Ascites syndrome (AS) is a metabolic disease that seriously affects the growth and development of broiler chickens. Intestinal microbiota play a significant role in the growth of broiler chickens. Therefore, further research on the relationship between AS and intestinal microbiota will help to better understand the impact of AS on broiler growth. In this study, 0.2% sodium chloride was added to the drinking water, which induced AS in broiler chickens, and we detected the influence of AS on the growth performance and cecal microbiota of broiler chickens. The results showed that AS significantly reduced the cecal microbial diversity of broiler chickens and affected the cecal microbial composition at the phylum and genus levels (p = 0.05). Further, LEfSe analysis revealed that AS significantly increased the abundance of Bacteroidetes (p = 0.035) while simultaneously reducing the abundance of Actinobacteria (p = 0.031) in the cecum. Additionally, the differential metabolites associated with polycyclic aromatic hydrocarbon degradation were significantly diminished. The findings suggest that AS may further impact the growth rate of broiler chickens by altering cecal microorganisms.

Background: Cystic echinococcosis (CE) is a globally distributed zoonosis triggered by the larval stage of Echinococcus granulosus (E. granulosus), impacting humans and an extensive array of mammalian intermediate hosts. EGR-01664 is the major egg antigen of E. granulosus, but almost nothing is currently known about the function of EGR-01664 from E. granulosus. Methods: This study aimed to investigate the E. granulosus EGR-01664 gene (GenBank ID: 36337379), and the recombinant EGR-01664 protein was expressed successfully. Next, the transcription of the EGR-01664 gene across various developmental stages of E. granulosus was analyzed. Its spatial expression patterns in adult worms and protoscoleces were characterized using both quantitative PCR (qPCR) and immunofluorescence assays. Furthermore, the immunomodulatory effects of rEGR-01664 on cell proliferation, nitric oxide production, and cytokine secretion were examined by co-culturing the recombinant protein with canine PBMCs. Results: The rEGR-01664 could be recognized by sera from dogs infected with E. granulosus. Immunofluorescence assay (IFA) localization revealed the protein’s presence in the epidermis of protoscoleces, the adult epidermis, and some parenchymal tissues. qPCR revealed that EGR-01664 mRNA levels were significantly higher in protoscoleces compared to adults (p < 0.0001). At a concentration of 20 μg/mL, rEGR-01664 could significantly activate the transcription and expression of IL-10, TGF-β1, IL-17A, and Bax in canine PBMCs. However, with an increase in concentration, it inhibited the expression of IFN-γ, Bcl-2, GSDMD, IL-18, and IL-1β. These results suggest that the EGR-01664 gene plays a crucial role in the development, parasitism, and reproduction of E. granulosus. In vitro studies have shown that rEGR-01664 protein regulates the immune regulation function of canine PBMCs, suggesting its potential as a vaccine adjuvant or immunotherapy target. Conclusions: EGR-01664 may modulate canine PBMC functions to regulate host immune responses, thereby facilitating our understanding of how E. granulosus EGR-01664 contributes to the mechanism of parasitic immune evasion.

(1) Background: Echinococcosis is a significant zoonotic disease that the World Health Organization (WHO) aims to eliminate by 2050. Current drug-based control faces challenges such as drug resistance, highlighting the urgent need to develop vaccines as a supplementary strategy. Although some progress has been made in the study of intermediate host vaccines using antigens such as Eg95, there is still no commercial vaccine available for the definitive host, canines—which are crucial for transmission—and it is not yet suitable for large-scale use. While vaccine studies targeting the key enzyme lactate dehydrogenase (LDH) in parasite energy metabolism remain scarce, they represent a promising area of potential. (2) Methods: The B cell antigen epitopes of LDH were analyzed, and prokaryotic (pET-28a-EgLDH) and eukaryotic (pVAX1-EgLDH) DNA vaccine expression vectors were constructed. After verifying expression and immunogenicity via qRT-PCR and WB, in vitro validation was performed in 293T cells. Mice were immunized with the vaccine and then challenged with the parasite; blood was collected from the orbital sinus, and IgG levels and cytokines were measured by ELISA. Protective effects were assessed through counting liver cysts and histopathological analysis. (3) Results: We constructed the pVAX1-EgLDH plasmid and immunized Kunming (KM) mice. Compared with the PBS control group, the vaccine group showed an 80.95% reduction in liver cysts (Quil-A group: 19.00%). Histopathological analysis indicated no significant liver damage, although the spleens in the vaccine group were smaller. ELISA results demonstrated an increase in total IgG (p < 0.05), and cytokine analysis showed elevated levels of IL-1 (p < 0.01), IL-4, and IL-10 (p < 0.001), whereas IL-5 and IFN-γ showed no significant changes (p > 0.05). (4) Conclusions: The EgLDH DNA vaccine can elicit a specific immune response and significantly reduce cyst burden, providing theoretical basis and data support for its use as a candidate vaccine for the prevention and control of Echinococcosis.