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Retroviruses: From Oncogenic Viruses to Human Immunodeficiency Virus

Delve into the world of retroviruses, including mechanisms of viral oncogenesis and classification of family Retroviridae. Explore the structure of HIV, epidemiology, pathogenesis, clinical stages, laboratory diagnosis, and prevention and therapy. Learn about oncogenic viruses and their role in tumor production.

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Retroviruses: From Oncogenic Viruses to Human Immunodeficiency Virus

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  1. Retroviruses. Human immunodeficiency virus. Oncogenic viruses. Mechanisms of viral oncogenesis

  2. Classification • Family Retroviridae • Subfamilies: • Lentivirinae • Oncovirinae • Spumavirinae Species: HIV-1, HIV-2 Human T-cell leukemia virus

  3. Structure of HIV

  4. Major antigens of HIV • Envelope antigens: • gp 120 • gp 41 • Shell antigen: • p 18 • Core antigens: • p 24 (matrix protein) • p 7; p 9 • Viral enzymes – p11 (integrase); p31 (protease); p 51 (reverse transcriptase)

  5. Epidemiology • Three modes of transmission: • sexual intercourse • parenteral • perinatal

  6. Pathogenesis • Virus affects cells, carrying CD4 receptor • T- lymphocytes (helper), • B- lymphocytes, • monocytes, • macrophages, • glial cells, • microglia, • follicular dendritic cells

  7. Live cycle of the HIV into infected cell

  8. Releasing of the progeny virions from infected T-helper by budding

  9. Clinicalstages • Group 1 – Acute HIV infection. • Group 2 – Asymptomatic infection • Group 3 - Persistent generalized lymphadenopathy • Group 4 – Syptomatic HIV infections (AIDS)

  10. HIV-associated opportunistic infections • Bacterial infections: tuberculosis, shigellosis, salmonellosis, mycobacteriosis, staphylococcal and streptococcal purulent infections, etc. • Fungal infections: generalized candidosis, cryptococcal infection, histoplasmosis • Protozoan invasions: pneumocystosis, toxoplasmosis, amoebaean dysentery, lambliosis • Viral infections: generalized herpetic infection, CMV, VEB, sarcoma Kaposhi

  11. Sarcoma Kaposhi

  12. Laboratory diagnosis Specific tests for early diagnosis of HIV infections: • Antigen detections • Detection of viral nucleic acid Laboratory diagnosis during seroconversion period: Antibody detection: • Primary: ELISA test (anti gp120, anti gp41) • Confirming: Western blot test Non-specific tests (immune status assay) Tests for opportunistic infections and tumors

  13. Main markers of the HIV-infection in different stages of disease

  14. Prevention and therapy Prevention – non-specific Antiretroviral drugs include: • Nucleoside inhibitors • Non-nucleoside inhibitors of reverse transcriptase • Viral protease inhibitors • Fusion inhibitor

  15. Oncogenic Viruses • Viruses that produce tumours in their natural hosts or in experimental animals or induce malignant transformation of cell in culture, are known asoncogenic viruses.

  16. List of oncogenic viruses onc(+) • RNA viruses • Retroviruses Avian leucosis viruses Murine leucosis viruses Mammary tumour viruses of mice Leucosis-sarcoma viruses of various animals Human T-cell leukemia viruses

  17. List of oncogenic viruses • DNA viruses • Papovavirus • Papillomaviruses of human beings, rabbits and other animals • Polyomavirus • Simian virus 40 • BK and JV viruses • Poxvirus • Molluscum contagiosum virus • Yaba virus • Shope fibroma

  18. Papillomas (warts)

  19. List of oncogenic viruses (onc(-) • Adenovirus • Many human or nonhuman types • Herpes viruses • Epstein-Barr virus • Herpes simplex virus types 1 and 2 • Cytomegalovirus 5. Hepatitis B and C viruses– primary hepatocellular carcinoma

  20. Oncogenes • Viral oncogenes (V-onc). • Cellular oncogenes (C-onc) • Protooncogenes

  21. Mechanisms of viral oncogenesis of RNA-viruses • Following hypothesis are suggested: • Provirus hypothesis • Protovirus hypothesis • DNA oncogenic virus hypothesis

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