiced convalescent blood transfusion. To their awe, the method seemed to be useful. It is anticipated that these contemporary methods will outdo any other vaccination process in the time being, as blood transfusion is instead a cost-effective and time-friendly technique. Following a successful trial, this new approach of contemporary nature to a viral disease may serve as an emergency intervention to intercept infectious outbreaks and prevent an impending epidemic/pandemic. In this review, we document the most recent evidence regarding the efficiency of convalescent plasma and serum therapy on SARS, MERS, and particularly COVID-19, while discussing potential advantages and possible risks of such practice.

An Overview of Current Knowledge of Deadly CoVs and Their Interface with Innate Immunity

Coronaviruses are a large family of zoonotic RNA viruses, whose infection can lead to mild or lethal respiratory tract disease. Severe Acute Respiratory Syndrome-Coronavirus-1 (SARS-CoV-1) first emerged in Guangdong, China in 2002 and spread to 29 countries, infecting 8089 individuals and causing 774 deaths. In 2012, Middle East Respiratory Syndrome-Coronavirus (MERS-CoV) emerged in Saudi Arabia and has spread to 27 countries, with a mortality rate of ~34%. In 2019, SARS-CoV-2 emerged and has spread to 220 countries, infecting over 100,000,000 people and causing more than 2,000,000 deaths to date. These three human coronaviruses cause diseases of varying severity. Most people develop mild, common cold-like symptoms, while some develop acute respiratory distress syndrome (ARDS). The success of all viruses, including coronaviruses, relies on their evolved abilities to evade and modulate the host anti-viral and pro-inflammatory immune responses. However, we still do not fully understand the transmission, phylogeny, epidemiology, and pathogenesis of MERS-CoV and SARS-CoV-1 and -2. Despite the rapid application of a range of therapies for SARS-CoV-2, such as convalescent plasma, remdesivir, hydroxychloroquine and type I interferon, no fully effective treatment has been determined. Remarkably, COVID-19 vaccine research and development have produced several offerings that are now been administered worldwide. Here, we summarise an up-to-date understanding of epidemiology, immunomodulation and ongoing anti-viral and immunosuppressive treatment strategies. Indeed, understanding the interplay between coronaviruses and the anti-viral immune response is crucial to identifying novel targets for therapeutic intervention, which may even prove invaluable for the control of future emerging coronavirus.

Crosstalk Between Covid-19 and Associated Neurological Disorders: A Review

COVID-19 is a global pandemic, primarily affecting the pulmonary system but its effects on other systems are not certain. Coronavirus, the causative organism, binds with angiotensinconverting enzyme 2 (ACE2) receptors in the lungs and produces pneumonia-like symptoms. Other than lungs, ACE2 receptors are also seen in the endothelium of blood vessels. Therefore, viruses can bind to the ACE2 that is present in the endothelium of brain blood vessels and thus can invade BBB, leading to neuronal damage. It is also believed that olfactory cells rich in ACE2 receptors may act as the main route of viral spread into various parts of the brain. The reported neurological effects of SARS-CoV-2 include cerebrovascular diseases, ageusia and anosmia, Guillain Barre Syndrome, and viral encephalitis. The extent of neurological involvement in SARS-CoV-2 infection warrants the necessity of further research to systematically classify neurological complications associated with SARS-CoV-2 infection, its diagnosis, and treatment. As ACE2 receptors are present in various other organs, it is obligatory to study the effect of coronavirus on other organs also. Since the long-lasting effects of the COVID-19 are unclear, more studies should be conducted to confirm the effect of the virus on the central nervous system. This review highlights the reported neurological manifestations of SARS-CoV-2 and its mechanism.

Severe Acute Respiratory Syndrome Coronavirus 2: The Role of the Main Components of the Innate Immune System

At the end of December 2019, the COVID-19 pandemic began in Wuhan of China. COVID-19 affects different people with a wide spectrum of clinical manifestations, ranging from asymptomatic with recovery without hospitalization up to a severe acute respiratory syndrome (SARS). The innate and adaptive immunity appears responsible for the defense against the virus and recovery from the disease. The innate immune system, as the first line of defense, is essential for the detection of virus and subsequent activation of acquired immunity. The innate immune response is carried out by sentinel cells such as monocytes/macrophages and dendritic cells and by receptors known as pattern recognition receptors (PRR). These receptors can recognize various components of the virus, which lead to intracellular signaling and subsequently the synthesis of various cytokines. These cytokines then recruit other immune cells, activate adaptive immune responses, and inhibit viral spreading. The most common receptors include Toll-like receptors, C-type lectin receptors, and RIG-I like receptors. This review describes the current knowledge about the interplay between innate immune responses and SARS-CoV-2 with a focus on the innate immune cells and the role of their receptors in viral RNA recognition, as well as their mechanisms for recognizing SARS-CoV-2.

Impact of repurposed drugs on the symptomatic COVID-19 patients

An outbreak of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), a novel coronavirus capable of causing coronavirus disease 2019 (COVID-19), was declared as a global public health emergency on January 30, 2020, by the World Health Organization. In this devastating situation, precautionary measures, early diagnosis, and repurposed drugs appear to be timely and decisive factors by which to handle this problem until the discovery of an effective, dedicated vaccine or medicine is made. Currently, some researchers and clinicians have claimed evidence exists in favor of the use of some antimalarial drugs (chloroquine, hydroxychloroquine) antiviral drugs (remdesivir, favipiravir, lopinavir, ritonavir, umifenovir) vitamins, traditional Chinese medicines, and herbal medicines against SARS-CoV-2 infection. Based on the available literature, this review article sought to highlight the current understanding of the origin, transmission, diagnosis, precautionary measures, infection and drug action mechanisms, therapeutic role, and toxicities of targeted drugs for the prevention and cure of COVID-19. This review may be useful for developing further strategies as a blueprint and understanding the mentioned drugs' mechanisms to elucidate the possible target of action by which to successfully freeze the replication of the SARS-CoV-2 virus.

What are the drugs having potential against COVID-19?

