Evaluation of the association of zoonotic Ljungan virus with perinatal deaths and fetal malformation

More and more epidemiologic and experimental data support the notion that Ljungan virus (LV), originally isolated from some rodent populations in Sweden, Denmark, and the United States, plays an important role in stillbirth and fetal malformation. Mouse dams infected with LV may result in uterine resorption and perinatal deaths that may cross generations, and their offspring may suffer high rates of malformations including cranial, brain, and limb malformations. In humans, researches founded that LV infection is related to malformation, intrauterine fetal death, and even central nervous system malformation. Although molecularly characterized, little is known about the biophysical nature of LV. Consequently, the role of LV infections in sudden infant death syndrome is still confusing, and the mechanism of how LV infections cause diseases is not clear. More research is clearly necessary to explore the mechanisms of LV infection in human and animal diseases to bring improvement to the clinical outcomes. Birth Defects Research (Part C) 105:81–85, 2015. © 2015 Wiley Periodicals, Inc.     

Viral and host proteins involved in picornavirus life cycle

Picornaviruses cause several diseases, not only in humans but also in various animal hosts. For instance, human enteroviruses can cause hand-foot-and-mouth disease, herpangina, myocarditis, acute flaccid paralysis, acute hemorrhagic conjunctivitis, severe neurological complications, including brainstem encephalitis, meningitis and poliomyelitis, and even death. The interaction between the virus and the host is important for viral replication, virulence and pathogenicity. This article reviews studies of the functions of viral and host factors that are involved in the life cycle of picornavirus. The interactions of viral capsid proteins with host cell receptors is discussed first, and the mechanisms by which the viral and host cell factors are involved in viral replication, viral translation and the switch from translation to RNA replication are then addressed. Understanding how cellular proteins interact with viral RNA or viral proteins, as well as the roles of each in viral infection, will provide insights for the design of novel antiviral agents based on these interactions.     

免疫系统在病毒性心肌炎发病中的作用

心肌炎通常由病毒感染引起,有证据表明心肌炎最终发展成扩张性心肌病,是发达国家主要致死的原因,越来越多的人认为细胞因子在心肌炎和心肌病发病中起重要作用,心力衰竭病人血循环中细胞因子水平较正常人高。已证明多种细胞因子能在体内外抑制心肌收缩,细胞因子由活化的免疫细胞产生,它可诱生NO合酶,继而产生NO,已证明NO既有利又有害,关键在于产生NO量的多少,NO能抑制病毒复制,而保护心脏抗柯萨奇B病毒感染,无论是病毒感染对心脏的直接作用,还是免疫应答的利弊平衡,对此两者分子机制的了解都将是掌握人类心肌炎发病的关键。     

Investigation of the genotype III to genotype I shift in Japanese encephalitis virus and the impact on human cases

Japanese encephalitis is a mosquito borne disease and is the leading cause of viral encephalitis in the Asia-Pacific area. The causative agent, Japanese encephalitis virus(JEV) can be phylogenetically classified into five genotypes based on nucleotide sequence. In recent years, genotype I(GI) has displaced genotype III(GIII) as the dominant lineage, but the mechanisms behind this displacement event requires elucidation. In an earlier study, we compared host variation over time between the two genotypes and observed that GI appears to have evolved to achieve more efficient infection in hosts in the replication cycle, with the tradeoff of reduced infectivity in secondary hosts such as humans. To further investigate this phenomenon, we collected JEV surveillance data on human cases and, together with sequence data, and generated genotype/case profiles from seven Asia-Pacific countries and regions to characterize the GI/GIII displacement event. We found that, when comprehensive and consistent vaccination and surveillance data was available, and the GIII to GI shift occurred within a well-defined time period, there was a statistically significant drop in JEV human cases. Our findings provide further support for the argument that GI is less effective in infecting humans, who represent a dead end host. However, experimental investigation is necessary to confirm this hypothesis. The study highlights the value of alternative approaches to investigation of epidemics, as well as the importance of effective data collection for disease surveillance and control.     

