Advances on Innate Immune Evasion by Avian Immunosuppressive Viruses

Abstract

Innate immunity is not only the first line of host defense against pathogenic infection, but also the cornerstone of adaptive immune response. Upon pathogenic infection, pattern recognition receptors (PRRs) of host engage pathogen-associated molecular patterns (PAMPs) of pathogens, which initiates IFN production by activating interferon regulatory transcription factors (IRFs), nuclear factor-kappa B (NF-κB), and/or activating protein-1 (AP-1) signal transduction pathways in host cells. In order to replicate and survive, pathogens have evolved multiple strategies to evade host innate immune responses, including IFN-I signal transduction, autophagy, apoptosis, necrosis, inflammasome and/or metabolic pathways. Some avian viruses may not be highly pathogenic but they have evolved varied strategies to evade or suppress host immune response for survival, causing huge impacts on the poultry industry worldwide. In this review, we focus on the advances on innate immune evasion by several important avian immunosuppressive viruses (infectious bursal disease virus (IBDV), Marek’s disease virus (MDV), avian leukosis virus (ALV), etc.), especially their evasion of PRRs-mediated signal transduction pathways (IFN-I signal transduction pathway) and IFNAR-JAK-STAT signal pathways. A comprehensive understanding of the mechanism by which avian viruses evade or suppress host immune responses will be of help to the development of novel vaccines and therapeutic reagents for the prevention and control of infectious diseases in chickens.

The Immunological Basis for Vaccination

“…To be able to improve prophylactic strategies we will have to further understand the innate and acquired immune responses of birds and find new approaches to stimulate the protective immune responses in a specific way and drive the immune system toward long-lasting memory responses. Certainly, downsides of vaccination have to be considered as they may, especially in the context of insufficient herd immunity, favor immune evasion of pathogens and the development of new variants in the field (202–204). This further strengthens the need for vaccines with the potential of the induction of sterile immunity or, at least, the most efficient reduction of pathogen shedding in vaccinated birds.…”

Vitamin D and the Ability to Produce 1,25(OH)2D Are Critical for Protection from Viral Infection of the Lungs

“…Recently, Chauss et.al showed that 1,25D promotes anti-inflammatory responses by switching off IFN-γ production from Th1 cells and upregulating IL-10 [ 43 ]. IFN-γ and IFN-β production is essential for effective viral clearance; viruses have mechanisms to evade the IFN responses, and severe COVID-19 is associated with dysregulation of IFN responses [ 44 , 45 , 46 ]. Down-regulation of IFN-β by vitamin D is associated with protection from inflammation in the lung following a virus infection with either influenza or SARS-CoV-2.…”

Vitamin D and the ability to produce 1,25(OH)2D are critical for protection from viral infection of the lungs

“…The copyright holder for this preprint this version posted June 30, 2022. ; https://doi.org/10.1101/2022.06.29.498158 doi: bioRxiv preprint of IFN responses [45][46][47]. Down-regulation of IFN by vitamin D is associated with protection from inflammation in the lung following a virus infection with either influenza or SARS-CoV-2.…”

“…Recently, Chauss et.al showed that 1,25D promotes anti-inflammatory responses by switching off IFN production from Th1 cells and upregulating IL-10 [44]. IFN- and IFN production is essential for effective viral clearance, viruses have mechanisms to evade the IFN responses, and severe COVID-19 is associated with dysregulation of IFN responses [45][46][47]. Down-regulation of IFN by vitamin D is associated with protection from inflammation in the lung following a virus infection with either influenza or SARS-CoV-2.…”