A disease emerged in the city of Wuhan, Hubei Province, Central China in the last month of 2019. It was pneumonia caused by a newly emerged coronavirus called COVID-19, later. Coronaviruses are enveloped RNA viruses belong to the Betacoronavirus family and infected birds, humans, and other mammals. In March 2020, the World Health Organization declared the COVID-19 outbreak could be characterized as a global pandemic because the disease spread, and a large number of people were infected and died in many countries on different continents by virtue of this new virus. Now, intensive work is underway about the pathogenic mechanisms and epidemiological properties of COVID-19, and a great effort is made to develop effective specific therapeutic drugs, vaccines, and/or treatment strategies against these diseases. Herein, we have focused on all treatment options available against COVID-19 pneumonia in this text.

Coronavirus disease 2019 (COVID-19): current status and future perspectives

Coronavirus disease 2019 (COVID-19) originated in the city of Wuhan, Hubei Province, Central China, and has spread quickly to 72 countries to date. COVID-19 is caused by a novel coronavirus, named severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) [previously provisionally known as 2019 novel coronavirus (2019-nCoV)]. At present, the newly identified SARS-CoV-2 has caused a large number of deaths with tens of thousands of confirmed cases worldwide, posing a serious threat to public health. However, there are no clinically approved vaccines or specific therapeutic drugs available for COVID-19. Intensive research on the newly emerged SARS-CoV-2 is urgently needed to elucidate the pathogenic mechanisms and epidemiological characteristics and to identify potential drug targets, which will contribute to the development of effective prevention and treatment strategies. Hence, this review will focus on recent progress regarding the structure of SARS-CoV-2 and the characteristics of COVID-19, such as the aetiology, pathogenesis and epidemiological characteristics.

A review of candidate therapies for Middle East respiratory syndrome from a molecular perspective

There have been 2040 laboratory-confirmed cases of Middle East respiratory syndrome coronavirus (MERS-CoV) in 27 countries, with a mortality rate of 34.9 %. There is no specific therapy. The current therapies have mainly been adapted from severe acute respiratory syndrome (SARS-CoV) treatments, including broad-spectrum antibiotics, corticosteroids, interferons, ribavirin, lopinavir–ritonavir or mycophenolate mofetil, and have not been subject to well-organized clinical trials. The development of specific therapies and vaccines is therefore urgently required. We examine existing and potential therapies and vaccines from a molecular perspective. These include viral S protein targeting; inhibitors of host proteases, including TMPRSS2, cathepsin L and furin protease, and of viral M(pro) and the PL(pro) proteases; convalescent plasma; and vaccine candidates. The Medline database was searched using combinations and variations of terms, including ‘Middle East respiratory syndrome coronavirus’, ‘MERS-CoV’, ‘SARS’, ‘therapy’, ‘molecular’, ‘vaccine’, ‘prophylactic’, ‘S protein’, ‘DPP4’, ‘heptad repeat’, ‘protease’, ‘inhibitor’, ‘anti-viral’, ‘broad-spectrum’, ‘interferon’, ‘convalescent plasma’, ‘lopinavir ritonavir’, ‘antibodies’, ‘antiviral peptides’ and ‘live attenuated viruses’. There are many options for the development of MERS-CoV-specific therapies. Currently, MERS-CoV is not considered to have pandemic potential. However, the high mortality rate and potential for mutations that could increase transmissibility give urgency to the search for direct, effective therapies. Well-designed and controlled clinical trials are needed, both for existing therapies and for prospective direct therapies.

Severe Acute Respiratory Syndrome (SARS)

Severe acute respiratory syndrome (SARS) is caused by a novel coronavirus (SARS-CoV), spread largely via droplets. Patients present with rapidly progressive pneumonia and respiratory failure. Diagnosis requires the demonstration of epidemiological linkage, clinical profiles, and virological evidence of SARS-CoV infection. Treatment of SARS is largely anecdotal. High-dose corticosteroid therapy might be useful for critically ill patients, but previous use of ribavirin (a broad-spectrum antiviral agent) was probably not efficacious. Some survivors of SARS suffer from avascular necrosis of hip and knee joints. Poor prognostic factors include advanced age, comorbidities, and high serum lactate dehydrogenase and neutrophil levels.

A review of treatment modalities for Middle East Respiratory Syndrome

The Middle East Respiratory Syndrome coronavirus (MERS-CoV) has been a focus of international attention since its identification in 2012. Epidemiologically it is characterized by sporadic community cases, which are amplified by hospital-based outbreaks. Healthcare facilities in 27 countries from most continents have experienced imported cases, with the most significant outbreak involving 186 cases in Korea. The mortality internationally is 36% and guidance for clinical management has yet to be developed. Most facilities and healthcare providers outside of the Middle East receiving patients have no or little experience in the clinical management of MERS. When a case does occur there is likely little time for a critical appraisal of the literature and putative pharmacological options. We identified published literature on the management of both MERS-CoV and the Severe Acute Respiratory Syndrome coronavirus (SARS-CoV) through searches of PubMed and WHO and the US CDC websites up to 30 April 2016. A total of 101 publications were retrieved for critical appraisal. Most published literature on therapeutics for MERS are in vitro experiments, animal studies and case reports. Current treatment options for MERS can be categorized as: immunotherapy with virus-specific antibodies in convalescent plasma; polyclonal and monoclonal antibodies produced in vitro or in genetically modified animals; and antiviral agents. The use of any therapeutics in MERS-CoV remains investigational. The therapeutic agents with potential benefits and warranting further investigation include convalescent plasma, interferon-β/ribavirin combination therapy and lopinavir. Corticosteroids, ribavirin monotherapy and mycophenolic acid likely have toxicities that exceed potential benefits.

