Identification and characterization of long non-coding RNAs in intestinal immune regulation of largemouth bass, Micropterus salmoides, under acute heat stress

Long noncoding RNAs (lncRNAs), which are RNA molecules that do not code for proteins and have a length exceeding 200 base pairs, have been found to play a crucial role in regulating intestinal immunity. The high mortality of various fish species induced by high temperatures is known to be associated with enteritis. Our investigation demonstrated that acute heat stress was responsible for inducing fish enteritis. However, the specific lncRNAs involved this process remains unknown. In this current study, we utilized intestinal sequencing data from the largemouth bass species Micropterus salmoides under acute heat stress, resulting in a total of 347,351,492 clean reads obtained from six cDNA libraries. A total of 3399 novel lncRNA transcripts originating from 2488 distinct lncRNA genes were successfully identified. Consistent with previous findings in other fish species, these lncRNAs demonstrated comparatively shorter transcript lengths when compared to protein-coding genes. Furthermore, a total of 216 novel lncRNA exhibited differential expression (DE) in the intestine of largemouth bass, meeting the criteria of absolute log2 fold change exceeding 2 and a p-value below 0.05. Additionally, these DE-lncRNAs were found to regulate 210 neighboring genes in a cis-regulatory manner. An examination of GO/KEGG enrichment revealed a notable enrichment of immune regulation (p < 0.05) among these cis-genes, with lncRNA MSTRG.8573.1 playing a significant role in regulating the jak-stat signaling pathway during this process. This study presents a comprehensive inventory of novel DE-lncRNA implicated in the development of enteritis in largemouth bass under acute heat stress. These findings offer valuable insights for future investigations on the regulation of lncRNAs to mitigate heat stress-induced fish enteritis.

The protective effects of Bacillus licheniformis against inflammatory responses and intestinal barrier damage in broilers with necrotic enteritis induced by Clostridium perfringens

BACKGROUND

Bacillus licheniformis is a gram-positive bacterium that has strong environmental adaptability and can improve the growth performance, immunity, and antioxidant function of broilers. The current study aimed to elucidate the protective capability of B. licheniformis against inflammatory responses and intestinal barrier damage in broilers with necrotic enteritis (NE) induced by Clostridium perfringens (CP).

RESULTS

The results showed that B. licheniformis enhanced the final body weight in broilers compared with that of broilers in the CP group after the stress of infection (P < 0.05). Bacillus licheniformis reversed the decreased levels of serum and jejunum mucosa immunoglobulins and anti-inflammatory cytokines, reduced the values of villus height and the ratio of villus height to crypt depth, and mitigated the increased levels of serum d-lactic acid and diamine oxidase in CP-challenged broilers (P < 0.05). Moreover, B. licheniformis modulated the expression levels of genes involved in the TLR4/NF-κB signalling pathway, the NLRP3 inflammasome activation pathway, and the sirt 1/Parkin signalling pathway in CP-challenged broilers. Compared with the CP challenge group, the B. licheniformis-treated group exhibited reduced abundance values of Shuttleworthia and Alistipes and enhanced abundance values of Parabacteroides in the caecal contents (P < 0.05).

CONCLUSION

Bacillus licheniformis improved the final body weight and alleviated the inflammatory response and intestinal barrier function damage in birds with NE induced by CP by maintaining intestinal physiological function, enhancing immunity, regulating inflammatory cytokine secretion, modulating the mitophagy response, and increasing the abundance of beneficial intestinal flora. © 2023 Society of Chemical Industry.

Postmortem diagnoses and factors influencing diagnoses in captive white-tailed deer in Wisconsin, 2009-2021

There have been significant changes to Wisconsin agriculture since ~2010, one of which is the growth of commercial farming of white-tailed deer (WTD; Odocoileus virginianus). These high-density populations may lead to the emergence of previously unrecognized or under-recognized disease trends. I evaluated archived pathology records at the Wisconsin Veterinary Diagnostic Laboratory (WVDL) from 2009-2021 for captive WTD postmortem cases and included records from 277 WTD cases. Diagnoses were found in 81.9% of cases, with an average of 1.3 diagnoses per animal. Submissions with a clinical history of respiratory disease were 7.0 times more likely to have a diagnosis than the average case. Fawns were 1.9 times more likely to have a diagnosis. The most common diagnoses were bronchopneumonia and enteritis and/or enterocolitis (both 16.2% of total diagnoses). The most common isolates from bronchopneumonia cases were Pasteurella multocida, Bibersteinia trehalosi, and Trueperella pyogenes. The pathogens identified most often in enteritis and/or enterocolitis cases were rotavirus, Clostridium perfringens, and Escherichia coli. The most common non-infectious diagnoses were poor nutritional status or inanition, hepatic lipidosis, and selenium and/or vitamin E deficiency. Focusing on testing for pathogens in fawns and in cervid respiratory disease complex submissions may be recommended for laboratories expanding their WTD testing.

