A survey of gastrointestinal helminth infestation in smallholder backyard pigs and the first molecular identification of the two zoonotic helminths Ascaris suum and Trichuris suis in Myanmar.

BACKGROUND: Parasitic infestations have a substantial economic impact on pig production. This study aimed to investigate the gastrointestinal (GI) helminths in pigs and to molecularly characterise two important nematodes, Ascaris and Trichuris species. MATERIALS AND METHODS: A total of 500 pig faecal samples were collected from small holder backyard pig farms in five townships within Nay Pyi Taw, Myanmar. Microscopic examination was conducted to estimate the prevalence of GI helminth infestation in the pigs. DNA extraction and PCR were performed on faecal samples that were morphologically positive for Ascaris and Trichuris eggs. Molecular analysis was then conducted to characterise A. suum and T. suis, the most common and zoonotic helminths. RESULTS: According to microscopic examination, 69.2% (346/500) were positive for GI helminth eggs. The GI helminth species observed were A. suum, Strongyle, Strongyloides spp., T. suis, Metastrongylus spp., Hyostrongylus spp., Fasciolopsis spp., Paragonimus spp., and Schistosoma spp., with occurrences of 34.8%, 29.6%, 21.4%, 20.0%, 4.0%, 1.6%, 1.0%, 1.0%, and 0.4%, respectively. Mixed infections of GI helminths were noted in 31.0% of the samples. Overall, sampled pigs excreted mostly low levels (< 100 EPG) or moderate levels (> 100-500 EPG) of GI helminth eggs. The highest mean EPG for each parasite species was noted in A. suum. The presence of A. suum and T. suis was confirmed molecularly. The sequences of the internal transcribed spacer 1 (ITS1) region of A. suum showed high similarity with previously reported sequences. Likewise, the sequences of T. suis exhibited high similarity with the sequences reported from humans and pigs. Age was noted as an associated factor (P < 0.05) for GI helminth infection status. CONCLUSIONS: In this report, A. suum and T. suis were molecularly identified for the first time in Myanmar. It is important to extend the information among the farmers to be aware of the necessity of preventing zoonotic parasites by practicing regular deworming, proper use of anthelmintics and maintaining hygienic conditions in their pig farms.

Using Implementation Mapping to develop an intervention program to support veterinarians' adherence to the guideline on Streptococcus suis clinical practice in weaned pigs.

Streptococcus suis (S. suis) infections in weaned pigs are common and responsible for a high consumption of antimicrobials, and their presence is assumed to be multi-factorial. A specific evidence-based veterinary guideline to support the control of S. suis in weaned pigs was developed for veterinary practitioners in the Netherlands in 2014. Adherence to the S. suis clinical practice guideline helps veterinary practitioners to prevent and control the disease in a systematical approach and thereby improve antimicrobial stewardship and contribute to the prevention of antimicrobial resistance in animals and humans. The impact of such a clinical practice guideline on (animal) disease management depends not only on its content, but also largely on the extent to which practitioners adhere to the clinical guideline in practice. When the S. suis guideline was published, no specific activities were undertaken to support veterinarians' uptake and implementation, thereby contributing to suboptimal adherence in clinical practice. As the S. suis guideline was comprehensively written by veterinary experts following an evidence-based approach, our aim was not to judge the (scientific) quality of the guideline but to study the possibility to improve the currently low adherence of this guideline in veterinary practice. This paper describes the systematic development, using Implementation Mapping, of a theory-based intervention program to support swine veterinarians' adherence to the S. suis guideline. The knowledge, skills, beliefs about capabilities, and beliefs about consequences domains are addressed in the program, which includes seven evidence-based methods (modelling, tailoring, feedback, discussion, persuasive communication, active learning, and self-monitoring) for use in program activities such as a peer-learning meeting and an e-learning module. The intervention program has been developed for practicing swine veterinarians, lasts eight months, and is evaluated through a stepped-wedge design. The Implementation Mapping approach ensured that all relevant adopters and implementers were involved, and that outcomes, determinants (influencing factors), and objectives were systematically discussed.

Oral administration of PEDV-dissolved Alg-CS gel induces high and sustained mucosal immunity in mice.