A review of genetic methods and models for analysis of coronavirus-induced severe pneumonitis

Coronaviruses (CoVs) have been studied for over 60 years, but have only recently gained notoriety as deadly human pathogens with the emergence of severe respiratory syndrome CoV and Middle East respiratory syndrome virus. The rapid emergence of these viruses has demonstrated the need for good models to study severe CoV respiratory infection and pathogenesis. There are, currently, different methods and models for the study of CoV disease. The available genetic methods for the study and evaluation of CoV genetics are reviewed here. There are several animal models, both mouse and alternative animals, for the study of severe CoV respiratory disease that have been examined, each with different pros and cons relative to the actual pathogenesis of the disease in humans. A current limitation of these models is that no animal model perfectly recapitulates the disease seen in humans. Through the review and analysis of the available disease models, investigators can employ the most appropriate available model to study various aspects of CoV pathogenesis and evaluate possible antiviral treatments that may potentially be successful in future treatment and prevention of severe CoV respiratory infections.

Extraordinary GU-rich single-strand RNA identified from SARS coronavirus contributes an excessive innate immune response

A dangerous cytokine storm occurs in the SARS involving in immune disorder, but many aspects of the pathogenetic mechanism remain obscure since its outbreak. To deeply reveal the interaction of host and SARS-CoV, based on the basic structural feature of pathogen-associated molecular pattern, we created a new bioinformatics method for searching potential pathogenic molecules and identified a set of SARS-CoV specific GU-rich ssRNA fragments with a high-density distribution in the genome. In vitro experiments, the result showed the representative SARS-CoV ssRNAs had powerful immunostimulatory activities to induce considerable level of pro-inflammatory cytokine TNF-a, IL-6 and IL-12 release via the TLR7 and TLR8, almost 2-fold higher than the strong stimulatory ssRNA40 that was found previously from other virus. Moreover, SARS-CoV ssRNA was able to cause acute lung injury in mice with a high mortality rate in vivo experiment. It suggests that SARS-CoV specific GU-rich ssRNA plays a very important role in the cytokine storm associated with a dysregulation of the innate immunity. This study not only presents new evidence about the immunopathologic damage caused by overactive inflammation during the SARS-CoV infection, but also provides a useful clue for a new therapeutic strategy.

The SARS-coronavirus-host interactome: identification of cyclophilins as target for pan-coronavirus inhibitors

Coronaviruses (CoVs) are important human and animal pathogens that induce fatal respiratory, gastrointestinal and neurological disease. The outbreak of the severe acute respiratory syndrome (SARS) in 2002/2003 has demonstrated human vulnerability to (Coronavirus) CoV epidemics. Neither vaccines nor therapeutics are available against human and animal CoVs. Knowledge of host cell proteins that take part in pivotal virus-host interactions could define broad-spectrum antiviral targets. In this study, we used a systems biology approach employing a genome-wide yeast-two hybrid interaction screen to identify immunopilins (PPIA, PPIB, PPIH, PPIG, FKBP1A, FKBP1B) as interaction partners of the CoV non-structural protein 1 (Nsp1). These molecules modulate the Calcineurin/NFAT pathway that plays an important role in immune cell activation. Overexpression of NSP1 and infection with live SARS-CoV strongly increased signalling through the Calcineurin/NFAT pathway and enhanced the induction of interleukin 2, compatible with late-stage immunopathogenicity and long-term cytokine dysregulation as observed in severe SARS cases. Conversely, inhibition of cyclophilins by cyclosporine A (CspA) blocked the replication of CoVs of all genera, including SARS-CoV, human CoV-229E and -NL-63, feline CoV, as well as avian infectious bronchitis virus. Non-immunosuppressive derivatives of CspA might serve as broad-range CoV inhibitors applicable against emerging CoVs as well as ubiquitous pathogens of humans and livestock.

Immunosuppressive mechanisms during viral infectious diseases

For a virus to establish persistence in the host, it has to exploit the host immune system such that the active T-cell responses against the virus are curbed. On the other hand, the goal of the immune system is to clear the virus, following which the immune responses need to be downregulated, by a process known as immunoregulation. There are multiple known immunoregulatory mechanisms that appear to play a role in persistent viral infections. In the recent past, IL-10 and PD-1 have been identified to be playing a significant role in the regulation of antiviral immune responses. The evidence that viruses can escape immunologic attack by taking advantage of the host's immune system is found in LCMV infection of mice and in humans persistently infected with HIV and HCV. The recent observation that the functionally inactive T-cells during chronic viral infections can be made to regain their cytokine secretion and cytolytic abilities is very encouraging. Thus, it would be likely that neutralization negative immune regulation during persistent viral infection would result in the preservation of effector T-cell responses against the virus, thereby resulting in the elimination of the persistent infection.

A new mouse-adapted strain of SARS-CoV as a lethal model for evaluating antiviral agents in vitro and in vivo

Severe acute respiratory syndrome (SARS) is a highly lethal emerging disease caused by coronavirus SARS-CoV. New lethal animal models for SARS were needed to facilitate antiviral research. We adapted and characterized a new strain of SARS-CoV (strain v2163) that was highly lethal in 5- to 6-week-old BALB/c mice. It had nine mutations affecting 10 amino acid residues. Strain v2163 increased IL-1alpha, IL-6, MIP-1alpha, MCP-1, and RANTES in mice, and high IL-6 expression correlated with mortality. The infection largely mimicked human disease, but lung pathology lacked hyaline membrane formation. In vitro efficacy against v2163 was shown with known inhibitors of SARS-CoV replication. In v2163-infected mice, Ampligen was fully protective, stinging nettle lectin (UDA) was partially protective, ribavirin was disputable and possibly exacerbated disease, and EP128533 was inactive. Ribavirin, UDA, and Ampligen decreased IL-6 expression. Strain v2163 provided a valuable model for anti-SARS research.

Boosted expression of the SARS-CoV nucleocapsid protein in tobacco and its immunogenicity in mice

Vaccines produced in plant systems are safe and economical; however, the extensive application of plant-based vaccines is mainly hindered by low expression levels of heterologous proteins in plant systems. Here, we demonstrated that the post-transcriptional gene silencing suppressor p19 protein from tomato bushy stunt virus substantially enhanced the transient expression of recombinant SARS-CoV nucleocapsid (rN) protein in Nicotiana benthamiana. The rN protein in the agrobacteria-infiltrated plant leaf accumulated up to a concentration of 79 microg per g fresh leaf weight at 3 days post infiltration. BALB/c mice were intraperitoneally vaccinated with pre-treated plant extract emulsified in Freund's adjuvant. The rN protein-specific IgG in the mouse sera attained a titer about 1:1,800 following three doses of immunization, which suggested effective B-cell maturation and differentiation in mice. Antibodies of the subclasses IgG1 and IgG2a were abundantly present in the mouse sera. During vaccination of rN protein, the expression of IFN-gamma and IL-10 was evidently up-regulated in splenocytes at different time points, while the expression of IL-2 and IL-4 was not. Up to now, this is the first study that plant-expressed recombinant SARS-CoV N protein can induce strong humoral and cellular responses in mice.

