Human Immunodeficiency Virus -Learn It Easy With Stencildent

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 HUMAN IMMUNODEFICIENCY VIRUS 

  • HUMAN -It can live only in human
  • IMMUNODEFICIENCY -Damages the immune system of people it infects 
  • VIRUS -Retrovirus (RNA)

MORPHOLOGY:

  • Spherical enveloped virus diameter :90-120 nm

  • composed of 2 copies of positive single stranded RNA enclosed by conical capsid composed of viral protein p24

  • RNA genome consist of 9 gene 

  • 3 genes :gag,pol,env contain information needed to make the structural protein for new virus particle

CAPSID :

  • There are 3 enzyme required for HIV replication 

  1. REVERSE TRANSCRIPTASE
  2. INTEGRASE
  3. PROTEASE

MATRIX:

  • Composed of viral protein p17 surrounds the capsid 
  • ensuring integrity of virion particle
  • surrounded by phospholipid spikes 2 units -gp41 and gp120 



PATHOGENESIS:

1)HIV attachment to host CD4 cell
2)Reverse transcriptase makes DNA from the virus RNA
3)Integration into host cells nucleus
4)Reproduction of viral components
5)Assembly of new HIV viruses
6)Virus release by budding (enzyme -protease)
7)Viral replication ,fusion,integrase
8)CD4 cell death
9)Increased  opportunistic infection
10)AIDS 






STAGES OF HIV:

1)Incubation period (2-4 weeks)
2)Stages of primary manifestation (years)
3)Stage of secondary manifestation
4)Terminal stage 

CLINICAL MANIFESTATION:

Fever,sore throat ,skin rash 

DENTAL INDICATOR :

  • Acute necrotising ulcerative gingivitis (ANUG)
  • Bacterial ,viral ,fungal infection of mouth
  • Dental caries and gingivitis 
  • Herpes simplex infection may be present 
  • Lesion heal slower 
  • Hair leukoplakia +candida 
  • Tongue :white ,soft ,hairy excrescence on lateral margin 
  • Angular cheilitis ,ulcer at corner of mouth

D.LABORATORY DIAGNOSIS:

1)SPECIFIC TEST FOR HIV :

  • ANTIGEN DETECTION
  • Blood marker p24 antigen 
  • useful in diagnosis of window period 

  • VIRUS ISOLATION:
  • CD4 Lymphocytes,peripheral,blood serum 

  • DETECTION VIRAL NUCLEIC ACID :
  • Polymerase chain reaction  ,highly sensitive specific 

  • ANTIBODY DETECTION :
  • 3-4 weeks -IgM and IgG






2)SCREENING TEST :

ELISA :
  • Commonly used highly specific,sensitive 
RAPID :
  • Less than 30 minutes 
  • No expensive kit :
  • HIV spot and comb test
  • Dot-blot assay 
SIMPLE:
  • Take 1-2 hours 

3) SUPPLEMENTAL 

A)INDIRECT IMMUNOFLUORESCENCE:
  • HIV Infected cell
  • Glass slide fixed
  • Reacted with serum
  • fluorescein conjugated anti human gamma globulin
Fluorescent microscope:
  • apple green 

B)WESTERN BLOT 

  • GEL ELECTROPHORESIS:
  • HIV protein (separated from)
  • Blotted to strip of nitrocellulose paper 
  • Reacted with test sera 
  • Antibodies to hiv protein if present in test serum
  • Combine with different fragment of HIV
  • Position of colour band
  • Indicate fragment of antigen with which antibodies have reacted 
  • Initially :western blot was used as conformational test
  • But now,elisa +rapid test =confirmation 
2)NON-SPECIFIC TEST:
  1. Total and differential leucocyte count leucopenia,lymphocyte count :less than 400/millimetre cube 
  2. T-Lymphocyte assay :
CD4:CD8 T cell ratio 2:1 is reversed 0.5:1 
CD4:Below 200/millimetre cube 





AIM OF THIS POST :

Today we have started discussing introduction ,morphology,pathogenesis ,stages of hiv ,clinical manifestation ,laboratory diagnosis : specific test for hiv ,screening test,supplemental test and non-specific test .

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