OP03 AIDS Flashcards
(43 cards)
How does HIV fulfil Koch’s postulates as a cause of AIDS?
Epidemiological association
Isolation
Transmission pathogenesis
Read this slide on evidence that HIV causes AIDS - dont memorise
o AIDS and HIV infection are invariably linked in time, place and population group
o A single factor, HIV, predicts whether a person will develop AIDS,
o In cohort studies, severe immunosuppression and AIDS-defining illnesses occur almost exclusively in individuals who are HIV-infected
o Before HIV epidemic, AIDS-related diseases were rare in developed countries; today, they are common in HIV-infected individuals
o HIV can be detected in virtually everyone with AIDS.
o Newborn infants have no behavioural risk factors for AIDS, yet many children born to HIV-infected mothers have developed AIDS and died.
o The HIV-infected twin develops AIDS while the uninfected twin does not
o HIV causes the death and dysfunction of CD4+ T lymphocytes in vitro and in vivo.
What is the structure of HIV virus?
gp120 and gp41 attach to receptors in human cells
P17 makes the capsid envelope of the virus
P24
Inside is 2 pairs of RNA - integrase and reverse transcriptase
What do integrase and reverse transcriptase in the HIV virus do?
Integrase integrates the viral genome into human cells
Reverse transcriptase produces DNA at the expense of the RNA in the virus
How does HIV replicate?
- Virus entry into host (into CD4, macrophages, Fc receptors) eg CD4 cells have chemokine receptors which HIV attaches to
- Envelope and capsid attach to cell membrane and breakdown
- RT and viral RNA are reverse transcribed into DNA
- DNA integrated into host DNA using viral integrase
- Host RNA polymerase transcribed viral DNA to create more RNA and RT. Translation of envelope, capsid and RT.
- Assembly, and viral budding out of cells to infect other cells
What is the typical course of a HIV infection?
a) Transmitted through exchange of blood of bodily fluids: sexual contact, injection, perinatal
b) Primary acute infection with a characteristic clinical picture
c) Prolonged period without obvious visible symptoms
d) A severe immunodeficiency resulting in the development of secondary opportunistic infections and tumours that cause death in AIDS patients
Stages of HIV infection - time course
- Primary HIV infection
- 3-6 weeks: Acute HIV syndrome mononucleosis-like plasma viremia
- 1week-3months: HIV-specific immune response, seroconversion
- 1-2weeks: clinical latency, decline CD4 cell count, PGL
- 10years: Clinically apparent disease, AIDS-defining illness, ARC
- 2 years: Death from AIDS
What is seroconversion?
Immune system reacts to the presence of the virus and starts making antibodies to the virus
When can you detect the virus?
1 week - 3 months
What is PGL?
Persistent generalised lymphadenopathy = swollen palpable lymph nodes that persist in many places in the body
What are normal values for CD4 count?
500-1400/mm^3
What is the CD4 count in HIV and AIDS??
HIV: T-cell count 200-400/mm^3
AIDS: <200/mm^3
What are constitutional symptoms of AIDS?
Fever, weight loss, fatigure, night sweats, Diarrhoea, persistent generalised lymphadenopathy
AIDS defining conditions - what opportunistic infections can arise?
Mycobacterium tuberculosis, avium intracellulare
Pneumocystis carinii pneumonia
Candidiasis (trachea, bronchi, lungs, oesophagus)
Herpes simplex
Cryptococcosis
Cytomegalovirus
Histoplasmosis
Salmonella
AIDS defining conditions - what neoplastic disease can arise?
Kaposi’s sarcoma
Non-Hodgkin lymphoma
Cervical carcinoma
AIDS defining conditions - other
HIV encephalopathy (AIDS dementia)
Wasting syndrome due to HIV
Thrombocytopoenic purpura
Progressive multifocal leukoencephalopathy
What associated oral manifestations are there with AIDS? (doesn’t define but should make suspicious)
Candidal infections
Hairy leukoplakia
Kaposi’s sarcoma
AIDS related periodontal disease
ANUG
Recurrent herpetic infection
Other forms of malignant disease
What is the most frequent oral manifestation of HIV?
Candidal infections
How does candida present in HIV/AIDS patients?
Pseudomembraneous in any site
Erythematous mostly in palate and tongue dorsum
Hyperplastic cheeks, commissures rarely involved (unlike in HIV-seronegative)
What is hairy leukoplakia?
Asymptomatic white patch often found bilateral in the lateral border of the tongue, with hair-like corrugated appearance.
What cells are involved in hairy leukoplakia?
No associated inflammatory cells due to depletion of the Langerhan’s cells (APCs)
What is the aetiological virus causing hairy leukoplakia?
EBV is identifiable in epithelial cell nuclei
Is hairy leukoplakia premalignant?
No
How often in HIV patients does hairy leukoplakia occur?
20-30% of HIV patients, otherwise in other immunosuppressed patients