Porcine epidemic diarrhea (PED) is a serious disease in piglets that leads to high mortality. An effective measure that provides higher IgA levels in the intestine and milk is required to decrease losses. Porcine epidemic diarrhea virus (PEDV) was dissolved in calcium alginate (Alg) and combined with chitosan (CS) via electrostatic interactions between cationic chitosan and anionic alginate to create a porous gel (Alg-CS+PEDV). The gel was used to immunize mice orally or in combination with subcutaneous injections of inactivated PEDV vaccine. At 12 and 24 days after immunization, levels of IgA and IgG in Alg-CS+PEDV were higher than with normal PEDV oral administration. At 24 days after immunization, the concentration of IFN-γ in Alg-CS+PEDV was higher than with normal PEDV oral administration. Furthermore, oral administration combining subcutaneous immunization induced higher levels of IgG and IgA than oral administration alone. Our study provides a new method for the preparation and administration of oral vaccines to achieve enhanced mucosal immunity against PEDV.

Epidemiology, pathogenesis, immune evasion mechanism and vaccine development of porcine Deltacoronavirus.

Coronaviruses have been identified as pathogens of gastrointestinal and respiratory diseases in humans and various animal species. In recent years, the global spread of new coronaviruses has had profound influences for global public health and economies worldwide. As highly pathogenic zoonotic viruses, coronaviruses have become the focus of current research. Porcine Deltacoronavirus (PDCoV), an enterovirus belonging to the family of coronaviruses, has emerged on a global scale in the past decade and significantly influenced the swine industry. Moreover, PDCoV infects not only pigs but also other species, including humans, chickens and cattles, exhibiting a broad host tropism. This emphasizes the need for in-depth studies on coronaviruses to mitigate their potential threats. In this review, we provided a comprehensive summary of the current studies on PDCoV. We first reviewed the epidemiological investigations on the global prevalence and distribution of PDCoV. Then, we delved into the studies on the pathogenesis of PDCoV to understand the mechanisms how the virus impacts its hosts. Furthermore, we also presented some exploration studies on the immune evasion mechanisms of the virus to enhance the understanding of host-virus interactions. Despite current limitations in vaccine development for PDCoV, we highlighted the inhibitory effects observed with certain substances, which offers a potential direction for future research endeavors. In conclusion, this review summarized the scientific findings in epidemiology, pathogenesis, immune evasion mechanisms and vaccine development of PDCoV. The ongoing exploration of potential vaccine candidates and the insights gained from inhibitory substances have provided a solid foundation for future vaccine development to prevent and control diseases associated with PDCoV.

Dietary monoglyceride supplementation to support intestinal integrity and host defenses in health-challenged weanling pigs.

Frequent incidence of postweaning enterotoxigenic Escherichia coli (ETEC) diarrhea in the swine industry contributes to high mortality rates and associated economic losses. In this study, a combination of butyric, caprylic, and capric fatty acid monoglycerides was investigated to promote intestinal integrity and host defenses in weanling pigs infected with ETEC. A total of 160 pigs were allotted to treatment groups based on weight and sex. Throughout the 17-d study, three treatment groups were maintained: sham-inoculated pigs fed a control diet (uninfected control [UC], n = 40), ETEC-inoculated pigs fed the same control diet (infected control [IC], n = 60), and ETEC-inoculated pigs fed the control diet supplemented with monoglycerides included at 0.3% of the diet (infected supplemented [MG], n = 60). After a 7-d acclimation period, pigs were orally inoculated on each of three consecutive days with either 3 mL of a sham-control (saline) or live ETEC culture (3 × 109 colony-forming units/mL). The first day of inoculations was designated as 0 d postinoculation (DPI), and all study outcomes reference this time point. Fecal, tissue, and blood samples were collected from 48 individual pigs (UC, n = 12; IC, n = 18; MG, n = 18) on 5 and 10 DPI for analysis of dry matter (DM), bacterial enumeration, inflammatory markers, and intestinal permeability. ETEC-inoculated pigs in both the IC and MG groups exhibited clear signs of infection including lower (P < 0.05) gain:feed and fecal DM, indicative of excess water in the feces, and elevated (P < 0.05) rectal temperatures, total bacteria, total E. coli, and total F18 ETEC during the peak-infection period (5 DPI). Reduced (P < 0.05) expression of the occludin, tumor necrosis factor α, and vascular endothelial growth factor A genes was observed in both ETEC-inoculated groups at the 5 DPI time point. There were no meaningful differences between treatments for any of the outcomes measured at 10 DPI. Overall, all significant changes were the result of the ETEC infection, not monoglyceride supplementation.