Protective and pathologic roles of the immune response to mouse hepatitis virus type 1: implications for severe acute respiratory syndrome

Intranasal mouse hepatitis virus type 1 (MHV-1) infection of mice induces lung pathology similar to that observed in severe acute respiratory syndrome (SARS) patients. However, the severity of MHV-1-induced pulmonary disease varies among mouse strains, and it has been suggested that differences in the host immune response might account for this variation. It has also been suggested that immunopathology may represent an important clinical feature of SARS. Little is known about the host immune response to MHV-1 and how it might contribute to some of the pathological changes detected in infected mice. In this study we show that an intact type I interferon system and the adaptive immune responses are required for controlling MHV-1 replication and preventing morbidity and mortality in resistant C57BL/6J mice after infection. The NK cell response also helps minimize the severity of illness following MHV-1 infection of C57BL/6J mice. In A/J and C3H/HeJ mice, which are highly susceptible to MHV-1-induced disease, we demonstrate that both CD4 and CD8 T cells contribute to morbidity during primary infection, and memory responses can enhance morbidity and mortality during subsequent reexposure to MHV-1. However, morbidity in A/J and C3H/HeJ mice can be minimized by treating them with immune serum prior to MHV-1 infection. Overall, our findings highlight the role of the host immune response in contributing to the pathogenesis of coronavirus-induced respiratory disease.

Prior immunization with severe acute respiratory syndrome (SARS)-associated coronavirus (SARS-CoV) nucleocapsid protein causes severe pneumonia in mice infected with SARS-CoV

The details of the mechanism by which severe acute respiratory syndrome-associated coronavirus (SARS-CoV) causes severe pneumonia are unclear. We investigated the immune responses and pathologies of SARS-CoV-infected BALB/c mice that were immunized intradermally with recombinant vaccinia virus (VV) that expressed either the SARS-CoV spike (S) protein (LC16m8rVV-S) or simultaneously all the structural proteins, including the nucleocapsid (N), membrane (M), envelope (E), and S proteins (LC16m8rVV-NMES) 7-8 wk before intranasal SARS-CoV infection. The LC16m8rVV-NMES-immunized group exhibited as severe pneumonia as the control groups, although LC16m8rVV-NMES significantly decreased the pulmonary SARS-CoV titer to the same extent as LC16m8rVV-S. To identify the cause of the exacerbated pneumonia, BALB/c mice were immunized with recombinant VV that expressed the individual structural proteins of SARS-CoV (LC16mOrVV-N, -M, -E, -S) with or without LC16mOrVV-S (i.e., LC16mOrVV-N, LC16mOrVV-M, LC16mOrVV-E, or LC16mOrVV-S alone or LC16mOrVV-N + LC16mOrVV-S, LC16mOrVV-M + LC16mOrVV-S, or LC16mOrVV-E + LC16mOrVV-S), and infected with SARS-CoV more than 4 wk later. Both LC16mOrVV-N-immunized mice and LC16mOrVV-N + LC16mOrVV-S-immunized mice exhibited severe pneumonia. Furthermore, LC16mOrVV-N-immunized mice upon infection exhibited significant up-regulation of both Th1 (IFN-gamma, IL-2) and Th2 (IL-4, IL-5) cytokines and down-regulation of anti-inflammatory cytokines (IL-10, TGF-beta), resulting in robust infiltration of neutrophils, eosinophils, and lymphocytes into the lung, as well as thickening of the alveolar epithelium. These results suggest that an excessive host immune response against the nucleocapsid protein of SARS-CoV is involved in severe pneumonia caused by SARS-CoV infection. These findings increase our understanding of the pathogenesis of SARS.

Unraveling the complexities of the interferon response during SARS-CoV infection

Viruses employ different strategies to circumvent the antiviral actions of the innate immune response. SARS coronavirus (SARS-CoV), a virus that causes severe lung damage, encodes an array of proteins able to inhibit induction and signaling of type-I interferons. However, recent studies have demonstrated that interferons are produced during SARS-CoV infection in humans and macaques. Furthermore, nuclear translocation of activated STAT1 and a range of interferon-stimulated genes could be demonstrated in the lungs of SARS-CoV-infected macaques. In line with these observations, plasmacytoid dendritic cells have been shown to produce interferons upon SARS-CoV infection in vitro. Given the pivotal role of interferons during viral infections, (differential) induction of interferons may affect the outcome of the infection. Therefore, the functional implication of interferon production during SARS-CoV infection remains to be re-investigated.

Interferon and cytokine responses to SARS-coronavirus infection

The sudden emergence of severe acute respiratory syndrome (SARS) has boosted research on innate immune responses to coronaviruses. It is now well established that the causative agent, a newly identified coronavirus termed SARS-CoV, employs multiple passive and active mechanisms to avoid induction of the antiviral type I interferons in tissue cells. By contrast, chemokines such as IP-10 or IL-8 are strongly upregulated. The imbalance in the IFN response is thought to contribute to the establishment of viremia early in infection, whereas the production of chemokines by infected organs may be responsible for (i) massive immune cell infiltrations found in the lungs of SARS victims, and (ii) the dysregulation of adaptive immunity. Here, we will review the most recent findings on the interaction of SARS-CoV and related Coronaviridae members with the type I interferon and cytokine responses and discuss implications for pathogenesis and therapy.

