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Paper text:
we have not yet determined whether purified virus induces pdd or an adaptive immune response occurs in association with disease .
nonetheless , given what is known about bdv pathogenesis with other strains in other hosts ( 11 ) , the bornaviruses identified in these birds must be considered a biologically plausible candidate causative agent .
infection , lymphocyte infiltration , and dysfunction of the central , peripheral , and autonomic nervous system are common to pdd as well as to classical borna disease in natural disease and experimental models ( 2,12,13 ) .
proteins and antisera we have used for 2 decades for bdv diagnostics failed to detect this virus in our pcr - positive birds .
thus , it will be important to revisit epidemiologic surveys that we , and others , have undertaken to investigate the role of bornaviruses in human disease ( 14 ) . from a personal perspective
, we are intrigued that whereas molecular discovery of the first bdv in the late 1980s required an investment of 2 years in subtractive cloning ( 15 ) , high - throughput sequencing , bioinformatics , and sequence databases enabled discovery of these 2 strains in 2 weeks .
pyrosequencing of cdna from brains of parrots with proventricular dilatation disease ( pdd ) , an unexplained fatal inflammatory central , autonomic , and peripheral nervous system disease , showed 2 strains of a novel borna virus . 
 real - time pcr confirmed virus presence in brain , proventriculus , and adrenal gland of 3 birds with pdd but not in 4 unaffected birds .