Question: Is there an association between borna virus and brain tumor?

Context:
Borna disease virus (BDV), a nonsegmented, negative-strand RNA virus, infects a wide variety of mammalian species and readily establishes a long-lasting, persistent infection in brain cells. 
To investigate the biological characteristics of field isolates of Borna disease virus (BDV), as well as to understand BDV infections outside endemic countries, we isolated the virus from brain samples of a heifer with Borna disease in Japan.
Neonatal Borna disease virus (BDV) infection of the rat brain is associated with microglial activation and damage to the certain neuronal populations.
In addition, compared to uninfected mixed cultures, activation of microglia in BDV-infected mixed cultures was associated with a significantly greater lipopolysaccharide-induced release of tumor necrosis factor alpha, interleukin 1beta, and interleukin 10. Taken together, the present data are the first in vitro evidence that persistent BDV infection of neurons and astrocytes rather than direct exposure to the virus or dying neurons is critical for activating microglia.
Usually, Borna disease virus is not cleared from the brain but rather persists in neural cells.
Varied persistent life cycles of Borna disease virus in a human oligodendroglioma cell line.
Borna disease virus (BDV) establishes a persistent infection in the central nervous system of vertebrate animal species as well as in tissue cultures. 
Thus, our findings show that BDV may have established a persistent infection at low levels of viral expression in OL cells with the possibility of a latent infection.
These results suggested that BDV infection may cause direct damage in the developing brain by inhibiting the function of amphoterin due to binding by the p24 phosphoprotein.
We describe a model for investigating disorders of central nervous system development based on neonatal rat infection with Borna disease virus, a neurotropic noncytolytic RNA virus. 
Borna disease virus (BDV) replicates in brain cells. The neonatally infected rat with BDV exhibits developmental-neuromorphological abnormalities, neuronal cytolysis, and multiple behavioral and physiological alterations. 
Borna disease virus (BDV) causes central nervous system (CNS) disease in several vertebrate species, which is frequently accompanied by behavioral abnormalities.
Intrinsic responses to Borna disease virus infection of the central nervous system.
Immune cells invading the central nervous system (CNS) in response to Borna disease virus (BDV) antigens are central to the pathogenesis of Borna disease (BD). 
We report here the partial purification and characterization of cell-free BDV from the tissue culture supernatant of infected human neuroblastoma SKNSH cells.
We have used the reverse transcriptase-polymerase chain reaction technique to gain insight into the pathogenesis of encephalitis caused by Borna disease virus (BDV). 
In contrast, in the BDV-infected primary mixed cultures, we observed proliferation of microglia cells that acquired the round morphology and expressed major histocompatibility complex molecules of classes I and II.

Answer: There is no data to suggest an association between borna virus and brain tumor. Borna disease virus establishes a persistent infection in the central nervous system of vertebrate animal species as well as in tissue cultures causing cellular damage. Infected neural cells, include astrocytes, neurons, oligodendroglioma cell line. Borna disease virus replicates and can cause damage of brain cells.
Exact answer: no