Field evaluation of the safety and compatibility of a combined vaccine against porcine parvovirus 1 and porcine reproductive and respiratory syndrome virus in breeding animals

Strategy of Developing Oral Vaccine Candidates Against Co-infection of Porcine Diarrhea Viruses Based on a Lactobacillus Delivery System

The number of co-infections with multiple porcine diarrhea viruses has increased in recent years. Inducing mucosal immunity through oral immunization is an effective approach for controlling these pathogens. To generate a multi-pathogen vaccine against viral co-infection, we employed the Lactobacillus vector platform, which was previously used to generate potent candidate vaccines against various diseases. Two strategies were used to test the protective efficiency of recombinant Lactobacillus against multiple diarrhea viruses. First, we used a mixture of recombinant Lactobacillus separately expressing antigens of transmissible gastroenteritis virus (TGEV), porcine epidemic diarrhea virus (PEDV), and porcine rotavirus (PoRV). Next, we used a recombinant Lactobacillus expressing an antigen fusion protein of the above viruses. Twenty-four newborn piglets were divided into three groups and orally immunized with a mixture of recombinant Lactobacillus, recombinant Lactobacillus expressing the antigen fusion protein, or sterile phosphate-buffered saline daily for seven consecutive days after birth. After immunization, the piglets were randomly selected from each group for oral administration of PEDV, and these piglets were then cohabited with piglets without PEDV infection for 7 days. The protective effect against PEDV was evaluated based on clinical symptoms, viral shedding, and intestinal pathological damage. Piglets immunized with recombinant Lactobacillus showed specific mucosal and humoral immune responses to the three viruses and were protected against severe diarrhea and intestinal pathology. Our results highlight the potential of an oral multi-pathogen vaccine based on Lactobacillus to prevent transmission and limit the severity of viral co-infection.

Efficacy of Simultaneous Intradermal Vaccination of Swine against Porcine Circovirus 2, Porcine Reproductive and Respiratory Syndrome Virus, Mycoplasma hyopneumoniae and Lawsonia intracellularis

The combined application of vaccines in swine offers many benefits, including reduced time and labour costs, and improved animal welfare, due to fewer injections and manipulations. This study investigated if simultaneous intradermal vaccinations against porcine circovirus 2, porcine reproductive and respiratory syndrome virus, Mycoplasma hyopneumoniae, and Lawsonia intracellularis, using a specialised needle-free applicator would confer comparable protection against experimental infection compared to the single vaccines. In all cases, the administration of the vaccines together was as efficacious as the administration of the vaccines alone, significantly reducing clinical signs associated with each of the four pathogens.

Effects of three commercial vaccines against porcine parvovirus 1 in pregnant gilts

Porcine parvovirosis is a common and important cause of reproductive failure in naïve dams. Even though vaccination is generally effective at preventing disease occurrence, the homology between the vaccine and challenge strains has been recently suggested to play a role in protection. Therefore, the purpose of this study was to evaluate and compare the efficacy of three currently available commercial vaccines against porcine parvovirus genotype 1 (PPV1) in an experimental model using pregnant gilts. Seventy-seven PPV1-negative gilts were included in the trial and randomly allocated to four groups. In group 1, gilts received two doses, three weeks apart, of a PPV1 subunit vaccine (ReproCyc® ParvoFLEX). Following the same scheme, gilts from group 2 received two doses of a PPV1 bivalent vaccine (ERYSENG® PARVO). In group 3, gilts received two doses, four weeks apart, of a PPV1 octavalent vaccine (Porcilis® Ery + Parvo + Lepto). Lastly, gilts from group 4 were left untreated and were used as challenge controls. All gilts were artificially inseminated three weeks after completion of vaccination. Pregnant animals were subsequently challenged around 40 days of gestation with a heterologous PPV1 strain. Foetuses were harvested at around day 90 of gestation and evaluated for their macroscopic appearance (i.e., normal, mummified, or autolytic). Along the study, safety parameters after vaccination, antibody responses against PPV1 and viremia in gilts were also measured. All the foetuses in the challenge control group were mummified, which validated the challenge model, whereas the three evaluated vaccines protected the progeny against PPV1 by preventing the appearance of clinical manifestations associated to parvovirosis. Remarkably, the PPV1 subunit vaccine induced an earlier seroconversion of gilts and was the only vaccine that could prevent viremia after challenge. This vaccine also achieved the largest average litter size accompanied with a high average proportion of clinically healthy foetuses.

Gilt Vaccination with a Mixed Administration of a PRRS MLV and a PPV1 Subunit Vaccine Protects against Heterologous PRRSV1 Infection and Prevents Detrimental Effects on Piglet Performance

The efficacy of the combined administration of a porcine reproductive and respiratory syndrome (PRRS) modified live virus (MLV) vaccine and a porcine parvovirus 1 (PPV1) subunit vaccine in gilts was addressed in two experiments. Experiment A aimed to establish a 4-week onset of immunity (OOI). Gilts were randomly distributed in three treatment groups: non-vaccinated control animals (group 1), animals vaccinated with the combined vaccine (group 2), and a third group that consisted of animals vaccinated with the PRRS MLV vaccine alone (group 3). Four weeks after the first vaccination, gilts were challenged with a heterologous PRRS virus 1 (PRRSV1) and euthanized three weeks after. Besides this, experiment B pursued a 17-week duration of immunity (DOI). In this case, gilts were distributed in the same treatment groups, but for the third group, which consisted of non-vaccinated, non-challenged animals were used instead. For the DOI assessment, gilts were artificially inseminated 4 weeks after the first vaccination, challenged at day 90 of gestation, and followed up, together with their offspring, until day 20 post-farrowing. Serology and viremia post-challenge were determined in gilts from both experiments, while farrowing and piglet performance were only evaluated in experiment B. Overall, the combined vaccine helped to protect gilts from viremia post-challenge and, consequently, to prevent PRRS clinical symptoms and diminish the proportion of piglets infected congenitally or early in life. The combined vaccine also elicited a significant improvement in piglet survival rate and growth performance until weaning. The present results reveal efficacy and lack of interference of the mixed use of the tested vaccines against PRRSV1 infection, with at least 4-week OOI and 17-week DOI.