virology

AIDS

Dr. Mahmoud Y.M Taha
 1980: Beginning of the disease Pandemic threat human life 1981: Acquired immunodeficiency syndrome (AIDS) Starting of search for causative agent 1983: Luc Montagnier (Pasteur Institute) (L AV) 1983: Abraham Karpas (Cambridge) (C-LAV)  Paul Feorine (CDC) Atlanta  Virus resembles animal virus  1984: Robert Gallo (NCI) Maryland HTLV-I, III  E.M comparison of all isolates same virus 1986: ICTV HIV

Origin of the Virus

* Oncorna (human) or Lentivirus (animal) ?
HIV common ancestor with African Monkey virus (Simian virus)
Origin shrouded in tropical darkness
Virus jump species barrier in central Africa
* Politics: genetically engineered
* Genetics: human genome contains
sequence of HIV
Structure of the Virus

 SHAPE \* MERGEFORMAT 


Multiplication Cycle


 SHAPE \* MERGEFORMAT 


Stability of the Virus

* Destroyed by heat (autoclave or hot air oven).
100 fold each hour at temperature 60 Co.
* Survive up to 15 days at RT or body temp.
* Disinfectant (2% gluteraldehyde and
hypochloride at 103 ppm kills 105 unit of virus.
* Veridical activity of alcohol is relatively low.

Epidemiology

Exact number of people infected !?

* Test is not compulsory

* 3rd world countries
* Political reason

Transmission

* Sex

-homo and heterosexual
Traumatic sexual activity or ulceration of GT


Not necessary for transmission
artificially
Healthy women develop Abs to HIV
inseminated

principle factor is number of sexual contact

*Blood

- Blood transfusion (no risk for donor)
- Hemophiliacs
- Possibly following: ear piercing acupuncture
Dialysis
Tattooing
- Sharing needles ( I.V drugs and drug addicts)

* From mother to child
- Pregnancy
- At birth
- Breast milk
ٍSaliva and HIV Transmission
Small minority of HIV infected people harbor HIV in saliva
No cell free virus in the saliva
* Saliva contains IgA which neutralize viral infectivity
* HIV inhibitory factor ( high m.wt. mucins)
* Salivary leukocytes protease inhibitor which block
cell surface receptor
* Loss of viral infectivity when virus exposed to mixed saliva
for 30 min


* Animal study showed impossibility to transmit HIV by
sutface application on oral mucosa
* High dose of HIV is required for infection
No transmission by:
* Causal and social contact
* Human bite and kissing
* Swimming pool
Insects:
* HIV replicates in narrow range of cells Malaria enter
mosquito to salivary gland



Injected to other person

* Age distribution of HIV in Africa !
Malaria is more common in children
HIV is rare in children


Receiving contaminated blood born with it

Course of the Disease
A: Subclinical HIV infection
HIV +ve clinically well
25-50% seropositive AIDS
B: Persistent generalised lymphadenopathy (PGL)
* Asymptomatic * lymphadenopathy of 2 or more LN
* Reactive hyperplasia
C: AIDS Related Complex (ARC)
* fever ≥ 3 months * lymphadenopathy ≥ 3 or more
* Weight loss * Fatigue
*Diarrhea ≥ 3 months * Night sweat
D: AIDS:
1. Diagnostic for HIV:
* Kaposi sarcoma * Pneumocystic carinii
* Opportunistic infections:

-Protozoal: Toxoplasmosis, Cryptosporidium, isospora

-Fungal: Candida, Cryptococcus, Aspergellosis, Histoplasmosis
-Bacterial: T.B, Salmonella, Pygenic infections
-Viral: HSV, VZV, CMV


2. Diagnostic only if HIV +ve Antibody test:
Histoplasmosis , isosporiasis, broncheal and pulmonary
candidiasis, Non-Hodgkin lymphoma, Kaposi sarcoma in older than 60 years.

 SHAPE \* MERGEFORMAT 


Enlargment of 1-2 cervical LN and persist for 3 months
Persistent oral candidiasis
Painful herpes stomatitis
Oral Kaposi sarcoma
Sever gingivitis and periodontitis
Enlargment of 1-2 cervical LN and persist for 3 months
Persistent oral candidiasis
Painful herpes stomatitis
Oral Kaposi sarcoma
Sever gingivitis and periodontitis
Laboratory Diagnosis of HIV

ELISA detection of Abs ( does mean patient has AIDS)
Patient infected with HIV
Time between infection & appearance of Abs 1-4 mon. or longer
+ELISA confirmed by Western Blot analysis


 gp 120 gp 40 carrier

Western Blots

Negative: no
Positive: reactivity to gp41 + gp120/160 or p24+120160
Indeterminate: Presence of any band patterns that does not meet positive criteria
 SHAPE \* MERGEFORMAT 


Treatment and Prevention

 AZT Blocks RT (prevent RNA to DNA)
Combination of AZT and protease inhibitor

In the absence of vaccine

* prevent spread of the disease by reduce transmission
* care should be taken in dental clinic ( gloves, mask,
autoclave)
* public education
Advertising
* Do not die of ignorance
* The only way to reduce the transmission is by
persuading people to change their habit
*Once you get it, that is it, that is for your life and you
will die sooner or later











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