Lujun Zhang

Meta-Analysis of Infectious Agents and Depression

Depression is a debilitating psychiatric disorder and a growing global public health issue. However, the relationships between microbial infections and depression remains uncertain. A computerized literature search of Medline, ISI Web of Knowledge, PsycINFO, and the Cochrane Library was conducted up to May 2013, and 6362 studies were initially identified for screening. Case-control studies detected biomarker of microorganism were included. Based on inclusion and exclusion criteria, 28 studies were finally included to compare the detection of 16 infectious agents in unipolar depressed patients and healthy controls with a positive incident being defined as a positive biochemical marker of microbial infection. A customized form was used for data extraction. Pooled analysis revealed that the majority of the 16 infectious agents were not significantly associated with depression. However, there were statistically significant associations between depression and infection with Borna disease virus, herpes simplex virus-1, varicella zoster virus, Epstein-Barr virus, and Chlamydophila trachomatis.

Real-Time qPCR Identifies Suitable Reference Genes for Borna Disease Virus-Infected Rat Cortical Neurons

Quantitative real-time reverse transcription polymerase chain reaction (RT-qPCR) is the most commonly-used technique to identify gene expression profiles. The selection of stably expressed reference genes is a prerequisite to properly evaluating gene expression. Here, the suitability of commonly-used reference genes in normalizing RT-qPCR assays of mRNA expression in cultured rat cortical neurons infected with Borna disease virus (BDV) was assessed. The expressions of eight commonly-used reference genes were comparatively analyzed in BDV-infected rat cortical neurons and non-infected control neurons mainly across 9 and 12 days post-infection. These reference genes were validated by RT-qPCR and separately ranked by four statistical algorithms: geNorm, NormFinder, BestKeeper and the comparative delta-Ct method. Then, the RankAggreg package was used to construct consensus rankings. ARBP was found to be the most stable internal control gene at Day 9, and ACTB at Day 12. As the assessment of the validity of the selected reference genes confirms the suitability of applying a combination of the two most stable references genes, combining the two most stable genes for normalization of RT-qPCR studies in BDV-infected rat cortical neurons is recommended at each time point. This study can contribute to improving BDV research by providing the means by which to obtain more reliable and accurate gene expression measurements.

Human borna disease virus infection impacts host proteome and histone lysine acetylation in human oligodendroglia cells

Abstract Background Borna disease virus (BDV) replicates in the nucleus and establishes persistent infections in mammalian hosts. A human BDV strain was used to address the first time, how BDV infection impacts the proteome and histone lysine acetylation (Kac) of human oligodendroglial (OL) cells, thus allowing a better understanding of infection-driven pathophysiology in vitro. Methods Proteome and histone lysine acetylation were profiled through stable isotope labeling for cell culture (SILAC)-based quantitative proteomics. The quantifiable proteome was annotated using bioinformatics. Histone acetylation changes were validated by biochemistry assays. Results Post BDV infection, 4383 quantifiable differential proteins were identified and functionally annotated to metabolism pathways, immune response, DNA replication, DNA repair, and transcriptional regulation. Sixteen of the thirty identified Kac sites in core histones presented altered acetylation levels post infection. Conclusions BDV infection using a human strain impacted the whole proteome and histone lysine acetylation in OL cells.

Proteomics reveal energy metabolism and mitogen-activated protein kinase signal transduction perturbation in human Borna disease virus Hu-H1-infected oligodendroglial cells.

Abstract Borna disease virus (BDV) is a neurotropic, non-cytolytic RNA virus which replicates in the cell nucleus targeting mainly hippocampal neurons, but also astroglial and oligodendroglial cells in the brain. BDV is associated with a large spectrum of neuropsychiatric pathologies in animals. Its relationship to human neuropsychiatric illness still remains controversial. We could recently demonstrate that human BDV strain Hu-H1 promoted apoptosis and inhibited cell proliferation in a human oligodendroglial cell line (OL cells) whereas laboratory BDV strain V acted contrariwise. Here, differential protein expression between BDV Hu-H1-infected OL cells and non-infected OL cells was assessed through a proteomics approach, using two-dimensional electrophoresis followed by matrix-assisted laser desorption ionization-time of flight tandem mass spectrometry. A total of 63 differential host proteins were identified in BDV Hu-H1-infected OL cells compared to non-infected OL cells. We found that most changes referred to alterations related to the pentose phosphate pathway, glyoxylate and dicarboxylate metabolism, the tricarboxylic acid (TCA) cycle, and glycolysis /gluconeogenesis. By manual querying, two differential proteins were found to be associated with mitogen-activated protein kinase (MAPK) signal transduction. Five key signaling proteins of this pathway (i.e., p-Raf, p-MEK, p-ERK1/2, p-RSK, and p-MSK) were selected for Western blotting validation. p-ERK1/2 and p-RSK were found to be significantly up-regulated, and p-MSK was found to be significantly down-regulated in BDV Hu-H1-infected OL cells compared to non-infected OL cell. Although BDV Hu-H1 constitutively activated the ERK–RSK pathway, host cell proliferation and nuclear translocation of activated pERK in BDV Hu-H1-infected OL cells were impaired. These findings indicate that BDV Hu-H1 infection of human oligodendroglial cells significantly perturbs host energy metabolism, activates the downstream ERK–RSK complex of the Raf/MEK/ERK signaling cascade, and disturbs host cell proliferation possibly through impaired nuclear translocation of pERK, a finding which warrants further research.

