Salmonellosis remains a major medical and an unmet socioeconomic challenge. Worldwide, more than three million deaths per year are associated with Salmonella enterica serovar Enteritidis infections. Although commercially available vaccines for use in poultry exist, their efficacy is limited. We previously described a method for isolating a heat extract (HE) fraction of the cell surface of S. Enteritidis that contained major antigenic complexes immunogenic in hens naturally infected with the bacterium. One single dose of S. Enteritidis’ HE induced protection against lethal salmonellosis in mice. Furthermore, HE encapsulation in nanoparticles of the copolymer of methyl vinyl ether and maleic anhydride (PVM/MA), Gantrez AN, improved and prolonged the protection against the disease in mice. We formulated new preparations of Gantrez AN nanoparticles with HE S. Enteritidis and assessed their stability in drinking water and their efficacy in hens after experimental infection. The oral treatment of six-week-old hens with two doses of HE nanoparticles significantly reduced the Salmonella excretion in hens. Due to the effectiveness of the treatment in reducing bacterial excretion, we conclude that HE nanoencapsulation obtained from S. Enteritidis is a viable novel vaccination approach against salmonellosis in farms.

Salmonella enterica serovar Abortusovis (S. Abortusovis) infection is one of the most important causes of infectious late-term abortion as well as birth of weak lambs in sheep in many countries throughout the world. Implementation of protocols based on the application of effective vaccines is one of the most effective approaches for controlling this disease, but variable efficacy has been reported, possibly related to factors associated with the host, the vaccine, the parameters used for determining efficacy and the challenge protocols. In this context, a new commercial inactivated vaccine (INMEVA; Laboratorios Hipra S.A., Spain) was evaluated in 20 control and 17 vaccinated gestating ewes, subcutaneously challenged at 90 days of gestation with 5 × 106 colony-forming units (cfu) of a wild strain of S. Abortusovis. Incidence of reproductive failures, bacterial vaginal excretion (by real time PCR), and lamb survival were evaluated as indicators of the vaccine's level of protection. Moreover, humoral response (by ELISA test in serum samples) was studied. Vaccination was showed to be safe under the study conditions. Vaccine efficacy was demonstrated in two different ways: i) it significantly decreased the percentage of abortions [29.4% (5/17) in the vaccinated group compared to the control group (65%; 13/20)] and ii) there was a significant reduction of the overall vaginal excretion in the sampling period (3.05 log cfu/mL ± 0.84 in the vaccinated group vs. 5.68 ± 0.67 in the control group). Given these results, the vaccine evaluated can be considered as an effective alternative for controlling S. Abortusovis infection in ovine flocks.

Mycoplasma hyopneumoniae (Mhyo) and porcine circovirus type 2 (PCV2) infections cause enormous economic losses in the swine production sector. Vaccination remains the most effective strategy against the complex clinical entities caused by these pathogens. While effective vaccines against PCV2 are available, immunisation against Mhyo continues to be challenging. In parallel, intradermal (ID) vaccination can optimise time and costs while providing faster and user-safe administration. This study compares the safety and efficacy of commercial porcine vaccines against Mhyo and PCV2, including intramuscular (IM) and ID ones: (1) ID recombinant Mhyo-PCV2, (2) ID recombinant PCV2 + ID inactivated Mhyo, (3) IM bivalent inactivated Mhyo and recombinant PCV2, (4) IM bivalent inactivated Mhyo and inactivated chimeric PCV1-PCV2 and (5) IM inactivated Mhyo + IM inactivated PCV2. Safety, evaluated through clinical signs, adverse effects, local reactions, and average daily weight gain, has been confirmed for all vaccines. Following challenge with both pathogens, all products reduced PCV2 viremia and faecal shedding, proving efficacy against PCV2 infection. In contrast, only the ID recombinant Mhyo-PCV2 and the IM inactivated Mhyo + IM inactivated PCV2 vaccines, significantly reduced lung lesions related to Mhyo infection, indicating a better protection compared to the other vaccines.

Background/Objectives: Rabbit hemorrhagic disease (RHD) is an incurable, highly contagious disease caused by different RHD virus (RHDV) strains, such as the coexisting RHDV2 and classical RHDV. Disease control is based on vaccination using different or polyvalent vaccines. This study assessed the protective efficacy, onset of immunity (OOI), and duration of immunity (DOI) of a new recombinant vaccine containing a single active substance developed to target both strains: against RDHV2, highly virulent RDHV2 (hvRHDV2), and classical RDHV strains. Methods: This study included six randomized, controlled, blinded trials in clinically healthy New Zealand White rabbits. Rabbits were grouped to receive the recombinant vaccine or placebo (1:1 ratio) and challenged with RHDV2 (2¹⁵ hemagglutination [HA], infective dose; n = 39 for duration and n = 43 for onset), hvRHDV2 (2¹⁵ HA; n = 48 and n = 40), or classical RHDV (2¹² hemagglutination [HA], infective dose; n = 20 and n = 22) strains to evaluate OOI and DOI. Results: Rabbits receiving the vaccine showed a lower mortality than those receiving placebo upon challenge with any of the three strains. OOI trials showed that vaccinated rabbits exhibited higher levels of antibodies against RHDV2 than controls seven days post-vaccination. DOI trials revealed that, compared with controls, vaccinated rabbits had increased levels of antibodies against RHDV2 across all time points assessed, at least until the day of the viral challenge with any of the RHDV strains (approximately 12 months post-vaccination). Conclusions: This recombinant vaccine is the first to show a durable and robust protection against all tested strains, including the RHDV2, hvRHDV2, and classical RHDV strains, underscoring its potential as a comprehensive tool for RHD prevention.