Infections by protozoa in immunocompromised hosts

Protozoa are among the most important pathogens that can cause infection in immunocompromised patients. They infect particularly individuals with impaired cell immunity, such as those with hematologic neoplasias, those submitted to transplant of solid organs, those under high-dose corticosteroid therapy, and carriers of the human immunodeficiency virus. Among the protozoa that most commonly cause disease in immunocompromised individuals are Toxoplasma gondii, Trypanosoma cruzi, Cryptosporidium parvum, Isospora belli, Cyclospora cayetanensis and microsporidia; the former two cause severe encephalitis and myocarditis, and the others cause gastrointestinal infections. Early diagnosis and prompt institution of specific therapy for each of these organisms are basic measures to decrease morbidity and mortality associated with these infections.     

Diagnosing and treating active myocarditis.

The treatment of dilated cardiomyopathy is palliative and, hence, has little effect on the natural history. Therapy directed toward the cause rather than the effect will be necessary before mortality can be affected. Active myocarditis is postulated to be the cause of dilated cardiomyopathy in a subset of patients. A model of murine coxsackievirus B3 myocarditis has immunopathogenic parallels to the disease in humans and suggests that persistent autoimmune reactivity following viral clearance leads to progressive myocyte damage and dilated cardiomyopathy. In preliminary uncontrolled studies, patients with myocarditis have shown clinical and histologic improvement with the addition of immunosuppressive therapy, but there may also be a significant rate of spontaneous improvement. A multicenter study currently acquiring patients is designed to determine the efficacy of immunosuppression and the natural history of active myocarditis.     

Central nervous system involvement in experimental Trypanosomiasis cruzi.

A review of the available literature on central nervous system involvement in experimental trypanosomiasis cruzi is undertaken. From a critical analysis of 26 works on experimental infections with Trypanosoma cruzi (23 on the acute phase, 2 on the chronic phase, and one describing sequentially both phases), all supported by neuropathologic studies, it can be concluded that: 1) central nervous system involvement during the acute phase, in the form of encephalitis in multiple foci, with variable intensity of the parasitism and inflammatory changes, is frequent and well documented; 2) in animals with more severe central nervous system involvement death occurs as a result of the brain lesions or acute chagasic myocarditis, the latter being always present; 3) in animals with more discrete brain involvement death during the acute phase is due to complications not related to the nervous system, among which congestive heart failure secondary to acute chagasic myocarditis, a condition that is always present, regardless of whether or not the central nervous system is infected; 4) it is possible that in surviving animals that had mild encephalitis the inflammatory changes from the acute phase usually regress as the infection progress to the chronic phase.     

Calpain inhibition protects against virus-induced apoptotic myocardial injury

Viral myocarditis is an important cause of human morbidity and mortality for which reliable and effective therapy is lacking. Using reovirus strain 8B infection of neonatal mice, a well-characterized experimental model of direct virus-induced myocarditis, we now demonstrate that myocardial injury results from apoptosis. Proteases play a critical role as effectors of apoptosis. The activity of the cysteine protease calpain increases in reovirus-infected myocardiocytes and can be inhibited by the dipeptide alpha-ketoamide calpain inhibitor Z-Leu-aminobutyric acid-CONH(CH(2))3-morpholine (CX295). Treatment of reovirus-infected neonatal mice with CX295 protects them against reovirus myocarditis as documented by (i) a dramatic reduction in histopathologic evidence of myocardial injury, (ii) complete inhibition of apoptotic myocardial cell death as identified by terminal deoxynucleotidyltransferase-mediated dUTP-biotin nick end labeling, (iii) a reduction in serum creatine phosphokinase, and (iv) improved weight gain. These findings are the first evidence for the importance of a calpain-associated pathway of apoptotic cell death in viral disease. Inhibition of apoptotic signaling pathways may be an effective strategy for the treatment of viral disease in general and viral myocarditis in particular.     

