Autophagy Is a Potential Therapeutic Target Against Duck Tembusu Virus Infection in vivo.

Zhiqiang Hu,Yanling Yu,Mujeeb Ur Rehman,Bin Tian,Mafeng Liu,Yunya Liu,Juan Huang,Renyong Jia,Anchun Cheng,Mingshu Wang,Zhongqiong Yin,Xumin Ou,Ling Zhang,Xingcui Zhang,Dekang Zhu,Xinxin Zhao,Sai Mao,Ying Wu,Leichang Pan,Shun Chen,Qiao Yang,Shaqiu Zhang,Yuhong Pan

doi:10.3389/fcimb.2020.00155

Zhiqiang Hu, Yanling Yu + Show 21 more

Open Access

https://doi.org/10.3389/fcimb.2020.00155

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Abstract

Duck tembusu virus (DTMUV) is newly emerged in poultry and causes great losses to the breeding industry in China and neighboring countries. Effective antiviral strategies are still being studied. Autophagy is a cellular degradative pathway, and our lab's previous data show that autophagy promotes DTMUV replication in vitro. To study the role of autophagy further in vivo, we utilized ducks as the animal model to investigate the autophagy responses in DTMUV-targeted tissues. And also, we utilized autophagy regulators, including Rapamycin (Rapa) as the autophagy enhancer, 3-Methyladenine (3-MA) and Chloroquine (CQ) as the autophagy inhibitors, to adjust the host autophagic levels and then study the effects of autophagy on tissue damages and virus replication. As a result, we first found DTMUV infection trigged autophagy and autophagy regulator treatments regulated autophagy levels successfully in duck spleens and brains. Next, we found that autophagy inhibitors inhibited DTMUV replication and alleviated DTMUV-induced pathological symptoms, whereas the autophagy inducer treatment led to the opposite effects. And we also found that autophagic regulation was correlated with the expression of innate immune genes, including pattern recognition receptors, type I interferons, and cytokines, and caused different effects in different tissues. In summary, we demonstrated that autophagy facilitated DTMUV replication, aggravated the developments of pathological symptoms and possibly counteracts the host's innate immunity response in vivo.

Highlights

Autophagy is a cellular degradative pathway that delivers intracellular senescent organelles, longlived proteins, and exogenous pathogenic microorganisms to lysosomes for degradation (Klionsky and Emr, 2000)
We found that Rapa treatment further improved LC3-II increase and p62 decrease in both spleens and brains (Figures 1A,B), which indicated the promotion of autophagic activation. 3-MA treatment, an inhibitor of autophagy initiation, decreased the levels of LC3-II but increased p62 levels in spleens compared to those in Duck tembusu virus (DTMUV)-infected ducks with saline treatment
As we have investigated that autophagy promotes the replication of DTMUV in vitro (Hu et al, 2020), to further provide the clinical evidence on the effects of autophagy on DTMUV replication and pathogenesis, we utilized ducks as the animal model to study the role of autophagy in DTMUV-targeted organs

Summary

Introduction

Autophagy is a cellular degradative pathway that delivers intracellular senescent organelles, longlived proteins, and exogenous pathogenic microorganisms to lysosomes for degradation (Klionsky and Emr, 2000). Some mTOR inhibitors have been used as autophagy inducers, such as Rapa (Jung et al, 2010) and Everolimus (Crazzolara et al, 2009). Another critical signal is phosphatidylinositol 3-kinases (PI3K), which is required for autophagy. There are some autophagy inhibitors targeting the process of autophagic degradation. Chloroquine (CQ) has been reported to inhibit autophagy by raising the lysosomal pH, which leads to inhibition of both fusion of autophagosome with lysosome and lysosomal protein degradation (Shintani and Klionsky, 2004). Bafilomycin A1 inhibits autophagic degradation by inhibiting fusion between autophagosomes and lysosomes (Yamamoto et al, 1998)

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