Artificial Insemination and Its Role in Transmission of Swine Viruses

1. Introduction Artificial insemination (AI) in swine is not a new technique and reports as early as the 1930s (Lush, 1925) describe collecting semen for AI. However, because of farm structure changes, increasing farm sizes and separation of production stages, interest in intensive pig production is growing and AI has become a critical component in modern pig production. In 2001, nearly 60% of North American swine herds utilized AI (Singleton, 2001), a drastic increase from the estimated 5% in the 1990’s (Flowers & Esbenshade, 1993). This is still relatively low compared to the 90% or greater use of AI in Western Europe (Madsen, 2005; Maes et al., 2008). The extensive use of AI in pig reproduction in the last decade has facilitated the exchange of desirable genetic characteristics at an international level, allowing producers to make greater use of superior genetics at a lower cost than some natural-service systems (Gerrits et al., 2005). However, the growth in use of AI has increased the risk of quick and widespread transmission of venereally transmissible pathogens (Thacker et al., 1984). It has been reported that the porcine male reproductive tract is highly susceptible to viral infections (Phillips et al., 1972; Spradbrow, 1968). This, coupled with the ability of boars to produce tens to thousands of insemination doses per week and the widespread distribution of the processed semen (both nationally and internationally), further increases the risk of wide transmission of viral pathogens by semen.This book chapter is published as Opriessnig T, Giménez-Lirola LG, Halbur PG. (2012). Artificial insemination and its role in transmission of swine viruses. In: Carlos C Perez-Marin (Ed), A Bird’s-Eye View of Veterinary Medicine, pp. 255-280. InTech, Croatia. ISBN 978-953-51-0031-7. DOI: 10.5772/17961. Copyright 2012 InTech. Attribution 3.0 International (CC BY 3.0). Posted with permission

Characterization of a novel porcine parvovirus tentatively designated PPV5

A new porcine parvovirus (PPV), provisionally designated as PPV5, was identified in U.S. pigs. Cloning and sequencing from a circular or head-to-tail concatemeric array revealed that the PPV5 possesses the typical genomic organization of parvoviruses with two major predicted open reading frames (ORF1 and ORF2), and is most closely related to PPV4 with overall genomic identities of 64.1-67.3%. The amino acid identities between PPV5 and PPV4 were 84.6%-85.1% for ORF1 and 54.0%-54.3% for ORF2. Unlike PPV4, but similar to bovine parvovirus 2 (BPV2), PPV5 lacks the additional ORF3 and has a much longer ORF2. Moreover, the amino acid sequences of ORF1 and ORF2 of BPV2 showed higher homologies to PPV5 than to PPV4. The conserved motifs of the Ca(2+) binding loop (YXGXG) and the catalytic center (HDXXY) of phospholipase A2 (PLA2) were identified in VP1 (ORF2) of PPV5, as well as in BPV2, but were not present in PPV4. Phylogenetic analyses revealed that PPV5, PPV4 and BPV2 form a separate clade different from the genera Parvovirus and Bocavirus. Further epidemiologic investigations of PPV4 and PPV5 in U.S. pigs of different ages indicated a slightly higher prevalence for PPV5 (6.6%; 32/483) compared to PPV4 (4.1%; 20/483), with detection of concurrent PPV4 and PPV5 in 15.6% (7/45) of lungs of infected pigs. Evidence for potential vertical transmission or association with reproductive failure was minimal for both PPV4 and PPV5. The high similarity to PPV4 and the lack of ORF3 may suggest PPV5 is an intermediate of PPV4 during the evolution of parvoviruses in pigs

Detection of pseudorabies virus antibody in swine oral fluid using a serum whole-virus indirect ELISA

