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Nipah virus (NiV), of the Paramyxoviridae family, causes highly fatal infections in humans and is associated with severe neurological and respiratory diseases. Currently, no commercial vaccine is available for human use. Here, eight structure-based mammalian-expressed recombinant proteins harboring the NiV surface proteins, fusion glycoprotein (F), and the major attachment glycoprotein (G) were produced. Specifically, prefusion NiV-F and/or NiV-G glycoproteins expressed in monomeric, multimeric (trimeric F and tetra G), or chimeric forms were evaluated for their properties as sub-unit vaccine candidates. The antigenicity of the recombinant NiV glycoproteins was evaluated in intramuscularly immunized mice, and the antibodies in serum were assessed. Predictably, all homologous immunizations exhibited immunogenicity, and neutralizing antibodies to VSV-luciferase-based pseudovirus expressing NiV-GF glycoproteins were found in all groups. Comparatively, neutralizing antibodies were highest in vaccines designed in their multimeric structures and administered as bivalent (GMYtet + GBDtet) and trivalent (Ftri + GMYtet + GBDtet). Additionally, while all adjuvants were able to elicit an immunogenic response in vaccinated groups, bivalent (GMYtet + GBDtet) and trivalent (Ftri + GMYtet + GBDtet) induced more potent neutralizing antibodies when administered with oil-in-water nano-emulsion adjuvant, AddaS03. For all experiments, the bivalent GMYtet + GBDtet was the most immunogenic vaccine candidate. Results from this study highlight the potential use of these mammalian-expressed recombinant NiV as vaccine candidates, deserving further exploration.

Live coccidiosis vaccines have mainly been used to reduce Eimeria species infection, which is considered the most economically important disease in the poultry industry. Evaluation data on vaccine effectiveness through large-scale field experiments are lacking, especially in broilers. Thus, the effectiveness of a commercial coccidiosis vaccine was evaluated in approximately 900,000 chicks reared on three open-broiler farms where coccidiosis is prevalent. The vaccine’s effectiveness after vaccination of 1-day-old chicks was monitored using three parameters (lesion score, fecal oocyst shedding, and production index, PI) in nine trials performed three times on each farm. Lesion scores were confirmed in three different areas of the intestine because the vaccine contained four Eimeria species. The average lesion scores were 0.36 to 0.64 in the duodenal region, 0.30 to 0.39 in the jejuno-ileal region, and 0.18 to 0.39 in the cecal region. The average fecal oocyst shedding rate ranged from 19,766 to 100,100 oocysts per gram, showing large variations depending on farms and buildings within the farm. Compared with the PI of the previous 9–10 trials on each farm, the PI increased by 2.45 to 23.55. Because of the potential for perturbation of the fecal microbiota by live coccidiosis vaccines, the fecal microbiota was investigated using 16S rRNA microbial profiling. Although the β-diversity was significantly different in distribution and relative abundance among farms (PERMANOVA, pseudo-F = 4.863, p = 0.009), a Kyoto Encyclopedia of Genes and Genomes pathway analysis found no significant bacterial invasion of the epithelial cell pathway across farms. This large-scale field trial of a live Eimeria vaccine indicates that coccidiosis vaccines can have meaningful effects on the poultry industry and could be used as an alternative to the prophylactic use of anticoccidial drugs under field conditions.

African swine fever (ASF), a highly contagious disease of swine, has posed a significant global threat to the swine industry. As an archipelago, the Philippines has a geographic advantage when it comes to the risk of ASF transmission. However, since its introduction to the Philippines in 2019, it has proliferated not only in backyard and commercial farms but also in wild pig populations. While certain parts of the country were more affected than others, the epidemiologic features of ASF necessitate that all affected areas must be closely monitored and that confirmed cases be treated with the utmost care. With the very limited data on ASF epidemiology and surveillance in the Philippines, future efforts to combat ASF must place even greater emphasis on improved prevention and control strategies. It is worth mentioning that the government’s efforts toward comprehensive ASF surveillance and epidemiological investigation into the possible ASFV sources or transmission pathways are the most important measures in the prevention and control of ASF outbreaks. This review article provides a comprehensive overview of the current swine industry and ASF situation in the Philippines, which includes its epidemiology, surveillance, prevention, and control strategies.

