HERV-W upregulation expression in bipolar disorder and schizophrenia: unraveling potential links to systemic immune/inflammation status

BACKGROUND

Bipolar disorder (BD) and schizophrenia (SZ) are the two main mental disorders with unknown etiology that significantly impact individuals' quality of life. The potential pro-inflammatory role in their pathogenesis is postulated and Human Endogenous Retrovirus W (HERV-W) is an emerging candidate to modulate this pathogenic finding. HERVs, ancient retroviruses in the human genome, may play roles in inflammation and disease pathogenesis. Despite HERVs' involvement in autoimmune diseases, their influence on mental disorders remains underexplored. Therefore, the aim of this study was to assess the level of HERV-W-env expression and the systemic inflammatory profile through the concentration of IL-2, IL-4, IL-6, IL-10, TNF-α and INF-γ cytokines in BD and SZ patients.

RESULTS

All participants showed HERV-W-env expression, but its expression was higher in mental disorder patients (p < 0.01) than in control. When separated, SZ individuals exhibited higher HERV-W expression than the control group (p < 0.01). Higher serum levels of TNF-α and IL-10 were found in BD (p = 0.0001 and p = 0.001, respectively) and SZ (p = 0.01) and p = 0.01, respectively) than in the control group, while SZ showed decreased levels IFN-γ and IL-2 as compared to controls (p = 0.05) and BD patients (p = 0.05), respectively. Higher TNF-α/IL-4 and TNF-α/IL-10 ratios, and lower IFN-γ/IL-10 were observed in BD and SZ patients than controls. Significant negative correlation between HERV-W-env expression and IL-10 (r=-0.47 p < 0.05), as well as positive correlations between HERV-W-env expression and TNF-α/IL-10 or IFN-γ/IL-10 ratios (r = 0.48 p < 0.05 and r = 0.46 p < 0.05, respectively) were found in BD patients.

CONCLUSION

These findings suggest not only a potential link between HERV-W-env expression both in BD and SZ, but also a possible involvement of systemic inflammatory status in BD patients.

HERV-W Envelope Triggers Abnormal Dopaminergic Neuron Process through DRD2/PP2A/AKT1/GSK3 for Schizophrenia Risk

An increasing number of studies have begun considering human endogenous retroviruses (HERVs) as potential pathogenic phenomena. Our previous research suggests that HERV-W Envelope (HERV-W ENV), a HERV-W family envelope protein, is elevated in schizophrenia patients and contributes to the pathophysiology of schizophrenia. The dopamine (DA) hypothesis is the cornerstone in research and clinical practice related to schizophrenia. Here, we found that the concentration of DA and the expression of DA receptor D2 (DRD2) were significantly higher in schizophrenia patients than in healthy individuals. Intriguingly, there was a positive correlation between HERV-W ENV and DA concentration. Depth analyses showed that there was a marked consistency between HERV-W ENV and DRD2 in schizophrenia. Studies in vitro indicated that HERV-W ENV could increase the DA concentration by regulating DA metabolism and induce the expression of DRD2. Co-IP assays and laser confocal scanning microscopy indicated cellular colocalization and a direct interaction between DRD2 and HERV-W ENV. Additionally, HERV-W ENV caused structural and functional abnormalities of DA neurons. Further studies showed that HERV-W ENV could trigger the PP2A/AKT1/GSK3 pathway via DRD2. A whole-cell patch-clamp analysis suggested that HERV-W ENV enhanced sodium influx through DRD2. In conclusion, we uncovered a relationship between HERV-W ENV and the dopaminergic system in the DA neurons. Considering that GNbAC1, a selective monoclonal antibody to the MSRV-specific epitope, has been promised as a therapy for treating type 1 diabetes and multiple sclerosis (MS) in clinical trials, understanding the precise function of HERV-W ENV in the dopaminergic system may provide new insights into the treatment of schizophrenia.

A model of human endogenous retrovirus (HERV) activation in mental health and illness

Despite strong evidence for the heritability of major depressive disorder (MDD), efforts to identify causal genes have been disappointing. Furthermore, although there is strong support for life stress as a major predictor of MDD, there are also considerable individual differences in susceptibility and resilience that remain poorly understood. Efforts to identify specific gene-by-environment risk factors produced results that were initially encouraging, but that were not supported by later large-scale studies. Here I propose a novel mechanism that could address the "missing heritability" of MDD, the role of environmental risk factors, and individual differences in susceptibility and resilience. This mechanism focuses on a class of transposable elements, Human Endogenous Retroviruses (HERVs), which make up approximately 8% of the human genome as the result of ancient retroviral infections that entered mammalian germ lines throughout the course of evolution. My primary hypothesis is that exposure to either exogenous viruses or traumatic experiences can activate HERVs in the brain to cause depressive (and possibly other psychiatric) symptoms. My secondary hypothesis is that individual differences in vulnerability or resilience result from the balance of activated HERVs with pathogenic versus protective functions in the brain. Future research can test these hypotheses by analysis of postmortem human brain tissue from donors with known viral or trauma histories; animal studies manipulating HERV expression; cell culture studies examining regulatory mechanisms of HERV expression; and from brain imaging studies of individuals with known HERV-expression. Such research may reveal novel functions of HERVs in neural tissue and may lead to a new generation of psychiatric interventions designed to target aberrant HERV activation.

Transcription of human endogenous retroviruses in human brain by RNA-seq analysis

Background

Human endogenous retroviruses (HERV) comprise 8% of the human genome and can be classified into at least 31 families. Increased levels of transcripts from the W and H families of HERV have been observed in association with human diseases, such as multiple sclerosis and schizophrenia. Although HERV transcripts have been detected in many tissues and cell-types based on microarray and PCR studies, the extent of HERV expression in different cell-types and diseases state has been less comprehensively studied.

Results

We examined overall transcription of HERV, and particularly of HERV-W and HERV-H elements in human postmortem brain samples obtained from individuals with psychiatric diagnoses (n = 111) and healthy controls (n = 51) by analyzing publicly available RNA sequencing datasets. Sequence reads were aligned to prototypical sequences representing HERV, downloaded from Repbase. We reported a consistent expression (0.1~0.2% of mappable reads) of different HERV families across three regions of human brains. Spearman correlations revealed highly correlated expression levels between three brain regionsacross 475 consensus sequences. By mapping sequences that aligned to the consensus sequences of HERV-W and HERV-H families to individual loci on chromosome 7, more than 60 loci from each family were identified, part of which are being transcribed. The ERVWE1, locus located at chr7q21.2, exhibited high levels of transcription across the three datasets. Notably, we demonstrated a trend of increased expression of overall HERV, as well as HERV-W family in samples from both schizophrenia and bipolar disorder patients.

