Tehran University of Medical Sciences Iranian Journal of Microbiology 2008-3289 16 5 2024 10 19 676 683 Golnaz Irani Mokhtari Cellular and Molecular Research Center, Ahvaz Jundishapur University, Ahvaz, Iran; Department of Virology, Ahvaz Jundishapur University, Ahvaz, Iran Azarakhsh Azaran Department of Virology, Ahvaz Jundishapur University, Ahvaz, Iran Elham Rajahi Department of Rheumatology, Golestan Hospital, Ahvaz Jundishapur University of Medical Sciences, Ahvaz, Iran Saeed Hesam Department of Biostatistics and Epidemiology, Faculty of Public Health, Ahvaz Jundishapur University of Medical Sciences, Ahvaz, Iran Azam Dehghani Ghahfarokhi Department of Virology, Ahvaz Jundishapur University, Ahvaz, Iran Manoochehr Makvandi Cellular and Molecular Research Center, Ahvaz Jundishapur University, Ahvaz, Iran; Department of Virology, Ahvaz Jundishapur University, Ahvaz, Iran 2024 04 14 2024 09 03 Background and Objectives: Vitamin D deficiency in viral infection associated with autoimmune diseases is well documented. This study assessed the prevalence of JC virus in patients with rheumatoid arthritis (RA) and systemic lupus erythematosus (SLE), and its correlation with vitamin D level. Materials and Methods: Serum and urine samples were collected from 50 patients with RA and SLE. DNA was extracted and subjected to PCR test. Positive PCR products were sequenced, phylogenetic tree was constructed to determine the JC virus genotype. The patient’s vitamin D level was evaluated. Results: Of 50 patients, 19 (38%) were diagnosed as RA, and 31 (62%) were identified as SLE. JC virus DNA was detected in 17 (34%) patients’ urine samples including 5 (26.3%) RA and 12 (38.7%) SLE cases. JC virus DNA was detected 2 (4%) in patients’ serum samples (one RA. and one SLE). JC virus genotype 3A was dominant. Interestingly, the SLE patients with positive JC virus showed lowered vitamin D compared to patients with negative JC virus (P<0.005). Conclusion: Given the high rate of JC virus, DNA detection and susceptibility of patients for PML development, it is recommended that detection of JC virus DNA and vitamin D level should be implemented for patients with RA/SLE prior to treatment. https://ijm.tums.ac.ir/index.php/ijm/article/view/4724 https://ijm.tums.ac.ir/index.php/ijm/article/download/4724/1714