HIV Life Cycle and Treatment Notes

Introduction to HIV Life Cycle

  • Overview of HIV life cycle and replication.
  • Mention of complex processes involved in the life cycle.

Nature of HIV

  • HIV is classified as an RNA retrovirus.
  • Functions as an intracellular parasite with no mutualistic relationship with host cells.
    • Intracellular Parasite:
    • Uses the host cell's mechanisms to reproduce.
  • Takes over CD4+ T lymphocytes (also called helper T cells).
  • Requires a living host cell to thrive and propagate the virus.

Viral Replication Process

  • HIV infects host cells to replicate and persist.
  • Importance of early treatment to prevent progression to AIDS.
    • AIDS Diagnosis:
    • HIV positive status plus significant CD4 count decline or presence of opportunistic infections.

Key Cell Types Involved

  • CD4 cells:
    • Critical for the immune response.
    • Higher CD4 counts indicate a stronger immune system.
    • Lower counts increase susceptibility to opportunistic infections.

Mechanism of HIV Entry into Host Cells

  • To infect, HIV must enter the bloodstream and bind to host cells.
  • Two main types of co-receptors involved:
    • CCR5 co-receptor
    • CXCR4 co-receptor
  • HIV binds to the CD4 receptor and at least one of the co-receptors for entry into the cell.

Key Docking Proteins

  • The virus utilizes docking proteins:
    • gp120: Attaches to the CD4 receptor.
    • gp41: Facilitates membrane fusion.

Process Visualization

  • Illustration detailing the interaction between HIV and the host cell.
  • Components Represented:
    • HIV particle with gp120 and gp41
    • Host cell with CD4 receptor and co-receptors (CCR5 or CXCR4).

Treatment and Medications

  • CCR5 Antagonists:
    • Block HIV from binding to the CCR5 co-receptor, inhibiting entry.
  • Antiretroviral Therapy (ART):
    • Combination therapies targeting various stages of the HIV life cycle.

Second Stage: Viral DNA Integration

  • Upon entry, viral RNA is reverse transcribed into DNA that integrates into the host cell's genome.
    • Integration: Virus enters the nucleus and incorporates its DNA into the host DNA, effectively taking over cell functions.
    • Transcription & Translation:
    • Production of new viral components occurs within the host cell.
    • Transcription creates RNA copies of the viral DNA.

Medications Targeting Integration and Transcription

  • Integrase Strand Transfer Inhibitors (INSTIs):
    • Prevent viral DNA from integrating into host DNA.
  • NRTIs and NNRTIs:
    • Inhibit reverse transcription, preventing replication of the virus.

Third Stage: Viral Assembly and Release

  • Host's cellular machinery assembles new viral particles.
    • After assembly, new virus particles bud off from the host cell.
    • Protease Inhibitors:
    • Prevent the maturation of new virus particles by inhibiting protease enzymes, leading to non-infectious particles.

Immune Response Dynamics

  • HIV replication leads to a decrease in CD4 cells and an increase in viral load.
    • As the immune system weakens, opportunistic infections become more likely.

Transition from HIV to AIDS

  • Normal CD4 count: 800-1000 cells/mm³.
  • Diagnosis of AIDS if:
    • CD4 count falls below 200 cells/mm³ or 14% of total. - There is the emergence of any defined opportunistic infections.

Patient Management and Antiretroviral Therapies

  • Importance of adherence to ART regimens to maintain or improve CD4 counts and reduce viral load.
  • Even with successful treatment, once diagnosed with AIDS, the patient cannot revert to HIV-only status but can manage their condition effectively.

Post-Exposure Prophylaxis (PEP) Procedures

  • Steps to take following potential exposure:
    • Immediate washing of the exposed area.
    • Follow-up medical evaluation with lab tests for CD4 count and viral load.
    • Importance of strict adherence to follow-up and treatment protocols to prevent infection spread.

Anaphylaxis Overview

Definition and Immediate Treatment

  • First-line treatment: Epinephrine.
  • Additional medications may include antihistamines and corticosteroids.

Patient Education

  • Importance of recognizing the signs of anaphylaxis.
  • Carrying an EpiPen and knowing how to use it properly.
  • Seeking immediate medical attention post-administration.
  • Understanding personal triggers and creating an action plan is crucial for safety.