Heinrich Kreutzmann

Exsudative Epidermitis (EE) – meist, aber nicht ausschließlich ausgelöst durch Staphylococcus (St.) hyicus – ist ein verbreitetes Problem auf Ferkelerzeugerbetrieben. So auch in einem westdeutschen eigenremontierenden Betrieb mit 350 produktiven Sauen. Beginnend mit schwärzlich-schuppigen Hautläsionen bei einzelnen Saug- und Aufzuchtferkeln sowie Jung- und Altsauen, bestand bereits in der nächsten Absetzgruppe bei etwa 50% der Ferkel die klinische Verdachtsdiagnose der EE. Die Mortalitätsrate im Aufzuchtstall stieg bei betroffenen Ferkelgruppen auf 10%. Sowohl die (histo)pathologische Untersuchung als auch der wiederholte Nachweis von St. hyicus aus Hauttupfern sowie Tupfern aus anderen Organen bestätigten die klinische Verdachtsdiagnose. Neben St. hyicus konnte aus einzelnen Hauttupfern zudem St. chromogenes isoliert werden. In der weiterführenden Charakterisierung der St. hyicus-Stämme wurden ExhA und SHETA als beteiligte Toxine identifiziert, und die Isolate zeigten unter anderem Resistenzen gegen Penicilline und Aminopenicilline. Kurzfristig verbesserte eine bestandsweise antibiotische Therapie mit einem Trimethoprim-Sulfadiazin-haltigen Präparat in Kombination mit der individuellen Behandlung einzelner Tiere und dem Waschen mit einer jodhaltigen Lösung die klinische Symptomatik. Zur dauerhaften Reduktion des Einsatzes antibiotischer Mittel wurde sich für die Herstellung eines bestandsspezifischen Impfstoffs mit den isolierten St. hyicus- und St. chromogenes-Stämmen entschieden, welcher als Mutterschutzvakzine an die Sauen appliziert wurde. Zusätzlich wurde die externe und interne Biosicherheit anhand eines objektiven Fragebogens (Bio-check.UGent^TM) evaluiert und angepasst. Die Kombination der Maßnahmen führte zu einer langfristigen Besserung des klinischen Geschehens. Das erneute Auftreten leichter Hautläsionen bei einzelnen Ferkeln konnte mit der Anpassung des bestandsspezifischen Impfstoffes durch neu gewonnene St. hyicus-Isolate zielführend in den Griff bekommen werden. Der Fallbericht verdeutlicht, wie mit der Kombination aus kontinuierlichem Monitoring, Einzeltier- und Gruppentherapie, Evaluierung der Biosicherheit und dem Einsatz einer angemessenen Immunprophylaxe selbst hartnäckige Fälle der EE auf ein Minimum reduziert werden können. A massive outbreak of exudative epidermitis (EE) occurred on a Western German piglet producing farm with 350 productive sows. Gilts are produced on site. In one group of piglets, more than 50% of suckling and nursery piglets were clinically affected; furthermore, gilts as well as sows showed localized blackish-squamous skin lesions in the neck area. Generalized infection in suckling and nursery piglets resulted in mortality rates of up to 10% per weaning group. Swabs of moist, affected areas of skin taken on the farm in addition to swab and organ samples collected during necropsy were examined via bacterial cultivation. Both Staphylococcus (St.) hyicus and St. chromogenes strains were detected in affected skin lesions, with St. hyicus also present in systemic localizations. Further characterization of the St. hyicus strains identified ExhA and SHETA as toxins involved, and isolates showed resistance to penicillin and aminopenicillin. In the short term, antibiotic treatment with trimethoprim-sulfadiazine of the whole age group combined with individual treatment of severely affected animals as well as washing with an iodine-containing solution improved the clinical signs. In order to reduce the antibiotic use, an autogenous vaccine against the isolated St. hyicus and St. chromogenes strains for gilts and sows was produced and applied as a basic immunization twice before farrowing. In addition, external and internal biosecurity was evaluated and adjusted using an objective questionnaire (Bio-check.UGent^TM). The combination of taken measures resulted in a long-term improvement of the overall health status. Several months after the severe EE outbreak, the sporadic occurrence of new EE cases in individual piglets could be controlled by the adjustment of the autogenous vaccine with an additional St. hyicus isolate. The case report illustrates how the combination of continuous monitoring, individual and group antibiotic treatment, biosecurity evaluation, and the use of appropriate immune prophylaxis can improve the clinical picture of EE. ^* Diese Autoren haben gleichermaßen zur vorliegenden Arbeit beigetragen. Received: 06 October 2022 Accepted: 22 February 2023 Article published online: 08 August 2023 © 2023. The Author(s). This is an open access article published by Thieme under the terms of the Creative Commons Attribution-NonDerivative-NonCommercial-License, permitting copying and reproduction so long as the original work is given appropriate credit. Contents may not be used for commercial purposes, or adapted, remixed, transformed or built upon. (https://creativecommons.org/licenses/by-nc-nd/4.0/). Georg Thieme Verlag KG Rüdigerstraße 14, 70469 Stuttgart, Germany

