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

Abstract

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.

Introduction

Borna disease virus (BDV) is a neurotropic, enveloped, nonsegmented, negative single-stranded RNA virus and causes changes in brain function resulting in disturbed movement and behavior and may be associated with human psychiatric disorders (Amsterdam et al., 1985, Chen et al., 1999, Nakamura et al., 2000, Fukuda et al., 2001, Horning and Lipkin, 2001, Bode et al., 2001, Taieb et al., 2001).

The first report of spontaneous canine BDV in Japan (Okamoto et al., 2002) and epidemiological investigations have revealed that BDV may also infect humans (Bode et al., 1993, Waltrip et al., 1995).

The predilection of the virus for the limbic–hypothalamic region and production in some animals of a syndrome somewhat resembling human affective disorders suggested the possibility that BDV may be involved in some human affective disorders (Amsterdam et al., 1985).

BDV is highly neurotropic in natural and experimental hosts. It replicates in neurons and astrocytes without inducing cytopathic effects (Schneider et al., 2005). This virus infects the central nervous system (CNS) of many animal species and may cause behavioral disturbances reminiscent of autism, schizophrenia and mood disorders (Pletnikov et al., 2002, Tomonaga, 2004).

Bode et al. (1993) reported that the proportion of BDV antibody carriers was higher than 30% among patients with major depression. In addition, they also detected a high rate of viral RNA in peripheral blood mononuclear cells (PBMC) derived from psychiatric patients at a high rate by reverse transcriptase-polymerase chain reaction (RT-PCR) (Bode et al., 1995).

Molecular analysis has indicated that BDV genome consists of at least six open reading frames (ORFs). The ORFs encode nucleoprotein (p40), phosphoprotein (p24), transcriptional activator, matrix protein (gp18), envelope protein (p56), and a predicted RNA-dependent RNA polymerase (p180) in 5′ to 3′order (Schneider et al., 1997).

The second open reading frame (ORFII) codes for a 24 kDa protein (also known as p24), representing the putative phosphoprotein. In addition to the p24 protein, the second ORF also produces a 16 kDa protein by translation from the second in-frame AUG codon. This 16 kDa protein has been detected in BDV infected cultured cells and in brains of experimentally infected animals (Ikuta et al., 2002). Among these proteins, BDV-p40 and p24 are found as abundant proteins in BDV-infected brain cells of experimentally and naturally infected animals (Stitz et al., 2002).

Over the past few years, many reports of patients presenting psychiatric symptoms during viral infection were described. Mood disorder patients were reported to have BDV serum antibodies compared to samples from control group without psychotic and mood disorders (Taieb et al., 2001).

Most epidemiological studies employed RT-PCR or RT PCR-nested methodology to trace viral RNA in biological specimens. Thus, in the work we report the major findings regarding a RT-nested-PCR study of Borna disease virus p24-RNA in mood and psychotic disorder in Brazilian patients and healthy control individuals.