Oncovirus

These viruses promote tumor formation. Initially described in birds and animals, recent data shows their involvement in human tumors. For example, the Epstein-Barr virus causes Burkitt lymphoma, the papilloma virus causes skin and genital tumors, and the human immunodeficiency virus leads to sarcomas. There are two types of oncoviruses: DNA viruses and RNA viruses.

DNA viruses, such as SV40, herpes, varicella-zoster, and adenoviruses, partially or completely integrate into the human cell genome. They initiate the expression of viral genes, and the newly formed proteins disrupt cell cycle regulation. These viruses cause infectious diseases and, in rare cases, lead to malignant changes. For example, the hepatitis B virus can result in liver tumors, with infection occurring 20-25 years before the tumor appears.

Retroviruses or RNA viruses synthesize DNA using reverse transcriptase when they enter human cells. They insert this DNA into the eukaryotic genome as a provirus. Using recombinant DNA methods, researchers deciphered the genome structure of the Rous sarcoma virus. They found a gene regulating malignant changes, called the src oncogene. This gene encodes a 60 kDa protein, tyrosine protein kinase, which acts on the cell membrane. By inserting the src gene into the genome of cultured cells, the cells acquire altered properties.

Source | Glossary of Most Commonly Used Biomedical Terms and Concepts | Lithuanian University of Health Sciences | Academician Professor Antanas Praškevičius, Professor Laima Ivanovienė