Objective: The mechanism for type 1 diabetes still remains unclear. This study was focused on the viral morphology, endogenous retrovirus expression, immunology and molecular biology.
Methods: Type C retrovirus-like particles were observed in beta cells of the diabetic pancreases under electron microscope. Human endogenous retroviral pol gene expression was detected by PCR in cDNA libraries from IDDM pancreases, brain, splenocytes and control subjects. These DNA segments were sequenced.
Results: ERV9, HERV-K-MIN, HERV-K10, RTVL related sequences were significantly higher in IDDM group than control subjects and DR2-related MMTV-like sequences were significant lower in IDDM group than control subjects. ERV9- related genes, gag, pol, env and 3' LTR were amplified and sequenced by PCR from cDNA libraries of 2 newly onset diabetic pancreases. Retrovirus sequences were further searched for their distribution on the chromosome genome and their locations at the centromeres, telomeres, immune reaction genes (MHC, TCR, Ig autoantigens) and at many disease loci, such as the loci for IDDM, Mody, the candidate genes for NIDDM, diabetic complications, autoimmune diseases, cancer and other genetic diseases.
Conclusions: These facts indicate that the endogenous retrovirus genes may be the important genetic factor of IDDM and play key role in the structure and physical function of chromosome and the pathogenesis of genetic-related diseases.