Coronavirus spike protein inhibits host cell translation by interaction with eIF3f

In response to viral infection, the expression of numerous host genes, including predominantly a number of proinflammatory cytokines and chemokines, is usually up-regulated at both transcriptional and translational levels. It was noted that in cells infected with coronavirus, transcription and translation of some of these genes were differentially induced. Drastic induction of their expression at the transcriptional level was observed in cells infected with coronavirus. However, induction of the same genes at the translational level was usually found to be minimal to moderate. To investigate the underlying mechanisms, yeast two-hybrid screen was carried out using SARS-CoV proteins as baits, revealing that a subunit of the eukaryotic initiation factor 3 (eIF3), eIF3f, may interact with the N-terminal region of the SARS-CoV spike (S) protein. This interaction was subsequently confirmed by co-immunoprecipitation and immunofluorescent staining. Meanwhile, parallel experiments confirmed that eIF3f could also interact with the S protein of another coronavirus, the avian coronavirus infectious bronchitis virus (IBV). These interactions led to the inhibition of translation of a reporter gene in both in vitro expression system and intact cells. Interestingly, IBV-infected cells stably expressing a Flag-tagged eIF3f showed much higher translation of IL-6 and IL-8, suggesting that the interaction between coronavirus S protein and eIF3f plays a functional role in controlling the expression of host genes, especially genes that are induced during coronavirus infection cycles. This study reveals a novel mechanism exploited by coronavirus to regulate viral pathogenesis.

Severe acute respiratory syndrome coronavirus as an agent of emerging and reemerging infection

Before the emergence of severe acute respiratory syndrome (SARS) coronavirus (SARS-CoV) in 2003, only 12 other animal or human coronaviruses were known. The discovery of this virus was soon followed by the discovery of the civet and bat SARS-CoV and the human coronaviruses NL63 and HKU1. Surveillance of coronaviruses in many animal species has increased the number on the list of coronaviruses to at least 36. The explosive nature of the first SARS epidemic, the high mortality, its transient reemergence a year later, and economic disruptions led to a rush on research of the epidemiological, clinical, pathological, immunological, virological, and other basic scientific aspects of the virus and the disease. This research resulted in over 4,000 publications, only some of the most representative works of which could be reviewed in this article. The marked increase in the understanding of the virus and the disease within such a short time has allowed the development of diagnostic tests, animal models, antivirals, vaccines, and epidemiological and infection control measures, which could prove to be useful in randomized control trials if SARS should return. The findings that horseshoe bats are the natural reservoir for SARS-CoV-like virus and that civets are the amplification host highlight the importance of wildlife and biosecurity in farms and wet markets, which can serve as the source and amplification centers for emerging infections.

Association of ICAM3 genetic variant with severe acute respiratory syndrome

Genetic polymorphisms have been demonstrated to be associated with vulnerability to human infection. ICAM3, an intercellular adhesion molecule important for T cell activation, and FCER2 (CD23), an immune response gene, both located on chromosome 19p13.3 were investigated for host genetic susceptibility and association with clinical outcome. A case-control study based on 817 patients with confirmed severe acute respiratory syndrome (SARS), 307 health care worker control subjects, 290 outpatient control subjects, and 309 household control subjects unaffected by SARS from Hong Kong was conducted to test for genetic association. No significant association to susceptibility to SARS-CoV infection was found for the FCER2 and the ICAM3 single nucleotide polymorphisms. However, patients with SARS homozygous for ICAM3 Gly143 showed significant association with higher lactate dehydrogenase levels (P=.0067; odds ratio [OR], 4.31 [95% confidence interval [CI], 1.37–13.56]) and lower total white blood cell counts (P=.022; OR, 0.30 [95% CI, 0.10–0.89]) on admission. These findings support the role of ICAM3 in the immunopathogenesis of SARS.

Temporal changes in cytokine/chemokine profiles and pulmonary involvement in severe acute respiratory syndrome

Objective and background:  Pathological changes in severe acute respiratory syndrome (SARS) suggest that SARS sequelae are associated with dysregulation of cytokine and chemokine production. To improve understanding of the immuno‐pathological processes involved in lung injury associated with SARS, the temporal changes in cytokine/chemokine profiles in the sera of SARS patients were compared with those of patients with community‐acquired pneumonia (CAP), according to the degree of lung involvement.

Methods:  Serum levels of 11 cytokines and chemokines, in 14 patients with SARS and 24 patients with CAP, were serially checked using a bead‐based multiassay system. Sera from 12 healthy subjects were used as normal controls.

Results:  The serum levels of interferon‐γ‐inducible protein‐10 (IP‐10), IL‐2 and IL‐6 were significantly elevated during SARS infection. In patients with CAP, but not in those with SARS, the levels of interferon‐γ, IL‐10, IL‐8 and monokine induced by interferon‐γ (MIG) were significantly elevated compared with the levels in healthy controls. Among the chemokines/cytokines, IL‐6 levels correlated most strongly with radiographic scores (r = 0.62). The elevation of IP‐10 and IL‐2 antedated the development of chest involvement and reached peak levels earlier than the radiographic scores. In contrast, the dynamic changes in IL‐6, C‐reactive protein and neutrophils occurred synchronously with the changes in radiographic scores. The mean ratio of IL‐6 to IL‐10 in SARS patients (4.84; range 0.41–21) was significantly higher than that in CAP patients (2.95; range 0.02–10.57) (P = 0.04).

Conclusions:  The early induction of IP‐10 and IL‐2, as well as the subsequent over‐production of IL‐6 and lack of IL‐10 production, probably contribute to the main immuno‐pathological processes involved in lung injury in SARS. These changes in cytokine/chemokine profile are remarkably different from those observed in CAP patients.

Control of coronavirus infection through plasmacytoid dendritic-cell-derived type I interferon

This study demonstrates a unique and crucial role of plasmacytoid dendritic cells (pDCs) and pDC-derived type I interferons (IFNs) in the pathogenesis of mouse coronavirus infection. pDCs controlled the fast replicating mouse hepatitis virus (MHV) through the immediate production of type I IFNs. Recognition of MHV by pDCs was mediated via TLR7 ensuring a swift IFN-α production following encounter with this cytopathic RNA virus. Furthermore, the particular type I IFN response pattern was not restricted to the murine coronavirus, but was also found in infection with the highly cytopathic human severe acute respiratory syndrome (SARS) coronavirus. Taken together, our results suggest that rapid production of type I IFNs by pDCs is essential for the control of potentially lethal coronavirus infections.

