Reproductive disorders induced by porcine reproductive and respiratory syndrome virus (PRRSV) cause high economic losses in the pig industry worldwide. In this study, we aimed to phenotypically characterize a virulent PRRSV-1 subtype 1 isolate (AUT15-33) in a reproductive model. Furthermore, the protective effect of a heterologous modified live virus vaccine (ReproCyc® PRRS EU) was evaluated. In addition, PRRSV AUT15-33 was genotypically compared to other well-characterized isolates. Sixteen gilts were equally divided into four groups: a vaccinated and infected group (V–I), a vaccinated and non-infected group (V–NI), a non-vaccinated and infected group (NV–I), and a non-vaccinated and non-infected (NV–NI) group. After PRRSV infection on gestation day 84, all gilts were clinically examined on a daily basis, and blood samples were taken at five timepoints. Necropsy was performed 3 weeks after infection. The fetal preservation status was assessed, and PRRSV RNA concentrations were measured in the blood and tissue samples from all gilts and fetuses. After infection, all four gilts in the NV–I group were viremic throughout 17 days post-infection (dpi), whereas two gilts in the V–I group were viremic at only one timepoint at 6 dpi. The viral load was significantly higher in gilt serum, tracheobronchial lymph nodes, uterine lymph nodes, maternal endometrium, and fetal placenta of NV–I gilts compared to the V–I ones (p < 0.05). Moreover, the preservation status of the fetuses derived from NV–I gilts was significantly impaired (55.9% of viable fetuses) compared to the other groups (p < 0.001). Upon comparison with other known isolates, the phylogenetic analyses revealed the closest relation to a well-characterized PRRSV-1 subtype 1 field isolate from Belgium. In conclusion, the high virulence of AUT15-33 was phenotypically confirmed in an experimental reproductive model. The vaccination of the gilts showed promising results in reducing viremia, fetal damage, and transplacental transmission of the PRRSV-1 strain characterized in this study.

Simple Summary: Antibiotics are commonly used in prevention and therapy of bacterial diseases in pig production. Although the main target of antibiotics are the pathogenic bacteria, they often disrupt the commensal gut microbiota as a whole, leading to intestinal disturbances. These detrimental effects have been well established for oral administration of antibiotics, whereas knowledge about potential disturbing effects of single parenteral antibiotic treatments on the gut microbiota development is limited. In this research, the impact of a single antibiotic injection on the first day of life on the maturation of the fecal microbiome and host growth performance was evaluated from the suckling to the growing phase. Results showed that a single antibiotic injection early in life influenced the bacterial community development in the short-and long-term and that this disturbance in the bacterial community was sex-specific. Present results further demonstrated that changes in the bacterial ecosystem of the gut may impair the growth performance of the growing pig. Thus, the results of the present study emphasize the importance of a proper and strict use of antibiotics in swine herds.Abstract: Using ceftiofur during the first days of life is a common preventative strategy against several bacterial diseases in pig production. This study aimed to evaluate short-and long-term effects of early use of ceftiofur on the fecal microbiota development in suckling and growing pigs. Sixty-four piglets from eight litters were assigned to the antibiotic (AB; n = 32) or control group (control; n = 32). Twelve hours postpartum (day 0) AB piglets received an intramuscular injection of ceftiofur (5.0 mg/kg body weight) or a placebo. DNA was extracted from fecal samples collected on days 0, 12, 28, and 97 for deep-sequencing of the 16S rRNA gene. The AB administration disturbed the maturational changes in the fecal microbiome, whereby effects were sex-specific. Sex-related differences in AB metabolism in females and males may have caused these diverging AB-effects on the fecal microbiota. Especially the loss of bacterial diversity and of certain taxa in female AB pigs may have contributed to the decreased body weight of these females on day 97 of life. Taken together, this study showed that an AB injection with ceftiofur 12 h postpartum markedly affected the successional changes in the fecal microbiota composition in male and female pigs, with long-term consequences for host performance.