Immunity status against coxsackie viruses B in 25 patients with acute myocarditis

Viruses are an important cause of myocarditis, particularly the enterovirus group B coxsackievirus. Viral infection may be suspected on the basis of history and presentation and can be proved by direct or serological identification of virus. Twenty-five patients were diagnosed with acute myocarditis and were investigated with a serologic test battery covering Coxsackie viruses group B types 1 to 5 at the National Reference Center for Enteroviruses in Cantacuzino Institute Bucharest, Romania. A possible Coxsakie B virus etiology could be documented in 11 from 25 cases with acute myocarditis and high titers against Coxsackie virus B type 2 (1 patient), type 3 (5 patients) and type 5 (in 4 patients) were detected. In one HIV positive patient (17 years old), a concomitant infection with Coxsackie virus B types 2 and 4 was detected. The earlier detection of enterovirus myocarditis could be followed by antiviral therapies with a potential therapeutic role.     

Inhibition of apoptosis prevents West Nile virus induced cell death

Background  

West Nile virus (WNV) infection can cause severe meningitis and encephalitis in humans. Apoptosis was recently shown to contribute to the pathogenesis of WNV encephalitis. Here, we used WNV-infected glioma cells to study WNV-replication and WNV-induced apoptosis in human brain-derived cells.     

Suppressor of cytokine signaling 1 DNA administration inhibits inflammatory and pathogenic responses in autoimmune myocarditis

Myocarditis and subsequent dilated cardiomyopathy are major causes of heart failure in young adults. Myocarditis in humans is highly heterogeneous in etiology. Recent studies have indicated that a subgroup of myocarditis patients may benefit from immune-targeted therapies, because autoimmunity plays an important role in myocarditis as well as contributing to the progression to cardiomyopathy and heart failure. Suppressor of cytokine signaling (SOCS) 1 plays a key role in the negative regulation of both TLR- and cytokine receptor-mediated signaling, which is involved in innate immunity and subsequent adaptive immunity. In this study, we investigated the therapeutic effect of SOCS1 DNA administration on experimental autoimmune myocarditis (EAM) in mice. EAM was induced by s.c. immunization with cardiac-specific peptides derived from α myosin H chain in BALB/c mice. In contrast to control myocarditis mice, SOCS1 DNA-injected mice were protected from development of EAM and heart failure. SOCS1 DNA administration was effective for reducing the activation of autoreactive CD4(+) T cells by inhibition of the function of Ag-presenting dendritic cells. Our findings suggest that SOCS1 DNA administration has considerable therapeutic potential in individuals with autoimmune myocarditis and dilated cardiomyopathy.     

Coxsackievirus group B type 3 infection upregulates expression of monocyte chemoattractant protein 1 in cardiac myocytes, which leads to enhanced migration of mononuclear cells in viral myocarditis

Coxsackievirus group B type 3 (CVB3) is an important cause of viral myocarditis. The infiltration of mononuclear cells into the myocardial tissue is one of the key events in viral myocarditis. Immediately after CVB3 infects the heart, the expression of chemokine(s) by infected myocardial cells may be the first trigger for inflammatory infiltration and immune response. However, it is unknown whether CVB3 can induce the chemokine expression in cardiac myocytes. Monocyte chemoattractant protein 1 (MCP-1) is a potent chemokine that stimulates the migration of mononuclear cells. The objective of the present study was to investigate the effect of CVB3 infection on MCP-1 expression in murine cardiac myocytes and the role of MCP-1 in migration of mononuclear cells in viral myocarditis. Our results showed that the expression of MCP-1 was significantly increased in cardiac myocytes after wild-type CVB3 infection in a time- and dose-dependent manner, which resulted in enhanced migration of mononuclear cells in mice with viral myocarditis. The migration of mononuclear cells was partially abolished by antibodies specific for MCP-1 in vivo and in vitro. Administration of anti-MCP-1 antibody prevented infiltration of mononuclear cells bearing the MCP-1 receptor CCR2 in mice with viral myocarditis. Infection by UV-irradiated CVB3 induced rapid and transient expression of MCP-1 in cardiac myocytes. In conclusion, our results indicate that CVB3 infection stimulates the expression of MCP-1 in myocardial cells, which subsequently leads to migration of mononuclear cells in viral myocarditis.     