Infection caused by the bacterium known as enterotoxigenic Escherichia coli (ETEC) is a common disruptor of weaned pigs' health, leading to economic losses for the producers. To determine if nutritional supplementation could help protect against these losses, weaned pigs were assigned to one of three treatments: 1) uninfected and fed a standard nursery pig diet, 2) infected with ETEC and fed the same standard diet, or 3) infected with ETEC and fed the standard diet supplemented with a combination of butyric, caprylic, and capric fatty acid monoglycerides. Growth performance was tracked throughout the 17-d study and health outcomes were measured at the peak and resolution of ETEC infection. At the peak-infection time point, pigs that were infected with ETEC had lower fecal moisture content, greater fecal bacterial concentrations, and elevated body temperatures compared with uninfected pigs. Additionally, infection reduced expression of genes related to inflammation, angiogenesis, and the intestinal barrier during the peak-infection period. Overall, all significant changes were the result of the ETEC infection, and there were no meaningful differences observed between the different treatments.

The role of vehicle movement in swine disease dissemination: Novel method accounting for pathogen stability and vehicle cleaning effectiveness uncertainties.

Several propagation routes drive animal disease dissemination, and among these routes, contaminated vehicles traveling between farms have been associated with indirect disease transmission. In this study, we used near-real-time vehicle movement data and vehicle cleaning efficacy to reconstruct the between-farm dissemination of the African swine fever virus (ASFV). We collected one year of Global Positioning System data of 823 vehicles transporting feed, pigs, and people to 6363 swine production farms in two regions in the U.S. Without cleaning, vehicles connected up to 2157 farms in region one and 437 farms in region two. Individually, in region one vehicles transporting feed connected 2151 farms, pigs to farms 2089 farms, pigs to market 1507 farms, undefined vehicles 1760 farm, and personnel three farms. The simulation results indicated that the contact networks were reduced the most for crew transport vehicles with a 66% reduction, followed by vehicles carrying pigs to market and farms, with reductions of 43% and 26%, respectively, when 100% cleaning efficacy was achieved. The results of this study showed that even when vehicle cleaning and disinfection are 100% effective, vehicles are still connected to numerous farms. This emphasizes the importance of better understanding transmission risks posed by vehicles to the swine industry and regulatory agencies.

Immune response enhancement by dietary supplementation with Caesalpinia sappan extract in weaned pigs challenged with porcine reproductive and respiratory syndrome virus.

BACKGROUND: At present, porcine reproductive and respiratory syndrome (PRRS) caused by the PRRS virus (PRRSV) is one of the most severe epidemics impacting pig farming globally. Despite the fact that a number of studies have been conducted on potential solutions to this problem, none have proven effective. The focus of problem solving is the use of natural ingredients such as plant extracts. Popular throughout Asia, Caesalpinia sappan (CS) is a therapeutic plant that inhibits PRRSV in vitro. Therefore, this study was performed to determine the efficacy of CS extract dietary supplementation on the productive performance, antibody levels, immunological indicators, and lung pathology of PRRSV-challenged weaned pigs. A total of 32 weaned piglets (28 days old) were randomized into 4 groups and kept separately for 14 days. The treatments were organized in a 2 × 2 factorial design involving two factors: PRRSV challenge and supplementation with 1 mg/kg CS extract. The pigs in the PRRSV-challenged groups were intranasally inoculated with 2 mL of PRRSV (VR2332) containing 104 TCID50/mL, while those in the groups not challenged with PRRSV were inoculated with 2 mL of normal saline. RESULTS: In the PRRSV-challenged group (CS + PRRSV), supplementation with CS extract led to an increase in white blood cells (WBCs) on Day 7 post infection (p < 0.05) and particularly in lymphocytes on Days 7 and 14. The antibody titer was significantly greater in the CS + PRRSV group than in the PRRSV-challenged group not administered CS (PRRSV group) on Day 14 postinfection (S/P = 1.19 vs. 0.78). In addition, CS extract administration decreased the prevalence of pulmonary lesions, which were more prevalent in the PRRSV-challenged pigs that did not receive the CS extract. CONCLUSION: The findings of this study suggest that supplementation with CS extract is beneficial for increasing WBC counts, especially lymphocytes, increasing the levels of antibodies and reducing the prevalence of lung lesions in PRRSV-infected pigs.

Creating PRRS-resistant pigs for the supermarket.

Georgina Mills reports on a bid from a UK-based company to have pigs that are bred to be resistant to porcine reproductive and respiratory syndrome approved for sale in the USA.

Optimized production of full-length PCV2d virus-like particles in Escherichia coli: A cost-effective and high-yield approach for potential vaccine antigen development.

