Porcine reproductive and respiratory syndrome (PRRS) causes decreased reproductive performance and respiratory problems in pigs. The goals of the current study were 1) to examine whether individual variation applies to infection with PRRSV European strains and 2) to investigate the association of a single nucleotide polymorphism (SNP) WUR10000125 (WUR) at the interferon-inducible guanylate-binding protein 1 gene (GBP1) with average daily gain (ADG) in PRRSV infected and uninfected pigs. The experimental procedure consisted of two trials in which pigs from negative PRRSV farms were infected with a wild-type (n=80) or vaccinated with an attenuated European PRRS virus strain (n=40) and then monitored after infection or vaccination. Viral load and ADG were determined for each pig. In a third trial, the ADG for PRRSV-free pigs was monitored. All pigs were genotyped for WUR at the GBP1 gene (AA and AG genotype were defined). Results indicated that there was individual variation in the viral load from pigs challenged with a wild-type or low virulent European PRRSV strain. Secondly, our data showed that WUR SNP was associated to ADG in vaccinated pigs. Thus, ADG in AG pigs was significantly higher than in AA ones after vaccinating with an attenuated PRRSV strain. However, the reverse happened in a PRRSV-free environment where the AA pigs were those that grew faster. Based on these results, there is a scope for selecting pigs according to their responses to PRRS virus infection with European strains and that WUR SNP may play a role in causing PRRSV resistance.

The Porcine Reproductive and Respiratory Syndrome Virus (PRRSV) is the etiological agent of one of the most important swine diseases with a significant economic burden worldwide. Unfortunately, available vaccines are partially effective highlighting the need of novel approaches. Previously, antigenic viral proteins were described in serum-derived extracellular vesicles (EVs) from pigs previously infected with PRRSV. Here, a targeted-pig trial was designed to determine the safety and immunogenicity of such extracellular vesicles enriched fractions. Our results showed that immunizations with EV-enriched fractions from convalescence animals in combination with montanide is safe and free of virus as immunizations with up-to two milligrams of EV-enriched fractions did not induce clinical symptoms, adverse effects and detectable viral replication. In addition, this vaccine formulation was able to elicit specific humoral IgG immune response in vaccinated animals, albeit variably. Noticeably, sera from vaccinated animals was diagnosed negative when tested for PRRSV using a commercial ELISA test; thus, indicating that this new approach differentiates vaccinated from infected animals. Lastly, after priming animals with EV-enriched fractions from sera of convalescence animals and boosting them with synthetic viral peptides identified by mass spectrometry, a distinctive high and specific IFN-γ response was elicited. Altogether, our data strongly suggest the use of serum EV-enriched fractions as a novel vaccine strategy against PRRSV.

Novel techniques of data mining and time series analyses allow the development of new methods to analyze information relating to the health status of the swine population in near real-time. A swine health monitoring system based on the reporting of clinical events detected at farm level has been in operation in Northeastern Spain since 2012. This initiative was supported by swine stakeholders and veterinary practitioners of the Catalonia, Aragon, and Navarra regions. The system aims to evidence the occurrence of endemic diseases in near real-time by gathering data from practitioners that visited swine farms in these regions. Practitioners volunteered to report data on clinical events detected during their visits using a web application. The system allowed collection, transfer and storage of data on different clinical signs, analysis, and modeling of the diverse clinical events detected, and provision of reproducible reports with updated results. The information enables the industry to quantify the occurrence of endemic diseases on swine farms, better recognize their spatiotemporal distribution, determine factors that influence their presence and take more efficient prevention and control measures at region, county, and farm level. This study assesses the functionality of this monitoring tool by evaluating the target population coverage, the spatiotemporal patterns of clinical signs and presumptive diagnoses reported by practitioners over more than 6 years, and describes the information provided by this system in near real-time. Between January 2012 and March 2018, the system achieved a coverage of 33 of the 62 existing counties in the three study regions. Twenty-five percent of the target swine population farms reported one or more clinical events to the system. During the study period 10,654 clinical events comprising 14,971 clinical signs from 1,693 farms were reported. The most frequent clinical signs detected in these farms were respiratory, followed by digestive, neurological, locomotor, reproductive, and dermatological signs. Respiratory disorders were mainly associated with microorganisms of the porcine respiratory disease complex. Digestive signs were mainly related to colibacilosis and clostridiosis, neurological signs to Glässer's disease and streptococcosis, reproductive signs to PRRS, locomotor to streptococcosis and Glässer's disease, and dermatological signs to exudative epidermitis.