Diverse origins and causes are described for papyraceous mummifications of porcine foetuses, but the porcine reproductive and respiratory syndrome virus (PRRSV) is not one of them. In contrast, PRRSV is unlikely to cause mid-term placental transmission but may cause late-term abortions and weakness of piglets. This case report describes a sudden occurrence of mummified foetuses of various sizes and stillborns and delayed birth (>115 days) in more than 50% of sows from one farrowing batch, while newborn piglets were mostly vital. Neither increased embryonic death nor infertility was reported. Three litters with mummies, autolysed piglets and stillborn piglets were investigated, and infections with porcine parvoviruses, porcine teschoviruses, porcine circoviruses, encephalomyocarditis virus, Leptospira spp. and Chlamydia spp. were excluded. Instead, high viral loads of PRRSV were detected in the thymus pools of piglets at all developmental stages, even in piglets with a crown–rump length between 80 and 150 mm, suggesting a potential mid-term in utero transmission of the virus. Genomic regions encoding structural proteins (ORF2–7) of the virus were sequenced and identified the virulent PRRSV-1 strain AUT15-33 as the closest relative. This case report confirms the diversity of PRRSV and its potential involvement in foetal death in mid-gestation.

Reproductive disorders caused by porcine reproductive and respiratory syndrome virus-1 are not yet fully characterized. We report QuPath-based digital image analysis to count inflammatory cells in 141 routinely, and 35 CD163 immunohistochemically stained endometrial slides of vaccinated or unvaccinated pregnant gilts inoculated with a high or low virulent PRRSV-1 strain. To illustrate the superior statistical feasibility of the numerical data determined by digital cell counting, we defined the association between the number of these cells and endometrial, placental, and fetal features. There was strong concordance between the two manual scorers. Distributions of total cell counts and endometrial and placental qPCR results differed significantly between examiner1’s endometritis grades. Total counts’ distribution differed significantly between groups, except for the two unvaccinated. Higher vasculitis scores were associated with higher endometritis scores, and higher total cell counts were expected with high vasculitis/endometritis scores. Cell number thresholds of endometritis grades were determined. A significant correlation between fetal weights and total counts was shown in unvaccinated groups, and a significant positive correlation was found between these counts and endometrial qPCR results. We revealed significant negative correlations between CD163+ counts and qPCR results of the unvaccinated group infected with the highly virulent strain. Digital image analysis was efficiently applied to assess endometrial inflammation objectively.

The emergence of recombinant PRRSV strains has been observed for more than a decade. These recombinant viruses are characterized by a genome that contains genetic material from at least two different parental strains. Due to the advanced sequencing techniques and a growing number of data bank entries, the role of PRRSV recombinants has become increasingly important since they are sometimes associated with clinical outbreaks. Chimeric viruses observed more recently are products of PRRSV wild-type and vaccine strains. Here, we report on three PRRSV-1 isolates from geographically distant farms with differing clinical manifestations. A sequencing and recombination analysis revealed that these strains are crossovers between different wild-type strains and the same modified live virus vaccine strain. Interestingly, the recombination breakpoint of all analyzed isolates appears at the beginning of open reading frame 5 (ORF5). RNA structure predictions indicate a conserved stem loop in close proximity to the recombination hotspot, which is a plausible cause of a polymerase template switch during RNA replication. Further research into the mechanisms of the stem loop is needed to help understand the PRRSV recombination process and the role of MLVs as parental strains.

