Goose astrovirus (GoAstV) infection has become prevalent in major goose-producing regions, causing substantial economic losses to the industry. In this study, an indirect competitive ELISA (ic-ELISA) was developed based on a monoclonal antibody (mAb) targeting the GoAstV VP27 protein. The recombinant VP27 protein was expressed in E. coli and purified, followed by the generation of murine mAbs using the purified antigen. Through screening with GoAstV particles, mAb 3G11 exhibited strong immunoreactivity, which was further confirmed by Western blot and immunofluorescence assay (IFA). The ic-ELISA conditions were optimized as follows: GoAstV particle coating concentration of 10⁴ TCID₅₀ per well, 3G11 mAb dilution of 1:8000, and incubation times of 120 min for coating, 60 min for serum samples, and 60 min for mAb binding. The assay exhibited satisfactory performance in terms of sensitivity, specificity, and reproducibility. Using this method, serum samples collected from major goose farming areas in Shandong province were tested and showed an overall seropositivity rate of 11.7%. This study provided a reliable serological tool for detecting GoAstV-specific antibodies and would support future vaccine evaluation efforts.

Goose astrovirus (GoAstV) infection has become prevalent in major goose-producing regions, causing substantial economic losses to the industry. In this study, an indirect competitive ELISA (ic-ELISA) was developed based on a monoclonal antibody (mAb) targeting the GoAstV VP27 protein. The recombinant VP27 protein was expressed in E. coli and purified, followed by the generation of murine mAbs using the purified antigen. Through screening with GoAstV particles, mAb 3G11 exhibited strong immunoreactivity, which was further confirmed by Western blot and immunofluorescence assay (IFA). The ic-ELISA conditions were optimized as follows: GoAstV particle coating concentration of 10⁴ TCID₅₀ per well, 3G11 mAb dilution of 1:8000, and incubation times of 120 min for coating, 60 min for serum samples, and 60 min for mAb binding. The assay exhibited satisfactory performance in terms of sensitivity, specificity, and reproducibility. Using this method, serum samples collected from major goose farming areas in Shandong province were tested and showed an overall seropositivity rate of 11.7%. This study provided a reliable serological tool for detecting GoAstV-specific antibodies and would support future vaccine evaluation efforts.

This study aimed to explore the protective mechanism of silybin against heat stress-induced liver injury in Peking ducks as a result of oxidative stress, inflammation, and lipid metabolism. One hundred and ninety-five 1-day-old healthy male Peking ducks with similar body weights were randomly divided into a control group, a heat-stress group, and three intervention groups treated with 400, 800, and 1600 mg/kg silybin under heat-stress from 21 d to 35 d for two weeks. The function indices, oxidative stress, inflammatory factor levels, histopathological changes and non-targeted lipidomic profiling in liver as well as growth performance were evaluated. Results showed that silybin supplementation partially alleviated the heat-stress-induced decreases in average daily feed intake and body weight gain (p > 0.05). Silybin supplementation at 400 and 800 mg/kg significantly reduced the heat-stress-induced increases in alanine aminotransferase (ALT), aspartate aminotransferase (AST), and γ-glutamyl transpeptidase (γ-GGT) (p < 0.05), whereas the effect of 1600 mg/kg silybin was not significant. Albumin (ALB) and globulin (GLB) levels were mainly improved in the 800 mg/kg group, and GLB was also increased in the 400 mg/kg group (p < 0.05). Silybin supplementation significantly improved hepatic antioxidant capacity, especially in the 400 and 800 mg/kg groups, as indicated by increased superoxide dismutase (SOD) activity and total antioxidant capacity (T-AOC), and decreased malondialdehyde (MDA) and reactive oxygen species (ROS) levels (p < 0.05). In addition, the 400 and 800 mg/kg groups showed more significant reductions in the pro-inflammatory factors IL-6 and TNF-α, while IL-10 was increased in silybin-supplemented groups (p < 0.05). Lipid metabolism disorders were improved through regulation of the sphingolipid and glycerophospholipid metabolism pathways, while it alleviated heat stress damage by reducing the expression of heat shock proteins. In conclusion, silybin holds promise as an effective feed additive to alleviate heat stress in poultry. This study provides a theoretical basis and practical approach for improving the health and productive performance of Peking ducks under heat-stress conditions.

