Antimicrobial resistance (AMR) is a significant global health concern, and the use of antibiotics in livestock, including swine production, is a major contributor. Vaccines offer a promising alternative for controlling bacterial infections in pigs, but their widespread use is often hindered by biological, economic, and practical challenges. This study surveyed U.S. swine veterinarians to identify which bacterial diseases require better vaccines and to understand the barriers to their adoption. Nineteen veterinarians with an average of 24.7 years of experience were surveyed across 21 states. The results identified Streptococcus suis, Escherichia coli, Mycoplasma hyopneumoniae, and Glaesserella parasuis as the most critical pathogens needing improved vaccines. Veterinarians anticipated significant improvements in vaccine efficacy for S. suis and E. coli during the nursery stage and expressed a willingness to pay 1.8 and 1.9 times their current prices, respectively. While expectations for M. hyo vaccine improvements were not significant, veterinarians expressed the highest willingness to pay (4.2 times the current price), citing the potential for disease eradication. This research highlights that developing effective vaccines for S. suis and E. coli should be the most urgent priority due to their significant economic impact and rising AMR concerns. However, M. hyo vaccine development holds the most economic potential due to the possibility of eradication. Our research provides a roadmap for future efforts to combat AMR in the swine industry, emphasizing key economic, policy, and educational considerations for successful vaccine implementation.

Antimicrobial resistance (AMR) is an increasing concern in food animal production. In swine herds, viral infections often lead to secondary bacterial disease and higher antimicrobial use (AMU). This study describes how U.S. swine veterinarians view the role of viral vaccines in reducing this reliance on antimicrobials. We conducted a national survey of swine practitioners and follow-up semi-structured interviews with a subset of respondents. Across participants, porcine reproductive and respiratory syndrome (PRRS), swine influenza (SIV), and rotaviral enteritis were most often named as viral diseases in urgent need of improved vaccines. These diseases cause substantial economic losses and frequently trigger AMU in commercial herds. Veterinarians reported several recurring challenges with current vaccines, including limited cross-protection against field strains, interference from maternally derived antibodies, and short duration of protection. Despite these limitations, most respondents supported vaccination as a key tool to curb AMU and indicated they would accept higher prices for clearly improved products. These findings reveal both a clear need and specific opportunities for future vaccine development to provide broader and more reliable protection, reduce AMU, and help slow the development of AMR.

African swine fever (ASF), a highly contagious and lethal viral disease, continues to devastate the global swine industry. The emergence of ASF virus (ASFV) variants with varying genomic deletions poses significant challenges to ASF control. This study presents a novel, sensitive, and reliable quadplex real-time PCR assay for detecting ASFV variants lacking key genes (I177L, EP402R, and MGF360-14L), either individually or in combination. The assay targets conserved regions within these genes, ensuring broad coverage of diverse ASFV genotypes. A porcine beta-actin (ACTB) internal control was incorporated to minimize false-negative results. Optimization and evaluation using spike-in tests demonstrated high sensitivity with a limit of detection (LOD) ranging from 1-10 plasmid copies or 0.1 TCID₅₀ of ASFV isolates per reaction. No cross-reactivity was observed when testing serum samples from pigs infected with other common swine viruses. Further validation across a diverse panel of samples, comprising those from naturally ASFV-infected field pigs (n=54), experimentally ASFV-infected pigs (n=50), PBS-inoculated pigs (n=50), ASFV-free field pigs (n=100), and feral pigs (n=6), confirmed 100% specificity. This robust assay provides a valuable tool for rapid and accurate ASF surveillance and control efforts, facilitating the timely detection and mitigation of outbreaks caused by emerging ASFV variants.

Antimicrobial resistance (AMR) is a growing global threat driven by the overuse of antibiotics, especially in livestock. In the swine industry, viral diseases often lead to secondary bacterial infections, which increases the need for widespread antimicrobial use (AMU). This study explores the views of U.S. swine veterinarians on using viral vaccines as a way to reduce reliance on antimicrobials. Through a combination of surveys and interviews, our findings found an urgent need for better vaccines for por-cine reproductive and respiratory syndrome, swine influenza, and rotaviral enteritis. These swine diseases cause major economic losses and are a primary reason for AMU. Veterinarians identified several challenges with existing vaccines, including poor cross-protection against different strains, safety concerns, and issues with cost and availability. Despite these limitations, the study found that veterinarians are willing to invest more in improved vaccines, highlighting a strong demand for more effective tools to reduce antimicrobial use. This research identifies key opportunities for future vaccine development and veterinary strategies to create more effective approaches that protect both animal and public health.

