Dynamic 3D morphology of chick embryos and allantois depicted nondestructively by 3.0T clinical magnetic resonance imaging.

Driven by a global trend of applying replace-reduce-refine or 3Rs' guidance for experimental animals in life sciences, chick embryo and particularly allantois with its chorioallantoic membrane have been increasingly utilized to substitute laboratory animals, which call for more extensive and updated knowledge about this novel experimental setup. In this study, being noninvasive, nonionizing, and super-contrasting with high spatiotemporal resolutions, magnetic resonance imaging (MRI) was chosen as an imaging modality for in ovo monitoring morphologic evolution of the chick embryo, allantois, and chorioallantoic membrane longitudinally throughout embryonic day (ED) 1 until ED20. Cooled in 0°C ice bath for 60 min to reduce MRI motion artifacts, 3 chick embryos (n = 60 in total) on each ED were scanned by a clinical 3.0T MRI scanner to demonstrate 3D images of both T2- and T1-weighted imaging (T2WI, T1WI) sequences at axial, sagittal, and coronal slices. The volumes of both the entire chick embryo and allantois were semi-automatically segmented based on intensity-based thresholding and region-growing algorithms. The morphometries or quantified 3D structures were achieved by refined segmentation, and confirmed by histological analyses (one for each ED). After MRI, the rest of chick embryos (n = 40) continued for incubation. The images from ED2 to ED4 could demonstrate the structural changes of latebra, suggesting its transition into a nutrient supplying channel of yolk sac. The allantois could be recognized by MRI, and its relative volumes on each ED revealed an evolving profile peaked on ED12, with a statistically significant difference from those of earlier and later EDs (P < 0.01). The hypointensity of the yolk due to the susceptibility effect of its enriched iron content overshadowed the otherwise hyperintensity of its lipid components. The chick embryos survived prior cooling and MRI till hatching on ED21. The results could be further developed into a 3D MRI atlas of chick embryo. Clinical 3.0T MRI proved effective as a noninvasive approach to study in ovo 3D embryonic development across the full period (ED1-ED20), which can complement the present knowhow for poultry industry and biomedical science.

Palmitic acid-modified GnRH-Th epitope peptide immunocastration vaccine (W/O/W adjuvant) can effectively ensure the castration and reduce the smelly smell in boars.

Introduction: Recent studies have demonstrated the effectiveness of Gonadotropin-releasing hormone (GnRH) in inhibiting testicular growth and development in male animals to achieve castration while improving the meat quality of various livestock species, including cattle, sheep, goats, and pigs. Methods: In this research, a GnRH-Th vaccine was synthesized using the Fmoc solid-phase synthesis technique, and the T helper (Th) antigen was modified with palmitic acid to improve its efficacy. The vaccine was then coated with a water-in-oil-in-water adjuvant to improve stability and safety. After passing safety and stability tests, the vaccine was administered to 13-week-old boars. Results: The results showed that it was stable, safe, and effective for up to 15 months. Moreover, the vaccine did not negatively affect the growth rate and body weight of the pigs. The palmitic acid-modified "GnRH-Th epitope peptide immunocastration vaccine (Water-in-Oil-in-Water (W/O/W)) effectively reduced the testosterone concentration and achieved castration. The concentration of androstenone and skatole hormones significantly decreased, leading to improved meat quality in the boars. The boars were then slaughtered at 33 weeks of age, and the results showed that the meat quality of the vaccinated boars was superior to that of the non-vaccinated control group (p < 0.05). Discussion: This study demonstrated that GnRH can safely and effectively achieve immune castration in boars after coupling T cell epitopes, palmitic acid modification and W-O-W coating. Provide a better method for the further development of GnRH and the realization of animal welfare.

N-Acetyltransferase 9 Inhibits Porcine Reproductive and Respiratory Syndrome Virus Proliferation by N-Terminal Acetylation of the Structural Protein GP5.

Porcine reproductive and respiratory syndrome virus (PRRSV) is a serious threat to the global swine industry. As a typical immunosuppressive virus, PRRSV has developed a variety of complex mechanisms to escape the host innate immunity. In this study, we uncovered a novel immune escape mechanism of PRRSV infection. Here, we demonstrate for the first time that the endoplasmic reticulum (ER)-resident N-acetyltransferase Nat9 is an important host restriction factor for PRRSV infection. Nat9 inhibited PRRSV proliferation in an acetyltransferase activity-dependent manner. Mechanistically, glycoprotein 5 (GP5) of PRRSV was identified as interacting with Nat9 and being N-terminally acetylated by it, which generates a GP5 degradation signal, promoting the K27-linked-ubiquitination degradation of GP5 to decrease virion assembly. Meanwhile, the expression of Nat9 was inhibited during PRRSV infection. In detail, two transcription factors, ETV5 and SP1, were screened out as the key transcription factors binding to the core promoter region of Nat9, and the PRRSV nonstructural protein 1ß (Nsp1ß), Nsp4, Nsp9, and nucleocapsid (N) proteins were found to interfere significantly with the expression of ETV5 and SP1, thereby regulating the transcription activity of Nat9 and inhibiting the expression of Nat9. The findings suggest that PRRSV decreases the N-terminal acetylation of GP5 to support virion assembly by inhibiting the expression of Nat9. Taken together, our findings showed that PRRSV has developed complex mechanisms to inhibit Nat9 expression and trigger virion assembly. IMPORTANCE To ensure efficient replication, a virus must hijack or regulate multiple host factors for its own benefit. Understanding virus-host interactions and the molecular mechanisms of host resistance to PRRSV infection is necessary to develop effective strategies to control PRRSV. The N-acetyltransferase Nat9 plays important roles during virus infection. Here, we demonstrate that Nat9 exhibits an antiviral effect on PRRSV proliferation. The GP5 protein of PRRSV is targeted specifically by Nat9, which mediates GP5 N-terminal acetylation and degradation via a ubiquitination-dependent proteasomal pathway. However, PRRSV manipulates the transcription factors ETV5 and SP1 to inhibit the expression of Nat9 and promote virion assembly. Thus, we report a novel function of Nat9 in PRRSV infection and elucidate a new mechanism by which PRRSV can escape the host innate immunity, which may provide novel insights for the development of antiviral drugs.