Introduction

Marek’s disease virus

Avian leukosis virus subgroup J

Influenza A virus

Other viruses

Pathways significantly enriched by the targets of dysregulated miRNAs during viral infection

Conclusions

Acknowledgments

References

Abstract

In poultry, viral infections (e.g., Marek’s disease virus, avian leukosis virus, influenza A virus, and so on) can cause devastating mortality and economic losses. Because viruses are solely dependent on host cells to propagate, they alter the host intracellular microenvironment. Thus, understanding the virus-host interaction is important for antiviral immunity and drug development in the poultry industry. MicroRNAs are crucial posttranscriptional regulators of gene expression in a wide spectrum of biological processes, including viral infection. Recently, microRNAs have been identified as key players in virus-host interactions. In this review, we will discuss the intricacies involved in the virus-host cross-talk mediated by host and viral microRNAs in poultry (i.e., chicken and ducks), as well as recent trends and challenges in this field. These findings may provide some insights into the rapidly developing area of research regarding viral pathogenesis and antiviral immunity in poultry production.

Introduction

Many types of viruses will cause high mortality rates and enormous economic losses to the poultry industry. For example, Marek’s disease virus (MDV) and avian leukosis virus can induce neoplastic diseases in chickens. Moreover, influenza A virus (IAV) is highly variable and can spread across species, thereby resulting in a threat to global public health. Therefore, the cross-talk between the host (i.e., chickens) and viruses during infections is critical to understanding viral pathogenesis and antiviral immunity in chicken production. Over the past decade, studies have attempted to depict the cross-talk between the host and virus from different aspects (e.g., microRNA [miRNAs] perspective) and have made progress in this area (Li et al., 2014a; Skalsky and Cullen, 2010).

miRNAs Are short noncoding 18- to 25-nucleotidelong RNAs that regulate gene expression at the posttranscriptional level. Substantial evidence demonstrates that a single miRNA can have extensive and crucial effects on a range of fundamental biological processes, and miRNA dysregulation can result in biological dysfunction and diseases (Bartel, 2004; Ha and Kim, 2014). Pathogen-induced phenotypic changes in hosts are always accompanied by remarkable alterations at the transcriptional level (Jenner and Young, 2005). The miRNA expression profile is profoundly influenced by viral infection and contributes to the repertoire of virus-host interactions. Differential miRNA expression can be attributed to both host antiviral defenses and alterations in cellular environment that are affected by viral factors (Scaria et al., 2007; Skalsky and Cullen, 2010; tenOever, 2013; Harwig et al., 2014; Powdrill et al., 2016; Nejad et al., 2018). Moreover, miRNAs have been reported to be biomarkers of viral infections (Wang et al., 2014) and have roles in viral reactivation from latency (Hicks et al., 2019). Therefore, the identification of deregulated miRNAs in virally infected chickens will provide novel insight into understanding virus-host interaction. In this review, we will summarize recent advances into the critical role of virally influenced poultry and viral miRNAs in the cross-talk between the host and virus to help understand viral pathogenesis and antiviral immunity in the poultry industry.