Porcine circovirus type 2 (PCV2) is a globally prevalent infectious pathogen affecting swine, with its capsid protein (Cap) being the sole structural protein critical for vaccine development. Prior research has demonstrated that PCV2 Cap proteins produced in Escherichia coli (E. coli) can form virus-like particles (VLPs) in vitro, and nuclear localization signal peptides (NLS) play a pivotal role in stabilizing PCV2 VLPs. Recently, PCV2d has emerged as an important strain within the PCV2 epidemic. In this study, we systematically optimized the PCV2d Cap protein and successfully produced intact PCV2d VLPs containing NLS using E. coli. The recombinant PCV2d Cap protein was purified through affinity chromatography, yielding 7.5 mg of recombinant protein per 100 ml of bacterial culture. We augmented the conventional buffer system with various substances such as arginine, ß-mercaptoethanol, glycerol, polyethylene glycol, and glutathione to promote VLP assembly. The recombinant PCV2d Cap self-assembled into VLPs approximately 20 nm in diameter, featuring uniform distribution and exceptional stability in the optimized buffer. We developed the vaccine and immunized pigs and mice, evaluating the immunogenicity of the PCV2d VLPs vaccine by measuring PCV2-IgG, IL-4, TNF-α, and IFN-γ levels, comparing them to commercial vaccines utilizing truncated PCV2 Cap antigens. The HE staining and immunohistochemical tests confirmed that the PCV2 VLPs vaccine offered robust protection. The results revealed that animals vaccinated with the PCV2d VLPs vaccine exhibited high levels of PCV2 antibodies, with TNF-α and IFN-γ levels rapidly increasing at 14 days post-immunization, which were higher than those observed in commercially available vaccines, particularly in the mouse trial. This could be due to the fact that full-length Cap proteins can assemble into more stable PCV2d VLPs in the assembling buffer. In conclusion, our produced PCV2d VLPs vaccine elicited stronger immune responses in pigs and mice compared to commercial vaccines. The PCV2d VLPs from this study serve as an excellent candidate vaccine antigen, providing insights for PCV2d vaccine research.

Exploring preventive factors against insufficient antibody positivity rate for foot-and-mouth disease in pig farms in South Korea: a preliminary ecological study.

BACKGROUND: Foot-and-mouth disease (FMD) is a highly contagious viral disease in livestock that has tremendous economic impact nationally. After multiple FMD outbreaks, the South Korean government implemented a vaccination policy for efficient disease control. However, during active surveillance by quarantine authorities, pig farms have reported an insufficient antibody positivity rate to FMD. OBJECTIVE: In this study, the spatial and temporal trends of insufficiency among pig farms were analyzed, and the effect of the number of government veterinary officers was explored as a potential preventive factor. METHODS: Various data were acquired, including national-level surveillance data for antibody insufficiency from the Korea Animal Health Integrated System, the number of veterinary officers, and the number of local pig farms. Temporal and geographical descriptive analyses were conducted to overview spatial and temporal trends. Additionally, logistic regression models were employed to investigate the association between the number of officers per pig farm with antibody insufficiency. Spatial cluster analysis was conducted to detect spatial clusters. RESULTS: The results showed that the incidence of insufficiency tended to decrease in recent years (odds ratio [OR], 0.803; 95% confidence interval [95% CIs], 0.721-0.893), and regions with a higher density of governmental veterinary officers (OR, 0.942; 95% CIs, 0.918-0.965) were associated with a lower incidence. CONCLUSIONS: This study implies that previously conducted national interventions would be effective, and the quality of government-provided veterinary care could play an important role in addressing the insufficient positivity rate of antibodies.

Salmonella vector induces protective immunity against Lawsonia and Salmonella in murine model using prokaryotic expression system.

BACKGROUND: Lawsonia intracellularis is the causative agent of proliferative enteropathy and is associated with several outbreaks, causing substantial economic loss to the porcine industry. OBJECTIVES: In this study, we focused on demonstrating the protective effect in the mouse model through the immunological bases of two vaccine strains against porcine proliferative enteritis. METHODS: We used live-attenuated Salmonella Typhimurium (ST) secreting two selected immunogenic LI antigens (Lawsonia autotransporter A epitopes and flagellin [FliC]-peptidoglycan-associated lipoprotein-FliC) as the vaccine carrier. The constructs were cloned into a Salmonella expression vector (pJHL65) and transformed into the ST strain (JOL912). The expression of immunogenic proteins within Salmonella was evaluated via immunoblotting. RESULTS: Immunizing BALB/c mice orally and subcutaneously induced high levels of LI-specific systemic immunoglobulin G and mucosal secretory immunoglobulin A. In immunized mice, there was significant upregulation of interferon-γ and interleukin-4 cytokine mRNA and an increase in the subpopulations of cluster of differentiation (CD) 4+ and CD 8+ T lymphocytes upon splenocytes re-stimulation with LI antigens. We observed significant protection in C57BL/6 mice against challenge with 106.9 times the median tissue culture infectious dose of LI or 2 × 109 colony-forming units of the virulent ST strain. Immunizing mice with either individual vaccine strains or co-mixture inhibited bacterial proliferation, with a marked reduction in the percentage of mice shedding Lawsonia in their feces. CONCLUSIONS: Salmonella-mediated LI gene delivery induces robust humoral and cellular immune reactions, leading to significant protection against LI and salmonellosis.