We evaluated the detection of pseudorabies virus (PRV) antibodies in swine oral fluid. Oral fluid and serum samples were obtained from 40 pigs allocated to 4 treatment groups (10 pigs/group): negative control (NC); wild-type PRV inoculation (PRV 3CR Ossabaw; hereafter PRV); PRV vaccination (Ingelvac Aujeszky MLV; Boehringer Ingelheim; hereafter MLV); and PRV vaccination followed by PRV inoculation at 21 d post-vaccination (MLV-PRV). Using a serum PRV whole-virus indirect IgG ELISA (Idexx Laboratories) adapted to the oral fluid matrix, PRV antibody was detected in oral fluid samples from treatment groups PRV, MLV, and MLV-PRV in a pattern similar to serum. Vaccination alone produced a low oral fluid antibody response (groups MLV and MLV-PRV), but a strong anamnestic response was observed following challenge with wild-type virus (group PRV). Analyses of the oral fluid PRV indirect IgG ELISA results showed good binary diagnostic performance (area under ROC curve = 93%) and excellent assay repeatability (intra-class correlation coefficient = 99.3%). The demonstrable presence of PRV antibodies in swine oral fluids suggests the possible use of oral fluids in pseudorabies surveillance

Porcine Hemagglutinating Encephalomyelitis Virus: A Review

The porcine hemagglutinating encephalomyelitis virus (PHEV) is classified as a member of genus Betacoronavirus, family Coronaviridae, sub-family Cornavirinae, and order Nidovirales. PHEV shares the same genomic organization, replication strategy, and expression of viral proteins as other nidoviruses. PHEV produces vomiting and wasting disease (VWD) and/or encephalomyelitis, being the only known neurotropic coronavirus affecting pigs. First clinical outbreak was reported in 1957 in Ontario, Canada. Although pigs are the only species susceptible to natural PHEV infections, the virus displays neurotropism in mice and Wistar rats. Clinical disease, morbidity, and mortality is age-dependent and generally reported only in piglets under 4 weeks old. The primary site of replication of PHEV in pigs is the respiratory tract, and it can be further spread to the central nervous system through the peripheral nervous system via different pathways. The diagnosis of PHEV can be made using a combination of direct and indirect detection methods. The virus can be isolated from different tissues within the acute phase of the clinical signs using primary and secondary pig-derived cell lines. PHEV agglutinates the erythrocytes of mice, rats, chickens, and several other animals. PCR-based methods are useful to identify and subsequently isolate animals that are actively shedding the virus. The ability to detect antibodies allows producers to know the status of first-litter gilts and evaluate their risk of tier offspring to infection. PHEV is highly prevalent and circulates subclinically in most swine herds worldwide. PHEV-related disease is not clinically relevant in most of the swine-producing countries, most likely because of dams are immune to PHEV which may confer passive immunity to their offspring. However, PHEV should be considered a major source of economic loss because of the high mortality on farms with high gilt replacement rates, specific pathogen-free animals, and gnotobiotic swine herds. Thus, in the absence of current PHEV vaccines, promoting virus circulation on farms with early exposure to gilts and young sows could induce maternal immunity and prevent disease in piglets

The porcine circovirus 3 humoral response: characterization of maternally derived antibodies and dynamic following experimental infection

Since Porcine Circovirus 3 (PCV3) was first identified in 2016, our understanding of the humoral response is still relatively scarce. Current knowledge of the PCV3 humoral response is primarily based on field studies identifying the seroprevalence of PCV3 Cap-induced antibodies. Studies on the humoral response following experimental PCV3 infection have conflicting results where one study reports the development of the Cap IgG response 7 days postinfection with no concurrent Cap IgM response, while a second study shows a Cap IgM response at the same time point with no detection of Cap IgG. The dynamics of the PCV3 Cap and Rep IgG following maternal antibody transfer and experimental infection have not been well characterized. Additionally, the cross-reactivity of convalescent serum from PCV2 and PCV3 experimentally infected animals to serologic methods of the alternate PCV has limited evaluation. Here, we show that maternally derived antibodies were detectable in piglet serum 7–9 weeks postfarrowing for the Cap IgG and 5-weeks-post farrowing for the Rep IgG using Cap- and Rep-specific enzyme linked immunosorbent assays (ELISA) and immunofluorescent assays (IFA) methods. Following experimental inoculation, Cap IgG was detected at 2-weeks-post inoculation and Rep IgG detection was delayed until 4-weeks-post inoculation. Furthermore, convalescent serum from either PCV2 or PCV3 methods displayed no cross-reactivity by serological methods against the other PCV. The information gained in this study highlights the development of both the Cap- and Rep-specific antibodies following experimental infection and through the transfer of maternal antibodies. The increased understanding of the dynamics of maternal antibody transfer and development of the humoral response following infection gained in the present study may aid in the establishment of husbandry practices and potential application of prophylactics to control PCV3 clinical disease.This article is published as Kroeger, Molly, Gun Temeeyasen, Steven Dilberger-Lawson, Eric Nelson, Ronaldo Magtoto, Luis Gimenez-Lirola, and Pablo Piñeyro. "The porcine circovirus 3 humoral response: characterization of maternally derived antibodies and dynamic following experimental infection." Microbiology Spectrum (2024): e00870-24. doi: https://doi.org/10.1128/spectrum.00870-24. Copyright © 2024 Kroeger et al. This is an open-access article distributed under the terms of the Creative Commons Attribution 4.0 International license (https://creativecommons.org/licenses/by/4.0/)

