You are here: Home » USMLE* » USMLE Snippets » Human Immunodeficiency Virus

Human Immunodeficiency Virus

HIV

HIV virion contains:

  • Enveloped truncated conical capsid (type D)
  • 2 copies of single stranded (+) RNA
  • RNA dependent DNA Polymerase (Reverse Transcriptase)
  • Integrase
  • Protease

Gp 120 interacts with CD4+ co-receptors on T-cells

Gp 41 is a fusion protein that fuses with cell membrane to allow entry of the virus.

Gp 24 Capsid- First Antibody detected in HIV infection

 

 

 

HIV Gene Products Function
A.     Structural Genes- Responsible for the morphology of the virus
Gag Gene

(Group Antigens)

Group Specific Antigen

·        P 24

·        P7P9

 

·        P17

Structural proteins

·        Capsid Protein

·        Core Nucleocapsid Protein

·        Matrix Protein

Pol Gene

(Polymerase Gene)

·        Reverse Transcriptase (RNA Dependent DNA Polymerase)

·        Integrase

 

 

·        Protease

·        Produces double-stranded DNA Provirus

 

·        Integrates viral DNA into host cell DNA

·        Cleaves Viral Poly proteins

Env Gene

(Envelope)

·        Gp 120

 

 

 

 

 

·        Gp41

·        Surface protein that binds to CD4 receptors and coreceptors: CCR5 (in macrophage)

CXCR4 (in T-Cells)

·        Helps the virus to fuse with the cell membrane to allow entry into the host cell

B.     HIV Regulatory Genes
LTR (U3, U5) DNA Long Terminal Repeats Integration and viral gene expression
Tat Gene Transactivator Up-regulates transcription
Rev Regulatory Protein Up-regulates transportation of unspliced and spliced Viral genome into the cell cytoplasm
Nef Regulatory Protein Decreases CD4 and MHC –I expression on host cell. Interferes with T-cell activation pathway

*Required for progression to AIDS

 

Laboratory Analysis of HIV

  1. Initial Screening test: ELISA or Latex Particle Agglutination Test

 

  1. Confirmatory Test: Western Blot or Immunofluorescence Test

 

  1. Detection of HIV

infection in Neonates

of HIV infected mothers:        Polymerase Chain Reaction (Provirus)

 

  1. Early Markers of infections:  P24 Antigen (Antibodies to P24 antigen develop

quickly)

 

  1. Detection of virus in the blood: RT-PCR (Reverse Transcriptase PCR)

 

  1. Evaluate Progression of the disease: CD4:CD8 T cell ratio

 

Fun Fact:

 

In an AIDS Patient:

1.     Bacillary Angiomatosis : a. Superficial Vascular Proliferation

b. Neutrophilic infiltration

c. Caused by Bartonella henselae

 

2.     Kaposi Sarcoma:              a. Superficial Vascular Proliferation

b. Lymphocytic infiltration

c. Caused by Human Herpes Virus-8

 

 

Dr.Harpreet Singh MD, FACP is a Chief Executive Officer and Founder of Vital Checklist and iCrush.org. The text, graphics, images, videos and other material contained in the videos and iCrush Website ("Content") are for informational purposes only. The Content is not intended to be a substitute for professional medical advice, diagnosis, or treatment. Always seek the advice of your physician or other qualified health provider with any questions you may have regarding a medical condition.
Himanshu Deshwal- Assistant Editor
Dr. Himanshu Deshwal is a fresh graduate out of a reputed medical school in India, the Armed Forces Medical College, Pune. Dr. Deshwal is an active researcher constantly on the look out for projects that may help him hone his talents and abilities to the next level. Being an active sportsman he understands the importance of a holistic approach to healthcare and wellbeing. He has been a keen advocate of following an active lifestyle in midst of our busy lives.

Leave a Reply

Your email address will not be published. Required fields are marked *

*


Scroll To Top