Treatment of severe acute respiratory syndrome with glucosteroids: the Guangzhou experience

STUDY OBJECTIVE

To investigate the efficacy and safety profiles of corticosteroid therapy in severe acute respiratory syndrome (SARS) patients.

DESIGN

Four hundred one of 1,278 SARS cases treated in Guangzhou China between December 2002 and June 2003 fulfilled the diagnostic criteria issued by the World Health Organization for confirmed identification of SARS. Among them, the diagnosis of critical SARS was defined by criteria of SARS guidelines incorporated with a low oxygenation index (OI) [< 300 mm Hg]. Data of these patients retrieved from a database were retrospectively analyzed by logistic regression and Cox regression for the effect of corticosteroid therapy on death, hospitalization days, and complication presentation.

RESULTS

Among the 401 SARS patients studied, 147 of 249 noncritical patients (59.0%) received corticosteroids (mean daily dose, 105.3 +/- 86.1 mg) [+/- SD], and all survived the disease; 121 of 152 critical patients (79.6%) received corticosteroids at a mean daily dose of 133.5 +/- 102.3 mg, and 25 died. Analysis of these 401 confirmed cases did not show any benefits of corticosteroid on the death rate and hospitalization days. However, when focused on 152 critical SARS cases, factors correlated with these end points indicated by univariate analysis included use of corticosteroid, age, rigor at onset, secondary respiratory infections, pulmonary rales, grading of OI, and use of invasive ventilation. After adjustment for possible confounders, treatment with corticosteroid was shown contributing to lower overall mortality, instant mortality, and shorter hospitalization stay (p < 0.05). Incidence of complications was significantly associated with the need for invasive ventilation but not with use of corticosteroids.

CONCLUSION

This Guangzhou retrospective study revealed that proper use of corticosteroid in confirmed critical SARS resulted in lowered mortality and shorter hospitalization stay, and was not associated with significant secondary lower respiratory infection and other complications.

SARS-CoV virus-host interactions and comparative etiologies of acute respiratory distress syndrome as determined by transcriptional and cytokine profiling of formalin-fixed paraffin-embedded tissues

These studies attempt to understand more fully the host response and pathogenesis associated with severe acute respiratory syndrome (SARS) coronavirus (SARS-CoV) by monitoring gene expression using formalin-fixed paraffin-embedded (FFPE) pulmonary autopsy tissues. These tissues were from patients in different hospitals in Singapore who were diagnosed with various microbial infections, including SARS-CoV, that caused acute respiratory distress syndrome (ARDS). Global expression patterns showed limited correlation between end-stage ARDS and the initiating pathogen, but when focusing on a subset of genes implicated in pulmonary pathogenesis, molecular signatures of pulmonary disease were obtained and appeared to be influenced by preexisting pulmonary complications and also bacterial components of infection. Many factors detected during pulmonary damage and repair, such as extracellular matrix (ECM) components, transforming growth factor (TGF) enhancers, acute-phase proteins, and antioxidants, were included in the molecular profiles of these ARDS lung tissues. In addition, differential expression of cytokines within these pulmonary tissues were observed, including notable genes involved in the interferon (IFN) pathway, such as Stat1, IFN regulatory factor-1 (IRF-1), interleukin-6 (IL-6), IL-8, and IL-18, that are often characterized as elevated in ARDS patients.

The severe acute respiratory syndrome (SARS)

The world was shocked in early 2003 when a pandemic of severe acute respiratory syndrome (SARS) was imminent. The outbreak of this novel disease, caused by a novel coronavirus (the SARS-coronavirus), hit hardest in the Asian Pacific region, though eventually it spread to five continents. The speed of the spread of the SARS epidemic was unprecedented due to the highly efficient intercontinental transportation. An international collaborative effort through the World Health Organization (WHO) has helped to identify the aetiological agent about 1 month after the onset of the epidemic. The power of molecular biology and bioinformatics has enabled the complete decoding of the viral genome within weeks. Over 1000 publications on the phylogeny, epidemiology, genomics, laboratory diagnostics, antiviral, immunization, pathogenesis, clinical disease, and management accumulated within just 1 year. Although the exact animal reservoir of virus and how it evolved into a human pathogen are still obscure, accurate diagnosis and epidemiological control of the disease are now possible. This article reviews what is currently known about the virus and the disease.

Longitudinal alteration of circulating dendritic cell subsets and its correlation with steroid treatment in patients with severe acute respiratory syndrome

In this study, we found that 74 patients with severe acute respiratory syndrome (SARS) exhibited a rapid, dramatic decrease in numbers of circulating myeloid and plasmacytoid dendritic cells (mDCs and pDCs) during the first 2 weeks of illness (5.3- and 28.4-fold reductions for mDCs and pDCs compared with 25 healthy individuals, respectively), with slow return to normal cell numbers during convalescence (weeks 5–7 of illness on average). In addition, numbers of circulating CD4 and CD8 T cells exhibited milder reductions (2.1- and 1.8-fold at week 1) and earlier return to normal at a mean of weeks 3 and 4, respectively. A significant inverse correlation was found between numbers of DC and T-cell subsets and high-dose steroid treatment. Our novel findings thus suggest that the acute SARS-coronavirus infection probably contributes to the initial reduction of DC and T-cell subsets in blood, and that high-dose steroid administration may subsequently exacerbate and prolong low expression of the cell subsets. These findings will aid the framing of further studies of the immunopathogenesis of SARS.