Detection of porcine reproductive and respiratory syndrome virus (PRRSV)-specific IgM-IgA in oral fluid samples reveals PRRSV infection in the presence of maternal antibody

The ontogeny of PRRSV antibody in oral fluids has been described using isotype-specific ELISAs. Mirroring the serum response, IgM appears in oral fluid by 7 days post inoculation (DPI), IgA after 7 DPI, and IgG by 9 to 10 DPI. Commercial PRRSV ELISAs target the detection of IgG because the higher concentration of IgG relative to other isotypes provides the best diagnostic discrimination. Oral fluids are increasingly used for PRRSV surveillance in commercial herds, but in younger pigs, a positive ELISA result may be due either to maternal antibody or to antibody produced by the pigs in response to infection. To address this issue, a combined IgM-IgA PRRSV oral fluid ELISA was developed and evaluated for its capacity to detect pig-derived PRRSV antibody in the presence of maternal antibody. Two longitudinal studies were conducted. In Study 1 (modified-live PRRS vaccinated pigs), testing of individual pig oral fluid samples by isotype-specific ELISAs demonstrated that the combined IgM-IgA PRRSV ELISA provided better discrimination than individual IgM or IgA ELISAs. In Study 2 (field data), testing of pen-based oral fluid samples confirmed the findings in Study 1 and established that the IgM-IgA ELISA was able to detect antibody produced by pigs in response to wild-type PRRSV infection, despite the presence of maternal IgG. Overall, the combined PRRSV IgM-IgA oral fluid ELISA described in this study is a potential tool for PRRSV surveillance, particularly in populations of growing pigs originating from PRRSV-positive or vaccinated breeding herds

Detection of African Swine Fever Virus Antibodies in Serum and Oral Fluid Specimens Using a Recombinant Protein 30 (p30) Dual Matrix Indirect ELISA

In the absence of effective vaccine(s), control of African swine fever caused by African swine fever virus (ASFV) must be based on early, efficient, cost-effective detection and strict control and elimination strategies. For this purpose, we developed an indirect ELISA capable of detecting ASFV antibodies in either serum or oral fluid specimens. The recombinant protein used in the ELISA was selected by comparing the early serum antibody response of ASFV-infected pigs (NHV-p68 isolate) to three major recombinant polypeptides (p30, p54, p72) using a multiplex fluorescent microbead-based immunoassay (FMIA). Non-hazardous (non-infectious) antibody-positive serum for use as plate positive controls and for the calculation of sample-to-positive (S:P) ratios was produced by inoculating pigs with a replicon particle (RP) vaccine expressing the ASFV p30 gene. The optimized ELISA detected anti-p30 antibodies in serum and/or oral fluid samples from pigs inoculated with ASFV under experimental conditions beginning 8 to 12 days post inoculation. Tests on serum (n = 200) and oral fluid (n = 200) field samples from an ASFV-free population demonstrated that the assay was highly diagnostically specific. The convenience and diagnostic utility of oral fluid sampling combined with the flexibility to test either serum or oral fluid on the same platform suggests that this assay will be highly useful under the conditions for which OIE recommends ASFV antibody surveillance, i.e., in ASFV-endemic areas and for the detection of infections with ASFV isolates of low virulence

How do deer respiratory epithelial cells weather the initial storm of SARS-CoV-2 WA1/2020 strain?