Conclusions

The current analyses indicate that RNA sequencing is a useful approach for investigating global expression of repetitive elements, such as HERV, in the human genome. HERV-W/H with the tendency of transcription up-regulation in patients suggests potential implication of HERV-W/H in psychiatric diseases.

Determining the IgM and IgG antibodies titer against HSV1, HSV2 and CMV in the serum of schizophrenia patients

Schizophrenia is a destructive clinical syndrome with diverse mental pathologies. Different mechanisms and factors have a role in this disease. A possible mechanism is that teratogenic viruses cause brain changes and results in the disease appearance. The schizophrenia patients were diagnosed by psychologists and with the consent of patients, five CC of venous blood was drawn. Than Serum samples were isolated and immunoglobulin M (IgM) and immunoglobulin G (IgG) antibodies against herpes simplex virus-1 (HSV-1), herpes simplex virus-2 (HSV-2) and cytomegalovirus (CMV) were quantified by ELISA sandwich kit. The Results showed that anti-CMV and anti-HSV1 and anti-HSV2 IgG antibodies in schizophrenia patients were increased significantly (p< 0.05). The increasing of the anti-HSV2 IgM was also observed but increasing amount of the anti-HSV1 IgM was not statistically significant (p< 0.05). Therefore, as a result of this study CMV and HSV1 and HSV2 infection can probably intensify the symptoms in schizophrenia patients.

Infection and inflammation in schizophrenia and bipolar disorder: a genome wide study for interactions with genetic variation

Inflammation and maternal or fetal infections have been suggested as risk factors for schizophrenia (SZ) and bipolar disorder (BP). It is likely that such environmental effects are contingent on genetic background. Here, in a genome-wide approach, we test the hypothesis that such exposures increase the risk for SZ and BP and that the increase is dependent on genetic variants. We use genome-wide genotype data, plasma IgG antibody measurements against Toxoplasma gondii, Herpes simplex virus type 1, Cytomegalovirus, Human Herpes Virus 6 and the food antigen gliadin as well as measurements of C-reactive protein (CRP), a peripheral marker of inflammation. The subjects are SZ cases, BP cases, parents of cases and screened controls. We look for higher levels of our immunity/infection variables and interactions between them and common genetic variation genome-wide. We find many of the antibody measurements higher in both disorders. While individual tests do not withstand correction for multiple comparisons, the number of nominally significant tests and the comparisons showing the expected direction are in significant excess (permutation p=0.019 and 0.004 respectively). We also find CRP levels highly elevated in SZ, BP and the mothers of BP cases, in agreement with existing literature, but possibly confounded by our inability to correct for smoking or body mass index. In our genome-wide interaction analysis no signal reached genome-wide significance, yet many plausible candidate genes emerged. In a hypothesis driven test, we found multiple interactions among SZ-associated SNPs in the HLA region on chromosome 6 and replicated an interaction between CMV infection and genotypes near the CTNNA3 gene reported by a recent GWAS. Our results support that inflammatory processes and infection may modify the risk for psychosis and suggest that the genotype at SZ-associated HLA loci modifies the effect of these variables on the risk to develop SZ.

Virus etiology of schizophrenia: the characteristics of the "*Little Ice Age" and its consequences

The data of the "Little Ice Age" (1500-1850) in Croatia and those which applied to human health were especially emphasized were analyzed. They are some which stand out like: importance of the sort of soil and relief, the influence of cutting down of woods and cattle-breeding and especially the war which lasted for 250 years in the territory of Croatia. The important interactions between those parameters were defined. The important correlations were also defined between freezing and long winters as well as wet springs and summers which caused starvation, malnutrition and the increase of infant mortality and also epidemics with enormous psychological stress among people in that period. The result was witch-hunting and burning (which was also advocated in the other parts of Europe) and they sometimes reached the levels of madness. Considering that such events were unknown in the earlier periods (in such proportions) and that (even today) the influence of the slow virus is emphasized in connection to the etiology of schizophrenia so why should't it be supposed that the "Litlle Ace Age" could be the cause of the larger prevalence of schizophrenia in the teritory of Croatia.

[Pathogenic significance and possible pathogenic mechanism of human endogenous viruses in development of schizophrenia]

The association between psychogenic illness and human endogenous viruses (HEVs), including human endogenous retrovirus and Borna disease virus, remains unclear. As the component of human genome, HEVs may become the joint of various pathogenic factors of schizophrenia (SZ), such as heredity, environment, and immunity. In this review, we strive to uncover the clinical and laboratory evidence for the roles and possible pathogenic mechanism of HEVs in the development of SZ.

Persistent infection with neurotropic herpes viruses and cognitive impairment

BACKGROUND

Herpes virus infections can cause cognitive impairment during and after acute encephalitis. Although chronic, latent/persistent infection is considered to be relatively benign, some studies have documented cognitive impairment in exposed persons that is untraceable to encephalitis. These studies were conducted among schizophrenia (SZ) patients or older community dwellers, among whom it is difficult to control for the effects of co-morbid illness and medications. To determine whether the associations can be generalized to other groups, we examined a large sample of younger control individuals, SZ patients and their non-psychotic relatives (n=1852). Method Using multivariate models, cognitive performance was evaluated in relation to exposures to herpes simplex virus type 1 (HSV-1), herpes simplex virus type 2 (HSV-2) and cytomegalovirus (CMV), controlling for familial and diagnostic status and sociodemographic variables, including occupation and educational status. Composite cognitive measures were derived from nine cognitive domains using principal components of heritability (PCH). Exposure was indexed by antibodies to viral antigens.

RESULTS

PCH1, the most heritable component of cognitive performance, declines with exposure to CMV or HSV-1 regardless of case/relative/control group status (p = 1.09 × 10-5 and 0.01 respectively), with stronger association with exposure to multiple herpes viruses (β = -0.25, p = 7.28 × 10-10). There were no significant interactions between exposure and group status.

CONCLUSIONS

Latent/persistent herpes virus infections can be associated with cognitive impairments regardless of other health status.

GABBR1 has a HERV-W LTR in its regulatory region--a possible implication for schizophrenia

Schizophrenia is a complex disease with uncertain aetiology. We suggest GABBR1, GABA receptor B1 implicated in schizophrenia based on a HERV-W LTR in the regulatory region of GABBR1. Our hypothesis is supported by: (i) GABBR1 is in the 6p22 genomic region most often implicated in schizophrenia; (ii) microarray studies found that only presynaptic pathway-related genes, including GABA receptors, have altered expression in schizophrenic patients and (iii) it explains how HERV-W elements, expressed in schizophrenia, play a role in the disease: by altering the expression of GABBR1 via a long terminal repeat that is also a regulatory element to GABBR1.

