## HPV Genome Structure and Organization **Key Point:** HPV possesses a circular double-stranded DNA genome, NOT single-stranded RNA. This is a fundamental characteristic that distinguishes HPV from many other oncogenic viruses. ### Correct Features of HPV | Feature | Details | | --- | --- | | **Genome type** | Circular, double-stranded DNA (dsDNA) | | **Genome size** | ~8 kb (8,000 base pairs) | | **Virion structure** | Non-enveloped, icosahedral | | **Virion diameter** | 50–55 nm | | **Capsid proteins** | L1 (major) and L2 (minor) | ### Genome Organization **High-Yield:** The HPV genome is organized into three functional regions: 1. **Early genes (E1–E7):** Encode regulatory and transforming proteins - E6 and E7 are the major oncoproteins - E1 and E2 regulate viral replication and transcription 2. **Late genes (L1, L2):** Encode structural capsid proteins - L1: Major capsid protein (~72 copies per virion) - L2: Minor capsid protein (~12 copies per virion) 3. **Long control region (LCR):** Non-coding regulatory sequence containing the origin of replication **Clinical Pearl:** The circular dsDNA genome allows HPV to persist as an episomal element in infected cells, enabling chronic infection and malignant transformation. **Warning:** Do not confuse HPV with retroviruses (which have single-stranded RNA genomes) or with other DNA viruses. HPV's genome is definitively double-stranded DNA. [cite:Robbins 10e Ch 7]
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