Background: About 8% of human genome is constituted by retroviral sequences. Some of these have been classified as human endogenous retroviruses (HERVs), which have been implicated in both health and disease. Recently, indirect evidence for a possible role of retroviral elements in neurological diseases has been provided by several studies.
Objectives: In the present study, we aimed to evaluate the relationship between HERVs and sporadic Creutzfeldt-Jakob disease (CJD), one of the human forms of prion diseases.
Study design: We investigated the prevalence of HERV families by RT-PCR in cell-free cerebrospinal fluids (CSFs) samples from normal controls, patients with sporadic CJD and other neurological diseases (OND).
Results: The incidence rate of some HERV families were significantly different in CSF samples from the group of sporadic CJD compared to samples from normal individuals; HERV-W (P=0.001), T (P=0.039), FRD (P<0.001), L (P=0.003) and ERV-9 (P<0.001) and the incidence rate of HERV-W (P=0.021) and HERV-L (P=0.049) were significantly increased in CSF samples from the group of sporadic CJD compared to samples from OND group. Moreover, our results from combining frequencies of two HERV families indicated that the prevalence of many combination groups was significantly different between sporadic CJD and normal CSF samples and between two patients' CSF samples. In addition, a large number of HERV sequences were newly identified in CSFs from normal and diseased individuals.
Conclusions: Our study about distinct prevalence patterns of HERVs reflects that some HERVs families may be associated with the development of prion diseases, and considered as a candidate marker for the diagnosis of sporadic CJD.