RESUMO
Subgroup K avian leukosis virus (ALV-K) is a novel subgroup of ALV isolated from Chinese native chickens. As for a retrovirus, the interaction between its envelope protein and cellular receptor is a crucial step in ALV-K infection. Tva, a protein previously determined to be associated with vitamin B12/cobalamin uptake, has been identified as the receptor of ALV-K. However, the molecular mechanism underlying the interaction between Tva and the envelope protein of ALV-K remains unclear. In this study, we identified the C-terminal loop of the LDL-A module of Tva as the minimal functional domain that directly interacts with gp85, the surface component of the ALV-K envelope protein. Further point-mutation analysis revealed that E53, L55, H59, and G70, which are exposed on the surface of Tva and are spatially adjacent, are key residues for the binding of Tva and gp85 and facilitate the entry of ALV-K. Homology modeling analysis indicated that the substitution of these four residues did not significantly impact the Tva structure but impaired the interaction between Tva and gp85 of ALV-K. Importantly, the gene-edited DF-1 cell line with precisely substituted E53, L55, H59, and G70 was completely resistant to ALV-K infection and did not affect vitamin B12/cobalamin uptake. Collectively, these findings not only contribute to a better understanding of the mechanism of ALV-K entry into host cells but also provide an ideal gene-editing target for antiviral study.
Assuntos
Vírus da Leucose Aviária , Doenças das Aves Domésticas , Receptores Virais , Vitamina B 12 , Animais , Vírus da Leucose Aviária/genética , Galinhas/metabolismo , Receptores de Superfície Celular/metabolismo , Receptores Virais/metabolismo , Proteínas do Envelope Viral/metabolismo , Complexo Vitamínico B , Vitamina B 12/metabolismoRESUMO
Probiotics are increasingly recognized for their capacity to combat pathogenic bacteria. In this study, we isolated a strain of Ligilactobacillus salivarius XP132 from the gut microbiota of healthy chickens. This strain exhibited resistance to low pH and bile salts, auto-aggregation capabilities, and the ability to co-aggregate with pathogenic Salmonella. The in vitro antibacterial activity of Ligilactobacillus salivarius XP132 was tested using an Oxford cup antibacterial test, and the results showed that Ligilactobacillus salivarius XP132 exhibited broad-spectrum antibacterial activity, with especially strong antibacterial activity against Salmonella. In animal experiments with white feather broilers and specific-pathogens-free (SPF) chickens, we orally administered 1 × 109 CFU XP132 live bacteria per chicken per day, and detected the content of Salmonella in the liver, spleen, intestinal contents, and eggs of the chickens by RT-qPCR. Oral administration of Lactobacillus salivarius XP132 group significantly reduced the levels of Salmonella in chicken liver, spleen, intestinal contents and eggs, and the oral administration of Ligilactobacillus salivarius XP132 significantly inhibited the horizontal and vertical transmission of Salmonella in SPF chickens and white-feathered broilers. After oral administration of XP132, the production of chicken serum anti-infective cytokine IFN-γ was also significantly up-regulated, thereby enhancing the host's ability to resist infection. In addition, the production of various serum inflammatory cytokines, including IL-1ß, IL-6, IL-8, and TNF-α, was down-regulated, leading to significant amelioration of the inflammatory response induced by S. Pullorum in chickens. These findings suggest that Ligilactobacillus salivarius XP132 possesses potent antibacterial and immunomodulatory properties that effectively prevent both horizontal and vertical transmission of Salmonella Pullorum, highlighting its potential as a valuable tool for the prevention and control of Salmonella disease.
RESUMO
Commensal bacteria modulate acute immune responses to infection in hosts. In this study, Enterococcus faecium C171 was screened and isolated. This strain has similar basic characteristics to the reference probiotic, including strong anti-inflammatory and anti-infective effects. E. faecium C171 inhibits the production of pro-Caspase-1 and significantly reduces the production of interleukin-1ß (IL-1ß) in vitro. These reactions were confirmed using the Transwell system. Live E. faecium C171 mainly exerted an inhibitory effect on acute inflammation, whereas the anti-infective and immune-activating effects were primarily mediated by the E. faecium C171-produced bacterial extracellular vesicles (Efm-C171-BEVs). Furthermore, in the specific pathogen-free (SPF) chicken model, oral administration of E. faecium C171 increased the relative abundance of beneficial microbiota (Enterococcus and Lactobacillus), particularly Enterococcus, the most important functional bacteria of the gut microbiota. E. faecium C171 significantly inhibited the acute inflammatory response induced by a highly virulent infectious disease, and reduced mortality in SPF chickens by 75%. In addition, E. faecium C171 induced high levels of CD3+, CD4-, and CD8- immunoregulatory cells and CD8+ killer T cells, and significantly improved the proliferative activity of T cells in peripheral blood mononuclear cells, and the secretion of interferon-γ. These findings indicate that E. faecium C171 and Efm-C171-BEVs are promising candidates for adjuvant treatment of acute inflammatory diseases and acute viral infections.
Assuntos
Enterococcus faecium , Probióticos , Viroses , Animais , Leucócitos Mononucleares , Galinhas , ImunidadeRESUMO
OBJECTIVE: To explore the way to induce mesenchymal stem cells (MSCs) to differentiate into dopaminergic neurons in vitro. METHODS: MSCs were obtained from rat bone marrow, cultured and passaged. MSCs used in this experiment had multipotency, which was indirectly proved by being induced to differentiate into chondrocytes and adipocytes. MSCs were cultured in medium containing 0.5 mmol/L IBMX for 2 days. Then the medium was replaced with induction medium, which contained GDNF, IL-1beta, mesencephalic glial-cell-conditioned medium and flash-frozen mesencephalic membrane fragments. The surface markers of the differentiated neurons, such as NSE, nestin, MAP-2a, b and TH were detected by immunocytochemistry and Western blot after MSCs were cultured in induction medium for 7 days and 15 days. RESULTS: MSCs differentiated into neural progenitors and expressed nestin after MSCs were incubated with medium containing IBMX for 2 d. After the medium was replaced with induction medium containing many inducing agents, MSCs differentiated into neuron-like cells and dopaminergic neuron-like cells and expressed NSE, MAP-2a, b and TH. The percentage of NSE-positive cells, MAP-2a, b-positive cells and TH-positive cells was 30.032 +/- 2.489%, 41.580 +/- 5.101% and 34.958 +/- 5.534%, respectively after MSCs were induced in medium containing GDNF, IL-1beta, mesencephalic glial-cell-conditioned medium and flash-frozen mesencephalic membrane fragments for 15 days. CONCLUSION: MSCs can differentiate into dopaminergic neuron-like cells and are a new cell source for the treatment of neurodegeneration diseases and have a great potential for wide application.