Acholeplasma laidlawii is a Mycoplasma species widely distributed in the environment. It is often regarded as an opportunistic pathogen capable of causing respiratory infections in animals and humans. To date, only a few studies have reported A. laidlawii infection in poultry. In the present study, an A. laidlawii strain was isolated from the lungs and trachea of diseased ducks presenting with air sac lesions. Antimicrobial susceptibility testing revealed that the isolate was susceptible to tylvalosin, tylosin, and valnemulin, with relatively low minimum inhibitory concentrations (MICs). The pathogenicity of the isolate was evaluated using specific-pathogen-free (SPF) ducks via subcutaneous inoculation. No clinical signs were observed during the experimental period. Oral and cloacal swabs, as well as tissue samples, were tested by PCR. The results showed that the pathogen was detectable in swabs from 5 to 21 days post-inoculation (dpi), and all lung and tracheal samples from infected ducks tested positive. Histopathological examination of the lungs and trachea revealed pathological changes in both tissues. Collectively, these findings demonstrated that A. laidlawii was capable of colonizing ducks and inducing mild histopathological changes, suggesting that this pathogen might pose an epidemiological risk in duck farming. Furthermore, these results indicate that A. laidlawii could colonize ducks, underscoring the need for continued surveillance to monitor for emerging pathogens in ducks.

TRK-fused gene (TFG, tropomyosin-receptor kinase fused gene) is known to negatively regulate the retinoic acid inducible gene (RIG)-I-like receptor (RLR)-mediated interferon (IFN)-I pathway in human cells, thereby participating in the paramyxovirus infection process. We showed that pigeon paramyxovirus type 1 (PPMV-1) infection significantly upregulates TFG expression in infected cells at an early stage. We speculated that PPMV-1 would inhibit IFN activation by upregulating a negative regulator of the IFN pathway. This hypothesis was proved when TFG protein expression was knocked down by RNAi and the replication level of PPMV-1 virus decreased, which indicated that TFG upregulation in the early infection stage benefit virus replication. We next used the IFN-β promoter reporter system to evaluate the role of the TFG in the IFN pathway. The results showed that the TFG inhibited the IFN-β expression stimulated by RIG-I, MAVS (mitochondrial antiviral signaling protein) and TANK-binding kinase 1 (TBK1), but did not inhibit IFN-β activated by the interferon regulatory transcription factor 3 (IRF3), indicating that TFG may affect the function of TBK1, which play an important role in phosphorylation of the IRF3. Further experiments showed that the TFG inhibited the phosphorylation of TBK1, resulting in IRF3 being unable to be phosphorylated. Subsequent experiments on IFN pathway activation confirmed that the IRF3 phosphorylation level was significantly downregulated after overexpression of TFG, while the IFN-β promoter reporting experiment showed that TFG did not directly inhibit the IFN response activated by IRF3. This confirmed that TFG protein negatively regulates the IFN-β pathway by inhibiting TBK1 phosphorylation.

The duck Tembusu virus (DTMUV), an emerging flavivirus, has led to severe neurological disorders and substantial economic losses in the duck industry throughout Asia. Considering South Korea’s increasing duck production and its strategic location along the East Asian–Australasian Flyway, this study aimed to assess the presence of DTMUV in South Korea to evaluate potential risks to the poultry industry. We performed a comprehensive serological survey of 1796 serum samples from broiler and breeder ducks collected between 2011 and 2023, alongside molecular detection tests on 51 duck flocks exhibiting suspected clinical signs of DTMUV infection. The absence of serological and molecular evidence for DTMUV or other flavivirus infections suggests that these viruses have not yet affected South Korean duck populations. These findings underscore the critical need for ongoing surveillance, given the virus’s potential to disrupt agriculture and pose public health risks. The study also emphasizes the importance of maintaining stringent biosecurity measures and conducting further research to monitor and prevent DTMUV transmission, particularly due to the possible role of migratory birds and other vectors in spreading zoonotic diseases.