In an individual Human Immunodeficiency virus infects \ \ \ \ \ \ cell in the immune system. - RRB Nsg Superintendent -29 April 2025 (Shift-1st)

RRB Nsg Superintendent -29 April 2025 (Shift-1st)

Microbiology

Easy

Appeared in: RRB Nsg Superintendent -29 April 2025 (Shift-1st)

Explanation

The primary target of HIV is the T helper lymphocyte, a type of white blood cell crucial for the immune system.
These cells are targeted because they have a protein called CD4 on their surface, which the virus uses as a door to enter the cell.
The virus's gp120 envelope protein binds specifically to this CD4 receptor, initiating the infection process.
The progressive destruction of these CD4+ T helper cells leads to the severe immunodeficiency characteristic of AIDS.

Option A: Mast cells are primarily involved in allergic reactions and inflammatory responses. They are not a significant target for HIV infection as they do not typically express the CD4 receptor in a way that facilitates viral entry.
Option C: While dendritic cells play a role in HIV pathogenesis, they are not the primary cell infected and destroyed. They act more as transporters, capturing the virus at mucosal surfaces and carrying it to lymph nodes, where they present it to T helper cells, thereby facilitating their infection.
Option D: Monocytes and their tissue counterparts, macrophages, can be infected by HIV as they also express the CD4 receptor. However, they are considered a secondary target and a viral reservoir. They are more resistant to being killed by the virus and serve as a long-term hiding place for HIV, but their destruction is not the primary cause of AIDS.

Visual 1: Diagram - A diagram illustrating the HIV life cycle, showing the virus binding to the CD4 receptor and a co-receptor (CCR5/CXCR4) on a T helper cell, followed by fusion, entry, reverse transcription, integration, replication, and budding.
Visual 2: Graph - A graph showing the typical course of HIV infection over time, plotting the levels of viral load (plasma HIV RNA) and CD4+ T cell count. This visualizes the initial spike in virus, the period of clinical latency, and the eventual decline of CD4 cells leading to AIDS.

Clinical Relevance

Nursing practice connection: This is primarily an exam-oriented knowledge point with limited direct bedside application, so retain HIV Pathogenesis and Target Cells as background academic context rather than a clinical decision trigger.
The cornerstone of monitoring HIV progression is the measurement of the CD4+ T cell count. A count below 200 cells/mm³ is a diagnostic criterion for AIDS and indicates a high risk for opportunistic infections.
Antiretroviral therapy (ART) works by inhibiting various stages of the HIV life cycle, preventing the virus from replicating and destroying T helper cells. The goal of ART is to suppress the viral load to undetectable levels and allow the CD4 count to recover.
Understanding that monocytes/macrophages act as a reservoir is crucial because these latently infected cells are not eliminated by ART and are a major reason why HIV cannot currently be cured, only controlled.

How to Approach the Question

First, identify the key terms in the question: 'Human Immunodeficiency Virus' (HIV) and 'infects'.
This is a factual recall question that tests your knowledge of the pathophysiology of HIV.
Recall that the defining feature of HIV is its attack on the immune system. Specifically, it targets a particular type of lymphocyte.
Remember the specific name or marker for this cell. HIV is known for targeting cells with the CD4 receptor.
Evaluate the options to see which one is the primary CD4-expressing cell. T helper cells are also known as CD4+ T cells.
Eliminate the other options by recalling their primary functions and their role (or lack thereof) in HIV infection. Monocytes and dendritic cells are involved but are not the primary target for depletion, and mast cells are unrelated.

Concept Tested & Keywords

QknRcmaQqWH9r3od_pwPvs