Cherry Valley Duck Galectin-2 Plays an Essential Role in Avian Pathogenic Escherichia coli Infection-Induced Innate Immune Response.

Galectins play important roles in the host's innate immunity as pattern recognition receptors. In this study, the coding sequences of galectin-2 were identified from Cherry Valley ducks. Tissue distribution of duck galectin-2 (duGal-2) in healthy ducks and ducks infected with avian pathogenic Escherichia coli (APEC) was studied, respectively. The results showed that duGal-2 expression was higher in the gut, kidney, and liver tissue, and weakly expressed in the lung and brain, in healthy ducks; however, the expression level of duGal-2 was detected as being up-regulated after infection with APEC. In addition, knockdown or overexpression of duGal-2 in DEFs was achieved by small interference RNA (siRNA) transfection and plasmid transduction, respectively. The knockdown of duGal-2 led to a decrease in the expression of some inflammatory cytokines such as IL-1ß, IL-6, and IL-8, while the expression levels of anti-inflammatory factor IL-10 were up-regulated. At the same time, the bacterial load of APEC was increased after knockdown of duGal-2 in vitro. However, the opposite results were obtained in the duGal-2 overexpression group. Taken together, duGal-2 plays an important role in the host against APEC infection.

Detection of microbial aerosols in hospital wards and molecular identification and dissemination of drug resistance of Escherichia coli.

Antibiotic-resistant bacteria (ARB) present a global public health problem. Microorganisms are the main cause of hospital-acquired infections, and the biological contamination of hospital environments can cause the outbreak of a series of infectious diseases. Therefore, it is very important to understand the spread of antibiotic-resistant bacteria in hospital environments. This study examines the concentrations of aerobic bacteria and E. coli in ward environments and the airborne transmission of bacterial drug resistance. The results show that the three wards examined have an average aerobic bacterial concentration of 132 CFU∙m-3 and an average inhalable aerobic bacterial concentration of 73 CFU∙m-3, with no significant difference (P > 0.05) among the three wards. All isolated E. coli showed multi-drug resistance to not only third-generation cephalosporin antibiotics, but also quinolones, aminoglycosides, and sulfonamides. Furthermore, 51 airborne E. coli strains isolated from the air in the three wards and the corridor were screened for ESBLs, and 12 (23.53%) were ESBL-positive. The drug-resistance gene of the 12 ESBL-positive strains was mainly TEM gene, and the detection rate was 66.67% (8/12). According to a homology analysis with PFGE, 100% homologous E. coli from the ward at 5 m and 10 m outside the ward in the corridor shared the same drug-resistance spectrum, which further proves that airborne E. coli carrying a drug-resistance gene spreads out of the ward through gas exchange. This leads to biological pollution inside, outside, and around the ward, which poses a direct threat to the health of patients, healthcare workers, and surrounding residents. It is also the main reason for the antibiotic resistance in the hospital environment. More attention should be paid to comprehensive hygiene management in the surrounding environment of hospitals.

Galectin-1 induces immune response and antiviral ability in Cherry Valley ducks after duck plague virus infection.

Galectin-1, as a typical animal galactose-binding protein, it is found on the cell surface and in the extracellular matrix. Cloning the full-length coding sequence of galectin-1 from the spleens of Cherry Valley ducks revealed that the coding sequence of duck galectin-1 (duGal-1) comprises 405 bp, encoding 134 amino acids. Homologic analysis revealed its amino acid sequence is most identical to that of Anas platyrhynchos (98.8%) followed by Gallus gallus. Quantitative real-time PCR analysis indicated that duGal-1 mRNA is broadly expressed in healthy Cherry Valley duck tissues, primarily in the heart and trachea but minimally in the lung and skin. Meanwhile, the duGal-1 expression is slightly upregulated in the infected liver and spleen. Furthermore, the expression levels of ISGs (Mx, PKR, OAS) and some cytokines such as IFN-α, IL-1ß, IL-2, are up-regulated to varying degrees after overexpression the duGal-1, In contrast, Knockdown of duGal-1 found that the expression levels of ISGs and some inflammatory cytokines were down-regulated. Antiviral assay showed that duGal-1 could inhibit viral replications early during infection. This is the first study of the cloning, tissue distribution, and antiviral immune responses of duGal-1, and findings imply it is involved in the early stages of antiviral innate immune responses to duck plague virus infections in ducks.

