Tehran University of Medical Sciences Iranian Journal of Microbiology 2008-3289 17 1 2025 02 05 137 143 EN Mahsa Javadi Cancer Research Center, Ahvaz Jundishapur University of Medical Sciences, Ahvaz, Iran; Department Virology, School of Medicine, Ahvaz Jundishapur University of Medical Sciences, Ahvaz, Iran Gholamabbas Kaydani Department of Laboratory Sciences, School of Allied Medical Sciences, Ahvaz Jundishapur University of Medical Sciences, Ahvaz, Iran Roya Pirmoradi Cancer Research Center, Ahvaz Jundishapur University of Medical Sciences, Ahvaz, Iran Abdolhassan Talaiezadeh Cancer Research Center, Ahvaz Jundishapur University of Medical Sciences, Ahvaz, Iran Azadeh Haghi Navand Cancer Research Center, Ahvaz Jundishapur University of Medical Sciences, Ahvaz, Iran; Department Virology, School of Medicine, Ahvaz Jundishapur University of Medical Sciences, Ahvaz, Iran Mohammad Karimi Baba Ahmadi Department of Medical Biotechnology, School of Medicine, Ahvaz Jundishapur University of Medical Sciences, Ahvaz, Iran Manoochehr Makvandi Cancer Research Center, Ahvaz Jundishapur University of Medical Sciences, Ahvaz, Iran 2024 07 29 2025 02 04 Background and Objectives: BK polyomavirus infection is prevalent and primarily asymptomatic, except for complications in kidney transplant recipients. Furthermore, its involvement in a tumorigenic family necessitates consideration in various malignancies such as urogenital tumors, prostate cancer, colorectal cancer (CRC), and brain cancer. Materials and Methods: This investigation encompassed 50 specimens of colorectal adenocarcinoma tumors, 50 adjacent tissues, and 40 urine samples, with patients having a mean age of 61 years ± 12.4 years. The detection of BK virus DNA VP1 gene and genotyping were carried out through nested-PCR and sequencing techniques. Results: Through the utilization of nested-PCR, BK virus DNA was identified in 15/50 (30%) colorectal tumor samples and 3/50 (6%) adjacent tissues (p-value = 0.008). Additionally, 6/40 (15%) urine samples exhibited positive results for BK virus DNA. Notably, among these findings, 9/15 BK virus positive tumor tissues (60%) and 3/6 BK virus positive urine samples (50%) were confirmed to be positive for BK virus subtype 4 (p-value < 0.001), whereas 2 tumor samples and 3 urine samples were attributed to BK virus type 1b2. Conclusion: It is imperative to enhance one's understanding of the etiological and risk factors pertaining to cancers. The present findings offer substantiation of a potential correlation between BK virus infection and colorectal cancer. BK virus genotype 4 was found to be dominant among the CRC patients in this study. https://ijm.tums.ac.ir/index.php/ijm/article/view/4947 https://ijm.tums.ac.ir/index.php/ijm/article/download/4947/1751