Antibody to severe acute respiratory syndrome (SARS)-associated coronavirus spike protein domain 2 cross-reacts with lung epithelial cells and causes cytotoxicity

Both viral effect and immune-mediated mechanism are involved in the pathogenesis of severe acute respiratory syndrome-associated coronavirus (SARS-CoV) infection. In this study, we showed that in SARS patient sera there were autoantibodies (autoAbs) that reacted with A549 cells, the type-2 pneumocytes, and that these autoAbs were mainly IgG. The autoAbs were detectable 20 days after fever onset. Tests of non-SARS-pneumonia patients did not show the same autoAb production as in SARS patients. After sera IgG bound to A549 cells, cytotoxicity was induced. Cell cytotoxicity and the anti-epithelial cell IgG level were positively correlated. Preabsorption and binding assays indicated the existence of cross-reactive epitopes on SARS-CoV spike protein domain 2 (S2). Furthermore, treatment of A549 cells with anti-S2 Abs and IFN-gamma resulted in an increase in the adherence of human peripheral blood mononuclear cells to these epithelial cells. Taken together, we have demonstrated that the anti-S2 Abs in SARS patient sera cause cytotoxic injury as well as enhance immune cell adhesion to epithelial cells. The onset of autoimmune responses in SARS-CoV infection may be implicated in SARS pathogenesis.

Severe acute respiratory syndrome and the innate immune responses: modulation of effector cell function without productive infection

Severe acute respiratory syndrome (SARS) caused by a novel human coronavirus (CoV), designated SARS-CoV, is a highly contagious respiratory disease with the lungs as a major target. Although the exact mechanism of SARS-CoV pathogenesis remains unknown, an intense, ill-regulated local inflammatory response has been suggested as partially responsible for the devastating lung pathology. We investigated the interaction of SARS-CoV with human macrophages (Mphi) and dendritic cells (DC), two key innate immune cells of the host immune system, by focusing on their susceptibility to viral infection and subsequent responses (e.g., phenotypic maturation, T cell-priming activity, phagocytosis, and cytokine production). We found neither cell to be permissive for SARS-CoV replication. However, incubation of Mphi and DC with live, but not gamma irradiation-inactivated, viruses appeared to better sustain their viability. Also, exposure to infectious SARS-CoV led to the phenotypic and functional maturation of DC, with regard to MHC class II and costimulatory molecule expression, T cell-stimulatory capacity, and cytokine production, respectively. Cytokine production was also observed for Mphi, which were refractory to cell surface phenotypic changes. Strikingly, live SARS-CoV could further prime cell types to respond to a suboptimal dose of bacterial LPS (100 ng/ml), resulting in massive release of IL-6 and IL-12. However, the endocytic capacity (e.g., Ag capture) of Mphi was significantly compromised upon exposure to infectious SARS-CoV. This study is the first demonstration that although SARS-CoV does not productively infect human Mphi or DC, it appears to exert differential effects on Mphi and DC maturation and functions, which might contribute to SARS pathogenesis.

Gene expression profiles in peripheral blood mononuclear cells of SARS patients

AIM: To investigate the role of inflammatory and anti-viral genes in the pathogenesis of SARS.

METHODS: cDNA microarrays were used to screen the gene expression profiles of peripheral blood mononuclear cells (PBMCs) in two SARS patients (one in the acute severe phase and the other in the convalescent phase) and a healthy donor. In addition, real-time qualitative PCR was also performed to verify the reproducibility of the microarray results. The data were further analyzed.

RESULTS: Many inflammatory and anti-viral genes were differentially expressed in SARS patients. Compared to the healthy control or the convalescent case, plenty of pro-inflammatory cytokines such as IL-1, TNF-α, IL-8, and MAPK signaling pathway were significantly upregulated in the acute severe case. However, anti-inflammatory agents such as IL-4 receptor, IL-13 receptor, IL-1Ra, and TNF-α-induced proteins 3 and 6 also increased dramatically in the acute severe case. On the contrary, a lot of IFN-stimulated genes like PKR, GBP-1 and 2, CXCL-10 and 11, and JAK/STAT signal pathway were downregulated in the acute severe case compared to the convalescent case.

CONCLUSION: Gene expression in SARS patients mirrors a host state of inflammation and anti-viral immunity at the transcription level, and understanding of gene expression profiles may make contribution to further studies of the SARS pathogenesis.

Pathogenesis of severe acute respiratory syndrome

Severe acute respiratory syndrome (SARS) is a zoonotic infectious disease caused by a novel coronavirus (CoV). The tissue tropism of SARS-CoV includes not only the lung, but also the gastrointestinal tract, kidney and liver. Angiotensin-converting enzyme 2 (ACE2), the C-type lectin CD209L (also known L-SIGN), and DC-SIGN bind SARS-CoV, but ACE2 appears to be the key functional receptor for the virus. There is a prominent innate immune response to SARS-CoV infection, including acute-phase proteins, chemokines, inflammatory cytokines and C-type lectins such as mannose-binding lectin, which plays a protective role against SARS. By contrast there may be a lack of type 1 interferon response. Moreover, lymphopenia with decreased numbers of CD4+ and CD8+ T cells is common during the acute phase. Convalescent patients have IgG-class neutralizing antibodies that recognize amino acids 441-700 of the spike protein (S protein) as the major epitope.

Cytokine profiles in human immunodeficiency virus-infected children treated with highly active antiretroviral therapy

CONTEXT

There have been few longitudinal studies of cytokine production in neonatally acquired HIV-1 infection and none in Asian or Chinese children.

OBJECTIVE

To determine whether monitoring cytokine production could contribute to the better management of pediatric patients with HIV-1 infection.

SETTING

Clinical Immunology Laboratory and Pediatrics Department, University Hospital, Hong Kong.

PATIENTS

Ten Asian and 2 Eurasian children infected with HIV-1 by mother-to-child transmission were followed for up to 5 years while on treatment with highly active antiretroviral therapy (HAART).

MAIN OUTCOME MEASURES

Numbers of unstimulated and mitogen-activated cytokine-secreting cells (IFN-gamma, interleukin [IL]-2, IL-4, IL-6, IL-10, IL-12, and TNF-alpha) were measured by ELISPOT assay at frequent intervals, and correlations were sought with CD4+ and CD8+ cell counts and viral loads.