Effects of two commonly found strains of influenza A virus on developing dopaminergic neurons, in relation to the pathophysiology of schizophrenia

Influenza virus (InfV) infection during pregnancy is a known risk factor for neurodevelopment abnormalities in the offspring, including the risk of schizophrenia, and has been shown to result in an abnormal behavioral phenotype in mice. However, previous reports have concentrated on neuroadapted influenza strains, whereas increased schizophrenia risk is associated with common respiratory InfV. In addition, no specific mechanism has been proposed for the actions of maternal infection on the developing brain that could account for schizophrenia risk. We identified two common isolates from the community with antigenic configurations H3N2 and H1N1 and compared their effects on developing brain with a mouse modified-strain A/WSN/33 specifically on the developing of dopaminergic neurons. We found that H1N1 InfV have high affinity for dopaminergic neurons in vitro, leading to nuclear factor kappa B activation and apoptosis. Furthermore, prenatal infection of mothers with the same strains results in loss of dopaminergic neurons in the offspring, and in an abnormal behavioral phenotype. We propose that the well-known contribution of InfV to risk of schizophrenia during development may involve a similar specific mechanism and discuss evidence from the literature in relation to this hypothesis.

Serum antibodies to Toxoplasma gondii and Herpesvidae family viruses in individuals with schizophrenia and bipolar disorder: a case-control study

BACKGROUND

Recent etiological studies for schizophrenia and bipolar disorder have focused on the protozoan Toxoplasma gondii and Herpesvirdae family viruses.

OBJECTIVE

To determine the magnitude of T. gondii, cytomegalovirus (CMV), herpes simplex virus type 1 (HSV-1) and herpes simplex virus type 2 (HSV-2) infection in individuals with schizophrenia, bipolar disorder and healthy controls by using serologic diagnostic methods.

MATERIAL AND METHODS

Serologic diagnostic method was used to determine the prevalence and level of antibodies to T gondii, CMV HSV-1 and HSV-2 in individuals with schizophrenia, bipolar disorder, and unaffected controls recruited from Butajira, Ethiopia. The study was conducted from March to May 2009. A total of 495 serum samples were analysed for the presence and level of immunoglobulin G (IgG) to T. gondii, CMV HSV-1, and HSV-2.

RESULTS

The seroprevalence of T gondii infection was higher in individuals with schizophrenia [adjusted odds ratio = 4.7; 95% CI (1.5, 15.1)] and bipolar disorder [adjusted odds ratio = 3.0; 95% CI (1.1, 8.6)] than in unaffected controls. The level of IgG to CMV was also significantly higher in individuals with schizophrenia and bipoar disorder than in unaffected controls. Younger individuals with schizophrenia (< 25 years old) also had a significantly higher level of IgG to CMV than matched unaffected controls.

CONCLUSION

This study provides additional evidence that infection with 7T gondii and CMV may be associated with some cases of schizophrenia and bipolar disorder. Additional studies should focus on antibodies to these agents in the sera and CSF of individuals with recent-onset psychosis.

Grey matter changes associated with host genetic variation and exposure to Herpes Simplex Virus 1 (HSV1) in first episode schizophrenia

BACKGROUND

We previously reported reduced prefrontal cortex (PFC) grey matter volume among first episode, antipsychotic-naïve schizophrenia subjects (SZ) exposed to HSV1 but not among healthy subjects (HS) (Prasad et al., 2007). Independently, rs1051788, an exonic polymorphism of the MHC Class I polypeptide-related sequence B (MICB) gene was associated with HSV1 seropositivity, as well as SZ risk. In this study, we examined whether PFC grey matter changes associated with HSV1 exposure varied against the background of MICB genotypes.

METHODS

We examined Caucasian individuals from the sample we studied in our previous report (Prasad et al., 2007) (SZ, n=21 and HS, n=19). Whole brain voxelwise analysis of structural MRI scans was conducted using Statistical Parametric Mapping, ver 5 (SPM5). The impact of rs1051788 variation and HSV1 seropositivity on grey matter volumes was examined using regression models on the combined sample of cases and controls, and then within each diagnostic group.

RESULTS

In the combined sample of cases and controls, we observed the main effects of HSV1 seropositivity and genotypes, and a significant joint effect of HSV1 seropositivity and genotype mainly in the PFC. The joint effect was more prominent among cases than among controls.

DISCUSSION

Our observations suggest that rs1051788 and HSV1 seropositivity are associated individually and jointly with reduced PFC grey matter volume. The patterns of these associations differ by diagnostic status, and these factors explain only a "small" portion of the variance in the grey matter volume reductions.

Borna disease virus circulating immunocomplex positivity and psychopathology in psychiatric patients in the Czech Republic

OBJECTIVES

Borna disease virus (BDV) is an RNA virus belonging to the family Bornaviridae. BDV is a neurotropic virus that causes changes in mood, behaviour and cognition. Patients with psychiatric disorders have a higher incidence of BDV positivity than healthy individuals.

METHODS

We examined the seropositivity of BDV circulating immunocomplexes (CIC) in psychiatric patients and healthy individuals (blood donors). We examined 39 psychiatric inpatients for the presence of BDV CIC in the serum by ELISA on day 0, 28 and 56. During the same period psychopathology was measured using psychiatric scales (CGI, CGI-I, MADRS, SDS, PANSS). This is the first such study performed in the Czech Republic.

RESULTS

BDV CIC positivity was detected in 66.7% of psychiatric patients (26/39) on day 0, in 53.9% (14/26) on day 28 and in 52.9% on day 56 (9/17). The control group was 22.2% (28/126) positive. The incidence of BDV CIC was significantly higher in psychiatric patients than in healthy individuals (p=0.001). The significantly higher level of BDV CIC was associated with the higher severity of psychopathology in comparison with patients with mild or moderate psychopathology (p=0.03). We did not find any association between BDV CIC positivity and other characteristics (age, diagnosis, family, personal history, the history of infectious diseases, contact with animals).

CONCLUSION

In our study psychiatric patients had significantly higher levels of BDV CIC than the control group. The highest levels of BDV CIC were detected in patients with more severe psychopathology.

Schizophrenia and viral infection during neurodevelopment: a pathogenesis model?

The neurodevelopmental hypothesis of schizophrenia proposes that a portion of schizophrenia is the result of an early brain insult which affects brain development and in which several types of virus might play an etiological role. The main arguments in favor of the neurodevelopmental hypothesis and the involvement of prenatal exposure to virus infection as a risk factor for adult schizophrenia are reviewed. Schizophrenia is associated with an increased incidence of craniofacial asymmetries and dermatoglyphic irregularities which might reflect an abnormal development of the ectoderm and the neural crest as a result of a viral infection between the first and second trimester of pregnancy. The brain histology of deceased schizophrenic patients shows disturbed neuronal migration and formations such as disorganized lamina strata or ectopic pyramidal cells, abnormal expression of the neural cell adhesion molecule, and absence of gliosis. The main epidemiological arguments are derived from studies of obstetrical complications and influenza virus infection during pregnancy, both considered to be early risk factors of schizophrenia. Because no virus has been consistently linked with the pathogenesis of schizophrenia, the most plausible hypothesis is that an endemic virus could initiate schizophrenia by direct brain lesion or by triggering an autoimmune response during the neurodevelopmental period on a genetically susceptible brain. In a neurodevelopmental model, the viral hypothesis is a step toward the goal of building a comprehensive theory that integrates the environmental, genetic, immune, and neuropsychological features of schizophrenia.

