Viruses And Cancer

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Viruses And Cancer

  1. 1. Jason M. Walker<br />Chapter 13<br /><ul><li>Viruses and Cancer
  2. 2. Latent Viral Infection
  3. 3. Persistent Viral infections</li></li></ul><li>Viruses and Cancer <br />The earliest relationship between cancer and viruses was demonstrated in early 1900s, when chicken leukemia and chicken sarcoma were transferred to healthy animals by cell-free filtrates.<br />
  4. 4. The transformation of Normal Cells into Tumor Cells<br />When activated, oncogenes transforms normal cells into cancerous cells.<br />Viruses capable of producing tumors are called oncogenic viruses.<br />Several DNA viruses and retroviruses are oncogenic.<br />The genetic material of oncogenic viruses become integrated into the host cell’s DNA.<br />Transformed cells lose contact inhibition, contain virus specific antigens (TSTA and T antigen), exhibit chromosome and abnormalities, and can produce tumors when injected into susceptible animals.<br />
  5. 5. DNA Oncogenic Viruses <br />Oncogenic viruses are found among:<br />Adenoviridae<br />Herpesviridae<br />Poxviridae<br />Papovaviridae<br />
  6. 6. <ul><li>The EB virus, a herpes virus, causes Burkitt’s Lymphoma and nasopharyngeal carcinoma.</li></ul>(Burkitt’s lymphoma)<br />(Nasopharyngeal carcinoma)<br />
  7. 7. RNA Oncogenic Viruses <br />Among the RNA viruses, only retroviruses seem to be oncogenic. <br />The virus’s ability to produce tumors is related to the production of reverse transcriptase. The DNA synthesized from the viral RNA becomes incorporated as a provirus into the host cell’s DNA.<br />A provirus can remain latent, can produce viruses, or can transform the host cell.<br />
  8. 8. Chickenpox (Varicellovirus)<br />Chickenpox is one of the classic childhood diseases, and one of the most contagious. The affected child or adult may develop hundreds of itchy, fluid-filled blisters that burst and form crusts. Chickenpox is caused by a virus.<br />
  9. 9. Latent Viral Infections<br />A latent viral infection is one in which the virus remains in the host cell for long periods without producing an infection.<br />Examples are cold sores and shingles.<br />
  10. 10. Persistent Viral Infections<br />Persistent viral infections are disease process that occur over a long period and are generally fatal.<br />Persistent viral infections are caused by conventional viruses; viruses accumulate over a long period. <br />

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