The emergence and spread of highly pathogenic avian influenza virus A subtype H5N1 (HP H5N1-IAV), particularly clade H5N1 2.3.4.4b, pose a severe global health threat, affecting various species, including mammals. Historically, cattle have been considered less susceptible to IAV, but recent outbreaks of H5N1-IAV 2.3.4.4b in dairy farms suggest a shift in host tropism, underscoring the urgency of expanded surveillance and the need for adaptable diagnostic tools in outbreak management. This study investigated the presence of anti-nucleoprotein (NP) antibodies in serum and milk and viral RNA in milk on dairy farms affected by outbreaks in Texas, Kansas, and Michigan using a multi-species IAV ELISA and RT-qPCR. The analysis of ELISA results from a Michigan dairy farm outbreak demonstrated a positive correlation between paired serum and milk sample results, confirming the reliability of both specimen types. Our findings also revealed high diagnostic performance during the convalescent phase (up to 96%), further improving sensitivity through serial sampling. Additionally, the evaluation of diagnostic specificity using serum and milk samples from IAV-free farms showed an excellent performance (99.6%). This study underscores the efficacy of the IAV NP-blocking ELISA for detecting and monitoring H5N1-IAV 2.3.4.4b circulation in dairy farms, whose recent emergence raises significant animal welfare and zoonotic concerns, necessitating expanded surveillance efforts.

Atypical porcine pestivirus (APPV) was found to be associated with pigs demonstrating congenital tremors (CT), and clinical signs in pigs have been reproduced after experimental challenge. Subsequently, APPV has been identified in both symptomatic and asymptomatic swine of all ages globally. The objective of this research was to perform a longitudinal study following two cohorts of pigs, those born in litters with pigs exhibiting CT and those born in litters without CT, to analyze the virus and antibody dynamics of APPV infection in serum from birth to market. There was a wide range in the percentage of affected pigs (8–75%) within CT-positive litters. After co-mingling with CT-positive litters at weaning, pigs from CT-negative litters developed viremia that was cleared after approximately 2 months, with the majority seroconverting by the end of the study. In contrast, a greater percentage of pigs exhibiting CT remained PCR positive throughout the growing phase, with less than one-third of these animals seroconverting. APPV RNA was present in multiple tissues from pigs in both groups at the time of marketing. This study improved our understanding of the infection dynamics of APPV in swine and the impact that the immune status and timing of infection have on the persistence of APPV in serum and tissues.

Porcine deltacoronavirus (PDCoV), belonging to family Coronaviridae and genus Deltacoronavirus, is a major enteric pathogen in swine. Accurate PDCoV diagnosis relying on laboratory testing and antibody detection is an important approach. This study evaluated the potential of the receptor-binding subunit of the PDCoV spike protein (S1), generated using a mammalian expression system, for specific antibody detection via indirect enzyme-linked immunosorbent assay (ELISA). Serum samples were collected at day post-inoculation (DPI) −7 to 42, from pigs (n = 83) experimentally inoculated with different porcine coronaviruses (PorCoV). The diagnostic sensitivity of the PDCoV S1-based ELISA was evaluated using serum samples (n = 72) from PDCoV-inoculated animals. The diagnostic specificity and potential cross-reactivity of the assay was evaluated on PorCoV-negative samples (n = 345) and samples collected from pigs experimentally inoculated with other PorCoVs (n = 472). The overall diagnostic performance, time of detection, and detection rate over time varied across different S/P cut-offs, estimated by Receiver Operating Characteristic (ROC) curve analysis. The higher detection rate in the PDCoV group was observed after DPI 21. An S/P cut-off of 0.25 provided 100% specificity with no serological cross-reactivity against other PorCoV. These results support the use of S1 protein-based ELISA for accurate detection of PDCoV infections, transference of maternal antibodies, or active surveillance.

