Virology — MCQs

Q: The paramyxovirus that lacks both hemagglutinin and neuraminidase activities is:

Respiratory syncytial virus. ***Respiratory syncytial virus*** - **Respiratory syncytial virus (RSV)** is unique among paramyxoviruses because it **lacks both hemagglutinin (HA) and neuraminidase (NA)** surface glycoproteins. - Instead, RSV uses its **fusion (F) protein** to mediate viral entry and induce syncytia formation. *Mumps virus* - Mumps virus possesses both **hemagglutinin and neuraminidase (HN) activity** on a single surface glycoprotein. - This HN protein is crucial for **viral attachment and release** from host cells. *Measles virus* - Measles virus has **hemagglutinin (H)** activity for attachment but **lacks neuraminidase activity**. - Its F protein is essential for **cell fusion** and spread. *Parainfluenza virus* - Parainfluenza viruses, like mumps, possess a **hemagglutinin-neuraminidase (HN) protein** with both activities. - This dual function is important for their **lifecycle and pathogenesis**.

Q: The virus HIV is produced and propagated in:

Circulating T4 lymphocytes. ***Circulating T4 lymphocytes*** - HIV primarily targets and replicates within **CD4+ T lymphocytes** (also known as T4 lymphocytes), which are crucial for the immune response. - The virus uses its **gp120 protein** to bind to the **CD4 receptor** and a coreceptor (CCR5 or CXCR4) on these cells, initiating entry and subsequent replication. *Dendritic cells in the lymph nodes* - Dendritic cells can be infected by HIV, but they primarily function as **reservoirs** and vehicles for transporting the virus to lymph nodes, rather than the main site of productive replication. - While they can transfer HIV to CD4+ T cells, the *primary propagation* occurs in the activated T cells themselves. *B-lymphocytes in the lymph nodes* - **B-lymphocytes** lack the primary **CD4 receptor** and co-receptors (CCR5/CXCR4) necessary for efficient HIV entry and replication. - Therefore, B-cells are generally **not productively infected** by HIV and do not serve as a site for significant viral propagation. *Epithelial cells of the reproductive system* - While HIV can be found in bodily fluids of the reproductive system, **epithelial cells** are generally not the target cells for HIV infection and replication. - The virus primarily targets immune cells, particularly **CD4+ T cells and macrophages**, not epithelial cells of mucosal surfaces for propagation.

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DNA Viruses: Herpesviruses

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Hepatitis Viruses

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RNA Viruses: Orthomyxoviruses

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RNA Viruses: Paramyxoviruses

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Enteroviruses and Rhinoviruses

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Arboviruses

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HIV and Retroviruses

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Oncogenic Viruses

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Virology — MCQs

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