Postnatally, short-chain fatty acids (SCFA) are important energetic and signaling agents, being involved in host nutrition, gut imprinting and immune and barrier function. Whether SCFA exert similar effects during the late fetal phase has been insufficiently elucidated. This study aimed to evaluate whether the fetal jejunum senses SCFA and whether SCFA modify the muscle tension and epithelial permeability and related signaling in jejunal tissue from the porcine fetus in late gestation. Exposure of fetal jejunal tissue to a mix of SCFA (70 µmol/mL) in an organ bath for 20 min lowered the muscle tension. Moreover, SCFA decreased the transepithelial conductance while increasing the short-circuit current in the Ussing chamber, indicating reduced permeability and increased SCFA absorption. Gene expression in the tissues harvested from the Ussing chamber after 30 min indicated downregulation of the expression of receptors (i.e., FFAR2 and TLR2), MCT1 and tight-junction and adherens proteins, which may be a negative feedback response to the applied high SCFA concentration compared with the micromolar concentration detected in fetal gastric fluid. Taken together, our data demonstrate that the fetal jejunum senses SCFA, which trigger electrophysiological, muscle contraction and related gene transcription responses. Hence, SCFA may play a role in prenatal gut nutrition and imprinting.

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.

PRRSV is one of the most important viruses in the global swine industry and is often controlled by the use of modified live virus (MLV) vaccines. This study assessed the impact of a PRRSV-1 MLV vaccine applied to 1-day-old piglets challenged on day 28 of life with a PRRSV-1 field isolate (AUT15-33). Twenty-one piglets were vaccinated within 24 h of birth (T02), whereas 20 piglets were left unvaccinated (T01). Necropsy was performed two weeks post-challenge. Comparing the two groups, T02 piglets showed significantly higher (p = 0.017) average daily weight gain. In addition, significantly lower (p < 0.0001) PRRSV RNA loads were measured in serum of T02 piglets at all investigated time points. All T01 piglets were viremic and shed virus in nasal swabs, whereas only 71.4% and 38.1% of the T02 group were viremic or shed virus, respectively. Piglets from T02 had significantly higher numbers (p < 0.0001) of IFN-γ producing lymphocytes compared to T01. At necropsy, differences in gross and histologic lung lesions were statistically significant (p = 0.012 and p < 0.0001, respectively) between the two groups. Hence, this MLV vaccine administered to 1-day-old piglets was able to protect piglets against PRRSV infection at weaning.

Vaccination with the live attenuated vaccine Salmoporc is an effective measure to control Salmonella Typhimurium (STM) in affected swine populations. However, the cellular immune response evoked by the Salmoporc vaccine including differences in vaccinated pigs versus non-vaccinated pigs upon STM infection have not been characterized yet. To investigate this, tissue-derived porcine lymphocytes from different treatment groups (vaccination-only, vaccination and infection, infection-only, untreated controls) were stimulated in vitro with heat-inactivated STM and abundances of IFN-γ, TNF-α and/or IL-17A-producing T-cell subsets were compared across organs and treatment groups. Overall, our results show the induction of a strong CD4⁺ T-cell response after STM infection, both locally and systemically. Low-level induction of STM-specific cytokine-producing CD4⁺ T cells, notably for the IFN-γ/TNF-α co-producing phenotype, was detected after vaccination-only. Numerous significant contrasts in cytokine-producing T-cell phenotypes were observed after infection in vaccinated and infected versus infected-only animals. These results suggest that vaccine-induced STM-specific cytokine-producing CD4⁺ T cells contribute to local immunity in the gut and may limit the spread of STM to lymph nodes and systemic organs. Hence, our study provides insights into the underlying immune mechanisms that account for the efficacy of the Salmoporc vaccine.