Buffered formic acid and a monoglyceride blend improve performance and modulate gut bacteria and immunity gene expression in broilers under necrotic enteritis challenge

Due to the removal of antibiotics from animal feed, alternatives have been sought to control necrotic enteritis (NE) in broilers. The current study investigated the effects of buffered formic acid (Amasil NA) and monoglycerides of short- and medium-chain fatty acids (Balangut LS P) on the performance and gut health of broilers challenged with NE. A total of 816 as-hatched 1-d-old chicks (Cobb 500) were randomly assigned to 6 treatments with 8 replicates. Treatments were: T1) nonchallenged control; T2) NE challenged control; T3) Amasil NA (challenge plus Amasil NA, 0.3% throughout all phases); T4) Balangut LS P (challenge plus Balangut LS P, 0.5%, 0.3%, and 0.2% in the starter, grower and finisher phases, respectively; T5) Combined (challenge plus combination of T3 and T4); T6) Antibiotic (challenge plus Zn bacitracin, 0.05 % throughout all phases). Birds were orally gavaged with live Eimeria vaccine species (d 9) and with Clostridium perfringens (d 14 and 15). On d 16, birds were sampled to evaluate gut permeability, microbiota, and mRNA abundance in the jejunum. The data were analyzed in JMP software using one-way ANOVA with Tukey's test to separate means, and Kruskal-Wallis test was used for non-normally-distributed parameters. Results showed that Balangut LS P decreased (P<0.05) feed conversion ratio compared to nonchallenged ones at the end of the study. Balangut LS P reduced (P < 0.05) the level of cecal Bacteriods compared to nonchallenged group, whereas Amasil NA shifted the levels of ileal Bifidobacteria, Enterobacteriaceae, and Lactobacillus towards nonchallenged control (P > 0.05). NE challenge upregulated (P < 0.001) the expression of IL-21R, zeta chain of T cell receptor (ZAP70), and dual specificity phosphatase 4 (DUSP4) compared to nonchallenged birds, whereas Balangut LS P showed an intermediate (P > 0.05) expression pattern of these genes towards nonchallenged and antibiotic groups. In conclusion, combination of Balangut LS P and Amasil NA has the potential to be used as an additive to improve the performance and gut health of broiler chickens, especially under challenging conditions such as NE infections.

Hyperimmune egg yolk antibodies developed against Clostridium perfringens antigens protect against necrotic enteritis

Necrotic enteritis (NE) is a widespread infectious disease caused by Clostridium perfringens that inflicts major economic losses on the global poultry industry. Due to regulations on antibiotic use in poultry production, there is an urgent need for alternative strategies to mitigate the negative effects of NE. This paper presents a passive immunization technology that utilizes hyperimmune egg yolk immunoglobulin Y (IgY) specific to the major immunodominant antigens of C. perfringens. Egg yolk IgYs were generated by immunizing hens with 4 different recombinant C. perfringens antigens, and their protective effects against NE were evaluated in commercial broilers. Six different spray-dried egg powders were produced using recombinant C. perfringens antigens: α-toxin, NE B-like toxin (NetB; EB), elongation factor-Tu (ET), pyruvate:ferredoxin oxidoreductase, a mixture of 4 antigens (EM-1), and a nonimmunized control (EC). The challenged groups were either provided with different egg powders at a 1% level or no egg powders (EN). The NE challenge model based on Eimeria maxima and C. perfringens dual infection was used. In Experiments 1 and 2, the EB and ET groups exhibited increased body weight gain (BWG; P < 0.01), decreased NE lesion scores (P < 0.001), and reduced serum NetB levels (P < 0.01) compared to the EN and EC groups. IgY against NetB significantly reduced Leghorn male hepatocellular cytotoxicity in an in vitro test (P < 0.01). In Experiment 3, the protective effect of the IgYs mixture (EM-2) against C. perfringens antigens (NetB and EFTu) and Eimeria antigens (elongation factor-1-alpha: EF1α and Eimeria profilin: 3-1E) was tested. The EM-2 group showed similar body weight, BWG, and feed intake from d 7 to 22 compared to the NC group (P < 0.05). On d 20, the EM-2 group showed comparable intestinal permeability, NE lesion scores, and jejunal NetB and collagen adhesion protein levels to the NC group (P < 0.05). In conclusion, dietary mixture containing antibodies to NetB and EFTu provides protection against experimental NE in chickens through passive immunization.