Gut microbiota-derived LCA mediates the protective effect of PEDV infection in piglets.

BACKGROUND: The gut microbiota is a critical factor in the regulation of host health, but the relationship between the differential resistance of hosts to pathogens and the interaction of gut microbes is not yet clear. Herein, we investigated the potential correlation between the gut microbiota of piglets and their disease resistance using single-cell transcriptomics, 16S amplicon sequencing, metagenomics, and untargeted metabolomics. RESULTS: Porcine epidemic diarrhea virus (PEDV) infection leads to significant changes in the gut microbiota of piglets. Notably, Landrace pigs lose their resistance quickly after being infected with PEDV, but transplanting the fecal microbiota of Min pigs to Landrace pigs alleviated the infection status. Macrogenomic and animal protection models identified Lactobacillus reuteri and Lactobacillus amylovorus in the gut microbiota as playing an anti-infective role. Moreover, metabolomic screening of the secondary bile acids' deoxycholic acid (DCA) and lithocholic acid (LCA) correlated significantly with Lactobacillus reuteri and Lactobacillus amylovorus, but only LCA exerted a protective function in the animal model. In addition, LCA supplementation altered the distribution of intestinal T-cell populations and resulted in significantly enriched CD8+ CTLs, and in vivo and in vitro experiments showed that LCA increased SLA-I expression in porcine intestinal epithelial cells via FXR receptors, thereby recruiting CD8+ CTLs to exert antiviral effects. CONCLUSIONS: Overall, our findings indicate that the diversity of gut microbiota influences the development of the disease, and manipulating Lactobacillus reuteri and Lactobacillus amylovorus, as well as LCA, represents a promising strategy to improve PEDV infection in piglets. Video Abstract.

[Food hygiene and safety - What is your diagnosis?] / Lebensmittelhygiene ­ Was ist Ihre Diagnose?

INTRODUCTION: A healthy, 1,5 year old female wild boar (Sus scrofa) was shoot in a hunting district in Switzerland on June 22, 2023. The meat inspection revealed noticeable skin changes on all four distal extremities which were described histologically as multifocal epidermal hyperplasia and moderate orthokeratotic hyperkeratosis. The rest of the animal body, the organs and the lymph nodes were without any obvious lesions. The diagnosis of papilloma virus-associated exophytically growing papillomas was made. The venison was approved as fit for human consumption.

INTRODUCTION: Un sanglier femelle (Sus scrofa) en bonne santé, âgé d'un an et demi, a été abattu dans le nord de la Suisse le 22 juin 2023. L'inspection de la viande a révélé des modifications cutanées notables sur les quatre extrémités distales des membres qui ont été décrites histologiquement comme une hyperplasie épidermique multifocale et une hyperkératose orthokératosique modérée. Le reste du corps de l'animal, les organes et les ganglions lymphatiques ne présentaient aucune lésion évidente. Le diagnostic de papillomes à croissance exophytique associés à des papillomavirus a été posé. La venaison a été déclarée propre à la consommation humaine.

Synbiotics improve growth performance and nutrient digestibility, inhibit PEDV infection, and prevent intestinal barrier dysfunction by mediating innate antivirus immune response in weaned piglets.