Background Mycoplasma hyorhinis is an invader of the upper respiratory tract in swine that is considered to have ubiquitous distribution. It is mainly known for causing polyserositis and polyarthritis in weaned piglets, even though the mechanisms of systemic spread are not fully understood. Mycoplasma hyorhinis has also been associated with other diseases in pigs such as pneumonia or otitis media, but so far has not been known to cause central nervous disorders. This case series reports the isolation of Mycoplasma hyorhinis from cerebrospinal fluid and/ or meningeal swabs from piglets originating from four different piglet producing farms in Austria. Case presentation On farm 1, coughing, stiff movement and central nervous signs occurred in nursery piglets. Mycoplasma hyorhinis was the only pathogen isolated from meningeal swabs from two piglets showing central nervous signs. Fibrinopurulent leptomeningitis was only observed in one piglet. Only one of two nursery piglets from farm 2 showed mild central nervous signs but no histologic lesions; Mycoplasma hyorhinis was isolated from cerebrospinal fluid of the piglet with neurologic signs. Mycoplasma hyorhinis was isolated from cerebrospinal fluid of all three investigated piglets from farm 3, all of which showed central nervous signs and purulent leptomeningitis. Further, Streptococcus suis was isolated from the cerebrospinal fluid of one piglet. Fibrinopurulent leptomeningitis was detected in two piglets from farm 4 that had died overnight without showing any clinical signs and Mycoplasma hyorhinis was isolated from meningeal swabs from both piglets. Conclusion While causality has yet to be proven by experimental infection and in situ detection of the pathogen in histologic sections, the findings of this study and the absence of other pathogens suggest Mycoplasma hyorhinis as a potential causative agent of meningitis in swine.

The ingestion of mycotoxins can cause adverse health effects and represents a severe health risk to humans and livestock. Even though several acute and chronic effects have been described, the effect on the gut metaproteome is scarcely known. For that reason, we used metaproteomics to evaluate the effect of the mycotoxins deoxynivalenol (DON) and zearalenone (ZEN) on the gut microbiome of 15 weaned piglets. Animals were fed for 28 days with feed contaminated with different concentrations of DON (DONlow: 870 μg DON/kg feed, DONhigh: 2493 μg DON/kg feed) or ZEN (ZENlow: 679 μg ZEN/kg feed, ZENhigh: 1623 μg ZEN/kg feed). Animals in the control group received uncontaminated feed. The gut metaproteome composition in the high toxin groups shifted compared to the control and low mycotoxin groups, and it was also more similar among high toxin groups. These changes were accompanied by the increase in peptides belonging to Actinobacteria and a decrease in peptides belonging to Firmicutes. Additionally, DONhigh and ZENhigh increased the abundance of proteins associated with the ribosomes and pentose-phosphate pathways, while decreasing glycolysis and other carbohydrate metabolism pathways. Moreover, DONhigh and ZENhigh increased the abundance of the antioxidant enzyme thioredoxin-dependent peroxiredoxin. In summary, the ingestion of DON and ZEN altered the abundance of different proteins associated with microbial metabolism, genetic processing, and oxidative stress response, triggering a disruption in the gut microbiome structure.

BackgroundListeria (L.) monocytogenes as the causative agent of listeriosis in humans and different animal species, has its reservoir in the environment. It can be found in the gut and faeces of healthy pigs, but under certain circumstances it may cause clinical disease. Fatteners are usually not known to get affected by Listeria-associated septicaemia and enteritis. This case report shows, that L. monocytogenes should be part of the list of differential diagnoses, when fattening pigs suffer from haemorrhagic diarrhoea and septicaemia.Case presentationHere, we report of an episode of fatal listeriosis in fattening pigs in a piglet producing farm in Lower Austria, which was combined with a fattening unit with space for 450 fatteners. The mortality rate resulted in 7.8% among fattening pigs after suffering from clinical symptoms such as anorexia, bloody diarrhoea and increased body temperature. Two fattening pigs with clinical symptoms and maize silage samples were used for further diagnostics. L. monocytogenes were isolated from serosa samples of the pigs and in the corresponding fed maize silage. One animal was positively tested for Brachyspira hyodysenteriae, which may have also been involved in the development of colitis. Immunohistochemically, L. monocytogenes could be detected in high amounts in lymphatic tissue of the gut. Molecular biological characterisation of the L. monocytogenes isolates from pigs and maize silage resulted in an identical DNA-fingerprint assigned to sequence type (ST) 21. Additionally, a high content of deoxynivalenol (3000 parts per billion) was found in maize silage. Therefore, the maize silage produced under inappropriate ensilaging conditions in a silo, was most likely the source of infection. Antimicrobial therapy with amoxicillin led to a fast cure of the remaining affected fatteners.ConclusionTo conclude, we were able to show, that L. monocytogenes can cause clinical disease in finishing pigs, which may have been a result of immunosuppression due to high deoxynivalenol exposure. When feeding silage it is important that all ensilaging procedures occur under appropriate anaerobic conditions to guarantee suppression of listerial growth.Electronic supplementary materialThe online version of this article (10.1186/s12917-018-1687-6) contains supplementary material, which is available to authorized users.