Immortalized Duck Embryo Fibroblasts

Induction of Adipogenesis in CCL-141 Cells by Different Culture Components

Ducks are important for poultry meat production, with fats in their meat influencing taste and quality. Adipogenesis, regulated by multiple genes, is crucial for breeding desirable fat traits. Previous studies used primary cells, which are limited for gene editing. This study used chicken serum, fatty acids, insulin, and all-trans retinoic acid to induce adipogenesis in immortalized duck embryo fibroblasts CCL-141 cells, confirmed by Oil Red O staining and gene expression analysis.

Findings show duck embryo fibroblasts have enhanced adipogenic potential under chicken serum, oleic acid, linoleic acid, insulin, atRA, etc. Compared to the fetal bovine serum control, lipid deposition increased in groups b, c, and d (Fig. 1A), with significant differences among groups (Fig. 1B, p < 0.05). Group d (added atRA) had the highest deposition, indicating atRA's strong pro-adipogenic effect. Group b (chicken serum) showed few lipid droplets, while group a (fetal bovine serum) showed almost none, suggesting chicken serum contains pro-adipogenic components. Adding fatty acids and insulin (group c) further increased deposition compared to group b, indicating their enhancing effect. Adipogenic gene expression was higher at 72 h than at 48 h (Fig. 2), better reflecting differentiation status. Therefore, 72 h samples were used for lipid droplet assays.

Fig. 1. Inducing effects of different culture medium components on immortalized duck embryo fibroblasts CCL-141 cells (Sun D D, Li X Q, et al., 2024).

Fig. 2. Differential expression of marker genes for adipogenesis in differentiating groups induced by culture medium containing different components for 48 h and 72 h (Sun D D, Li X Q, et al., 2024).

Experimental Pathogenesis of Aquatic Bird Bornavirus 1 in Pekin Ducks

Aquatic bird bornavirus 1 (ABBV-1) is a neurotropic virus causing persistent infection in wild waterfowl, associated with neurological signs and inflammation. Previous studies showed ABBV-1 infection in Muscovy ducks and chickens, with minimal clinical signs but histologic lesions.

The ABBV-1 strain for this experiment was initially isolated from the brain of a naturally infected Canada goose, and propagated in immortalized duck embryo fibroblasts. Then, Pekin ducks were inoculated with ABBV-1 via intracranial, intramuscular, and choanal routes. Virus distribution, lesions, and clinical signs were assessed at 1, 12, and 21 weeks post-infection. Perivascular cuffs, made of lymphocyte-like mononuclear cells, were randomly distributed in the cerebrum, cerebellum, brainstem, and spinal cord (Fig. 3a–c). These cuffs were mainly in IC and IM ducks at 12 and 21 wpi, with only one CH duck (#461) showing them at 21 wpi. All inflamed birds were positive for ABBV-1 RNA in the CNS. Inflammation peaked at 12 wpi, with most IC (7/9; 77.8%) and IM (6/8; 75.0%) ducks affected, dropping sharply by 21 wpi, with perivascular cuffs only in 1 IC and 5 IM ducks. Lesion severity also peaked at 12 wpi and dropped by 21 wpi (Fig. 4). In the IC group, cerebrum inflammation score at 12 wpi was significantly higher than in the brainstem and the cerebrum at 21 wpi (Fig. 4a). In the IM group, inflammation severity decreased from 12 to 21 wpi, though not significantly (Fig. 4b).

Fig. 3. Microscopic lesions observed in Pekin ducks experimentally infected with aquatic bird bornavirus 1 (ABBV-1) through the intracranial (IC), intramuscular (IM), and choanal (CH) routes at 12 weeks postinfection (Ampuero F, Leacy A, et al., 2023).

Fig. 4. Pathology subscores for inflammation in different areas of the central nervous system of Pekin ducks experimentally inoculated with aquatic bird bornavirus-1 (ABBV-1) intracranially (a) and intramuscularly (b) (Ampuero F, Leacy A, et al., 2023).