RESULTS

Mitogen-stimulated IL-2-secreting cells were directly associated with recovery of CD4+ cells. Correlations with viral load were found for Con A-induced IFN-gamma, Con A-induced IL-4, and unstimulated IL-10, suggesting that these cytokines were either suppressed by high virus levels or that higher cytokine levels suppressed virus. IFN-gamma, IL-2-, IL-4-, and IL-12-secreting cells induced by PHA, Con A, and/or SAC tended to increase for the first 3-4 years of treatment but declined thereafter.

CONCLUSIONS

Alterations in cytokine profiles were not associated with adverse clinical events and there was little evidence to indicate that monitoring cytokine enzyme-linked immunospots (ELISPOTs) could contribute to pediatric patient management.

Cytokine profiles in human immunodeficiency virus-infected children treated with highly active antiretroviral therapy

Context

There have been few longitudinal studies of cytokine production in neonatally acquired HIV-1 infection and none in Asian or Chinese children.

Objective

To determine whether monitoring cytokine production could contribute to the better management of pediatric patients with HIV-1 infection.

Setting

Clinical Immunology Laboratory and Pediatrics Department, University Hospital, Hong Kong.

Patients

Ten Asian and 2 Eurasian children infected with HIV-1 by mother-to-child transmission were followed for up to 5 years while on treatment with highly active antiretroviral therapy (HAART).

Main Outcome Measures

Numbers of unstimulated and mitogen-activated cytokine-secreting cells (IFN-gamma, interleukin [IL]-2, IL-4, IL-6, IL-10, IL-12, and TNF-alpha) were measured by ELISPOT assay at frequent intervals, and correlations were sought with CD4+ and CD8+ cell counts and viral loads.

Results

Mitogen-stimulated IL-2-secreting cells were directly associated with recovery of CD4+ cells. Correlations with viral load were found for Con A-induced IFN-gamma, Con A-induced IL-4, and unstimulated IL-10, suggesting that these cytokines were either suppressed by high virus levels or that higher cytokine levels suppressed virus. IFN-gamma, IL-2-, IL-4-, and IL-12-secreting cells induced by PHA, Con A, and/or SAC tended to increase for the first 3-4 years of treatment but declined thereafter.

Conclusion

Alterations in cytokine profiles were not associated with adverse clinical events and there was little evidence to indicate that monitoring cytokine enzyme-linked immunospots (ELISPOTs) could contribute to pediatric patient management.

Characterization of cytokine/chemokine profiles of severe acute respiratory syndrome

RATIONALE

There is currently no optimal treatment or effective drug for severe acute respiratory syndrome (SARS), because the immunopathologic mechanism is poorly understood.

OBJECTIVES

To explore the immune mechanism underlying the pathogenesis of SARS, we studied the expression profile of cytokines/chemokines in the blood and the immunopathology of the lung and lymphoid tissues.

METHODS

Fourteen cytokines/chemokines in the blood of 23 patients with SARS were dynamically screened, using a bead-based multiassay system. Reverse transcription-polymerase chain reaction was performed to amplify mRNA. Histopathology of the lung and lymphoid tissues at autopsy was examined, using methods of immunohistochemistry and double immunofluorescence staining.

MAIN RESULTS

Interferon-inducible protein-10 (IP-10) was markedly elevated in the blood during the early stage of SARS, and remained at a high level until convalescence. Moreover, IP-10 was highly expressed in both lung and lymphoid tissues, where monocyte-macrophage infiltration and depletion of lymphocytes were observed. The levels of interleukin-6, interleukin-8, and monocyte chemoattractant protein-1 were concomitantly increased in the blood of the patients with superinfection, and the mRNAs for these cytokines were also increased in lung tissues.

CONCLUSIONS

Induction of IP-10 is a critical event in the initiation of immune-mediated acute lung injury and lymphocyte apoptosis during the development of SARS. Superinfection after the immune injury is the main cause of death. The prompt elevation of interleukin-6, interleukin-8, and monocyte chemoattractant protein-1 is a sign of superinfection, indicating a high risk of death.

Severe acute respiratory syndrome

Severe acute respiratory syndrome (SARS) was caused by a previously unrecognized animal coronavirus that exploited opportunities provided by 'wet markets' in southern China to adapt to become a virus readily transmissible between humans. Hospitals and international travel proved to be 'amplifiers' that permitted a local outbreak to achieve global dimensions. In this review we will discuss the substantial scientific progress that has been made towards understanding the virus-SARS coronavirus (SARS-CoV)-and the disease. We will also highlight the progress that has been made towards developing vaccines and therapies The concerted and coordinated response that contained SARS is a triumph for global public health and provides a new paradigm for the detection and control of future emerging infectious disease threats.

Mechanisms of host defense following severe acute respiratory syndrome-coronavirus (SARS-CoV) pulmonary infection of mice

We describe a model of severe acute respiratory syndrome-coronavirus (SARS-CoV) infection in C57BL/6 mice. A clinical isolate of the virus introduced intranasally replicated transiently to high levels in the lungs of these mice, with a peak on day 3 and clearance by day 9 postinfection. Viral RNA localized to bronchial and bronchiolar epithelium. Expression of mRNA for angiotensin converting enzyme 2, the SARS-CoV receptor, was detected in the lung following infection. The virus induced production in the lung of the proinflammatory chemokines CCL2, CCL3, CCL5, CXCL9, and CXCL10 with differential kinetics. The receptors for these chemokines were also detected. Most impressively, mRNA for CXCR3, the receptor for CXCL9 and CXCL10, was massively up-regulated in the lungs of SARS-CoV-infected mice. Surprisingly Th1 (and Th2) cytokines were not detectable, and there was little local accumulation of leukocytes and no obvious clinical signs of pulmonary dysfunction. Moreover, beige, CD1-/-, and RAG1-/- mice cleared the virus normally. Infection spread to the brain as it was cleared from the lung, again without leukocyte accumulation. Infected mice had a relative failure to thrive, gaining weight significantly more slowly than uninfected mice. These data indicate that C57BL/6 mice support transient nonfatal systemic infection with SARS-CoV in the lung, which is able to disseminate to brain. In this species, proinflammatory chemokines may coordinate a rapid and highly effective innate antiviral response in the lung, but NK cells and adaptive cellular immunity are not required for viral clearance.