In mammals, interferon-inducible transmembrane proteins (IFITMs) prevent infections by various enveloped viruses. The expression of IFITMs in chicken was herein examined in the adult and embryonic organs using a quantitative reverse-transcription-polymerase chain reaction. The results obtained revealed that IFITM3 was expressed at a higher level than IFITM1, 2 and 5, in both embryonic and adult organs. However, the expression levels of IFITMs in embryonic organs were less than 5 % of those in adult lungs. Among the embryonic tissues examined, primordial germ cells (PGCs) at day 2.5 expressed relatively higher levels of IFITM3. IFITM3 expression levels were 1.5-fold higher in the chicken cell line DF-1 than in PGCs. The knockdown of IFITM3 in DF-1 cells by siRNA increased the infectivity of a vesicular stomatitis virus G protein-pseudotyped lentiviral vector, suggesting that lower levels of IFITM3 are still sufficient to restrict this viral vector.

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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.

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Transgenic birds are commonly used for time‐lapse imaging and fate mapping studies in developmental biology. When researchers use transgenic birds expressing fluorescent protein, they need to understand the integration site of the transgene in the genome and the intensity of fluorescence in the tissues of interest. In this study, we determined the integration site of the transgene and fluorescence property of developing organs in our transgenic chicken line generated by lentivirus infection. The transgene was localized between exons 3 and 4 of MED27. Some homozygotes and heterozygotes appeared to be lethal at early embryonic stages. We performed histological analysis of EGFP expression in transgenic embryos at St. 14, 17, and 24 by immunohistochemistry with anti‐GFP antibody on paraffin sections. Next, we cut cryosections and quantified direct EGFP intensity from the transgene in each tissue without performing immunohistochemistry. These results revealed that EGFP intensity in each tissue was unique in developing embryos and changed according to developmental stages. Finally, we demonstrated that EGFP‐expressing cells in a micromass culture with co‐culturing wild‐type cells were clearly distinguishable via live cell imaging. These results provide essential information on the potential of our transgenic line and indicate that these transgenic chicken lines are useful for research associated with developmental biology.

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The transgenic chicken is a candidate for the production of biopharmaceutical proteins with several economic superiorities. In general, the addition of sialic acid at the terminal of N-glycan is important for the bioactivity of biopharmaceuticals including plasma half-life; however, sialic acid has not been detected in the N-glycan of proteins produced in the egg white of genetically manipulated chickens. In this study, the extracellular domain of the TNF receptor and single chain Fv fused to Fc (referred to as TNFR/Fc and scFv/Fc, respectively) were purified from the egg yolk of genetically manipulated chickens and their sialylation in N-glycan was examined. In contrast to the glycan in egg white, yolk-derived proteins were partly sialylated. Lectin blot showed the existence of a2,6-sialic acid on TNFR/Fc, which disappeared with the removal of N-glycan by PNGase. In scFv/Fc, up to 7 % of N-glycan contained sialic acid. Disialyl glycans, which were detected in serumderived scFv/Fc in a previous study, were not found in the yolk sample. Ovarian follicular tissue, which surrounds growing yolk, expressed several neuraminidases, suggesting the partial truncation of glycan during the yolk transfer process from the blood.

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