Polymorphisms in MICB are associated with human herpes virus seropositivity and schizophrenia risk

Viral infection may be a risk factor for schizophrenia and has been associated with decreased cognitive functioning in patients. We report associations of SNPs at MICB (MHC class I polypeptide-related sequence B, chromosome 6p21) with cytomegalovirus and herpes simplex virus 1 seropositivity. We previously found associations with schizophrenia on chromosome 6p21 among patients seropositive for cytomegalovirus (CMV) and herpes simplex virus 1 (HSV1). To localize the associations further, we genotyped 26 SNPs spanning 100 kb in a sample of 236 Caucasian schizophrenia patients and 240 controls. Based on suggestive associations, we selected five SNPs at MICB to assay among two additional Caucasian samples that had been serotyped for CMV and HSV1: a case-control sample recruited in Baltimore (n=272 cases, 108 controls), and a case-parent trio sample recruited in Pittsburgh (n=221). Among Baltimore control individuals there were significant associations with antibody status for infectious agents: rs1051788 with HSV1 seropositivity (p=0.006) and rs2523651 with cytomegalovirus seropositivity (p=0.001). The former association was also detectable among the parents of cases recruited in Pittsburgh (p=0.024). Neither viral association was noted among the schizophrenia cases. With respect to schizophrenia risk, significant transmission distortion was noted at rs1051788 and rs1055569 among the case-parent trios regardless of antibody status (p=0.014 and 0.036 respectively). A similar trend for association with schizophrenia liability at rs1051788 in the Baltimore sample did not attain statistical significance. There are a number of explanations for the associations, including chance variation, as well as gene-virus interactions. Further replicate studies are warranted, as are functional studies of these polymorphisms.

Elevated levels of human endogenous retrovirus-W transcripts in blood cells from patients with first episode schizophrenia

We previously reported on the differential presence of transcripts related to the human endogenous retrovirus (HERV)-W family in cerebrospinal fluid and plasma from patients with first-episode schizophrenia compared with control individuals. Whether this is a consequence of qualitative or quantitative differences in transcription of genomic regions harboring HERV-W elements is not known. The purpose of the present study was therefore to characterize the transcribed HERV-W elements in mononuclear cells obtained from 30 patients first hospitalized for schizophrenia-related psychosis and from 26 healthy control individuals. We observed elevated total levels of HERV-W gag (2.1-fold, P < 0.01) but not env transcripts in the cells of patients compared with controls. By using the melting temperatures of the amplicons as a proxy marker for sequence identity, no absolute qualitative differences was detected between the two groups. Mapping of the detected transcripts identified several intronic and intergenic HERV-W elements transcribed in the cells, including elements previously considered transcriptionally silent. Element-specific assays revealed elevated levels of intronic transcripts containing HERV-W gag sequence from the putative gene PTD015 on chromosome 11q13.5 (1.6-fold, P < 0.05) in the patients compared with the controls. Thus, studies aiming to further understanding of complex human disease such as schizophrenia may need to be extended beyond the strictly protein-coding fraction of the transcriptome.

Prenatal influenza exposure and delivery complications: implications for the development of schizophrenia

This study assessed prenatal influenza exposure in relation to pregnancy complications and delivery complications. Participants of this study consisted of a community sample of all mothers of 1,795 children who were a birth cohort recruited at age 3 in a prospective longitudinal project in Mauritius. The onset of the 1968-1972 A2/Hong Kong influenza epidemic in January 1970 was established from officially published death rates and newspaper records. Data on pregnancy and delivery complications were derived from hospital and clinic records. The study found that prenatal exposure to influenza was associated with increased delivery complications, F(1,351) = 12.2, P = 0.001. There was no effect of influenza exposure on pregnancy complications. The findings have implications for theories on both the development of schizophrenia and other behavior processes. From a public health perspective, reducing influenza exposure in young women of childbearing age might be a critically important first step in the prevention of adverse psychiatric outcomes associated with obstetric complications.

Reduced expression of human endogenous retrovirus (HERV)-W GAG protein in the cingulate gyrus and hippocampus in schizophrenia, bipolar disorder, and depression

The human endogenous retrovirus (HERV)-W multicopy family was identified in human DNA from the previously characterized multiple sclerosis associated retroviral element (MSRV). Upregulation of the HERV-W POL has been reported in cerebrospinal fluid of patients with schizophrenia. The expression of capsid (GAG) protein of HERV-W was studied by immunohistochemistry and western blotting in postmortem brain tissue of the anterior cingulate cortex and hippocampal formation of normal controls and of patients with schizophrenia, bipolar disorder and major depression. A physiological expression of GAG protein was detected in neurons as well as astroglial cells in normal brain both in the anterior cingulate cortex and in the hippocampal formation. There was a statistically significant reduction of this expression in neurons and astroglial cells in brains from individuals with schizophrenia, major depression, and bipolar disorder. The results from the present study confirm that GAG protein encoded by the HERV-W multicopy gene family is expressed in cells of the central nervous system under normal conditions. Our findings of a cell type-, brain region- and disease-specific reduced expression in schizophrenia, major depression, and bipolar disorder are compatible with a pathophysiological role of HERVs in human brain disorders. The causes and biological consequences of this differential regulation will be the subject of further investigations.

Brain morphological changes associated with exposure to HSV1 in first-episode schizophrenia

Infectious agents have been proposed as one of the risk factors for schizophrenia. However, the data on the association of infectious agents with in vivo brain changes are scant. We evaluated the association of serological evidence of exposure to herpes simplex virus 1 (HSV1) with in vivo brain structural variations among first-episode antipsychotic-naive schizophrenia/schizoaffective disorder patients and control subjects. We assayed HSV1 immunoglobulin G (IgG) antibody in serum samples from 30 patients and 44 healthy subjects and obtained structural magnetic resonance imaging scans from the same individuals. There were proportionately more patients with elevated HSV1 antibody ratios than healthy comparison subjects (chi2=3.98, 1 df, P=0.046) and patients had significantly higher HSV1 IgG antibody ratios compared with healthy subjects. Using optimized voxel-based morphometry, we examined diagnosis by HSV1 serological status interaction followed by within- and between-group comparison across the serological status. We observed a diagnosis by HSV1 serological status interaction and a significant main effect of HSV1 serological status in the prefrontal gray matter. Patients exposed to HSV1 had decreased gray matter in Brodmann area 9 (dorsolateral prefrontal cortex) and 32 (anterior cingulate cortex) compared with patients without serological evidence of exposure to HSV1. HSV1-associated differences in brain structure were not detected among healthy subjects. These findings suggest that HSV1 exposure in schizophrenia is associated with specific regional gray matter differences that may not be attributable to medications, illness chronicity or comorbid substance use. This study provides suggestive evidence for a link between HSV1 exposure and some of the cerebral morphological changes often reported in schizophrenia.