African swine fever (ASF) is a highly contagious and often fatal disease of swine that causes substantial economic losses worldwide. Despite extensive efforts, the lack of safe and effective vaccines remains a major obstacle to ASF control. We previously de-veloped a cell-adapted live-attenuated virus (LAV) vaccine candidate, VNUA-ASFV-LAV2, through serial passage of a highly virulent genotype II ASF virus (ASFV) in cell culture. VNUA-ASFV-LAV2 demonstrated favorable safety and protec-tive efficacy against contemporary pandemic genotype II ASFV. In this study, we sys-tematically evaluated antibody responses in pigs immunized with VNUA-ASFV-LAV2. Fourteen indirect ELISAs were developed using ASFV structural, nonstructural, and previously uncharacterized proteins associated with the viral outer envelope, capsid, inner envelope, and replication functions. Serum samples collected from vaccinated and challenged pigs were used to assess the performance of these assays. The results de-monetarized that p17-, p22-, p30-, pE199L-, and pB602L-based ELISAs have strong po-tential for monitoring antibody responses in pigs vaccinated with VNUA-ASFV-LAV2. Among these assays, p22- and p30-based ELISAs enabled early detection of ASFV-specific antibodies in both vaccinated (as early as 7-14 days post vaccination) and wild-type ASFV infected pigs (17 days post infection). Notably, the pF317L-based ELISA successfully differentiated wild-type ASFV-infected pigs from VNUA-ASFV-LAV2-vaccinated pigs, demonstrating its potential as a DIVA-compatible diagnostic assay. These findings provide the first comprehensive analysis of humoral immune responses elicited by VNUA-ASFV-LAV2 in pigs and identify promising se-rological targets for vaccine monitoring and DIVA-based surveillance, supporting the future field application and commercialization of this vaccine candidate.

African swine fever (ASF) is a highly contagious and often fatal disease of swine that causes substantial economic losses worldwide. Despite extensive efforts, the lack of safe and effective vaccines remains a major obstacle to ASF control. We previously developed a cell-adapted live-attenuated virus (LAV) vaccine candidate, VNUA-ASFV-LAV2, through serial passage of a highly virulent genotype II ASF virus (ASFV) in cell culture. VNUA-ASFV-LAV2 demonstrated favorable safety and protective efficacy against contemporary epidemic genotype II ASFV. In this study, we systematically evaluated antibody responses in pigs immunized with VNUA-ASFV-LAV2. Fourteen indirect ELISAs were developed using ASFV structural, nonstructural, and previously uncharacterized proteins associated with the viral outer envelope, capsid, inner envelope, and replication functions. Serum samples collected from vaccinated and challenged pigs were used to assess the performance of these assays. The results demonstrated that p17-, p22-, p30-, pE199L-, and pB602L-based ELISAs have strong potential for monitoring antibody responses in pigs vaccinated with VNUA-ASFV-LAV2. Among these assays, p22- and p30-based ELISAs enabled early detection of ASFV-specific antibodies in both vaccinated (as early as 7–14 days post vaccination) and wild-type ASFV-infected pigs (17 days post infection). Notably, the pF317L-based ELISA showed potential to differentiate wild-type ASFV-infected pigs from VNUA-ASFV-LAV2-vaccinated pigs. Further diagnostic validation using larger, independently characterized serum panels representing diverse ASFV strains, vaccination statuses, and epidemiological settings is needed to establish its sensitivity, specificity, reproducibility, and diagnostic accuracy. These findings provide the first comprehensive analysis of humoral immune responses elicited by VNUA-ASFV-LAV2 in pigs and identify potential serological markers for vaccine monitoring and DIVA surveillance, supporting future field applications and commercialization of this vaccine candidate.