Identification of the functional domain of canine tetherin in antiviral activity against canine influenza virus

Jiajun Ou ^1* Yixin Dai ¹ Xu Liang ¹ Gang Lu ¹ Qingmei XIE ¹ Gaoming Lou ^2* Shoujun Li ^1*

• ¹ South China Agricultural University, Guangzhou, China
• ² Henry Fok School of Biology and Agriculture, Shaoguan University, China, Shaoguan, China

Canine influenza virus (CIV) is a respiratory pathogen causing fever, coughing, and sneezing in dogs, and is continuously circulating in canine populations. Tetherin is an antiviral host restriction factor mediated by interferon, capable of inhibiting the release of enveloped viruses from infected cells. The antiviral mechanism of tetherin is mainly due to its unusual topology, which includes a short N-terminal cytoplasmic tail (CT), a trans-membrane (TM), a coiled-coil extra-cellular region (CC), and a C-terminal glycosyl-phosphatidylinositol anchor (GPI). Previous studies have found that canine tetherin has the ability to limit the release of CIV, but its main antiviral domain remains unclear. In the present study, the potential CT, TM, CC, GPI domains of canine tetherin were predicted through systemic bioinformatic analysis and canine tetherin mutational variants based on the four domains were constructed. Confocal microscopy demonstrated CT, TM and CC domain was critical for cell membrane localization of canine Tetherin. The results of in vitro CIV infection experiments showed that the TM region is a critical functional domain of canine tetherin in limiting the replication of CIV. Our study will help better understand the antiviral activity of canine tetherin and the role of the structural domains of canine tetherin in inhibiting the replication CIV.