This experiment was conducted to explore the effects of dietary synbiotics (SYB) supplementation on growth performance, immune function, and intestinal barrier function in piglets challenged with porcine epidemic diarrhea virus (PEDV). Forty crossbred (Duroc × Landrace × Yorkshire) weaned piglets (26 ±â€…1 d old) with a mean body weight (BW) of 6.62 ±â€…0.36 kg were randomly allotted to five groups: control (CON) I and CONII group, both fed basal diet; 0.1% SYB group, 0.2% SYB group, and 0.2% yeast culture (YC) group, fed basal diet supplemented with 0.1%, 0.2% SYB, and 0.2% YC, respectively. On day 22, all piglets were orally administrated with 40 mL PEDV (5.6 × 103 TCID50/mL) except piglets in CONI group, which were administrated with the same volume of sterile saline. The trial lasted for 26 d. Before PEDV challenge, dietary 0.1% SYB supplementation increased final BW, average daily gain (ADG), and decreased the ratio of feed to gain during 0 to 21 d (P < 0.05), as well as improved the apparent nutrient digestibility of dry matter (DM), organic matter (OM), crude protein, ether extract (EE), and gross energy (GE). At the same time, 0.2% YC also improved the apparent nutrient digestibility of DM, OM, EE, and GE (P < 0.05). PEDV challenge increased diarrhea rate and diarrhea indexes while decreased ADG (P < 0.05) from days 22 to 26, and induced systemic and intestinal mucosa innate immune and proinflammatory responses, destroyed intestinal barrier integrity. The decrease in average daily feed intake and ADG induced by PEDV challenge was suppressed by dietary SYB and YC supplementation, and 0.1% SYB had the best-alleviating effect. Dietary 0.1% SYB supplementation also increased serum interleukin (IL)-10, immunoglobulin M, complement component 4, and jejunal mucosal IL-4 levels, while decreased serum diamine oxidase activity compared with CONII group (P < 0.05). Furthermore, 0.1% SYB improved mRNA expressions of claudin-1, zonula occludens protein-1, mucin 2, interferon-γ, interferon regulatory factor-3, signal transducers and activators of transcription (P < 0.05), and protein expression of occludin, and downregulated mRNA expressions of toll-like receptor 3 and tumor necrosis factor-α (P < 0.05) in jejunal mucosa. Supplementing 0.2% SYB or 0.2% YC also had a positive effect on piglets, but the effect was not as good as 0.1% SYB. These results indicated that dietary 0.1% SYB supplementation improved growth performance under normal conditions, and alleviated the inflammatory response and the damage of intestinal barrier via improving innate immune function and decreasing PEDV genomic copies, showed optimal protective effects against PEDV infection.

Porcine epidemic diarrhea virus (PEDV) infection causes watery diarrhea, vomiting, anorexia, and high mortality in piglets, which leads to serious economic losses in many pig-producing countries. Vaccination is commonly used for the prevention of PEDV infection. However, current vaccines are ineffective in preventing infections because of genetic variants of PEDV. Therefore, developing new and efficient strategies to reduce porcine epidemic diarrhea outbreaks for piglets is desirable. Synbiotics (SYB) refer to the biological mixture of probiotics and prebiotics, which combines the advantages of both. At present, the application of probiotics or prebiotics has been widely reported in piglets feeds, which improves growth performance, immune function, microbiota community, intestinal structure, and resistance to bacterial infection. However, there was little report on whether SYB can protect piglets against PEDV infection. Therefore, this study was conducted to investigate the effects of SYB on growth performance, intestinal barrier function, and immune function in PEDV-infected weaned piglets. Results indicated that dietary SYB supplementation improved growth performance, decreased the inflammatory response, and alleviated the damage of intestinal barrier by improving innate antiviral immunity and reducing PEDV genomic copies, ultimately offering optimal protective effects against PEDV infection.

PEDV-spike-protein-expressing mRNA vaccine protects piglets against PEDV challenge.

Porcine epidemic diarrhea virus (PEDV), a swine enteropathogenic coronavirus, causes severe diarrhea in neonatal piglets, which is associated with a high mortality rate. Thus, developing effective and safe vaccines remains a top priority for controlling PEDV infection. Here, we designed two lipid nanoparticle (LNP)-encapsulated mRNA (mRNA-LNP) vaccines encoding either the full-length PEDV spike (S) protein or a multiepitope chimeric spike (Sm) protein. We found that the S mRNA-LNP vaccine was superior to the Sm mRNA-LNP vaccine at inducing antibody and cellular immune responses in mice. Evaluation of the immunogenicity and efficacy of the S mRNA vaccine in piglets confirmed that it induced robust PEDV-specific humoral and cellular immune responses in vivo. Importantly, the S mRNA-LNP vaccine not only protected actively immunized piglets against PEDV but also equipped neonatal piglets with effective passive anti-PEDV immunity in the form of colostrum-derived antibodies after the immunization of sows. Our findings suggest that the PEDV-S mRNA-LNP vaccine is a promising candidate for combating PEDV infection.IMPORTANCEPorcine epidemic diarrhea virus (PEDV) continues to harm the global swine industry. It is important to develop a highly effective vaccine to control PEDV infection. Here, we report a PEDV spike (S) mRNA vaccine that primes a potent antibody response and antigen-specific T-cell responses in immunized piglets. Active and passive immunization can protect piglets against PED following the virus challenge. This study highlights the efficiency of the PEDV-S mRNA vaccine and represents a viable approach for developing an efficient PEDV vaccine.