Insertional polymorphism of endogenous retrovirus HERV-K115 in schizophrenia

Retroviruses are implicated in the pathogenesis of schizophrenia. Human endogenous retrovirus type K115 (HERV-K115) is a full-length, potentially transcriptional retrovirus and is also polymorphic. We investigated the frequency of HERV-K115 in Japanese schizophrenia patients and healthy controls. No difference was found in the frequency between patients and controls (8.4% versus 9.4%, respectively). However, a marginal difference was observed in age at onset between the HERV-K positive and negative patients (p=0.057). The HERV-K115 insertion appeared to be more frequent in patients with younger onset than those with later onset. These results preliminarily suggest that HERV-K115 may not be associated with schizophrenia in general, but that it could play a partial role in early precipitation of the disease.

Detection of adeno-associated virus 2 and parvovirus B19 in the human dorsolateral prefrontal cortex

Although animal parvoviruses have long been recognized as causes of brain pathology in multiple animal models, especially during early development, human parvoviruses are rarely thought of as neurotropic or causes of neuropathology in humans. However, several recent case reports have suggested possible associations of parvovirus B19 (B19) infection with various neurological and neuropsychiatric symptoms. Adeno-associated virus 2 (AAV2) is related to B19 but has thus far not been shown to be associated with any human disease but is of clinical interest because of the recent use of recombinant AAV vectors in human gene therapy, including gene delivery to the brain. To date, there have been no large-scale studies of the propensity of wild-type human parvoviruses to infect the brain. The Stanley Medical Research Institute Brain Collection offered a unique opportunity to study a large sample (n = 104) of dorsolateral prefrontal cortex (DLPC) DNAs isolated from unaffected control, schizophrenic, and bipolar disorder brains for the presence of parvoviral sequences. This is the first investigator-blinded study to document the presence of parvoviral sequences in the DLPC by utilizing highly sensitive nested polymerase chain reaction (nPCR) and DNA sequencing. Of the overall sample, 6.7% to 12.5% were positive for AAV2, and 14.4% to 42.3% were positive for B19 sequences, with no statistical differences among subgroups. This is the first report to demonstrate the presence of human parvoviruses in a large cohort of adult DLPC, which underscores the need to gain a better insight into the basic biology of parvovirus-brain interactions, including mechanisms of infection and persistence.

Human endogenous retroviral pol RNA and protein detected and identified in the blood of individuals with schizophrenia

Retrovirus has been speculated as one of the potential infectious agents involved in the development of schizophrenia. Here we used nested RT-PCR to detect the RNA of HERV pol gene in blood from schizophrenic patients and normal human. We found retroviral pol genes expressed in blood from 20 of 58 (34.5%) individuals with recent-onset schizophrenia, but not from 38 normal persons (p<0.01). Sequence analysis revealed that the expressed gene was homologous to those of the human endogenous retroviral (HERV) family. The ERV9 family was the closest, with 90% homology in the gene sequence. In addition, Western blots showed that antibody against ERV9 pol protein in serum from the HERV+ schizophrenia patients, but not from control (p<0.01). Our data suggested that the transcriptional activation of certain retroviral elements might be associated with the development of schizophrenia in some patients. Further characterization of retroviral elements in subjects with schizophrenia may aid in better diagnosis and treatment of this disorder.

Detection of Borna disease virus p24 RNA in peripheral blood cells from Brazilian mood and psychotic disorder patients

BACKGROUND

Borna disease virus (BDV) is a virus that naturally infects a broad range of warm-blooded animals. BDV is an enveloped virus, non-segmented, negative-stranded RNA genome and has an organization characteristic of a member of Bornaviridae in the order of Mononegavirale. In the present work we investigated the presence of BDV p24 RNA in peripheral blood cells from 30 psychiatric patients (19 with mood disorder and 11 with psychotic disorder) and 30 healthy volunteers as the control group.

METHODS

All subjects were interviewed by structured diagnostic criteria categorized according to the DSM-IV, Axis I (SCID-V). The presence of BDV p24 RNA was investigated by nested reverse transcriptase PCR (RT-PCR) using specific primers to p24 from BDV. The specificity of the detection was analyzed by the sequencing of PCR products.

RESULTS

The mean duration of illness in mood and psychotic patients with p24 RNA of BDV was 25 (+/-12.3) years and the median age was 43.77 (+/-15.2) years. There were no significant differences in gender and age among patients and control group, neither duration of illness among patients with mood and psychotic disorders in the presence or absence of p24 RNA of BDV. We found a frequency of 33.33% (10/30) of BDV-RNA on patient's group and 13.33% (4/30) on control group. The given sequences revealed identity with GenBank database sequence for BDV.

CONCLUSION

The detection of a higher level of BDV-RNA in the peripheral blood cells of patients than on control group should help our understanding of the pathogenesis in the disease.

Detection by radioligand assay of antibodies against Borna disease virus in patients with various psychiatric disorders

Using a radioligand assay, which preserves the natural form of the antigen, antibodies against Borna disease virus nucleoprotein and phosphoprotein were detected in 11 and 19 sera of 171 psychiatric patients, respectively. Compared with results by Western blotting, three and nine sera were concordantly positive, respectively. The four sera showing the highest levels of antibodies by radioligand assay were all negative by Western blotting; however, dilution and inhibition tests supported the positive results. Our results suggest the importance of conformational structure to detect human anti-Borna disease virus antibodies.

Human endogenous retrovirus expression profiles in samples from brains of patients with schizophrenia and bipolar disorders

The detection and identification of retroviral transcripts in brain samples, cerebrospinal fluid, and plasma of individuals with recent-onset schizophrenia and schizoaffective disorders suggest that activation or upregulation of distinct human endogenous retroviruses (HERVs) may play a role in the etiopathogenesis of neuropsychiatric diseases. To test this hypothesis, we performed a comprehensive microarray-based analysis of HERV transcriptional activity in human brains. We investigated 50 representative members of 20 HERV families in a total of 215 brain samples derived from individuals with schizophrenia or bipolar disorders and matched controls. A characteristic brain-specific retroviral activity profile was found that consists of members of the class I families HERV-E, HERV-F, and ERV9 and members of HERV-K taxa. In addition to these constitutively expressed HERVs, a number of differentially active HERV elements were identified in all brain samples independent of the disease pattern that may reflect differences in the genetic background of the tested individuals. Only a subgroup of the HML-2 family (HERV-K10) was significantly overrepresented in both bipolar-disorder- and schizophrenia-associated samples compared to healthy brains, suggesting a potential association with disease. Real-time PCR analysis of HERV env transcripts with coding capacity potentially involved in neuroinflammatory conditions revealed that env expression of HERV-W, HERV-FRD, and HML-2 remains unaffected regardless of the clinical picture. Our data suggest that HERV transcription in brains is weakly correlated with schizophrenia and related diseases but may be influenced by the individual genetic background, brain-infiltrating immune cells, or medical treatment.

