HPV 18

HPV 18 Full Name

Human papillomavirus type 18

HPV 18 Introduction

Human Papillomavirus Type 18 (HPV-18) is a high-risk HPV type strongly associated with cervical cancer progression. The E1 protein of HPV-18 is a pivotal component of the viral replication machinery, acting as a DNA helicase essential for unwinding the viral genome and promoting efficient replication. E1 interacts closely with the E2 protein, enhancing the binding efficacy of E2 to the viral origin of replication and stabilizing this interaction. E1 proteins from different HPV types exhibit varying capabilities to interact with host cellular factors, and for HPV-18, E1 also participates in the modulation of cellular immune responses by regulating the expression of genes involved in antiviral defense. Specifically, it downregulates genes such as IFNβ1 and CCL5, which are critical for immune responses, indicating a sophisticated interplay between viral proteins and host immunity.

E1's helicase activity not only facilitates HPV-18 replication but also involves competitive dynamics with other HPV types, notably HPV-16, where HPV-16 E1 can inhibit HPV-18 replication. Cellular signaling pathways, such as PKA-mediated differentiation signals in epithelial cells, further regulate E1 activity and replication capacity, demonstrating how external signaling can influence viral behavior within the host. Mutations in E1 can significantly impact replication efficiency, sometimes exerting dominant-negative effects, highlighting the delicate balance required for successful viral replication. Additionally, interactions with cellular factors, including the deubiquitinase complex UAF1, support long-term maintenance of the HPV episome, stimulate transient viral DNA replication, and ensure persistence of the viral genome in undifferentiated keratinocytes.

Integration of HPV-18 DNA into the host genome is frequently observed in cervical cancers, often disrupting the E1 and E2 genes and resulting in overexpression of the E6 and E7 oncogenes that drive transformation of cervical epithelial cells. The relationship between E1 integrity and methylation patterns has also been noted, with a higher frequency of E1 disruption observed in high-grade cervical cancers associated with HPV-18 compared to HPV-16. Such findings suggest that HPV-18 carcinogenesis involves not only E1 as a replication factor but also as a contributor to genomic stability through its interactions with the host cell. Overall, E1 plays a central role in viral replication, immune modulation, and oncogenic potential, and understanding its interactions with viral and host factors provides valuable insights into HPV-18 pathogenesis and potential therapeutic targets.

Alternate Names for HPV 18

HPV; L1; major capsid L1 protein; HPV-18; HPV-18 capsid; HPV18 capsid protein; HPV18 L1; HPV18 major capsid protein L1; Human papillomavirus type 18 L1; Human papillomavirus type 118 major capsid protein L1; Major capsid protein; Major capsid protein L1; Human papillomavirus

• 1. Piirsoo et al. Uncovering the Role of the E1 Protein in Different Stages of Human Papillomavirus 18 Genome Replication. Journal of Virology. 2020.
  2. Mori et al. Replication interference between human papillomavirus types 16 and 18 mediated by heterologous E1 helicases. Virology Journal. 2014.
  3. Castro-Mu?oz et al. The Human Papillomavirus (HPV) E1 protein regulates the expression of cellular genes involved in immune response. Scientific Reports. 2019.
  4. Lototskaja et al. Cyclic AMP-Dependent Protein Kinase Exhibits Antagonistic Effects on the Replication Efficiency of Different Human Papillomavirus Types. Journal of Virology. 2021.