A 28-year-old immunocompromised man (CD4 count 45 cells/μL) presents with retinitis and floaters. Fundoscopy reveals a hemorrhagic, granular appearance with perivascular sheathing. All of the following statements regarding the causative agent are correct EXCEPT:

Explanation

## Clinical Diagnosis: CMV Retinitis The presentation of hemorrhagic, granular retinitis with perivascular sheathing in a severely immunocompromised patient (CD4 < 50 cells/μL) is pathognomonic for **cytomegalovirus (CMV) retinitis**. This is a direct consequence of CMV's ability to evade immune control in advanced AIDS. ### Identifying the Incorrect Statement **Key Point:** CMV DNA does NOT integrate into the host chromosome. Unlike retroviruses or some DNA viruses (e.g., papillomaviruses), CMV persists as a **non-integrated episome** in latently infected cells. Integration is not a mechanism of CMV latency. ### CMV Molecular Biology & Latency | Feature | CMV | HSV | VZV | | --- | --- | --- | --- | | **Latency Site** | Lymphoid tissues, monocytes, endothelium | Sensory ganglia (neurons) | Dorsal root ganglia (neurons) | | **Viral DNA Form** | Non-integrated episome | Non-integrated episome | Non-integrated episome | | **Integration** | ❌ No | ❌ No | ❌ No | | **IE Gene Products** | IE86, IE122 (transactivators) | ICP0, ICP4, ICP27 | IE62, IE63 | | **Immune Evasion** | v-cyclin, v-Bcl-2, vIL-10 | ICP47 (MHC-I block) | gE, gI (Fc receptor mimics) | **High-Yield:** CMV latency is **episomal**, not integrated. This is a common NEET PG trap—students confuse CMV with integrated viruses (HPV, HBV). ### Why the Other Statements Are Correct - **Option 0 (v-cyclin, v-Bcl-2):** CMV encodes viral homologues of cell-cycle and anti-apoptotic proteins to block host cell death and maintain persistent infection. These are hallmarks of CMV immune evasion. - **Option 1 (IE86, IE122):** These are the major immediate-early transactivators of CMV, analogous to HSV's ICP4. They drive expression of early and late genes. - **Option 2 (Slippage mechanism):** CMV DNA polymerase exhibits a unique slippage mechanism during replication of repetitive sequences (e.g., in the UL/b region), generating genome rearrangements and strain heterogeneity. This is a distinguishing feature of CMV. **Clinical Pearl:** CMV retinitis in AIDS patients is a medical emergency requiring urgent antiretroviral therapy (ART) initiation and intravenous ganciclovir or foscarnet to prevent blindness. Immune recovery uveitis (IRU) may occur paradoxically after CD4 recovery.