Molecular analysis of chicken interferon-alpha inducible protein 6 gene and transcriptional regulation

RNA-Seq of Chicken Embryo Liver Reveals Transcriptional Pathways Influenced by Egg Formaldehyde Treatment

BACKGROUND/OBJECTIVES

Hatchery fumigation is recognized as a crucial step to control microbial bloom in the environment, and formaldehyde is one of the most widely used disinfectants to ensure successful hatchability and healthy production. While many of the benefits are thought to be derived from disinfectant properties, it is possible that additional host gene and genetic pathway modulation could contribute to these outcomes. The current study aimed to capture the in ovo transcriptional response of liver tissue to formaldehyde treatment.

METHODS

Chick embryos were subjected to formaldehyde fumigation treatment for 25 min at 24-25 °C and 75% relative humidity, keeping a control group as untreated. On the 18th day of incubation at 37.8 °C and 58-63% humidity, eggs were broken, and liver tissue was obtained for RNA isolation, cDNA library preparation, and RNA sequencing.

RESULTS

Bioinformatics analysis revealed 908 significant differentially expressed genes (DEGs), among which 814 were known genes and 94 were novel genes. A total of 672 DEGs were upregulated, whereas 236 genes were downregulated in response to FA treatment. Of the 94 novel genes, 80 were upregulated. Key DEGs, associated QTLs, and transcription factors were involved in immuno-inflammatory responses, oxidative stress, epigenetic modification, and cellular adaptation-related activities. Further research should focus on biological validation of key DEGs to clarify their roles, pathways, and relationships to FA treatment.

CONCLUSIONS

Overall, these findings (1) provide critical molecular detail as a first step towards genetic selection to improve formaldehyde treatment response and effectiveness, and (2) provide DEG signatures for FA treatment as a reference against which to compare other interventions to achieve hatchability and production benefits.

In vitro analysis of antiviral immune response against avian influenza virus in chicken tracheal epithelial cells

OBJECTIVE

Avian influenza virus (AIV) infections first affect the respiratory tract of chickens. The epithelial cells activate the host immune system, which leads to the induction of immune-related genes and the production of antiviral molecules against external environmental pathogens. In this study, we used chicken tracheal epithelial cells (TECs) in vitro model to investigate the immune response of the chicken respiratory tract against avian respiratory virus infections.

METHODS

Eighteen-day-old embryonic chicken eggs were used to culture the primary chicken TECs. Reverse transcription-polymerase chain reaction (RT-PCR) and immunocytochemistry (ICC) analysis of epithelial cell-specific gene makers were performed to confirm the characteristics, morphology, and growth pattern of primary cultured chicken TECs. Moreover, to investigate the cellular immune response to AIV infection or polyinosinic-polycytidylic acid (poly [I:C]) treatment, the TECs were infected with the H5N1 virus or poly (I:C). Then, immune responses were validated by RT-qPCR and western blotting.

RESULTS

The TECs exhibited polygonal morphology and formed colony-type cell clusters. The RT-qPCR results showed that H5N1 infection induced a significant expression of antiviral genes in TECs. We found that TECs treated with poly (I:C) and exposed to AIV infection-mediated activation of signaling pathways, leading to the production of antiviral molecules (e.g., pro-inflammatory cytokines and chemokines), were damaged due to the loss of junction proteins. We observed the activation of the nuclear factor kappa B and mitogen-activated protein kinase (MAPK) pathways, which are involved in inflammatory response by modulating the release of pro-inflammatory cytokines and chemokines in TECs treated with poly (I:C) and pathway inhibitors. Furthermore, our findings indicated that poly (I:C) treatment compromises the epithelial cell barrier by affecting junction proteins in the cell membrane.

CONCLUSION

Our study highlights the utility of in vitro TEC models for unraveling the mechanisms of viral infection and understanding host immune responses in the chicken respiratory tract.

Antiviral Effects of Avian Interferon-Stimulated Genes

Interferons (IFNs) stimulate the expression of numerous IFN-stimulating genes via the Janus kinase-signal transducers and activators of the transcription (JAK-STAT) signaling pathway, which plays an important role in the host defense against viral infections. In mammals, including humans and mice, a substantial number of IFN-stimulated genes (ISGs) have been identified, and their molecular mechanisms have been elucidated. It is important to note that avian species are phylogenetically distant from mammals, resulting in distinct IFN-induced ISGs that may have different functions. At present, only a limited number of avian ISGs have been identified. In this review, we summarized the identified avian ISGs and their antiviral activities. As gene-editing technology is widely used in avian breeding, the identification of avian ISGs and the elucidation of their molecular mechanism may provide important support for the breeding of avians for disease resistance.