Which one of the following is the primary target cell of HIV?

NVS Staff Nurse - 2022

Applied Microbiology & Infection control

Easy

Appeared in: NVS Staff Nurse - 2022

Explanation

The primary target for HIV is the CD4+ T lymphocyte, also known as the T-helper cell.
HIV's envelope protein, gp120, specifically binds to the CD4 receptor on the surface of these cells, which is the crucial first step for viral entry.
Infection and subsequent destruction of CD4+ T cells lead to a progressive decline in immune function, culminating in Acquired Immunodeficiency Syndrome (AIDS).
While other cells like macrophages and dendritic cells can be infected, CD4+ T cells are the principal targets and their depletion is the central feature of HIV pathogenesis.

Option A: Transitional B cells are immature B lymphocytes. They do not express the CD4 receptor and therefore are not a target for HIV infection.
Option B: B lymphocytes are not the primary target of HIV because they lack the necessary CD4 receptor for viral entry. Their function is impaired indirectly due to the loss of T-helper cell support.
Option C: Plasma cells and memory cells are differentiated forms of B lymphocytes. Like other B cells, they do not have CD4 receptors and are not directly infected by HIV.

Clinical Relevance

Nursing practice connection: This is primarily an exam-oriented knowledge point with limited direct bedside application, so retain Primary target cell of Human Immunodeficiency Virus (HIV) as background academic context rather than a clinical decision trigger.
Monitoring the CD4+ T cell count is a cornerstone of managing patients with HIV. It helps determine disease progression, predict the risk of opportunistic infections, and guide decisions about starting or changing antiretroviral therapy (ART).
A CD4 count below 200 cells/mm³ is a defining criterion for an AIDS diagnosis, signaling severe immunodeficiency and a high risk for life-threatening opportunistic illnesses.
What if a patient has a genetic mutation (like the CCR5-delta 32 deletion) that alters the co-receptor? This can confer natural resistance to infection by R5-tropic strains of HIV, as the virus cannot use this co-receptor to enter the T cell. This principle is the basis for some advanced therapeutic strategies.

How to Approach the Question

First, identify the core subject of the question, which is the 'primary target cell' of HIV.
Recall the basic pathophysiology of HIV. The virus is known for attacking the immune system in a very specific way.
Scan the options. Notice that three options are related to B cells (Transitional B cell, B lymphocytes, Plasma and memory cell), and one is a T cell (CD4+ T cell).
Remember that the 'CD4' in 'CD4+ T cell' refers to the specific receptor that HIV uses to enter the cell. This makes it the most likely primary target.
Select CD4+ T cell as the correct answer, as it is the central cell in HIV pathogenesis.

Concept Tested & Keywords

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E6 Medicine Harrison 22e Part 1 p. 1619-1621

E6 Pathology- ROBBINS & COTRAN PATHOLOGIC BASIS OF DISEASE 10TH Ed p. 259-261