en Epidemiologic studies including microbial genotyping, phenotyping and serotyping Epidemiologic studies including microbial genotyping, phenotyping and serotyping Original article Original article <strong>Introduction:</strong> Breast cancer is one of the most important causes of mortality in women. Various factors are involved in the development of cancer, including viruses. Toll-like receptors (TLRs) have an essential role in the innate immune system. The present study investigated the relationship between TLR2 <em>rs5743708</em> polymorphisms and Torque teno virus (TTV) infection with breast cancer. <strong>Methods:</strong> Blood samples from 80 women with breast cancer and 80 healthy women were collected, and after DNA extraction, the presence of TTV was investigated by a PCR assay and polymorphism in the TLR2 gene (<em>rs5743708</em>) was explored using the PCR-RFLP method. Also, the physical and chemical properties of TLR2 protein in the two wild and mutant forms were analyzed using the ExPASy database. <strong>Results: </strong>Statistical analysis showed that there was no significant relationship between the age and TTV infection; TTV infection and breast cancer; the grade of cancer, and TTV infection; while there were significant relationships between <em>rs5743708</em> polymorphisms and breast cancer; GG genotype and increased incidence of cancer; TTV infection and <em>rs5743708</em> polymorphisms. Also, instability index, aliphatic index, grand average of hydropathicity, and molecular weight of TLR2 protein varied in wild and mutant states. <strong>Conclusions:</strong> Although there was no significant relationship between TTV infection and breast cancer, the <em>rs5743708</em> polymorphisms might be involved in TTV infection and breast cancer. Virus, Single nucleotide polymorphisms, breast cancer, Toll-like receptor 116 121 http://jommid.pasteur.ac.ir/browse.php?a_code=A-10-348-1&slc_lang=en&sid=1 Majid Komijani 0000-0001-6206-5190 No Department of Biology, Faculty of Science, Arak University, Arak, 38156-8-8349, Iran Ahmad Hamta a-hamta@araku.ac.ir 0000-0003-4681-4731 Yes Department of Biology, Faculty of Science, Arak University, Arak, 38156-8-8349, Iran Sajedeh Khanmohamadi Hezaveh 0000-0003-4840-1885 No Department of Biology, Faculty of Science, Arak University, Arak, 38156-8-8349, Iran