Question

Which cells are attacked by HIV?

Short answer

HIV primarily attacks CD4+ T cells, weakening the immune system.

Step-by-step solution

- Understanding HIV

HIV stands for Human Immunodeficiency Virus. It is a virus that targets the body's immune system.

- Identifying the Target Cells

The primary cells that HIV attacks are a type of white blood cells called CD4+ T cells. These cells are crucial for the immune system because they help in fighting off infections.

- Mechanism of Attack

HIV attaches to the CD4+ T cells using its surface proteins and then enters the cells. Once inside, it uses the cell's machinery to replicate itself, ultimately leading to the destruction of the CD4+ T cells.

- Consequences of Attacking CD4+ T Cells

As HIV continuously destroys CD4+ T cells, it weakens the immune system over time. This makes the body more susceptible to infections and certain types of cancers.

Key concepts

CD4+ T cells

CD4+ T cells are a type of white blood cell important for a healthy immune system. They play a key role in fighting infections by sending signals to other cells in the immune system, like CD8+ T cells, to destroy infected cells. Without enough CD4+ T cells, the immune system can't work properly.
In HIV infection, the virus specifically targets these CD4+ T cells. HIV binds to the surface of these cells, enters them, and uses the cells' machinery to replicate. This gradually decreases the number of CD4+ T cells in the body, making the immune system weaker over time.

Immune System

The immune system is the body's defense mechanism against infections and diseases. It consists of various cells, including CD4+ T cells, that work together to identify and destroy harmful pathogens like viruses, bacteria, and fungi.
When HIV attacks CD4+ T cells, it disrupts the balance of the immune system. It becomes harder for the body to fight off other infections. Over time, as the number of CD4+ T cells decreases, this can lead to a condition called Acquired Immunodeficiency Syndrome (AIDS), where the immune system is severely compromised.

• White blood cells, including CD4+ T cells, are crucial for identifying and attacking invaders.
• With fewer CD4+ T cells, the body can't respond effectively to new infections.

This makes individuals with HIV more susceptible to opportunistic infections and certain cancers.

Virus Replication

Virus replication is the process by which viruses reproduce and create more copies of themselves. For HIV, this process begins when the virus attaches to a CD4+ T cell. The virus then enters the cell and releases RNA, which is converted into DNA by an enzyme called reverse transcriptase.
This new viral DNA is integrated into the host cell's DNA. Using the host cell's machinery, the virus replicates, producing new viral particles. These new viruses are then released to infect more CD4+ T cells, perpetuating the cycle.

• HIV's replication process is rapid, leading to quick depletion of CD4+ T cells.
• The replication cycle involves several stages, including attachment, entry, reverse transcription, integration, and release.

The continuous replication and destruction of CD4+ T cells weaken the immune system over time.

HIV Mechanism

The HIV mechanism involves several steps that allow the virus to infect and replicate within CD4+ T cells. This process begins with the attachment of HIV to the CD4+ T cell's surface.
Once HIV is attached, it fuses with the cell membrane and releases its RNA into the cell. The viral enzyme reverse transcriptase converts the RNA into DNA, which integrates into the host's DNA. The host cell then produces viral proteins and RNA, which assemble into new viral particles.

• Attachment: HIV binds to CD4 receptors on T cells.
• Entry: The virus enters the T cell and releases RNA.
• Reverse Transcription: Viral RNA is converted to DNA.
• Integration: Viral DNA integrates into the host cell's DNA.
• Replication and Assembly: The host cell produces new viruses.

The new viruses are then released from the cell to infect other CD4+ T cells. This cycle of infection and replication ultimately weakens the immune system by reducing CD4+ T cell numbers.