Suppression of annexin A1 and its receptor reduces herpes simplex virus 1 lethality in mice

Herpes simplex virus 1 (HSV-1)-induced encephalitis is the most common cause of sporadic, fatal encephalitis in humans. HSV-1 has at least 10 different envelope glycoproteins, which can promote virus infection. The ligands for most of the envelope glycoproteins and the significance of these ligands in virus-induced encephalitis remain elusive. Here, we show that glycoprotein E (gE) binds to the cellular protein, annexin A1 (Anx-A1) to enhance infection. Anx-A1 can be detected on the surface of cells permissive for HSV-1 before infection and on virions. Suppression of Anx-A1 or its receptor, formyl peptide receptor 2 (FPR2), on the cell surface and gE or Anx-A1 on HSV-1 envelopes reduced virus binding to cells. Importantly, Anx-A1 knockout, Anx-A1 knockdown, or treatments with the FPR2 antagonist reduced the mortality and tissue viral loads of infected mice. Our results show that Anx-A1 is a novel enhancing factor of HSV-1 infection. Anx-A1-deficient mice displayed no evident physiology and behavior changes. Hence, targeting Anx-A1 and FPR2 could be a promising prophylaxis or adjuvant therapy to decrease HSV-1 lethality.     

Pneumocystis carinii,Toxoplasma gondii,Cytomegalovirus and the Compromised Host

Pneumocystis carinii and Toxoplasma gondii are the two major parasitic protozoan pathogens in the immunocompromised host. Both organisms cause latent infection in humans and many animals. Cats are the definitive hosts for toxoplasmosis; the animal vector for pneumocystis (if any) has not been defined. Toxoplasma is an obligate intracellular parasite, whereas the available evidence suggests that Pneumocystis carinii exists primarily extracellularly. In compromised hosts, pneumocystis infection usually involves only lungs, whereas toxoplasma causes a generalized infection with encephalitis being the principal clinical manifestation. Both types of infection are treated with combinations of folate antagonists (trimethoprim or pyrimethamine with sulfonamide). Both parasites are associated with cytomegalovirus infection in immunosuppressed hosts, an association which may be due to symbiosis between parasites, or to an additive immunosuppressive effect of dual infection on the hosts.     

Fatal neonatal toxoplasmosis in a bobcat (Lynx rufus)

Toxoplasma gondii was found in tissues of a captive 1-week-old bobcat (Lynx rufus) that died of myocarditis, hepatitis and encephalitis. Although infection is common in wild Felidae, clinical toxoplasmosis is rarely seen. In this case, the infection was apparently congenitally acquired.     

Herpes B virus replication and viral lesions in the liver of a cynomolgus macaque which died from severe disease with rapid onset

Herpes B virus (BV, Macacine alphaherpesvirus 1) infects macaques asymptomatically, with rare exceptions, but can cause fatal encephalitis in humans. Here, we report disseminated BV infection in a cynomolgus macaque that had died within 12 hour after the onset of unspecific symptoms. Multifocal lesions surrounded by viral antigen were detected in liver while other organs remained inconspicuous, indicating that the liver is a major target. Moreover, high copy numbers of viral DNA were found in feces, underlining the excrements are a potential source of transmission.     

Japanese encephalitis virus infects neural progenitor cells and decreases their proliferation

Japanese encephalitis virus (JEV), a common cause of encephalitis in humans, especially in children, leads to substantial neuronal injury. The survivors of JEV infection have severe cognitive impairment, motor and behavioral disorders. We hypothesize that depletion of neural progenitor cells (NPCs) by the virus culminates in neurological sequelae in survivors of Japanese encephalitis (JE). We utilized both in vivo model of JEV infection and in vitro neurosphere cultures to study progressive JEV infection. Cellular infection and cell death was determined by flow cytometry. BrdU administration in animals and in neurospheres was used to determine the proliferative ability of NPCs. JEV leads to massive loss of actively proliferating NPC population from the subventricular zone (SVZ). The ability of JEV infected subventricular zone cells to form neurospheres is severely compromised. This can be attributed to JEV infection in NPCs, which however do not result in robust death of the resilient NPC cells. Instead, JEV suppresses the cycling ability of these cells, preventing their proliferation. JEV primarily targets at a critical postnatal age and severely diminishes the NPC pool in SVZ, thus impairing the process of recovery after the insult. This arrested growth and proliferation of NPCs might have an effect on the neurological consequences in JE survivors.     

