Background/Introduction: Porcine parvovirus (PPV), the causative agent of severe reproductive failures in pigs, is present worldwide. The witnessed spread of the virulent 27a type PPV strains since its recognition raised concerns about the efficacy of the available commercial vaccines. Methods: To address this question, vaccinated pregnant gilts were challenged with a PPV-27a-like virus strain and parameters related to vaccine efficacy were compared. Results: The K22 vaccine strain of Parvoruvax^® (PVX) was characterized as “Kresse-like” based on the epitope mapping data. Vaccination of the gilts induced a low level of antibody responses. Based on foetal mortality, the number of sows which had challenge virus-affected foetuses, the percent of PPV positive piglets/litters plus their PPV genome and viral load PVX outscored the other vaccinated groups. Conclusion: Stronger protection was provided by the “Kresse-like” K22 PPV strain-based vaccine than by the NADL-2 and NADL-like strain-based commercial vaccines against a PPV-27a cluster strain challenge. Vaccine-induced antibody levels as measured pre-challenge were not found to be an accurate indicator of protection.

Actinobacillus pleuropneumoniae is a major economically significant bacterial respiratory pig pathogen, and whole cell vaccines are used to prevent disease. However, there is little data available on multi-serovar whole cell vaccine protection. Therefore, we determined the protective efficacies of a whole-cell A. pleuropneumoniae serovar 1 and 2 vaccine comprising ApxI-III toxins (C-vaccine, Coglapix^®, Ceva, France) against serovars 1, 2, 4, 5, 6, 7, 9/11, and 13. The infection doses used induced disease representative of endemic field conditions, and standard protocols were used for all studies. Protection against homologous serovars 1 and 2 significantly reduced lung lesion scores (LLS) compared to positive controls: p = 0.00007 and p = 0.00124, respectively. The protection against heterologous serovars 4, 5, 6, 7, 9/11, and 13 also significantly reduced LLS: range p = 2.9 × 10⁻¹⁰ to p = 0.00953. As adjudged by the estimated random effect, reproducibility between studies was high. A highly significant serovar-independent reduction of pathological lung lesions by the C-vaccine was found for all the serovars tested (1, 2, 4, 5, 6, 7, 9/11, and 13). We conclude that the C-vaccine gives high serovar-independent protection against disease and is suitable for this use in the field.

Background: Porcine reproductive and respiratory syndrome virus (PRRSV) vaccination is usually based on administering periodically PRRS modified live virus (MLV) in sows throughout their life. Using this schedule, transfer of maternally derived antibodies to the offspring is limited. The aim of the present study was to test the concept of priming with an MLV and boosting with a commercial inactivated virus vaccine in sows to reduce PRRSV incidence and improve productivity. Methods: On two farms, all the sows were vaccinated with a MLV vaccine at week 8 of gestation. Then two groups were designated, one group was re‐vaccinated in the third week prior to farrowing and using a commercial inactivated vaccine (the PG group). The second group was the control group (C). Assays for PRRSV infection and productive parameters were evaluated. Results: For both farms, the incidence of PRRSV was lower at 6 weeks of age in PG than in C ( p < 0.05). At weaning the proportion of PRRSV seropositive piglets was higher for PG as well ( p < 0.05). The litters from C sows from both farms showed a higher pre‐weaning mortality (odds ratio, C vs. PG = 1.18 ± 0.09; p < 0.05). Conclusions: Administration of the vaccine in sows before farrowing was safe and associated with reduced incidence of PRRSV in piglets up to 6 weeks of age.