Riemerella anatipestifer (RA) is an economically important pathogen in the duck industry worldwide that causes high mortality and morbidity in infected birds. We previously found that upregulated IL-17A expression in ducks infected with RA participates in the pathogenesis of the disease, but this mechanism is not linked to IL-23, which primarily promotes Th17 cell differentiation and proliferation. RNA sequencing analysis was used in this study to investigate other mechanisms of IL-17A upregulation in RA infection. A possible interaction of IL-26 and IL-17 was discovered, highlighting the potential of IL-26 as a novel upstream cytokine that can regulate IL-17A during RA infection. Additionally, this process identified several important pathways and genes related to the complex networks and potential regulation of the host immune response in RA-infected ducks. Collectively, these findings not only serve as a roadmap for our understanding of RA infection and the development of new immunotherapeutic approaches for this disease, but they also provide an opportunity to understand the immune system of ducks.

The spread of antibiotic-resistant Enterococcus in the poultry industry poses significant public health challenges due to multidrug resistance and biofilm formation. We investigated the antibiotic resistance profiles and biofilm characteristics of E. faecalis and E. faecium isolates from chicken meat in poultry slaughterhouses in South Korea. Ninety-six isolates (forty-eight each of E. faecalis and E. faecium) were collected between March and September 2022. Both species were analyzed using MALDI-TOF, PCR, antibiotic susceptibility testing, and biofilm assays. A high level of multidrug resistance was observed in E. faecalis (95.8%) and E. faecium (93.8%), with E. faecium exhibiting a broader range of resistance, particularly to linezolid (52.1%) and rifampicin (47.9%). All E. faecalis isolates formed biofilm in vitro, showing stronger biofilm formation than E. faecium with a significant difference (p < 0.001) in biofilm strength. Specific genes (cob, ccf, and sprE) were found to be correlated with biofilm strength. In E. faecium isolates, biofilm strength was correlated with resistance to linezolid and rifampicin, while a general correlation between antibiotic resistance and biofilm strength was not established. Through analysis, correlations were noted between antibiotics within the same class, while no general trends were evident in other analyzed factors. This study highlights the public health risks posed by multidrug-resistant enterococci collected from poultry slaughterhouses, emphasizing the complexity of the biofilm-resistance relationship and the need for enhanced control measures.

Avian influenza virus (AIV) is a pathogen with zoonotic and pandemic potential. Migratory birds are natural reservoirs of all known subtypes of AIVs, except for H17N10 and H18N11, and they have been implicated in previous highly pathogenic avian influenza outbreaks worldwide. This study identified and characterized the first isolate of the H13N6 subtype from a Vega gull (Larus vegae mongolicus) in South Korea. The amino acid sequence of hemagglutinin gene showed a low pathogenic AIV subtype and various amino acid substitutions were found in the sequence compared to the reference sequence and known H13 isolates. High sequence homology with other H13N6 isolates was found in HA, NA, PB1, and PA genes, but not for PB2, NP, M, and NS genes. Interestingly, various point amino acid mutations were found on all gene segments, and some are linked to an increased binding to human-type receptors, resistance to antivirals, and virulence. Evolutionary and phylogenetic analyses showed that all gene segments are gull-adapted, with a phylogeographic origin of mostly Eurasian, except for PB2, PA, and M. Findings from this study support the evidence that reassortment of AIVs continuously occurs in nature, and migratory birds are vital in the intercontinental spread of avian influenza viruses.