Porcine circovirus type 3 (PCV3) is an emerging circovirus detected worldwide in pigs with and without clinical disease, including reproductive and systemic disorders. However, baseline information on PCV3 exposure in Philippine swine populations remains limited. A cross-sectional serosurvey was conducted in selected provinces of Central Luzon, Philippines, from May to June 2025. A total of 337 serum samples from slaughter pigs were tested using an indirect enzyme-linked immunosorbent assay based on recombinant PCV3 open reading frame 2 (ORF2) capsid antigen. Samples with sample-to-positive (S/P) ratios ≥ 0.5 were classified as seropositive. Overall, 143 of 337 pigs were seropositive, corresponding to an apparent seroprevalence of 42.4% (95% confidence interval [CI]: 37.1–47.9%). Province-level apparent seroprevalence was 46.1% in Bulacan, 38.0% in Nueva Ecija, and 42.2% in Pampanga, with no significant difference among provinces (p = 0.470). However, seroprevalence differed significantly between slaughterhouses in Bulacan (66.1% in Malolos versus 27.3% in Meycauayan; p < 0.0001). These findings provide the first serological evidence of PCV3 exposure in slaughter pigs from selected provinces of Central Luzon. Because molecular testing was not performed, the results should be interpreted as evidence of an antibody response to PCV3 rather than confirmation of active infection. Expanded surveillance integrating serology, qPCR, sequencing, farm-level epidemiological data, and clinicopathological investigations is warranted.

Background/Objectives: Environmental enrichment (EE) devices are required in various countries and markets to promote animal welfare, with dual-purpose devices more likely to encourage adoption. We developed an EE device that allows pigs to self-administer liquids, designed to align with natural and play behaviors, and utilized a maternal pheromone (MP) to attract pigs to the device. This study aimed to evaluate the efficacy of this device in delivering vaccines for Erysipelas, Ileitis, Mycoplasma, and Influenza to growing pigs. Methods: Pigs were assigned to three treatments groups: Control (unvaccinated), Hand-Vaccinated (via oral gavage or intramuscular injection), and Self-Vaccinated using the EE device. Baseline samples were collected to determine initial antibody status, and serum and oral fluids’ IgG and IgA levels were measured post-vaccination to assess immune response. Four studies were conducted with 36 pigs (12 per treatment) over a 49-day period. Results: Self-vaccination pigs receiving the avirulent live Erysipelas vaccine developed oral and serum antibodies comparable to Hand-Vaccinated pigs. Pigs self-administering the avirulent live Lawsonia intracelluaris vaccine developed oral fluid antibodies. In contrast, pigs who received Mycoplasma or Influenza vaccines through self-vaccination exhibited significantly lower antibody levels compared to the Hand-Vaccinated group. Conclusions: These findings demonstrated that self-vaccination using EE devices for the oral administration of avirulent live vaccines offers benefits such as reduced labor and improved animal welfare. However, killed vaccines did not elicit sufficient antibody responses, suggesting the need for modified vaccine formulations or administration strategies to improve self-vaccination efficacy.

Atypical porcine pestivirus (APPV) is a pestivirus that infects swine and has been associated with congenital tremor (CT) in piglets in the field, as well as those born to experimentally infected sows. However, APPV has also been detected in swine of various ages without clinical signs. Experimental and field studies have demonstrated prolonged detection of viral RNA in serum, secretions, and tissues. For this work, nine gilts from a longitudinal APPV field study were selected based on birth in CT-positive litters and evidence of prolonged detection of virus in the sera. These six-month old animals were transported to a research facility for further sampling, breeding, and necropsy. The gilts were placed in contact with naïve animals for approximately one month at two different timepoints, prior to and during gestation, to assess transmission. After farrowing, litters were monitored for CT and tested for APPV. Following arrival, serum samples were PCR-negative for APPV; however, the gilts consistently tested positive in oral fluids and had detectable APPV in the cerebellum months later at necropsy. The gilts had a delayed humoral immune response, with the majority not seroconverting until approximately ten months of age. There were PCR-positive tissues and evidence of seroconversion in animals from both contact groups; however, none of the litters tested PCR-positive for APPV. These findings improve our understanding of the temporal dynamics and transmission potential of APPV infection and can help guide control measures to reduce viral spread.