Prenatal viral infection in mouse causes differential expression of genes in brains of mouse progeny: a potential animal model for schizophrenia and autism

Schizophrenia and autism are neurodevelopmental disorders with genetic and environmental etiologies. Prenatal viral infection has been associated with both disorders. We investigated the effects of prenatal viral infection on gene regulation in offspring of Balb-c mice using microarray technology. The results showed significant upregulation of 21 genes and downregulation of 18 genes in the affected neonatal brain homogenates spanning gene families affecting cell structure and function, namely, cytosolic chaperone system, HSC70, Bicaudal D, aquaporin 4, carbonic anhydrase 3, glycine receptor, norepinephrine transporter, and myelin basic protein. We also verified the results using QPCR measurements of selected mRNA species. These results show for the first time that prenatal human influenza viral infection on day 9 of pregnancy leads to alterations in a subset of genes in brains of exposed offspring, potentially leading to permanent changes in brain structure and function.

Prevalence and genotypic distribution of hepatitis GB-C/HG and TT viruses in blood donors, mentally retarded children and four groups of patients in eastern Anatolia, Turkey

We investigated the prevalence and genotypic distribution of GB virus-C/hepatitis G virus (GBV-C/HGV) and TT virus (TTV) in blood donors, mentally retarded children and four groups of patients living in Eastern Anatolia, Turkey. The prevalence and genetic analysis of TTV were determined by using the primers of the UTR and ORF1 regions of TTV, respectively. Reverse transcription nested (RT-n)-PCR was used to amplify 5' UTR of GBV-C/HGV. Genotyping of HGV was carried out by PCR-based genotyping assay while RFLP was conducted to determine the genotypes of TTV. TTV DNA was detected in 118 of 410 sera tested, giving an overall prevalence of 28.7%; GBV-C/HGV-RNA was detected in only 17 cases, giving an overall prevalence of 4.1%. No significant differences were observed in the number of positive or negative tests for GBV-C/HGV and TTV according to duration of illness or mean duration of institutionalization in any of the groups studied. Although all samples from the study population belonged to genotypes 1 and 4, the most common TTV genotype is G2. In conclusion, our results indicate a low endemicity of GBV-C/HGV and TTV infection in Eastern Anatolia, Turkey. The presence of G2 strains reveals the limited genetic diversity of the GBV-C/HGV circulating in Turkey. We suggest that TTV infection of genotypes 1 and 4 is prevalent in the same region.

[Antiretroviral therapy for HIV-infected patients with schizophrenia. Coordinated multidisciplinary management (7 cases)]

OBJECTIVE

Schizophrenia might appear to be an obstacle to the initiation of and especially compliance with antiretroviral therapy for HIV-infected patients. The aims of this study were to describe the clinical, immunologic and virologic course after initiation of antiretroviral therapy in 7 HIV patients with schizophrenia (according to DSM-IV-R criteria), and to analyse the possibilities of an adequate antiretroviral therapy for those patients.

OBSERVATIONS

Multidisciplinary management by specialists in infectious diseases, addiction-related disorders, treatment adherence and compliance, and psychiatrists, as well as social workers, home care agencies, and patient advocacy and assistance groups, was organized with coordinated medical-psychiatric follow-up at least once a month. The patients, 6 men and 1 woman, were aged from 26 to 48 years; schizophrenia had been diagnosed in 5 patients 6 months to 20 years before the HIV infection was discovered; diagnoses of both diseases were essentially simultaneous for the other 2. All patients took long-term neuroleptics for their schizophrenia. Two were active drug addicts who received drug substitution treatment. Before antiretroviral treatment began, 6 patients had advanced infection: stage C with peak CD4 cell counts ranging from 6 to 70/mm3; they began treatment with protease inhibitors between May 1996 and August 1997. The seventh patient was first seen during primary HIV infection in July 1998, and treatment began then. Response to antiretroviral treatment with protease inhibitors was slow for all patients, but viral load became undetectable for 6 of the 7, after 5 months to 4 years; 3 had opportunistic infections. Follow-up ended in January 2002: 5 patients still had undetectable viral loads,, with CD4 cell counts ranging from 45 to 1 000/mm3. One patient died from mixed terminal cirrhosis (alcohol abuse and hepatitis C); the viral load in another was only partially controlled (10 000 copies/ml), because of poor treatment adherence.

CONCLUSION

Individuals with schizophrenia can respond well to antiretroviral treatment, although response may appear slow; they can adhere to complex treatment regimens as long as they receive well coordinated and sustained multidisciplinary support.

[Could the fetus' exposure to influenza increase the risk of schizophrenia in adult life?]

INTRODUCTION

Epidemiological studies indicate the existence of various environmental factors, which elevate the risk of schizophrenia in adult life. Influenza infection is a widely discussed causal factor in the relation to schizophrenia. The paper is a review of the studies on the theme of exposition to viral infections in foetal life--in connection with schizophrenia morbidity in adult life. Many of such studies, and yet not all of them show such a relationship.

AIM

The aim of our study was to find the effect of influenza exposition in foetal life on the increase in schizophrenia morbidity of the Polish population, by applying the seasonal decomposition method.

METHOD

All persons discharged from hospitals in Poland with a diagnosis of schizophrenia in the years 1997-2000 were taken up for the study. The data on the population births in the given months of the period 1964-1984 was also used. Monthly indices of the number of births of patients with a diagnosis of schizophrenia per 10,000 live births in the general population of men and women was applied in order to eliminate the seasonal variability due to the unstable number of births in the general population. The number of influenza cases in Poland was divided by the number of inhabitants and multiplied by 10,000 thus forming indices of influenza cases in the subsequent months of the period studied. The seasonal decomposition method--Census I--was used for the basic analyses--this being one of the methods of time interval analyses available in the Statistica programme.

RESULTS

The study results show that exposition to influenza infections 2-4 months prior to birth may be a risk factor in schizophrenia development in adult life.