Abstract Background Coccidiosis is a poultry disease that occurs worldwide and is caused by Eimeria species. The infection is associated with reduced feed efficiency, body weight gain, and egg production. This study aimed to investigate the current status of coccidiosis and anticoccidial resistance to anticoccidial drugs used as part of control strategies for this disease in Korean chicken farms. Results An overall prevalence of 75% (291/388) was found. Positive farms contained several Eimeria species (mean = 4.2). Of the positive samples, E. acervulina (98.6%), E. maxima (84.8%), and E. tenella (82.8%) were the most prevalent species. Compared with cage-fed chickens, broilers and native chickens reared in free-range management were more at risk of acquiring an Eimeria infection. Sensitivities to six anticoccidial drugs (clopidol, diclazuril, maduramycin, monensin, salinomycin, and toltrazuril) were tested using nine field samples. Compared with untreated healthy control chickens, the body weight gains of infected chickens and treated/infected chickens were significantly reduced in all groups. Fecal oocyst shedding was significantly reduced in four clopidol-treated/infected groups, three diclazuril-treated/infected groups, two toltrazuril-treated/infected groups, one monensin-treated/infected group, and one salinomycin-treated/infected group, compared with the respective untreated/infected control groups. Intestinal lesion scores were also reduced in three clopidol-treated/infected groups, one monensin-treated/infected group, and one toltrazuril-treated/infected group. However, an overall assessment using the anticoccidial index, percent optimum anticoccidial activity, relative oocyst production, and reduced lesion score index found that all field samples had strong resistance to all tested anticoccidial drugs. Conclusion The results of this large-scale epidemiological investigation and anticoccidial sensitivity testing showed a high prevalence of coccidiosis and the presence of severe drug resistant Eimeria species in the field. These findings will be useful for optimizing the control of coccidiosis in the poultry industry.

Riemerella anatipestifer is one of the most devastating pathogens affecting the global duck farms. Infection is involved in secretion of proinflammatory cytokines, including interleukin- (IL-) 17A. During the immune response to infection, IL-22 and IL-17A are often produced concurrently and at high levels in inflamed tissues. Little is known about duck IL-22 (duIL-22) during R. anatipestifer infection. We describe the characterization of duIL-22 and its mRNA expression analysis in splenic lymphocytes and macrophages treated with heat-killed R. anatipestifer and in the spleens and livers of R. anatipestifer-infected ducks. Full-length cDNA of duIL-22 encoded 197 amino acids. The deduced amino acid sequence of duIL-22 shared a 30.4–40.5% similarity with piscine counterparts, 57.4–60.1% with mammalian homologs, and 93.4% similarity to the chicken. Duck IL-22 mRNA expression level was relatively high in the skin of normal ducks. It was increased in mitogen-stimulated splenic lymphocytes and in killed R. anatipestifer-activated splenic lymphocytes and macrophages. Compared with healthy ducks, IL-22 transcript expression was significantly upregulated in the livers and spleens on days 1 and 4 postinfection, but not on day 7. IL-17A was significantly increased in the spleens only on day 4 postinfection and in the livers at all time points. When splenic lymphocytes were stimulated with heat-killed R. anatipestifer, CD4+ cells predominantly produced IL-22 while IL-17A was expressed both by CD4+ and CD4- cells. These results suggested that IL-22 and IL-17A are likely expressed in different cell types during R. anatipestifer infection.

3,3'-Diindolylmethane (DIM) is found in cruciferous vegetables and is used to treat various inflammatory diseases because of its potential anti-inflammatory effects. To investigate effects of DIM in Riemerella anatipestifer-infected ducks which induce upregulation of inflammatory cytokines, ducks were treated orally with DIM at dose of 200 mg/kg/day and infected the following day with R. anatipestifer. Infected and DIM-treated ducks exhibited 14% increased survival rate and significantly decreased bacterial burden compared to infected untreated ducks. Next, the effect on the expression level of inflammatory cytokines (interleukin [IL]-17A, IL-17F, IL-6, IL-1β) of both in vitro and in vivo DIM-treated groups was monitored by quantitative reverse-transcription PCR (qRT-PCR). Generally, the expression levels of the cytokines were significantly reduced in DIM-treated splenic lymphocytes stimulated with killed R. anatipestifer compared to stimulated untreated splenic lymphocytes. Similarly, the expression levels of the cytokines were significantly reduced in the spleens and livers of DIM-treated R. anatipestifer-infected ducks compared to infected untreated ducks. This study demonstrated the ameliorative effects of DIM in ducks infected with R. anatipestifer. Thus, DIM can potentially be used to prevent and/or treat R. anatipestifer infection via inhibition of inflammatory cytokine expression.