Characterization and Roles of Cherry Valley Duck NLRP3 in Innate Immunity During Avian Pathogenic Escherichia coli Infection.

The nucleotide-binding oligomerization domain-like receptor (NLR) pyrin domain containing 3 (NLRP3) is a pattern recognition receptor that is involved in host innate immunity and located in the cytoplasm. In the present study, the full-length cDNA of Cherry Valley duck NLRP3 (duNLRP3) (2,805 bp encode 935 amino acids) was firstly cloned from the spleen of healthy Cherry Valley ducks, and the phylogenetic tree indicated that the duNLRP3 has the closest relationship with Anas platyrhynchos in the bird branch. According to quantitative real-time PCR analysis, the duNLRP3 mRNA has a broad expression spectrum in healthy Cherry Valley duck tissues, and the highest expression is in the pancreas. There was significant up-regulation of duNLRP3 mRNA expression in the liver and down-regulation in the spleen after infection with avian pathogenic Escherichia coli (APEC) O1K1, especially at 3 days after the infection. Ducks hatched from NLRP3-lentiviral vector-injected eggs had significantly higher duNLRP3 mRNA expression in the liver, spleen, brain, and cecum, which are tissues usually with lower background expression. The mRNA expression levels of inflammatory cytokines IL-1ß, IL-18, and TNF-α significantly increased after the APEC infection in those tissues. The bacterial content in the liver and spleen decreased significantly compared with the NC-lentiviral vector-injected ducks. In addition, in the duck embryo fibroblasts, both of the overexpression and knockdown of duNLRP3 can trigger the innate immune response during the E. coli infection. Specifically, overexpression induced antibacterial activation, and knockdown reduced the antibacterial activity of the host cells. The IL-1ß, IL-18, and TNF-α mRNA expressions showed up-regulation or down-regulation. The results demonstrate that duNLRP3 has a certain antibacterial activity during E. coli infection. These findings also contribute to better understanding the importance of duNLRP3 in regulating the inflammatory response and the innate immune system of ducks.

Fowl Adenovirus Serotype 4 SD0828 Infections Causes High Mortality Rate and Cytokine Levels in Specific Pathogen-Free Chickens Compared to Ducks.

Hydropericardium syndrome and inclusion body hepatitis, together called hydropericardium-hepatitis syndrome, are acute infectious diseases found in chickens. These diseases are caused primarily by fowl adenovirus serotype 4 (FAdV-4) strains. In this study, we isolated a FAdV-4 strain (SD0828) from clinically diseased chickens and phylogenetically analyzed the L1 loops of the hexon protein sequences in 3-week-old specific pathogen-free chickens and ducks infected intramuscularly and orally, determining differences in the pathogenicity by observing clinical signs and gross and histological lesions. We also detected the viral load in tissue samples. Postinfection necropsy showed that all chickens but no ducks exhibited typical necropsy lesions. Additionally, all chickens infected intramuscularly died within 2 days postinfection (dpi), and all those infected orally died within 5 dpi, whereas no infected ducks died before 28 dpi. Quantitative real-time polymerase chain reaction analysis was used to determine the viral load in the tissues of hearts, livers, spleens, lungs, and kidneys and in cloacal cotton swabs from infected chickens and ducks at 1, 2, 3, 5, 7, 14, 21, and 28 dpi. The greatest number of viral DNA copies was found in the livers of infected chickens, yet no virus was found in any samples from infected ducks. In addition, the viral load increased over time in both chicken and duck embryo fibroblasts (CEFs and DEFs, respectively); in the former, replication speed was significantly greater than in the latter. Innate immune responses were also studied, both in vivo and in vitro. In CEFs, DEFs, and chickens infected intramuscularly, but not in infected ducks, mRNA expression levels of proinflammatory cytokines (interleukin-6 and -8) and interferon-stimulated genes (Mx and OAS) were significantly upregulated. Although some cytokines showed significant upregulation in the oral chickens, most did not change significantly. Finally, the duck retinoic acid-inducible gene I and its caspase activation and recruitment domain both had significant antiviral functions in CEFs, particularly after 24 h postinfection. Taken together, this research provides new insights into the interactions between FAdV-4 and the innate immune systems of studied hosts (chickens and ducks).