Successfully reported this slideshow.
We use your LinkedIn profile and activity data to personalize ads and to show you more relevant ads. You can change your ad preferences anytime.

Lect 10 - HIV disease and aids


Published on


Published in: Health & Medicine
  • Be the first to comment

Lect 10 - HIV disease and aids

  1. 1. HIV Disease and AIDS Historical Background 1981 : Few reports about a rare disease in previously healthy homosexual men with high incidence of : •Loss of immune function •Unusual opportunistic infections •Certain malignant tumors 1982 : Word AIDS was used 1st time by CDC 1983 : Viral cause was identified that selectively infects Th cells Was named as HTLV-III Now named as HIV (Human Immunodeficiency Virus)
  2. 2. Epidemiology • Worldwide >33 millions infected with HIV • Number 1 killer in Africa • >20 millions have died of AIDS • 4th leading cause of death in the world after heart diseases, strokes & pneumonia • A new infection occurs every 6 seconds • A person dies of AIDS every 5 minutes HIV Disease and AIDS
  3. 3. Routes of Transmission & Persons at High Risk 1. Sexual contact o Homosexual men : major infected group 2. Blood & Blood Products o Drug abusers & o Hemophiliacs 3. Mother to infant o During child birth o Breast feeding HIV Disease and AIDS
  4. 4. Causative Agent • HIV-1 : in most parts of the world • HIV-2 : in most parts of Africa & India • Family : Retroviridae • Subgroup : Lentivirus HIV Disease and AIDS
  5. 5. Structure of virus Important antigens • Surface glycoprotein (gp120) o Partly responsible for attachment to host cells • Transmembrane glycoprotein (gp41) o Probably plays a role in entry of virus into cell • Matrix protein (p17) o Helps maintain viral structure HIV Disease and AIDS
  6. 6. Structure of virus The Core of Virion • Capsid antigen (p24) • Two copies of ssRNA • Nucleocapsid • Viral enzymes o Reverse transcriptase o Protease o Integrase HIV Disease and AIDS
  7. 7. Types of Human Cells affected • CD4+ Th1 cells : o Principal target of HIV o Main cause of immunodeficiency • CD4+ Th2 cells • CD4+ macrophages, dendritic & other APC o Are continuing source of virus • Several types of brain cells o Probable cause of lethargy & dementia • Intestinal epithelium & lymphoid tissues o Probably contribute to chronic diarrhea & weight loss
  8. 8. Attachment, Entry & Replication of virus inside host cell
  9. 9. HIGH GENETIC VARIABILITY IN HIV • Is due to high rate of error when reverse transcriptase copies viral genome • Variant viruses show differences in: o Their preferred host cell o Rate of replication o Response to host immunity • Enormously complicates the development of vaccine against HIV
  11. 11. CLINICAL FEATURES OF HIV DISEASE A. Acute Retroviral syndrome (ARS) • Incubation period 1-6 weeks • In 50-70% of HIV infected subjects • Sore throat & Fever • Myalgia & headache • Enlarged lymph nodes • Symptoms may last for 1-4 weeks • Self-limiting without treatment
  12. 12. B. Asymptomatic period • Lasts for months to years • A silent struggle goes on between HIV & immune system • The virus continues to be present in blood and body secretions – a threat to others • Level of CD+ lymphocytes slowly falls • Leads to AIDS CLINICAL FEATURES OF HIV DISEASE
  13. 13. C. AIDS • The immune system slowly loses battle • Peripheral blood CD+ count slowly falls • Symptoms of AIDS appear when count falls below 300 cells per ul (Normal count 1000 cells per ul) Incubation period • 10% - 5 years ; 90% within 17 years • Weight loss, fatigue, diarrhea, fever • Enlarged lymph nodes • Opportunistic infections • Malignant tumors CLINICAL FEATURES OF HIV DISEASE
  14. 14. Malignant Tumours Associated with AIDS • Kaposi’Sarcoma o Unusual tumor arising from blood or lymphatic vessels o Caused by herpes virus-8 o Strong association with immunodeficiency • B-Lymphocytic Tumors of Brain o 60-100 times more common in AIDS • Cervical & Anal Carcinomas
  15. 15. • Pneumocystosis : o Pneumocystis carinii • Toxoplasmosis : o Toxoplasma gondii • Cytomegalovirus Disease : CMV • Tuberculosis o M. tuberculosis & o M. avium-intracellulare complex • Candidiasis Opportunistic infections Associated with AIDS
  16. 16. Lab Diagnosis • anti-HIV Abs by ELISA: Easier to detect than virus itself • Confirmed by Western Blot & RIBA • PCR : to detect viral RNA
  17. 17. Mechanism of action of antiretroviral drugs NRTI (Nucleoside RT Inhibitors) •Ziduvudine •Stavudine NNRTI (Nonnucleoside RT Inhibitors) •Nevirapine •Delaviridine TREATMENT OF AIDS • A cocktail of drugs with different mechanisms of action • HAART “Highly Active Antiretroviral Therapy” • Specific treatment for opportunistic infections
  18. 18. • Health education • Detection & Treatment of the HIV-pos cases • Changing sexual behaviors • Disinfection of all blood samples • Chemoprophylaxis with Ziduvidine to o HIV-positive pregnant mother & o Newborn infants to HIV-positive mother • Treatment of opportunistic infections PREVENTION OF AIDS
  19. 19. HIV Vaccine Prospects • No approved vaccine is currently available • A vaccine that is a combination of two previously unsuccessful vaccine candidates was reported in September 2009 to have resulted in a 30% reduction in infections in a trial conducted in Thailand • Theoretically two approaches: 1. Preventive Vaccine o To immunize uninfected persons 2. Therapeutic vaccine o To boost the immunity of already infected persons o Like post-exposure treatment of rabies PREVENTION OF AIDS