Background/Objectives: Porcine reproductive and respiratory syndrome virus (PRRSV) remains one of the most economically significant pathogens in the global swine industry. Despite the availability of commercial vaccines for over three decades, they fail to induce sterile immunity and often provide inconsistent protection against heterologous PRRSV strains. This study aimed to predict vaccine immunogenicity by detecting strain-specific immune responses that related to an immune correlates of protection (COPs) against different PRRSV-2 strains. Methods: Post-weaning pigs were vaccinated with five commercially available PRRSV-2 vaccines or received sterile PBS injection as a control. At 28 days post-vaccination (dpv), all pigs were humanely euthanized for large-volume blood collection to isolate peripheral blood mononuclear cells (PBMCs) and plasma, establishing the immune bank. PBMCs and plasma from each group were then tested against six PRRSV-2 strains to evaluate immune responses. In addition, T cell epitope coverage between vaccine and field PRRSV-2 strains was assessed using the EpiCC (in silico) tool to enhance predictive capacity. Results: While neutralizing antibodies were undetectable in all vaccinated pigs at 28 dpv, PRRSV-specific IFN g –producing cells were detected at various levels in each vaccinated group following restimulation with different PRRSV-2 strains. Additionally, a positive correlation was observed for the EpiCC coverage of the N gene and mean IFN g responses to VR2332 (SLA class I and II) and NC24-6 (SLA class II). Conclusions: The PRRSV immune bank demonstrated potential as a tool for predicting vaccine immunogenicity against different PRRSV-2 strains and EpiCC provide additional information on T cell epitope cross conservation. The combined approach may provide a valuable framework for selecting PRRSV vaccines for more effective prevention and control in endemic areas.

Background/Objectives: Porcine reproductive and respiratory syndrome virus (PRRSV) remains one of the most economically significant pathogens in the global swine industry. Despite the availability of commercial vaccines for over three decades, they fail to induce sterile immunity and often provide inconsistent protection against heterologous PRRSV strains. This study aimed to predict vaccine immunogenicity by detecting strain-specific immune responses that related to an immune correlate of protection (CoP) against different PRRSV-2 strains. Methods: Post-weaning pigs were vaccinated with five commercially available PRRSV-2 vaccines or received sterile PBS injection as a control. At 28 days post-vaccination (dpv), all pigs were humanely euthanized for large-volume blood collection to isolate peripheral blood mononuclear cells (PBMCs) and plasma, establishing the immune bank. PBMCs and plasma from each group were then tested against six PRRSV-2 strains to evaluate immune responses. In addition, T cell epitope coverage between vaccine and field PRRSV-2 strains was assessed using the EpiCC (in silico) tool to enhance predictive capacity. Results: While neutralizing antibodies were undetectable in all vaccinated pigs at 28 dpv, PRRSV-specific IFNγ–producing cells were detected at various levels in each vaccinated group following restimulation with different PRRSV-2 strains. Additionally, a positive correlation was observed for the EpiCC coverage of the N gene and mean IFNγ responses to VR2332 (SLA class I and II) and NC24-6 (SLA class II). Conclusions: The PRRSV immune bank demonstrated potential as a tool for predicting vaccine immunogenicity against different PRRSV-2 strains and EpiCC provides additional information on T cell epitope cross conservation. The combined approach may provide a valuable framework for selecting PRRSV vaccines for more effective prevention and control in endemic areas.

Influenza A virus can cause severe complications in pregnant women and infants, yet no influenza vaccines are approved for infants younger than six months. To address this, novel maternal vaccination strategies are needed to increase global access and coverage in these vulnerable populations. This study evaluated a hemagglutinin (HA) A/California/2009 (H1N1)-based human adenovirus 5 (huAd5) vector vaccine, adjuvanted with a TLR3 agonist, for its ability to induce influenza-specific passive immunity from pregnant and lactating pigs to their piglets following different immunization routes. Influenza naïve pregnant dams were vaccinated via oral, intranasal (IN), or intramuscular (IM) routes three weeks prepartum and boosted four weeks later. Serum, colostrum and milk samples were collected longitudinally to assess HA-specific antibody induced by vaccination. H1N1-Ca/09 neutralizing antibodies were evaluated in serum and IFNγ producing cells were assessed in blood, spleen and lymph node cells. IN and IM routes elicited robust serum HA-specific antibody responses when compared to control animals at one- and four-weeks post-boost, whereas the oral route resulted in poor antibody induction across all samples tested. Piglets nursing from IN and IM vaccinated dams showed a significantly higher level of HA-specific antibodies in serum at 2-3 weeks post-partum compared to control piglets. Notably, IN immunized dams and their piglets showed significantly elevated influenza neutralizing antibodies compared to controls. This work demonstrated that both IN and IM immunization with a huAd5-vectored vaccine robustly induced maternal influenza-specific immunity that supported passive transfer to nursing piglets, with IN immunization resulting in superior transfer of neutralizing antibodies.

Selenium (Se) is an essential trace mineral with antioxidant and anti-inflammatory properties. Se deficiency increases oxidative stress and immunosuppression. In swine, dietary Se supplementation enhances immune function and growth, and previous studies suggest it protects immune cells during viral infection (i.e., Influenza virus, Coronavirus). Porcine reproductive and respiratory syndrome virus (PRRSV) causes severe respiratory and reproductive failure in swine, resulting in annual losses of 1.2 billion USD. Vaccine efficacy is hampered by the high mutation rate of the virus, requiring alternative approaches. This study examines the effects of organic (DL-Selenomethionine, L-Selenomethionine, yeast-selenium) and inorganic (sodium selenite) Se on PRRSV infection in vitro. Porcine alveolar macrophages, the primary target of PRRSV in the lung, were isolated from healthy animals and infected with PRRSV-2 with or without Se. Mitochondrial function, gene expression, oxidative stress, and viral load were assessed post-infection. DL-selenomethionine restored ATP production, suggesting improved mitochondrial function. We observed no antiviral activity against PRRSV after Se treatment. Immune gene expression analysis revealed infection-driven modulation, but Se treatment had no significant effect. While Se did not exhibit antiviral activity in vitro, its enhancement of mitochondrial function offers additional molecular insight supporting its potential immunomodulatory benefits observed in previous in vivo studies.

Selenium (Se) is a trace mineral with antioxidant and anti-inflammatory properties. Se deficiency increases oxidative stress and immunosuppression. In swine, dietary Se supplementation enhances immunity and growth, and previous studies suggest it protects immune cells during viral infection. Porcine reproductive and respiratory syndrome virus (PRRSV) causes severe respiratory and reproductive failure in swine, resulting in annual losses of 1.2 billion USD. Vaccine efficacy is hampered by the virus’s high mutation rate, requiring alternative approaches. This study examines the effects of organic (DL-Selenomethionine, L-Selenomethionine, yeast-selenium) and inorganic (sodium selenite) Se on PRRSV infection in vitro. Porcine alveolar macrophages, the primary target of PRRSV in the lung, were isolated from healthy animals and infected with PRRSV-2 with or without Se. Mitochondrial function, gene expression, oxidative stress, and viral load were assessed post-infection. DL-selenomethionine showed increased glycolytic and mitochondrial ATP production relative to other compounds, suggesting improved mitochondrial function. No antiviral activity against PRRSV was observed. Transcriptome analysis revealed infection-driven modulation, with upregulation of IL6, IL8, IL1B1, MX1, and TXNRD1, but Se had no significant effect. While Se did not exhibit antiviral activity in vitro, its enhancement of mitochondrial function offers additional insight supporting its potential immunomodulatory benefits observed in previous in vivo studies.