Regulatory effects of IL-18 on cytokine profiles and development of myocarditis during Trypanosoma cruzi infection

Chagas disease, caused by Trypanosoma cruzi (Tc), is an important cause of heart disease. Resistance to Tc infection is multifactorial and associated with Th1 response. IL-18 plays an important role in regulation of IFN-γ production/development of Th1 response. However, the role of IL-18 in the setting of Tc infection remains unclear. Therefore, we investigated the role of IL-18 in the modulation of immune response and myocarditis in Tc infection. C57BL/6 and IL-18 KO mice were infected with Tc (Y or Colombian strain) and parasitemia, immune response and pathology were evaluated. Y strain infection of IL-18 KO did not alter any parameters when compared with C57BL/6 mice. However, during the acute phase (20 and 40 days post infection-dpi), Colombian strain infected-IL-18 KO mice displayed higher serum levels of IL-12 and IFN-γ, respectively, and at the chronic phase (100 dpi) an increase in splenic IFN-γ-producing CD4⁺ and CD8⁺ T memory cells. There was an IL-10, FOXP3 and CD4⁺CD25⁺ cells reduction during acute infection in spleen. Additionally, there was a significant reduction in leukocyte infiltration and parasite load in myocardium of chronically infected IL-18 KO mice. Collectively, these data indicate that IL-18 contributes to the pathogenesis of Tc-induced myocarditis when infected with Colombian but not Y strain. These observations also underscore that parasite and host strain differences are important in evaluation of experimental Tc infection pathogenesis.     

A new model for Hendra virus encephalitis in the mouse

Hendra virus (HeV) infection in humans is characterized by an influenza like illness, which may progress to pneumonia or encephalitis and lead to death. The pathogenesis of HeV infection is poorly understood, and the lack of a mouse model has limited the opportunities for pathogenetic research. In this project we reassessed the role of mice as an animal model for HeV infection and found that mice are susceptible to HeV infection after intranasal exposure, with aged mice reliably developing encephalitic disease. We propose an anterograde route of neuroinvasion to the brain, possibly along olfactory nerves. This is supported by evidence for the development of encephalitis in the absence of viremia and the sequential distribution of viral antigen along pathways of olfaction in the brain of intranasally challenged animals. In our studies mice developed transient lower respiratory tract infection without progressing to viremia and systemic vasculitis that is common to other animal models. These studies report a new animal model of HeV encephalitis that will allow more detailed studies of the neuropathogenesis of HeV infection, particularly the mode of viral spread and possible sequestration within the central nervous system; investigation of mechanisms that moderate the development of viremia and systemic disease; and inform the development of improved treatment options for human patients.     

柯萨奇病毒B5的VP1区域基因特征分析及蛋白二级结构预测

柯萨奇病毒B组5型(Coxsackievirus B5,CVB5)感染人体后可引起一系列疾病,包括上呼吸道感染、腹泻、手足口病(Hand,foot,and mouth disease,HFMD)、病毒性脑炎、无菌性脑膜炎、胰腺炎、弛缓性麻痹、扩张性心肌炎以及糖尿病等症状。为了解云南省手足口病和疱疹性咽峡炎患者中CVB5的分子特征,本研究从2018-2019年昆明市儿童医院收集的HFMD和疱疹性咽峡炎(Herpangina,HA)患者粪便中分离得到9株CVB5,基于CVB5的VP1区的系统进化树以及蛋白二级结构的预测来分析分离株的基因序列特征以及与CVB5原型株Faulkner之间的差异,并对CVB5的分子流行病学特征进行分析。结果显示,2018-2019年分离株均属于E基因簇,与Faulkner株相比,所有分离株的VP1区域的氨基酸出现共同的10个氨基酸突变且增加了1个蛋白连接位点。本研究初步探索了肠道病毒CVB5进化过程中突变导致患者症状的差异以及揭示CVB5的全球流行趋势。