Efficacy of Bacillus subtilis to replace in-feed antibiotics of broiler chickens under necrotic enteritis-challenged experiments: a systematic review and meta-analysis

Necrotic enteritis (NE) and coccidiosis are among the most prevalent infectious diseases in broiler chickens, contributing to large profitability losses. Bacillus subtilis is a promising direct-fed probiotic to counter various pathogens infection in broiler chickens. Here, we performed a meta-analysis to investigate the effects of B. subtilis on broiler chickens performance. A total of 28 studies were selected according to a PRISMA checklist. Random-effect model and mixed-effect model of meta-analysis were fitted to estimate the overall effects of B. subtilis (BS) treatment compared to either the control group (CON) or NE-infected group (NEinf) as a baseline. Hedges' g effect size and its variance were used as estimators of standardized mean difference (SMD) calculation where the results were presented at a 95% confidence interval (95% CI) of the SMD. Overall, NEinf broiler chickens depressed (P < 0.01) body weight (BW), average daily gain (ADG), and feed intake, and elevated (P < 0.01) feed conversion ratio (FCR). Treatment with BS improved ADG and final BW of NEinf with no difference (P = 0.15) between BS and antibiotics (AB), indicating that they had comparable efficacy to treat NE in broiler chickens. BS supplemented to uninfected CON (BSS) improved (P < 0.01) final BW, ADG, and FCR. Compared to CON, BS, and AB failed to recover the FCR but these treatments decreased (P < 0.01) FCR when compared to the NEinf group with similar efficacy (P = 0.97). As expected, NEinf birds had a higher mortality rate (P < 0.01) and higher lesion score (P < 0.01) compared to CON, and treatment using AB and BS successfully decreased (P < 0.01) the mortality rate and lesion score. Compared to BS, AB was more effective to lower (P = 0.01) mortality rate, but comparable (P = 0.65) to minimize lesion score. To conclude, B. subtilis could be an effective natural additive to replace in-feed antibiotics in broiler chickens challenged with C. perfringens. However, the efficacy to reduce mortality rate was better with antibiotics treatment.

Effect of in-water administration of quorum system inhibitors in broilers' productive performance and intestinal microbiome in a mild necrotic enteritis challenge

The poultry industry has been facing the impact of necrotic enteritis (NE), a disease caused by the bacterium Clostridium perfringens producing the haemolytic toxin NetB. NE severity may vary from mild clinical to prominent enteric signs causing reduced growth rates and affecting feed conversion ratio. NetB production is controlled by the Agr-like quorum-sensing (QS) system, which coordinates virulence gene expression in response to bacterial cell density. In this study, the peptide-containing cell-free spent media (CFSM) from Enterococcus faecium was tested in NE challenged broilers in two battery cage and one floor pen studies. Results showed a significant reduction of NE mortality. Metagenomic sequencing of the jejunum microbiome revealed no impact of the CFSM on the microbial community, and growth of C. perfringens was unaffected by CFSM in vitro. The expression of QS-controlled virulence genes netB, plc and pfoA was found to be significantly repressed by CFSM during the mid-logarithmic stage of C. perfringens growth and this corresponded with a significant decrease in haemolytic activity. Purified fractions of CFSM containing bioactive peptides were found to cause reduced haemolysis. These results showed that bioactive peptides reduce NE mortality in broilers by interfering with the QS system of C. perfringens and reducing bacterial virulence. Furthermore, the microbiome of C. perfringens-challenged broilers is not affected by quorum sensing inhibitor containing CFSM.