Health care professionals at risk of infection with Borna disease virus - evidence from a large hospital in China (Chongqing)

BackgroundHuman Borna disease virus (BDV) infections have recently been reported in China. BDV causes cognitive and behavioural disturbances in animals. The impact on human mental disorders is subject to debate, but previous studies worldwide have found neuropsychiatric patients more frequently infected than healthy controls. A few isolates were recovered from severely depressed patients, but contagiousness of BDV strain remains unknown.MethodWe addressed the risk of infection in health care settings at the first affiliated hospital of Chongqing Medical University (CQMU), located in downtown Chongqing, a megacity in Southwest China. Between February 2012 and March 2013, we enrolled 1529 participants, of whom 534 were outpatients with major depressive disorder (MDD), 615 were hospital personnel, and 380 were healthy controls who underwent a health check. Infection was determined through BDV-specific circulating immune complexes (CIC), RNA, and selective antibodies (blood).ResultsOne-fifth of the hospital staff (21.8%) were found to be infected (CIC positive), with the highest prevalence among psychiatry and oncology personnel, which is twice as many as were detected in the healthy control group (11.1%), and exceeds the prevalence detected in MDD patients (18.2%).ConclusionBDV circulates unnoticed in hospital settings in China, putting medical staff at risk and warranting clarification of infection modes and introduction of prevention measures.

GC-MS-Based Metabonomic Profiling Displayed Differing Effects of Borna Disease Virus Natural Strain Hu-H1 and Laboratory Strain V Infection in Rat Cortical Neurons.

Borna disease virus (BDV) persists in the central nervous systems of a wide variety of vertebrates and causes behavioral disorders. Previous studies have revealed that metabolic perturbations are associated with BDV infection. However, the pathophysiological effects of different viral strains remain largely unknown. Rat cortical neurons infected with human strain BDV Hu-H1, laboratory BDV Strain V, and non-infected control (CON) cells were cultured in vitro. At day 12 post-infection, a gas chromatography coupled with mass spectrometry (GC–MS) metabonomic approach was used to differentiate the metabonomic profiles of 35 independent intracellular samples from Hu-H1-infected cells (n = 12), Strain V-infected cells (n = 12), and CON cells (n = 11). Partial least squares discriminant analysis (PLS-DA) was performed to demonstrate discrimination between the three groups. Further statistical testing determined which individual metabolites displayed significant differences between groups. PLS-DA demonstrated that the whole metabolic pattern enabled statistical discrimination between groups. We identified 31 differential metabolites in the Hu-H1 and CON groups (21 decreased and 10 increased in Hu-H1 relative to CON), 35 differential metabolites in the Strain V and CON groups (30 decreased and 5 increased in Strain V relative to CON), and 21 differential metabolites in the Hu-H1 and Strain V groups (8 decreased and 13 increased in Hu-H1 relative to Strain V). Comparative metabonomic profiling revealed divergent perturbations in key energy and amino acid metabolites between natural strain Hu-H1 and laboratory Strain V of BDV. The two BDV strains differentially alter metabolic pathways of rat cortical neurons in vitro. Their systematic classification provides a valuable template for improved BDV strain definition in future studies.

Glutamate and Lipid Metabolic Perturbation in the Hippocampi of Asymptomatic Borna Disease Virus-Infected Horses

Borna disease virus (BDV) is a neurotropic, enveloped, non-segmented, negative-stranded RNA virus that infects a wide variety of vertebrate species from birds to humans across a broad global geographic distribution. Animal symptomatology range from asymptomatic infection to behavioral abnormalities to acute meningoencephalitis. Asymptomatic BDV infection has been shown to be more frequent than conventionally estimated. However, the molecular mechanism(s) underyling asymptomatic BDV infection remain largely unknown. Here, based on real-time quantitative PCR and Western blotting, a total of 18 horse hippocampi were divided into BDV-infected (n = 8) and non-infected control (n = 10) groups. A gas chromatography coupled with mass spectrometry (GC-MS) metabolomic approach, in conjunction with multivariate statistical analysis, was used to characterize the hippocampal metabolic changes associated with asymptomatic BDV infection. Multivariate statistical analysis showed a significant discrimination between the BDV-infected and control groups. BDV-infected hippocampi were characterized by lower levels of D-myo-inositol-1-phosphate, glutamate, phosphoethanolamine, heptadecanoic acid, and linoleic acid in combination with a higher level of ammonia. These differential metabolites are primarily involved in glutamate and lipid metabolism. These finding provide an improved understanding of hippocampal changes associated with asymptomatic BDV infection.

Amplification refractory mutation system polymerase chain reaction versus optimized polymerase chain reaction restriction-fragment length polymorphism for apolipoprotein E genotyping of majorly depressed patients

Major depressive disorder (MDD) is a prevalent, debilitating mood disorder that has been associated with several genetic polymorphisms. One such polymorphism, namely that of apolipoprotein E (APOE), has three allelic forms (ε2, ε3 and ε4) that encode for six unique isoforms of the APOE protein. A growing number of techniques have been developed for APOE genotyping; however, not all polymerase chain reaction (PCR)‑based genotyping techniques are equally accurate or cost‑effective. In order to find a more accurate and cost‑effective APOE genotyping method for MDD screening in large populations, the present study comparatively evaluated two genotyping methods, amplification refractory mutation system PCR (ARMS‑PCR) and optimized PCR restriction‑fragment length polymorphism (PCR‑RFLP), in blood samples taken from a population of 708 MDD patients. Although either of the two methods were able to detect all six unique APOE genotypes, comparisons of the two methods with Sanger sequencing demonstrated that ARMS‑PCR (94%) was significantly more accurate than optimized PCR‑RFLP (82%). ARMS‑PCR should prove useful in quickly verifying ambiguous results obtained by other APOE genotyping methods and can be cost-effectively performed in the setting of a small laboratory or a population-based screening program.