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Interaction analysis of miRNA and mRNA reveals the regulatory mechanism of immune response in golden pompano (Trachinotus ovatus) spleen to Streptococcus iniae infection.

Streptococcus iniae is a major warm-water pathogen that cause high mortality and severe economic losses in golden pompano industry. In the present study, we performed the mRNA-miRNA integrated transcriptomic analysis of spleen of golden pompano challenged with S. iniae to explore the possible regulatory mechanism to bacterial infection. In total, we excavated 5072 DEGs, of which 2765 up-regulated and 2307 down-regulated genes. KEGG enrichment analysis indicated that the DEGs were primarily enriched in immune-related pathways, such as proteasome, cytokine-cytokine receptor interaction, p53 signaling pathway, lysosome, phagosome, Herpes simplex virus 1 infection. Additionally, a protein-protein interaction (PPI) network was constructed to extract hub genes. And the result showed that 4 hub genes, comprising cd4, il10, tnfsf2, myd88, may play vital roles in response to S. iniae infection. Furthermore, a total of 46 differentially expressed miRNAs (DEMs) were identified, containing 23 known and 23 novel DEMs. By integrating mRNA and miRNA joint analysis, we established a miRNA-mRNA regulatory network, including 12 miRNAs and 14 genes. Among them, novel-miR-357 were identified as a multi-target hub miRNA. These results provide important insights into the molecular regulatory mechanisms of immune response and inflammation processes in the defense of golden pompano against S. iniae infection.

Integrative interaction

Optimization of a niosomal formulation for Quercetin delivery: Comparative effects on growth performance, antioxidant and immune responses, and disease resistance against Streptococcus iniae in rainbow trout (Oncorhynchus mykiss).

Quercetin (QUR) is a flavonoid with antibacterial and antioxidant properties that has been studied for its effects on fish health and the immune system. Due to the low bioavailability of QUR, the present study was primarily aimed at developing a niosomal formulation of QUR to enhance its bioavailability and therapeutic properties. The performance of niosomal QUR was then compared with that of its free form by evaluating their effects on the growth and immune system of rainbow trout, Oncorhynchus mykiss. For this purpose, an optimal QUR-containing niosome was formulated by testing different proportions of cholesterol, surfactant, and stabilizer, and the niosomes were then added to the fish diet. A QUR-free diet and a diet containing QUR-free niosomes (QFN) were considered control groups. Niosomes prepared at low hydrophilic-lipophilic balance (HLB) values showed higher QUR entrapment efficiency (QUR-EE%) (P&#x202f;<&#x202f;0.01). An increase in the molar ratio of cholesterol to surfactant significantly reduced QUR-EE% (P&#x202f;<&#x202f;0.05). A surfactant/cholesterol/stabilizer ratio of 1:1:0.1 increased QUR-EE% (P&#x202f;<&#x202f;0.05). The particle size of the niosomes was also affected by HLB and the surfactant/cholesterol/stabilizer ratio. Low HLB values resulted in smaller particle sizes (P&#x202f;<&#x202f;0.01). Furthermore, a surfactant/cholesterol/stabilizer ratio of 1:1:0.1 resulted in the smallest niosomal particle size (P&#x202f;<&#x202f;0.05). The presence of diacetyl phosphate as the stabilizer in the formulation improved the niosomal zeta potential to -40.55&#x202f;mV. The optimal niosomal formulation (HLB&#x202f;=&#x202f;6.6; surfactant/cholesterol/stabilizer ratio of 1:1:0.1) remained stable at 2&#x202f;&#xb0;C over 10 days of storage, as the niosomal QUR content and size did not show significant changes during this period (P&#x202f;>&#x202f;0.01). After preparation of the diets containing the optimal niosomal QUR, fish were fed the experimental diets for two months. QUR, in both niosomal and free forms, resulted in better growth performance than the QUR-free diets (P&#x202f;<&#x202f;0.01). There were no significant differences in growth performance between the free and niosomal forms of QUR; however, 500&#x202f;mg/kg QUR showed significantly better growth performance than 250&#x202f;mg/kg QUR (P&#x202f;<&#x202f;0.01). Although both the niosomal and free forms of QUR enhanced immune and antioxidant components in the fish, the effects of the niosomal form were more significant (P&#x202f;<&#x202f;0.01). In addition, QUR in both free and niosomal forms reduced fish mortality after challenge with Streptococcus iniae. In conclusion, the results of this study suggest that the niosomal form of QUR has strong potential for improving the immune system of fish and increasing resistance to S. iniae infection.

Animals

Genome-wide Identification and Expression Profiling Reveal the Galectin Gene Family Diversity and their Possible Role in Antibacterial Mucosal Immunity in Japanese Flounder (Paralichthys olivaceus).

Galectins are a family of proteins that bind specifically to &#x3b2;-galactosides. Their importance in innate immunity of mammals has been well-documented. However, the systematic identification and characterization of galectin gene family remain limited in teleost. In this study, we identified 13 galectin genes (lgals2, lgals2a, lgals2b, lgals3, lgals3a, lgals3b, lgals4, lgals8, lgals8a, lgals9, grp, grp-b, grp-c) from Paralichthys olivaceus genome and analyzed their tissue expressions and expressions in response to Gram-negative and Gram-positive bacterial infections in mucosal tissues (gills, intestine and skin). The P. olivaceus galections were classified into three distinct types based on carbohydrate recognition domains (CRDs). Phylogenetic and syntenic analyses revealed that these galectins are closely related to their counterparts in turbot and zebrafish. Moreover, the transcripts of the 13 galectins were widespread across all tested tissues of healthy fish and regulated following challenge with Vibrio anguillarum or Streptococcus iniae in mucosal tissues, indicating their involvement in P. olivaceus immune response to bacterial infections. The lgals2a was significantly upregulated in the three mucosal tissues by either bacterial infection, whereas lgals9 and grp were basically downregulated in these tissues by either infection. On the other hand, the lgals3b and lgals4 exhibited a bacteria-specific responsive expression as they were upregulated by V. anguillarum whereas remained stable upon S. iniae infection in the gills. We also observed a positive correlation between expression level and bacterial load for the upregulated galectin genes and a negative correlation for the downregulated galectin genes. These results suggest a functional divergence among galectin members in mucosal immunity against bacterial infection in P. olivaceus.

Animals