Pleuropneumonia remains an important challenge to swine production worldwide. The causative agent, Actinobacillus pleuropneumoniae serovar prevalence in countries can change over time. Few Taiwanese A. pleuropneumoniae prevalence studies have been published, and recent large-scale investigations remain notably scarce. This study aimed to identify the serovars and antimicrobial sensitivity of 96 current Taiwanese A. pleuropneumoniae clinical isolates. Among the 99 A. pleuropneumoniae determinations, 40 (40.4%) were serovar 15, 29 (29.3%) were serovar 5, 15 (15.2%) were serovar 1, 11 (11.1%) were serovar 7, and 4 (4.0%) were serovar 2. Therefore serovar 15 was the most predominant between 2015 and 2022. Resistance of the isolates was minimal to ceftiofur (3.2%), cephalexin (5.2%), cephalothin (6.3%) and enrofloxacin (9.3%), moderate to gentamicin (28.4%), and high for florfenicol, amoxicillin and ampicillin (45.1-68.4%). This study updates the serovar and antimicrobial sensitivity patterns of Taiwanese clinical A. pleuropneumoniae isolates, showing that serovars 15, 5, 1, 7, and 2 collectively predominate in clinical outbreaks. Local A. pleuropneumoniae isolates exhibited high resistance to antimicrobials currently used in the Taiwanese pig production, such as amoxicillin, ampicillin, and florfenicol. However, there was low resistance to cephalexin, cephalothin, tilmicosin and lincospectin (injectable only) which can be recommended for current use in Taiwan, considering both efficacy and public health risks. Notably, isolates of the same serovar collected from the same farm on the same day occasionally displayed distinct resistance patterns, emphasizing the complex dynamics of antimicrobial resistance. Our data will help veterinarians and producers refine vaccination and treatment protocols, highlighting the importance of ongoing surveillance to respond effectively to evolving resistance trends.

Porcine Parvovirus (PPV) is one of the most important infectious agents causing severe reproductive failure in pigs. In the last two decades a particular, a novel genotype emerged in Europe and PPV-27a was named as the prototype of this genetic cluster. It was suggested that members of the PPV-27a cluster may adversely influence effective vaccination against PPV. For a reliable updated 27a definition, we aligned 93 databank-deposited partial or full nucleotide and protein sequences of the VP2 of different PPV isolates. We confirmed that the 27a cluster could indeed be distinguished from other members of the species, however, some divergences were identified compared to earlier defined genetic markers. Based on genetic differences, we developed a dual allele-specific polymerase chain reaction for the easy and quick discrimination of members of the 27a cluster from other PPV strains. The detection limit of dual PCR was found <1.66 × 10⁴ copies/reaction. To sensitize and make it more user friendly, the method was further developed for qPCR application with fluorescent probes. Regarding the detection limit of the two PCRs (<1.66 × 10⁴ copies/reaction of the dual PCR versus <2.40 × 10² copy/reaction of the dual qPCR), approximately two log improvement was achieved in the sensitivity of the method.

Background: Actinobacillus pleuropneumoniae is a major economically significant bacterial respiratory pathogen of pigs, and vaccine use is considered an integral control method to prevent disease. The objective of this multi-study analysis was to evaluate the serovar independent efficacy in growing pigs of the C-vaccine (Coglapix®, Ceva, France), which comprises whole cells of A. pleuropneumoniae serovars 1 and 2 expressing ApxI, ApxII and ApxIII toxins. Efficacy was based on protection against lung lesions, since there is good correlation between the severity/extension of lung lesions and losses induced by pleuropneumonia. Vaccine efficacy was determined against challenge with the most common serovars (1, 2, 4, 5, 6, 7, 9/11 and 13) of A. pleuropneumoniae in a total of 13 studies of the same design and reproducibility was validated.Results: Protection against homologous serovars 1 and 2 significantly reduced lung lesion scores (LLS) compared to the positive controls: p = 0.00007 and p = 0.00124, respectively. The protection against heterologous serovars 4, 5, 6, 7, 9/11, and 13 also significantly reduced LLS: range p = 2.9e-10 to p = 0.00953. Reproducibility between challenge studies was excellent with the estimated random effect of study (the fraction of the total variation attributed by differences between studies) being only 2.6%, 2.2% and 4.8% for three serovar 2, two serovar 9/11 and serovar 4 challenge studies, respectively. An outlier was the 35% of variation attributable to trial between the two serovar 6 challenges, possibly explained by a Streptococcus spp. outbreak.Conclusions: A highly significant serovar independent reduction of pathological lung lesions by the C-vaccine was demonstrated for all the serovars tested (1, 2, 4, 5, 6, 7, 9/11 and 13). High levels of protection with similar significance-values were obtained for both homologous and heterologous serovar challenge. To our knowledge the aerosol chamber challenge concept based on accurate individual pig dosing and a standardized biologically weighted lung lesion scoring is the first to be validated statistically as reproducible and reliable. The C-vaccine was demonstrated to be a good candidate to fulfil the demands in the field for an A. pleuropneumoniae-vaccine i.e., high protective capability against disease caused by multiple serovars.