Effect of synbiotic supplementation on production performance and severity of necrotic enteritis in broilers during an experimental necrotic enteritis challenge

To evaluate the efficacy of synbiotic during a necrotic enteritis (NE) infection, a total of 360 day-old chicks were randomly assigned into 4 experimental groups in a 2 × 2 factorial setup: control, challenge, synbiotic (1 g/kg), and challenge + synbiotic, with 6 replicates. NE was induced by gavaging 1 × 104Eimeria maxima oocysts and 1 × 108 CFU/mL of Clostridium perfringens on d 14 (D14) and D19, 20, and 21, respectively. At D35, the NE challenge decreased the BW gain (P < 0.001) and increased feed conversion ratio (P = 0.03), whereas synbiotic supplementation decreased the feed intake (P = 0.04). At D21, NE challenge increased gut permeability (P < 0.001), decreased regulatory T cells (Tregs) in the cecal tonsil (CT) (P = 0.02), increased Tregs in the spleen (P = 0.02), decreased nitric oxide (NO) production in the spleen (P = 0.04) and decreased IL-10 expression in CT (P = 0.02), whereas synbiotic supplementation increased CD4+:CD8+ T cells in the spleen (P < 0.001) and decreased interferon (IFN)-γ expression in the jejunum (P = 0.07), however, synbiotic supplementation during NE challenge decreased mid-gut lesion score (P < 0.001), increased CD4+:CD8+ T cells in CT and decreased IgA production in bile (P < 0.001), compared to the control group. At D28, synbiotic supplementation decreased CD4+:CD8+ T cells in CT (P < 0.001), whereas synbiotic supplementation during NE challenge decreased Tregs in CT (P < 0.001) and increased NO production in the spleen (P = 0.04), compared to the control group. At D35, the NE challenge decreased CD4+:CD8+ T cells in the spleen (P = 0.03), decreased IgA production in bile (P = 0.02), decreased IL-10 expression in CT (P = 0.04), and decreased IL-10 (P = 0.009), IFN-γ (P = 0.03) and inducible nitric oxide synthase (P = 0.02) expression in the jejunum, whereas synbiotic supplementation increased Tregs in the spleen (P = 0.04), compared to control group. Synbiotic supplementation during the NE challenge decreased both IL-1β (P = 0.02) and IFN-γ (P = 0.001) expression in CT, compared to the control group. It can be concluded that synbiotic supplementation increases production performance by decreasing mid-gut lesions and enhancing protective immunity against NE, and efficiency of synbiotic could be improved by blending additional probiotics and prebiotics.

Baicalin-aluminum alleviates necrotic enteritis in broiler chickens by inhibiting virulence factors expression of Clostridium perfringens

Clostridium perfringens type A is the main cause of necrotic enteritis (NE) in chickens. Since the use of antibiotics in feed is withdrawn, it is imperative to find out suitable alternatives to control NE. Baicalin-aluminum complex is synthesized from baicalin, a flavonoid isolated from Scutellaria baicalensis Georgi. The present study investigated the effects of baicalin-aluminum on the virulence-associated traits and virulence genes expression of C. perfringens CVCC2030, it also evaluated the in vivo therapeutic effect on NE. The results showed that baicalin-aluminum inhibited bacterial hemolytic activity, diminished biofilm formation, attenuated cytotoxicity to Caco-2 cells, downregulated the expression of genes encoding for clostridial toxins and extracellular enzymes such as alpha toxin (CPA), perfringolysin O (PFO), collagenase (ColA), and sialidases (NanI, NanJ). Additionally, baicalin-aluminum was found to negatively regulate the expression of genes involved in quorum sensing (QS) communication, including genes of Agr QS system (agrB, agrD) and genes of VirS/R two-component regulatory system (virS, virR). In vivo experiments, baicalin-aluminum lightened the intestinal lesions and histological damage, it inhibited pro-inflammatory cytokines (TNF-α, IL-1β, IL-6) expression in the jejunal and ileal tissues. Besides, baicalin-aluminum alleviated the upregulation of C. perfringens and Escherichia coli and raised the relative abundance of Lactobacillus in the ileal digesta. This study suggests that baicalin-aluminum may be a potential candidate against C. perfringens infection by inhibiting the virulence-associated traits and virulence genes expression.