Viruses and schizophrenia: a focus on herpes simplex virus

Various factors have been implicated in the pathogenesis of schizophrenia. Evidence for an infectious cause includes the 5-8% increased risk among those born in the winter-spring months, when infectious diseases are more prevalent and at times when other infections (measles, varicella, poliomyelitis) show increased activity. Herpes simplex virus (HSV) has been implicated in schizophrenia as it has a tropism for the nervous system and is capable of replication in the brain. Although post-mortem studies of brain tissue of schizophrenic patients have failed to detect the virus, these studies have been hampered by the unknown cellular localization of HSV genomes and by attempting to detect the virus years after the symptom onset. A more recent, nested, case-control study evaluated pregnant women between 1959 and 1966 and identified 27 surviving offspring who were later diagnosed with schizophrenia. Analysis of stored blood samples showed an association between high levels of maternal antibody to HSV-2 and subsequent development of adult psychosis. No association was found between HSV-1 infection and psychosis. There is also evidence that human endogenous retroviruses (HERVs) may play a role in schizophrenia, as antibodies to these agents have been found at a greater frequency in the sera of affected individuals compared with controls. This is supported by the presence of reverse transcriptase, a retroviral marker, at levels four times higher in the cerebrospinal fluid (CSF) of people with recent onset schizophrenia compared with controls, and by its elevated presence in long-term schizophrenic patients. Further research to investigate the relationship between virus infection and schizophrenia is warranted.

Childhood central nervous system infections and risk for schizophrenia

Central nervous system (CNS) viral infections have been suggested to increase the risk of schizophrenia, although most of the evidence is indirect and comes from rather few studies on exposure to various infections in general. In the Northern Finland 1966 Birth Cohort the association between schizophrenia and other psychoses and childhood CNS infections has been analysed, and in this paper we present the follow-up results up to the end of 1994 and 1997. Data regarding the infections were collected prospectively between 1966-1980 and data on psychoses from 1982. The registered psychiatric diagnoses were validated using the DSM-III-R classification. Out of the 11017 subjects (96% of all births in that year) 145 had suffered a CNS infection during childhood, which in 102 cases was a viral infection. In the follow-up to the end of 1994, 76 had schizophrenia, and their number increased to 100 to the end of 1997. In addition, up to the end of 1994, 52 patients had a non-schizophrenic psychosis. Four cases in the schizophrenia patient group and none of the patients with other psychosis had suffered a viral CNS infection. None of the schizophrenia cases and two of the patients with other psychosis had had a bacterial infection. The adjusted odds ratio for schizophrenia after a viral CNS infection was 4.8 (95% confidence intervals [CI] 1.6-14.0) in the follow-up to the end of 1994 and 2.5 (0.9-7.0) in the follow-up to the end of 1997. The clinical course variables did not differ between the schizophrenia patients with or without CNS infection. Our results suggest that viral CNS infections during childhood may have a role as a risk factor for schizophrenia. Their role may be modest at the population level due to their relative rareness.

Antibodies to infectious agents in individuals with recent onset schizophrenia

We investigated the levels of antibodies to infectious agents in the serum and cerebral spinal fluids (CSFs) of individuals with recent onset schizophrenia and compared these levels to those of controls without psychiatric disease. We found that untreated individuals with recent onset schizophrenia had significantly increased levels of serum and CSF IgG antibody to cytomegalovirus and Toxoplasma gondii as compared to controls. The levels of serum IgM class antibodies to these agents were not increased. Untreated individuals with recent onset schizophrenia also had significantly lower levels of serum antibody to human herpesvirus type 6 and varicella zoster virus as compared to controls. Levels of antibodies to herpes simplex virus type 1, herpes simplex virus type 2, and Epstein Barr virus, and did not differ from cases and controls. We also found that treatment status had a major effect on the levels of antibodies in this population. Individuals who were receiving treatment had lower levels of antibodies to cytomegalovirus and Toxoplasma gondii, and higher levels of serum antibodies to human herpesvirus type 6 as compared to untreated individuals. The level of antibodies to Toxoplasma and human herpesvirus type 6 measured in treated individuals did not differ from the levels measured in controls. In the case of cytomegalovirus, the levels of CSF antibodies in treated individuals did not differ from those of controls, while the level of serum IgG antibodies to CMV remained slightly greater than controls in this population. Our studies indicate that untreated individuals with recent onset schizophrenia have altered levels of antibodies to cytomegalovirus, Toxoplasma gondii, and human herpesvirus type 6 while the levels of these antibodies in treated individuals with recent onset schizophrenia are similar to those of controls. These findings indicate that infectious agents may play a role in the etiopathogenesis of some cases of schizophrenia.

[Cerebrospinal fluid filtration as experimental therapy in therapy refractory psychoses in Borna disease virus seropositive patients. Therapeutic effects, findings]

According to previous investigations, mild Borna disease virus encephalitis may underlie a subgroup of affective or schizophrenic type psychoses. And virus-induced immune pathology may underlie even a larger subgroup of psychoses. We treated BDV seropositive patients suffering from therapy resistant schizophrenic or affective spectrum psychoses by cerebrospinal fluid filtration (CSFF) in an experimental add-on treatment. CSFF was shown previously to be an effective immune modulatory treatment in autoimmune neurological disease, Guillain-Barré syndrome. CSFF appears to be an effective treatment in therapy resistant psychosis also, but only 4 patients were treated yet.

Prenatal exposure to influenza as a risk factor for adult schizophrenia

OBJECTIVE

Several, but not all epidemiological studies, have demonstrated a positive correlation between exposure to the virus during the second trimester of pregnancy and an increased risk to the infants for subsequently developing schizophrenia. The present study is the first be designed in France to examine the risk of gestational exposure to the influenza virus and subsequent development of schizophrenia.

METHOD

A total of 974 adults with schizophrenia born between 1949 and 1981 were compared for risk of exposure to influenza with their non-schizophrenic siblings and with matched control patients.

RESULTS

Significantly more schizophrenic subjects than controls (both groups) had been exposed to the influenza virus during the fifth month of pregnancy (OR=2.24, CI: 1.49-3.35, and OR=1.61, CI: 1.04-2.49).

CONCLUSION

These results suggest that influenza infection during pregnancy is a neurodevelopmental risk factor for schizophrenia in adult life.

Herpesviruses and Toxoplasma gondii in orbital frontal cortex of psychiatric patients

Herpes simplex virus (HSV), Epstein-Barr virus (EBV), cytomegalovirus (CMV), and human herpesvirus-6 (HHV-6) are viruses capable of establishing latency. All of these infect the CNS and have been detected in human postmortem brains. Toxoplasma gondii is a protozoan organism which can reactivate in the brains of previously infected immunocompromised individuals. To screen for the presence of herpesviruses and T. gondii in postmortem orbital frontal brain samples from patients with schizophrenia, affective disorders, and controls, we used nested-polymerase chain reaction (n-PCR)/sequencing. We identified HHV-6B sequences in 2/51 postmortem brain samples but no sequences from other herpesviruses. We did not detect sequences of T. gondii in the postmortem brains. Additional studies including ones directed at the sensitive detection of viral nucleic acids in multiple brain regions should be directed at confirming or excluding a role for viruses and protozoa in the etiology of these disorders.

