Coordinated Expression of HPV-6 Genes with Predominant E4 and E5 Expression in Laryngeal Papilloma

• Main Authors: Taro Ikegami, Hitoshi Hirakawa, Narutoshi Tsukahara, Akikazu Murakami, Norimoto Kise, Asanori Kiyuna, Takayoshi Kosugi, Shinya Agena, Hidetoshi Kinjyo, Narumi Hasegawa, Masatomo Touyama, Shunsuke Kondo, Hiroyuki Maeda, Mikio Suzuki, Akira Ganaha
• Format: Article
• Language: English
• Published: MDPI AG 2021-03-01
• Series: Microorganisms
• Subjects: laryngeal papilloma; human papillomavirus 6; viral lineage; viral mRNA expression; long-term alteration of viral load; anti-E4 monoclonal antibody
• Online Access: https://www.mdpi.com/2076-2607/9/3/520

Laryngeal papilloma (LP) associated with human papillomavirus (HPV)-6 or -11 infection shows aggressive growth. However, the detailed molecular mechanism of virus-driven tumorigenesis has not been uncovered fully. HPV-6 viral gene expression and dynamic alterations were investigated with <i>in situ</i> localization of viral DNA and RNA in 13 patients with HPV-6-infected laryngeal papilloma. The average viral load was 4.80 × 10⁵ ± 1.86 × 10⁵ copies/ng DNA. <i>E4</i>, <i>E5a</i>, and <i>E5b</i> mRNAs accounted for 96% of the expression of 9 mRNAs. The alteration of viral DNA load during recurrence paralleled the mRNA expression levels, and the expression of all mRNAs showed a similar curve. <i>E4</i>, <i>E5a</i>, and <i>E5b</i> were expressed in the middle to upper part of the epithelium and were co-expressed in the same cells. E4 immunohistochemistry demonstrated an extensively positive reaction in the upper cell layer in accordance with <i>E4</i> mRNA expression. These results suggest that individual viral genes are coordinately expressed for viral replication, virus release, and immunosurveillance avoidance. The newly developed E4-specific monoclonal antibody can be applied to further functional studies and clinical applications such as targeted molecular therapies.