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Background Gonadotropin‐releasing hormone (GnRH) plays a pivotal role in regulating the reproductive endocrine system. Objective An immunocontraception vaccine aimed at inhibiting the functions of GnRH is tested as a potential tool for controlling animal populations. Methods We developed a recombinant immunocontraceptive vaccine composed of GnRH‐I and GnRH‐II (GnRH I+II), which was conjugated with Salmonella typhimurium flagellin. Forty‐eight BALB/c mice aged 4 weeks were divided into four groups (each group had n = 12): non‐vaccinated male (NVM), non‐vaccinated female (NVF), vaccinated male (VM), and vaccinated female (VF). Mice in the vaccinated groups were vaccinated twice by intramuscular injection at 0 and 2 weeks with 300 μg of the recombinant GnRH protein complex per mouse. Mice in the non‐vaccinated groups were injected with saline and served as the unimmunized controls. Twenty‐four pairs of male and female mice were mated for 10–12 weeks after initial immunization in four groups: 6 NVF × 6 NVM, 6 VF × 6 NVM, 6 NVF × 6 VM, and 6 VF × 6 VM. Results: An increase (p < 0.001) in antibody titers in VM and VF mice was observed. The testosterone levels and the number of spermatocytes were lower (p < 0.001) in VM mice than those in the control mice. The progesterone levels and the number of corpora lutea were lower (p < 0.001) than those in the control mice. Mating results in both VM and VF mice confirmed a 60% reduction in pregnancy rates and offspring numbers. Conclusions The recombinant GnRH vaccine can be used for birth control in both male and female animals. We developed a new form of immunocontraceptive vaccine composed of GnRH‐I and ‐II complex conjugated with STF‐2. We provide the vaccine efficacies with higher anti‐GnRH antibodies in mice. The vaccine containing the GnRH‐I + II peptide linked to STF‐2 induced the suppression of fertility by inhibiting testicular and ovarian functions and reducing sex hormone levels in both male and female mice. In addition, the effects of fertility reduction were confirmed through mating experiments .

Here, rabbits were immunized with a virus-like particle (VLP) vaccine prepared by expressing 239 amino acids of the swine hepatitis E virus (HEV)-3 capsid protein using a baculovirus system. Thirty specific-pathogen-free rabbits were divided into five groups (negative and positive control and 10, 50, and 100 μg VLP-vaccinated). Positive control group rabbits showed viremia and fecal viral shedding, whereas rabbits vaccinated with 10 μg VLP showed transient fecal viral shedding, and rabbits vaccinated with 50 and 100 μg VLP did not show viremia or fecal viral shedding. Serum anti-HEV antibody titers increased in a dose-dependent manner. Anti-HEV antibody titers were significantly higher (p < 0.05) in 100 μg VLP-vaccinated rabbits than in the negative control rabbits at week 4. Anti-HEV antibody titers were significantly higher in 50 and 10 μg VLP-vaccinated rabbits than in the negative control rabbits at weeks 8 and 11, respectively. Serum IFN-γ and IL-12 levels were significantly higher (p < 0.01) in rabbits vaccinated with 50 and 100 μg VLP than in the negative control rabbits at weeks 4 and 6. Liver tissues of 50 and 100 μg VLP-vaccinated rabbits displayed significantly less (p < 0.05) fibrosis than those of the positive control rabbits. The prepared VLP vaccine demonstrated dose-dependent immunogenicity sufficient for inducing anti-HEV antibody production, thus protecting rabbits against swine HEV-3.

It is increasingly recognized that innate T cells such as natural killer T (NKT) cells, mucosal associated invariant T (MAIT) cells, and γδ T cells play an important role in shaping adaptive immune responses following influenza infection or vaccination. This is largely through the multiple cytokines these cells release upon activation, which have downstream effects on the scope and magnitude of virus-specific T and B cells, and antibodies which they form. Here, we examined the contribution of NKT cells using pigs, which are considered a highly translational model of human influenza A infection. CD1D -expressing and CD1D -deficient pigs that respectively possess and lack NKT cells, were infected with the swine influenza virus H3N2 A/Swine/Colorado/23619/1999 (CO99), with or without prior mucosal immunization with a recombinant H3N2 A/Swine/Texas/4199–2/1998 (TX98) modified live vaccine encoding a truncated NS1 protein (TX98 NS1Δ126). Vaccination reduced virus load and pulmonary pathology by similar amounts in both genotypes. However, NKT cell status had a significant impact on the underlying immune response: Contrary to the post vaccination period, virus-specific T cell expansion after infection was greater in CD1D -deficient than CD1D -expressing pigs, indicating that NKT cells play opposing roles in different phases of the immune response. NKT cell-deficient pigs also had reduced T cell cuffing around airways. Furthermore, paired single-cell and immune receptor profiling revealed altered gene expression and higher numbers of expanded T and B cell clones in the absence of NKT cells. Our newly established assay using porcine-specific γ and δ chain primers provided new insights into the TCR repertoire of various pulmonary γδ Τcell subsets. Overall, our results indicate a homeostatic role for NKT cells in regulating several important features of the influenza immune response, particularly virus-specific T cell dynamics.

