• The effect of viral infections in causing various types of cancer
  • sara sedaghat,1,*
    1. Department of Microbiology, Faculty of Basic Siences, Lahijan Branch Islamic Azad University, Lahijan, Guilan, Iran.


  • Introduction: Cancer is caused by the uncontrollable growth of body cells in different parts of the body. Cancers share six characteristics: self-sufficiency in growth signals, insensitivity to anti-growth signals, escape from apoptosis, unlimited potential, stable angiogenesis, tissue invasion, and metastasis. Multiple factors have been associated with the oncogenic process such as environment, lifestyle, host factors, infectious agents, and inheritance. Recently, research has been conducted in the field of genetics, which has shown that there is a strange compatibility between mutation-causing agents and cancer-causing agents. Baer (1949) and Strong (1949) proposed one of the most prominent theories, claiming that the primary cancer cell is nothing more than a normal cell affected by a genetic mutation. Mutations created in the genome cause changes in the balance between proliferation and programmed cell death. Sometimes, infectious agents play an important role in the creation of various mutations. It has recently been estimated that viral infection is the main cause of more than 1,400,000 cancer cases per year, such as HPV, HBV, HCV, EBV, and HTLV. This review focuses on the effect of viral infections in causing various types of cancer.
  • Methods: This research was extracted from 15 valid articles from 1988 to 2021 and downloaded from the reliable sites Pubmed, Scopus, Web of Science, Google Scholar, and Elsevier.
  • Results: Viral infections that are caused by HPV, HBV, HCV, EBV, and HTLV lead to various types of cancer. High-risk infection (human papillomavirus) HPV is the main cause of cervical cancer. HPV disrupts the host chromosome, and this disruption increases the expression of E6 and E7, which leads to DNA damage and causes cervical cancer. HBV (hepatitis B virus) is one of the smallest DNA-enveloped viruses which causes acute infections in mammals and birds. HBV is a recognized cause of hepatocarcinogenesis. A recent study unraveled that the insertion of HBV-DNA into the human genome can cause dramatic genetic aberrations. HBV–DNA integration into human chromosomes has been detected in 80–90%. HCV (hepatitis C virus) infection has become a leading cause of hepatocellular carcinoma. EBV (Epstein-Barr virus) is a human herpes gamma virus that was first derived from Burkitt's lymphoma which plays a role in carcinogenesis by causing cell epigenetic changes such as DNA methylation and histone changes. HTLV1 is a type C complex retrovirus in the oncovirinae subfamily, and like other retroviruses, it has an envelope derived from the host cell membrane and two copies of the positive RNA genome. This virus infects lymphocytes and is the main cause of cell leukemia and lymphoma in adults. The diagnosis of HTLV-1 infection is based on the detection of specific antibodies by agglutination of enzyme-linked particles and subsequent confirmation by polymerase chain reaction (PCR) or western blot assay.
  • Conclusion: Cancer-related viruses such as HPV, HBV, EBV, and HTLV can develop carcinoma. These viruses create mutations in DNA and cause genetic changes and epigenetic changes in chromosomes and DNA. Chronic infections may play a significant role in carcinogenesis. The mechanisms of carcinogenesis caused by infections include cell proliferation and DNA replication by the mitogen-activated protein kinase pathway. Some toxins of viruses affect the cell cycle and lead to abnormal cell growth so identifying these viruses in the body as quickly as possible using biological biomarkers will be very effective in preventing cancer.
  • Keywords: Cancer, HPV, Viral infection, Mutation, Carcinogenesis, Infections