[Detection of Borna disease virus-p24 specific antibody in the sera of schizophrenic patients of China by means of Western-blot]

BACKGROUND

To investigate whether Borna disease virus (BDV) infection is related to the schizophrenic patients from China.

METHODS

A reliable Western-blot method for detection of BDV-p24 antibody was established by adjusting the reaction conditions of BDV-p24 recombinant protein and specific antibodies. The sera of schizophrenic patients and normal controls from Heilongjiang Province were screened for specific BDV-p24 antibody by this method, and the BDV-p24 antibody positive sera were confirmed by the Western-blot method with sera-GST protein absorption.

RESULTS

Ten of 116 (8.6%) schizophrenic patients were found to be positive for BDV-p24 specific antibody, while no BDV-p24 specific antibody was found in sera of normal controls.

CONCLUSIONS

The results demonstrate that the Borna disease virus infection also exists in China, and the infection is possibly associated with schizophrenia in some way.

Genes, germs, and schizophrenia: an evolutionary perspective

Literature on schizophrenia and other mental illnesses has emphasized the compatibility of evidence with genetic causation without adequately considering alternative hypotheses of disease causation. Although some studies from the mid-20th century reported associations between certain pathogens and schizophrenia, only recently has the possibility of infectious causation of schizophrenia again become an active focus of research. Infectious causation of schizophrenia is still, however, generally regarded as less well demonstrated than genetic causation. This article evaluates the evidence that has been used to support genetic and infectious causation. Our consideration of infectious causation focuses on the protozoan Toxoplasma gondii but also assesses other pathogens that may contribute to the development of some of the illnesses currently categorized as schizophrenia. Although evidence generally accepted as demonstrating genetic causation can be readily explained by hypotheses of infectious causation, some of the evidence implicating infectious causation cannot be similarly explained by genetic causation. This asymmetry indicates that a scientific approach to the causation of schizophrenia needs to put a greater emphasis on tests that distinguish hypotheses of genetic causation from those of infectious causation.

Schizophrenia and viral infection during neurodevelopment: a focus on mechanisms

The task of defining schizophrenia pathogenesis has fascinated and frustrated researchers for nearly a century. In recent years, unprecedented advances from diverse fields of study have given credence to both viral and developmental theories. This review considers possible mechanisms by which viral and developmental processes may interact to engender schizophrenia. Many of the current controversies in schizophrenia pathogenesis are reviewed in light of the viral hypothesis, including: epidemiological findings and the role of a genetic diathesis, phenotype heterogeneity, abnormalities in excitatory and inhibitory neurotransmitter systems, anomalous cerebral latereralization, and static vs progressive disease. The importance of animal models in elucidating the impact of viral infections on developing neurons is illustrated by recent studies in which neonatal rats are infected with lymphocytic choriomeningitis virus in order to examine alterations in hippocampal circuitry. Finally, consideration is given to a new hypothesis that some cases of schizophrenia could be instigated by a viral infection that disrupts developing inhibitory circuits, consequently unleashing glutamatergic neurotransmission leading to selective excitotoxicity, and a degenerative disease course.

A novel mechanism to explain protein abnormalities in schizophrenia based on the flavivirus resistance gene

The geographical distribution of schizophrenia was previously shown to correlate with the global distribution of tick-borne flaviviruses. The correlation suggests a natural resistance gene to flaviviruses could be involved in schizophrenia. The flavivirus resistance gene, Flv, a gene found in wild mice and certain in-bred strains, confers resistance to flaviviruses through the interaction of cellular proteins with the flaviviral 3' untranslated regions (UTRs). Although the sequence and product of Flv are unknown, translation elongation factor alpha-1 (EF-1) is a protein known to interact with the 3' UTR flavivirus RNA, forming some complexes with long half-lives that inhibit RNA growth. A study was performed to assess the homology between flaviviral UTRs, subunits of EF-1, and selected proteins reported as abnormal in schizophrenia. The UTRs of four flaviviruses with wide geographical and phylogenic distribution were manually translated. Using the National Biomedical Research Foundation protein databank, the amino acid sequences were correlated with the amino acid sequences of selected proteins. The amino acid sequences of the EF-1 subunits were then correlated with the same proteins. Similar amino acid correlations between the proteins, EF-1 subunits and viral UTRs suggest that translational pathophysiology resulting from the product of Flv can be postulated as the cause of protein abnormalities observed in schizophrenia.

[An ultrastructural study of the temporal lobe and peripheral blood in schizophrenic patients]

INTRODUCTION

In spite of the human, social and economic impact of schizophrenia and to be considered a disease of organic origin by several evidences, there are relatively few studies about this disease using electron microscopic techniques.

PATIENTS AND METHODS

For 23 years we made studies about the viral hypothesis of schizophrenia by means of this technique. We studied limbic structure samples from young adult s dead schizophrenic patients, from fetuses of schizophrenic mothers and from chicken embryos experimentally inoculated with cerebrospinal fluid from schizophrenic patients. In the last ten years we have performed studies of blood and cerebrospinal fluid samples from young schizophrenic patients. We have found some alterations with the same characteristic to those observed in the central nervous system, which are compatible with: a) the viral hypothesis and b) with herpes simplex hominis type I virus, when immuno electronmicroscopic techniques were made.

RESULTS AND CONCLUSION

The results obtained in this work can constitute a new element favoring the possible viral etiology of this disease.

[Sibships characteristics, influenza and risk of schizophrenia. A population-based cohort study]

INTRODUCTION

To address the hypothesis that infections, perhaps prenatal exposure to influenza virus, might increase the risk of schizophrenia we studied the possible association between schizophrenia risk and birth order, sibship size, interval between siblings, and influenza prevalence.

MATERIAL AND METHODS

We established a population-based cohort of 1,746,366 persons born to Danish woman who themselves were born since 1935 using data from the Civil Registration System. Schizophrenia in cohort members (n = 2669) and their parents was identified by linkage with the Danish Psychiatric Case Register. Influenza notifications per month in Denmark were obtained from the National Board of Health and Statens Serum Institut.

RESULTS

We found no association between birth order and schizophrenia risk or between schizophrenia risk and influenza prevalence during any month of prenatal life. Coming from a large sibship and having a short interval to the nearest older or younger sibling was associated with an increased risk of schizophrenia.

DISCUSSION

Our findings do not add support to the hypothesis that schizophrenia is associated with prenatal exposure to influenza virus or other common infections, but are compatible with the hypothesis that environmental exposure, perhaps to common infections in childhood, may be a risk factor.