The recent incursion of highly pathogenic influenza viruses into dairy cattle opens new insights for influenza virus ecology and its interspecies transmission and may have a significant impact on public health and agriculture. The aim of this study was to determine the stability of a bovine highly pathogenic avian influenza H5N1 virus isolate in the milk byproduct lactose and to evaluate two inactivation methods using industrial procedures. The bovine isolate of the highly pathogenic avian influenza H5N1 virus was stable for 14 days in a concentrated lactose solution under refrigerated conditions. Heat or citric acid treatments successfully inactivated the virus in lactose. This study highlights the persistence of HPAIV in lactose and its efficient inactivation under industrial standards.

Rapid evolution of highly pathogenic avian influenza viruses (HPAIVs) is driven by antigenic drift but also by reassortment, which might result in robust replication in and transmission to mammals. Recently, spillover of clade 2.3.4.4b HPAIV to mammals including humans, and their transmission between mammalian species has been reported. This study aimed to evaluate the pathogenicity and transmissibility of a mink-derived clade 2.3.4.4b H5N1 HPAIV isolate from Spain in pigs. Experimental infection caused interstitial pneumonia with necrotizing bronchiolitis with high titers of virus present in the lower respiratory tract and 100% seroconversion. Infected pigs shed limited amount of virus, and importantly, there was no transmission to contact pigs. Notably, critical mammalian-like adaptations such as PB2-E627 K and HA-Q222L emerged at low frequencies in principal-infected pigs. It is concluded that pigs are highly susceptible to infection with the mink-derived clade 2.3.4.4b H5N1 HPAIV and provide a favorable environment for HPAIV to acquire mammalian-like adaptations.

Geographical expansion and trans‐continental transmission of the African swine fever virus (ASFV) pose a significant risk to the global swine industry due to its high impact on swine health and agro‐economy. Several different modes of ASFV transmission make it difficult to predict and prevent ASFV introduction to the free area and its spread in the affected area. Indirect transmission through contaminated surfaces could be one of the possible routes to introduce ASFV to the United States due to its high resistance on environmental surfaces and the frequency of international movements. However, there is limited knowledge about environmental samples for ASFV surveillance, when compared to clinical samples from infected pigs. Therefore, the aim of this study was to develop methods for better detection of ASFV DNA in the presence of four different types of organic contaminants: soil, swine feces, feed dust, and their mixture. The presence of organic contaminants negatively affected the sensitivity of ASFV DNA detection. Centrifugation and filtration were crucial for ASFV detection in environmental samples with soil and mixture, whereas filtration reduced the sensitivity of ASFV DNA detection in samples from clean surfaces and swine feces‐ and feed dust‐contaminated surfaces. Detection of ASFV was significantly improved when sampled by the sponge stick with DNA/RNA shield when compared to the cost‐effective sampling strategy, the cotton gauze with phosphate‐buffered saline. These findings highlight the effect of organic contaminants and the use of the nucleic acid stabilization buffer on ASFV diagnostic performance and provide important background for ASFV preparedness.

Since the first emergence of highly pathogenic avian influenza (HPAI) H5N1 viruses in dairy cattle, the virus has continued to spread, reaching 17 states and at least 1000 dairy herds in the United States. Subsequently, spillovers of the virus from dairy cattle to humans have been reported. Pigs are an important host in influenza ecology because they serve as a mixing vessel in which novel reassortant viruses with pandemic potential can be generated. Here, we show that oro-respiratory infection of pigs resulted in productive replication of a bovine-derived HPAI H5N1 B3.13 virus. Infectious virus and viral antigen were mainly identified in the lower respiratory tract of principal infected pigs, and sero-conversion was observed in most of the principal pigs at later time points, suggesting replication of the bovine-derived HPAI H5N1 B3.13 virus in pigs. In one animal, we detected the emergence of a mutation in the hemagglutinin (HA) previously associated with increased affinity for \"mammalian-type\" α2,6-linked sialic acid receptors, but this mutation did not reach majority consensus levels. Sentinel contact pigs remained sero-negative throughout the study, indicating lack of transmission. These results support that pigs are susceptible to a bovine-derived HPAI H5N1 B3.13 virus, but this virus did not replicate as robustly in pigs as swine-adapted influenza viruses.