Effect of Saccharomyces cerevisiae Postbiotics and Essential Oil on Growth Performance and Intestinal Health of Weanling Pigs During K88 ETEC Infection.

Enterotoxigenic Escherichia coli (ETEC) is one of the major bacterial infections, causing substantial economic losses globally in the swine industry. This study aimed to investigate the impact of low Saccharomyces cerevisiae fermentation postbiotics (SCFP), high SCFP, essential oil (EO), or their combination on the growth performance and health of weanling pigs during ETEC infection. Forty-eight male weanling pigs were randomly allocated to five groups: 1) control group (CON-basal diet, n = 16); 2) low SCFP group (LSC-basal diet + 1.25 g/kg SCFP, n = 8); 3) high SCFP group (HSC-basal diet + 2 g/kg SCFP, n = 8); 4) essential oil group (EO-basal diet + 0.4 g/kg EO, n = 8); 5) the SCFP and EO combination group (SE-basal diet + 1.25 g/kg SCFP + 0.4 g/kg EO, n = 8). On day 15 of the trial, pigs in CON were divided into positive control (PC) and negative control (NC), and all pigs, except in NC, were challenged with ETEC. Under the normal condition, dietary LSC, HSC, EO, and EO all increased average daily gain (ADG) (P < 0.05), and decreased F:G ratio (P < 0.05) accompanied by decreased malondialdehyde (MDA) and increases in catalase (CAT), total superoxide dismutase (T-SOD), total antioxidant capacity (T-AOC) indicating enhanced anti-oxidative capacity, as well as decreased IL-2, IL-8, INF-γ, indicating mitigated systemic inflammation. During ETEC infection, all treatments alleviated ETEC-induced ADG reduction, diarrhea, damages in intestinal permeability and morphology, and down-regulation of tight junctions (Claudin1, ZO-1, and Occludin), while HSC and EO exhibited additional protections. All treatments increased CAT, T-SOD, and T-AOC, and decreased MDA in serum and jejunal mucosa at similar degrees (P < 0.05). Moreover, all treatments alleviated ETEC-induced inflammation as shown by decreased IL-6, TNF-α, INF-γ, and increased IL-4 and IL-10 in serum or jejunal mucosa (P < 0.05), and enhanced the immunity by increased serum IgG and mucosal sIgA (P < 0.05). HSC and SE further reduced mucosal INF-γ and TNF-α than LSC or EO aligning with their additional protection against diarrhea during ETEC infection. Additionally, the key gut bacteria (e.g., Terrisporobacter) related to the benefits of SCFP and EO were identified. In sum, all treatments enhanced growth performance and protected against ETEC-induced intestinal damage through the regulation of redox and immune homeostasis. HSP and SE offered extra protection during disease for their additional control of inflammation. Our study provided new insight into the use of feed additives in the context of animal health states.

Weanling pigs are vulnerable to a variety of stressors and pathogen infections. Enterotoxigenic Escherichia coli (ETEC) is one of the leading causes of diarrhea and growth retardation in weanling pigs. The postbiotics, Saccharomyces cerevisiae fermentation postbiotics (SCFP), and essential oil (EO, mainly thymol, and cinnamaldehyde) were reported to exert health benefits in different sites of the intestine. However, whether SCFP and EO have dose and synergistic effects on weanling pigs, especially against ETEC infection, is incompletely understood. Our research has revealed that SCFP, EO, and their combination all enhanced the growth performance and intestinal barrier function, and reduced diarrhea of piglets, albeit to varying degrees, under both health conditions and ETEC infection. We further elucidated the disparity in the regulation of redox and immune homeostasis by SCFP, EO, and their combination contributing to their different action in distinct states. This has led to a reevaluation of the function of additives in the context of gut health and disease susceptibility.

Oral phages prophylaxis against mixed Escherichia coli O157:H7 and Salmonella Typhimurium infections in weaned piglets.

