Expression of interferon-inducible transmembrane proteins in the chicken and possible role in prevention of viral infections

In Vitro Characterization of chIFITMs of Aseel and Kadaknath Chicken Breeds against Newcastle Disease Virus Infection

Newcastle disease (ND) is highly contagious and usually causes severe illness that affects Aves all over the world, including domestic poultry. Depending on the virus's virulence, it can impact the nervous, respiratory, and digestive systems and cause up to 100% mortality. The chIFITM genes are activated in response to viral infection. The current study was conducted to quantify the mRNA of chIFITM genes in vitro in response to ND viral infection. It also examined its ability to inhibit ND virus replication in chicken embryo fibroblast (CEF) cells of the Aseel and Kadaknath breeds. Results from the study showed that the expression of all chIFITM genes was significantly upregulated throughout the period in the infected CEF cells of both breeds compared to uninfected CEF cells. In CEF cells of the Kadaknath breed, elevated levels of expression of the chIFITM3 gene dramatically reduced ND viral growth, and the viral load was 60% lower than in CEF cells of the Aseel breed. The expression level of the chIFITMs in Kadaknath ranged from 2.39 to 11.68 log₂ folds higher than that of control CEFs and was consistently (p < 0.01) higher than Aseel CEFs. Similar to this, theIFN-γ gene expresses strongly quickly and peaks at 13.9 log₂ fold at 48 hpi. Based on these cellular experiments, the Kadaknath breed exhibits the potential for greater disease tolerance than Aseel. However, to gain a comprehensive understanding of disease resistance mechanisms in chickens, further research involving in vivo investigations is crucial.

Antiviral responses against chicken respiratory infections: Focus on avian influenza virus and infectious bronchitis virus

Some of the respiratory viral infections in chickens pose a significant threat to the poultry industry and public health. In response to viral infections, host innate responses provide the first line of defense against viruses, which often act even before the establishment of the infection. Host cells sense the presence of viral components through germinal encoded pattern recognition receptors (PRRs). The engagement of PRRs with pathogen-associated molecular patterns leads to the induction of pro-inflammatory and interferon productions. Induced antiviral responses play a critical role in the outcome of the infections. In order to improve current strategies for control of viral infections or to advance new strategies aimed against viral infections, a deep understanding of host-virus interaction and induction of antiviral responses is required. In this review, we summarized recent progress in understanding innate antiviral responses in chickens with a focus on the avian influenza virus and infectious bronchitis virus.

Siglec-F is induced by granulocyte-macrophage colony-stimulating factor and enhances interleukin-4-induced expression of arginase-1 in mouse macrophages

Siglecs are cell surface lectins that recognize sialic acids and are primarily expressed in hematopoietic cells. Previous studies showed that some Siglecs regulate macrophage function. In the present study, we examined the induction and putative roles of mouse Siglec-F in bone-marrow-derived macrophages in mice. A quantitative RT-PCR analysis showed that the basal expression of Siglec-F was weak in bone-marrow-derived macrophages differentiated by macrophage colony-stimulating factor. However, a 24-hr stimulation with granulocyte-macrophage colony-stimulating factor (GM-CSF) enhanced Siglec-F expression. GM-CSF also enhanced Siglec-F expression in thioglycollate-induced peritoneal macrophages. The inhibition of signal transducer and activator of transcription 5 (STAT5), but not that of phosphoinositide 3-kinase or mitogen-activated protein kinase kinase, significantly reduced the induction of Siglec-F. Interleukin-3, which uses a common β-chain shared with the GM-CSF receptor to stimulate the STAT5 pathway, also enhanced Siglec-F expression. The knockdown of Siglec-F by a specific small interfering RNA enhanced GM-CSF-induced STAT5 phosphorylation, suggesting that Siglec-F down-regulates its own expression upon prolonged GM-CSF stimulation. Furthermore, the knockdown of Siglec-F reduced the STAT6 phosphorylation and expression of arginase-1 in interleukin-4-stimulated macrophages. These results suggest that Siglec-F fine-tunes the immune responses of macrophages.

Characterization of chicken interferon-inducible transmembrane protein-10

Interferon-inducible transmembrane protein (IFITM) family proteins are antivirus factors. In the present study, we examined the expression pattern of chicken IFITM10 using quantitative reverse transcription-polymerase chain reaction. In adult chickens, IFITM10 levels were markedly lower than those of IFITM3, which exhibits antivirus activity. On the other hand, IFITM10 was expressed in levels similar to those of IFITM3 in embryonic organs. Primordial germ cells in 2.5-d embryos expressed high levels of IFITM10, which gradually decreased with time. The interferon-α stimulation of embryonic fibroblast cells did not enhance the expression of IFITM10. The forced expression of IFITM10 slightly inhibited the infectivity of the VSV-G-pseudotyped lentiviral vector. Furthermore, cell fusion was inhibited by IFITM10 when HeLa cells transfected with the VSV-G expression vector were treated with low pH buffer. Although it remains unclear whether IFITM10 inhibits viral infections under physiological conditions, these results suggest that chicken IFITM10 exhibits antivirus activity.