The potential infectivity of severe acute respiratory syndrome associated coronavirus-2 (SARS-CoV-2) in animals raises a public health and economic concern, particularly the high susceptibility of white-tailed deer (WTD) to SARS-CoV-2. The disparity in the disease outcome between humans and WTD is very intriguing, as the latter are often asymptomatic, subclinical carriers of SARS-CoV-2. To date, no studies have evaluated the innate immune factors responsible for the contrasting SARS-CoV-2-associated disease outcomes in these mammalian species. A comparative transcriptomic analysis in primary respiratory epithelial cells of human (HRECs) and WTD (Deer-RECs) infected with the SARS-CoV-2 WA1/2020 strain was assessed throughout 48 h post inoculation (hpi). Both HRECs and Deer-RECs were susceptible to virus infection, with significantly (P < 0.001) lower virus replication in Deer-RECs. The number of differentially expressed genes (DEG) gradually increased in Deer-RECs but decreased in HRECs throughout the infection. The ingenuity pathway analysis of DEGs further identified that genes commonly altered during SARS-CoV-2 infection mainly belong to cytokine and chemokine response pathways mediated via interleukin-17 (IL-17) and nuclear factor-κB (NF-κB) signaling pathways. Inhibition of the NF-κB signaling in the Deer-RECs pathway was predicted as early as 6 hpi. The findings from this study could explain the lack of clinical signs reported in WTD in response to SARS-CoV-2 infection as opposed to the severe clinical outcomes reported in humans.This article is published as Sarlo Davila, Kaitlyn M., Rahul K. Nelli, Kruttika S. Phadke, Rachel M. Ruden, Yongming Sang, Bryan H. Bellaire, Luis G. Gimenez-Lirola, and Laura C. Miller. "How do deer respiratory epithelial cells weather the initial storm of SARS-CoV-2 WA1/2020 strain?." Microbiology Spectrum (2024): e02524-23. doi: https://doi.org/10.1128/spectrum.02524-23. Copyright © 2024 Sarlo Davila et al. This is an open-access article distributed under the terms of the Creative Commons Attribution 4.0 International license

Differential antigenicity of individual Mycoplasma hyorhinis variable lipoproteins

The Mycoplasma hyorhinis (Mhr) variable lipoprotein (Vlp) family, comprising Vlps A, B, C, D, E, F, and G, are highly variable in expression, size, and cytoadhesion capabilities across Mhr strains. The ‘Vlp system’ plays a crucial role in cytoadhesion, immune evasion, and in eliciting a host immunologic response. This pilot study described the development of Vlp peptide-based ELISAs to evaluate the antigenic reactivity of individual Vlps against Mhr antisera collected throughout a longitudinal study focused on Mhr strain 38983, reproducing Mhr-associated disease under experimental conditions. Specifically, serum samples were collected at day post-inoculation 0, 7, 10, 14, 17, 21, 24, 28, 35, 42, 49, and 56 from Mhr- and mock (Friis medium)-inoculated cesarean-derived, colostrum-deprived pigs. Significant Mhr-specific IgG responses were detected at specific time points throughout the infection, with some variations for each Vlp. Overall, individual Vlp ELISAs showed consistently high accuracy rates, except for VlpD, which would likely be associated with its expression levels or the anti-Vlp humoral immune response specific to the Mhr strain used in this study. This study provides the basis and tools for a more refined understanding of these Vlp- and Mhr strain-specific variations, which is foundational in understanding the host immune response to Mhr.This article is published as Magtoto, P.D., Arruda, B.L., Magtoto, R.L., Mora-Díaz, J.C., Opulencia, R.B., Baum, D.H., Zimmerman, J.J. and Giménez-Lirola, L.G., 2024. Differential antigenicity of individual Mycoplasma hyorhinis variable lipoproteins. Veterinary Immunology and Immunopathology, p.110768. doi: https://doi.org/10.1016/j.vetimm.2024.110768. Works produced by employees of the U.S. Government as part of their official duties are not copyrighted within the U.S. The content of this document is not copyrighted