Escherichia coli and Salmonella Typhimurium are the main pathogens of diarrhea in weaned piglets. The prevention of bacterial diarrhea in weaned piglets by phage is rarely reported. We conducted this study to evaluate the preventive effect of phages on mixed Escherichia coli and Salmonella Typhimurium infections in weaned piglets. A novel phage named NJ12 was isolated by using Salmonella Typhimurium SM022 as host bacteria and characterized by electron microscopy, genomic analysis and in vitro bacteriostatic activity. Phage NJ12 and a previously reported phage EP01 were microencapsulated with sodium alginate to make phage cocktail. Microencapsulated phage cocktail and PBS (Phosphate buffer solution) were used to piglets the phage and phage-free group through oral administration before bacterial infection 2 h, respectively. Piglets of the phage and phage-free group were consumed with feed contaminated with 6 mL (108CFU/mL) Escherichia coli O157:H7 GN07 (GXEC-N07) and 6 mL (108CFU/mL) SM022 every day for seven consecutive days. The results showed that piglets in the phage-free group had more severe diarrhea, larger decreased average weight gain and higher levels of neutrophils compared with piglets in phage group. Meanwhile, piglets in the phage-free group had higher load of SM022 and GN07 in jejunal tissue and more severe intestinal damage compared with piglets in group phage in vivo. In addition, oral administration phage can significant decreased the relative abundance of Enterobacteriaceae but hardly repaired the changes of diversity and composition of gut microbiota caused by the mixed infection of SM022 and GN07. This implies that phage used as a feed additive have a marvelous preventive effect on bacterial diarrhea during weaning of piglets.

Immunogenicity and protective efficacy of recombinant adenovirus expressing a novel genotype G2b PEDV spike protein in protecting newborn piglets against PEDV.

IMPORTANCE: Porcine epidemic diarrhea (PED) is a highly infectious and economically significant gastrointestinal disorder that affects pigs of all ages. Preventing and controlling PED is achieved by immunizing sows with vaccines, enabling passive piglet immunization via colostrum. The prevalence of G2b porcine epidemic diarrhea virus (PEDV) continues in China despite the use of commercial vaccines, raising questions regarding current vaccine efficacy and the need for novel vaccine development. Adenovirus serotype 5 (Ad5) has several advantages, including high transduction efficiency, a wide range of host cells, and the ability to infect cells at various stages. In this study, we expressed the immunogenic proteins of spike (S) using an Ad5 vector and generated a PED vaccine candidate by inducing significant humoral immunity. The rAd5-PEDV-S prevented PED-induced weight loss, diarrhea, and intestinal damage in piglets. This novel vaccine candidate strain possesses the potential for use in the pig breeding industry.

Fast and sensitive differential diagnosis of pseudorabies virus-infected versus pseudorabies virus-vaccinated swine using CRISPR-Cas12a.

IMPORTANCE: Pseudorabies virus (PRV) causes high mortality and miscarriage rates in the infected swine, and the eradication policy coupled with large-scale vaccination of live attenuated vaccines has been adopted globally against PRV. Differential diagnosis of the vaccinated and infected swine is highly demanded. Our multienzyme isothermal rapid amplification (MIRA)-Cas12a detection method described in this study can diagnose PRV with a superior sensitivity comparable to the quantitative PCR (qPCR) and a competitive detection speed (only half the time as qPCR needs). The portable feature and the simple procedure of MIRA-Cas12a make it easier to deploy for clinical diagnosis, even in resource-limited settings. The MIRA-Cas12a method would provide immediate and accurate diagnostic information for policymakers to respond promptly.

Understanding if the reward is worth the influenza risk: The true cost of showing pigs.

Influenza A virus transmission between pigs and humans has been reported periodically worldwide, and spillover events across the animal-human species barrier could lead to the next influenza pandemic. Swine exhibitions serve as a unique interface conducive to zoonotic disease transmission due to extensive commingling of pigs and humans for prolonged periods of time. The majority of zoonotic influenza A virus transmission in the United States has been linked to swine exhibitions, leading some to suggest additional controls for influenza A virus at the swine-human interface. Determining the value of the exhibition swine industry and gauging the financial impacts influenza A virus outbreaks could have on society, helps to inform adoption decisions of mitigation recommendations. This study estimates the total value of the exhibition swine industry in the United States and calculates the predicted costs of the most extreme mitigation strategy, cancelling swine exhibitions to reduce zoonotic influenza A virus transmission. Mixed methods, including a survey, were used to collect data and inform the study model. We estimated that the direct economic impact of the exhibition swine sector in 2018 was $1.2 billion. If pig shows were to be cancelled for one year, the estimated direct economic impact would be $357.1 million. A permanent, > 3-year ban on swine exhibitions would result in a $665 million economic impact, which is a 45% reduction from baseline. The direct economic impact of cancelling the swine show circuit could not be determined, as youth exhibitors may pursue alternative activities that cannot be precisely accounted for. However, the estimated loss to the swine industry justifies seeking enhanced mitigation to prevent disease transmission. Moreover, economic losses secondary to exhibition cancellations may explain hesitancy to participate in active influenza A virus surveillance efforts.