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Characterization and functional analysis of chicken APOBEC4
Mengyu Shi1, Lei Tan1, Yaodan Zhang1
1Shanghai Veterinary Research Institute, Chinese Academy of Agricultural Sciences, Shanghai, 200241, PR China.
Insights
Chicken APOBEC4 (chA4) is a novel immune protein identified in birds. This study shows chA4 expression increases upon Newcastle Disease Virus infection and inhibits viral replication, suggesting a role in avian antiviral defense.
Area of Science:
- Immunology
- Virology
- Genomics
Background:
- APOBEC proteins are crucial for innate and adaptive immunity via deaminase activities.
- Chicken APOBEC1 and APOBEC3 are absent, prompting investigation into chicken APOBEC4 (chA4) functions.
- Understanding chA4 is vital given its potential role in avian health and disease resistance.
Purpose of the Study:
- To identify and characterize chicken APOBEC4 (chA4) mRNA and its functional significance.
- To investigate chA4 expression patterns in response to Newcastle Disease Virus (NDV) infection.
- To evaluate the antiviral potential of chA4 against NDV.
Main Methods:
- Bioinformatics analysis to identify conserved motifs and active sites in chA4.
- Quantitative analysis of chA4 mRNA expression in various chicken tissues and cell lines.
- In vitro and in vivo experiments to assess chA4 expression changes and antiviral activity upon NDV infection.
Main Results:
- Chicken APOBEC4 (chA4) mRNA was identified, revealing a conserved zinc-coordinating motif with active sites.
- chA4 expression was highest in lymphocytes and bursa of Fabricius, and significantly upregulated in immune cells and tissues upon NDV infection.
- Exogenous chA4 expression inhibited NDV replication and reduced viral RNA levels in infected cells.
Conclusions:
- Chicken APOBEC4 (chA4) is a newly identified immune-related gene in chickens.
- chA4 plays a role in the chicken immune system, particularly in antiviral responses against Newcastle Disease Virus.
- chA4 represents a potential target for enhancing avian antiviral immunity.
Abstract:
The APOBEC proteins play significant roles in the innate and adaptive immune system, probably due to their deaminase activities. Because APOBEC1 (A1) and APOBEC3 (A3) are absent in the chicken genome, we were interested in determining whether chicken APOBEC4 (A4) possessed more complex functions than its mammalian homologs. In this study, chicken A4 (chA4) mRNA was identified and cloned for the first time. Based on bioinformatics analyses, the conserved zinc-coordinating motif (HXE … PC(X)2-6C) was identified on the surface of chA4 and contained highly conserved His97, Glu99, Pro130, Cys131 and Cys138 active sites. The highest expression levels of constitutive chA4 were detected in primary lymphocytes and bursa of Fabricius. Newcastle Disease (ND) is one of the most serious infectious diseases in birds, causing major economic losses to the poultry industry. In vitro, Newcastle Disease Virus (NDV) early infection induced significant increases in chA4 expression in the chicken B cell line, DT40, the macrophage cell line, HD11 and the CD4+ T cell line, MSB-1, but not the fibroblast cell line, DF-1. In vivo, the expression levels of chA4 were up-regulated in several tissues from NDV-infected chickens, especially the thymus, testicles, duodenum and kidney. The high level expression of exogenous chA4 displayed inhibitory effects on NDV and reduced viral RNA in infected cells. Taken together, these data demonstrate that chA4 is involved in the chicken immune system and may play important roles in host anti-viral responses.
