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.