Influenza A virus (IAV) infection in pigs causes significant economic losses in the swine industry. More importantly, pigs serve as an intermediate host for generating reassortant viruses with pandemic potential. Previously, gene-edited pigs lacking the gene were generated and tested for susceptibility to IAV infection. Experimental infection of knockout pigs ( KO pigs) resulted in limited nasal shedding, posing the question about their ability to transmit IAV. Therefore, this study evaluated IAV transmission from principal-infected (donor) KO pigs to sentinel (recipient) KO and wild-type (WT) pigs. As expected, limited amounts of infectious virus were shed via the nasal cavity by the principal-infected KO pigs. After co-housing with principal-infected KO pigs at 2 days post-challenge, sentinel KO pigs remained uninfected until the end of observation period of 21 days as shown by the absence of infectious virus and seroconversion. In addition, there was significantly delayed transmission of IAV from principal-infected KO pigs to sentinel WT pigs when compared to WT-to-WT transmission. These results support a significant impairment of IAV transmission in KO pigs.

African swine fever (ASF) is a fatal viral disease of domestic and wild pigs, with mortality rates reaching up to 100%. In the absence of a safe and effective vaccine in non-endemic countries, it is imperative for the swine industry to implement enhanced biosecurity measures to control and prevent ASF outbreaks. Early detection is a key strategy to prevent the introduction of virus (ASFV) into naïve herds and confine the outbreak sites. Despite advanced modern technology for better diagnostics, knowledge regarding ASFV DNA detection in environmental samples is limited. Therefore, this study aimed to compare four DNA extraction methods for ASFV-contaminated feed and environmental samples: two magnetic bead-based extractions, one column-based PowerSoil Pro extraction, and one point-of-care M1 extraction. Three sets of samples were attained from our sample inventory saved from previous ASFV experiments: (1) surface samples contaminated with ASFV and different types of organic matter, (2) ASFV-contaminated feed and feed ingredients, and (3) feed mill surface samples collected during manufacturing of feed inoculated with ASFV. After DNA extraction, quantitative PCR was performed under identical conditions for all samples. ASFV DNA was detected by all four different extraction methods in the first two sets of sample collections. In these samples, significantly lower Cq values ( p  < 0.05) were detected in two magnetic bead-based extractions compared to the column-based PowerSoil Pro and point-of-care M1 extractions. Similarly, better DNA detection was observed using magnetic bead extractions in the feed mill surface samples. We conclude that all extraction methods evaluated in this study can be used for ASFV DNA detection in feed and environmental samples and higher sensitivity was observed using magnetic bead-based extraction which was also able to detect ASFV DNA in feed mill surface samples collected during manufacturing of ASFV-inoculated feed.

African swine fever is a devastating viral disease of swine causing up to 100% mortality and significant impacts to the swine industry. The causative agent, African swine fever virus (ASFV), is a large, enveloped virus containing a linear, double-stranded DNA genome with 170–190 kb in length. Since its introduction into the Caucasus region in 2007, the genotype II ASFV has continued to spread to Europe, Asia, and Caribbean countries. Early detection is crucial to prevent and control ASF outbreaks for biosecurity purposes, and environmental samples can be used to evaluate the level of biosecurity. Therefore, we evaluated the effect of freeze–thaw cycles and storage at 4°C and room temperature (RT) on ASFV DNA detection in environmental samples. ASFV DNA was stable in environmental samples with no organic contaminants after freeze–thaw and incubation at 4°C and RT. However, incubation at RT negatively affects ASFV detection in swine feces and feed dust samples that were collected using premoistened gauze. There were significant reductions in ASFV detection in environmental samples in the presence of soil and organic mixture after freeze–thaw and incubation at 4°C and RT. These results provide novel insights on the appropriate storage of environmental samples for ASFV detection and contribute to the control and prevention of ASF outbreaks and new introductions.