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viral oncogenesis
This document discusses viral oncogenesis, or how viruses can cause cancer. It defines oncogenes as viral genes that can cause tumors and proto-oncogenes as normal cellular genes that viruses can modify to become oncogenes. It describes the two main types of oncogenic viruses as DNA viruses and RNA viruses, listing some examples of each. For RNA viruses, it explains that all oncogenic viruses are retroviruses and describes the general life cycle of retroviruses, from entering the cell to replicating and exiting. The document concludes that while not all retroviruses contain viral oncogenes, they can integrate near proto-oncogenes and modulate host cell growth to cause cancer.
viral oncogenesis
- 1. Viral OncOgenesis Ifrah Ishaq UniversityOf The Punjab, Lahore.
- 2. Outline Oncogene Viral Oncogenesis Types OfOncogenesis Viruses • DNA Viruses • RNA Viruses Retroviruses Life Cycle Of RNA Virus Conclusion
- 3. intrOductiOn Oncogene A region ofthe viral genome that can cause a tumor. Proto-oncogene Genes that are found in all cells and its homologous is carried by a virus ( viral- oncogene).
- 4. • Viral Oncogene Genesin the viral genome; change host cell proliferation control • Tumor-suppressor Genes Genes whose products inhibit cell multiplication • Mutator Genes Genes whose products ensure accurate DNA replication and DNA repair
- 5. OncOgenic Viruses Oncogenic virusesare significant pathogens for humans, farm animals, and pets. These pathogens are classified into different virus families such as Hepadnaviridae, Flaviviridae, and Retroviridae. Oncogenic viruses (tumor viruses) consist of both DNA and RNA viruses
- 6. Types Of OncOgenesisViruses DNA Viruses Virus can containing either single stranded or double stranded DNA. Examples of DNA viruses are: Adenoviridae, Herpesviridae, Papillomaviridae, Polyomaviridae, Poxviridae etc.
- 7. RNA Viruses RNA viruscontains predominantly single stranded RNA; although viruses do exist that contain double stranded. Examples of RNA viruses: Alpharetrovirus,Deltaretrovirus, Gammaretrovirus, Retroviridae, Flaviviridae etc.
- 8. reTrOViruses All oncogenic RNAviruses are retroviruses. In 1961, Rous sarcoma virus. Retroviruses have 3 basic genes 1. Gag 2. pol 3. env
- 9. Life CyCLe ofRNA ViRuses Steps of life cycle explained below: 1.Approaches the cell membrane 2.Receptors on the lipid bilayer(binding) 3.Virus fuses with plasma membrane of the cell 4.Role of reverse transcriptase 5.Role retroviral integrase 6.Transcription of the viral DNA 7.Viral RNA as well as the viral proteins; move outward 8.Once outside, the virus matures
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- 13. Plus-Strand RNA Viruses servedirectly as mRNA ; translated into proteins. Minus-Strand RNA Viruses transcribed into the mRNA ; then translated.
- 14. ConClusion Many retroviruses donot have viral oncogenes. They integrate near some of the proto-oncogenes, activate their expression by pro-viral insertional mutagenesis, and modulate growth and differentiation of the host cells.
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