Publications by authors named "Megan C Niederwerder"

34 Publications

Zn-based physiometacomposite nanoparticles: distribution, tolerance, imaging, and antiviral and anticancer activity.

Nanomedicine (Lond) 2021 Jul 20. Epub 2021 Jul 20.

Department of Anatomy & Physiology, College of Veterinary Medicine, Kansas State University, Manhattan, KS 66506, USA.

The aim of this study was to investigate the distribution, tolerance, and anticancer and antiviral activity of Zn-based physiometacomposites (PMCs). Manganese, iron, nickel and cobalt-doped ZnO, ZnS or ZnSe were synthesized. Cell uptake, distribution into 3D culture and mice, and biochemical and chemotherapeutic activity were studied by fluorescence/bioluminescence, confocal microscopy, flow cytometry, viability, antitumor and virus titer assays. Luminescence and inductively coupled plasma mass spectrometry analysis showed that nanoparticle distribution was liver >spleen >kidney >lung >brain, without tissue or blood pathology. Photophysical characterization as tissue probes and LL37 peptide, antisense oligomer or aptamer delivery targeting RAS/Ras binding domain (RBD) was investigated. Treatment at 25 μg/ml for 48 h showed ≥98-99% cell viability, 3D organoid uptake, 3-log inhibition of β-Galactosidase and porcine reproductive respiratory virus infection. Data support the preclinical development of PMCs for imaging and delivery targeting cancer and infectious disease.
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http://dx.doi.org/10.2217/nnm-2021-0179DOI Listing
July 2021

The risk and mitigation of foot-and-mouth disease virus infection of pigs through consumption of contaminated feed.

Transbound Emerg Dis 2021 Jul 8. Epub 2021 Jul 8.

Foreign Animal Disease Research Unit, Agricultural Research Service, U.S. Department of Agriculture, Plum Island Animal Disease Center, Greenport, New York, USA.

Transboundary movement of animal feed and feed ingredients has been identified as a route for pathogen incursions. While imports of animals and animal-derived products are highly regulated for the purpose of infectious disease prevention, there has been less consideration of the viability of infectious agents in inanimate products, such as feed. This study investigated the ability of foot-and-mouth disease virus (FMDV) to remain infectious as a contaminant of commercial whole pig feed and select pig feed ingredients, and to establish the minimum infectious dose (MID ) required to cause foot-and-mouth disease (FMD) in pigs that consumed contaminated feed. FMDV viability in vitro varied depending on virus strain, feed product, and storage temperature, with increased duration of infectivity in soybean meal compared to pelleted whole feed. Specifically, both strains of FMDV evaluated remained viable through to the end of the 37 day observation period in experimentally contaminated soybean meal stored at 4 or 20°C . The MID for pigs consuming contaminated feed varied across virus strains and exposure duration in the range of 10 to 10 TCID . The ability of FMDV to cause infection in exposed pigs was mitigated by pre-treatment of feed with two commercially available feed additives, based on either formaldehyde (SalCURB®) or lactic acid (Guardian™). Our findings demonstrate that FMDV may remain infectious in pig feed ingredients for durations compatible with transoceanic transport. Although the observed MID was relatively high, variations in feeding conditions and biophysical characteristics of different virus strains may alter the probability of infection. These findings may be used to parameterize modelling of the risk of FMDV incursions and to regulate feed importation to minimize the risk of inadvertent importation.
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http://dx.doi.org/10.1111/tbed.14230DOI Listing
July 2021

Detection of African swine fever virus in feed dust collected from experimentally inoculated complete feed using quantitative PCR and virus titration assays.

Transbound Emerg Dis 2021 Jun 15. Epub 2021 Jun 15.

Department of Diagnostic Medicine/Pathobiology, College of Veterinary Medicine, Kansas State University, Manhattan, Kansas, USA.

African swine fever virus (ASFV) is a current threat to global pork production due to its high case fatality rate, lack of efficacious vaccine and recent transboundary spread into new regions of the world. Preventing introduction and further spread of ASFV is critical for countries currently negative for the virus. ASFV is stable in feed ingredients subjected to transoceanic conditions and transmission occurs through the natural consumption of contaminated feed. In this study, we investigated the use of feed dust collected from experimentally inoculated feed as a novel diagnostic sample type for ASFV detection. Moist swabs were used to collect dust from creep feeders after natural consumption of feed inoculated with 3.1-5.4 log TCID /g ASFV Georgia 2007 in the presence and absence of antimicrobial feed additives. Results validate the potential use of feed dust swabs as a novel diagnostic surveillance tool for detection and quantification of viral nucleic acid and infectious virus titre in ASFV-contaminated feed.
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http://dx.doi.org/10.1111/tbed.14176DOI Listing
June 2021

Risk and Mitigation of African Swine Fever Virus in Feed.

Animals (Basel) 2021 Mar 18;11(3). Epub 2021 Mar 18.

Department of Diagnostic Medicine/Pathobiology, College of Veterinary Medicine, Kansas State University, 1800 Denison Avenue, Manhattan, KS 66506, USA.

Since the 2013 introduction of porcine epidemic diarrhea virus into the United States (U.S.), feed and feed ingredients have been recognized as potential routes for the introduction and transmission of foreign animal diseases of swine. Feed ingredients for swine diets are commodities traded worldwide, and the U.S. imports thousands of metric tons of feed ingredients each year from countries with circulating foreign animal diseases. African swine fever (ASF) is the most significant foreign animal disease threat to U.S. swine production, and the recent introduction of ASF into historically negative countries has heightened the risk for further spread. Laboratory investigations have characterized the stability of the ASF virus (ASFV) in feed ingredients subjected to transoceanic shipment conditions, ASFV transmissibility through the natural consumption of plant-based feed, and the mitigation potential of certain feed additives to inactivate ASFV in feed. This review describes the current knowledge of feed as a risk for swine viruses and the opportunities for mitigating the risk to protect U.S. pork production and the global swine population from ASF and other foreign animal diseases.
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http://dx.doi.org/10.3390/ani11030792DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7998236PMC
March 2021

Genomics of response to porcine reproductive and respiratory syndrome virus in purebred and crossbred sows: antibody response and performance following natural infection vs. vaccination.

J Anim Sci 2021 May;99(5)

Department of Animal Science, Iowa State University, Ames, IA 50011, USA.

Antibody response, measured as sample-to-positive (S/P) ratio, to porcine reproductive and respiratory syndrome virus (PRRSV) following a PRRSV-outbreak (S/POutbreak) in a purebred nucleus and following a PRRSV-vaccination (S/PVx) in commercial crossbred herds have been proposed as genetic indicator traits for improved reproductive performance in PRRSV-infected purebred and PRRSV-vaccinated crossbred sows, respectively. In this study, we investigated the genetic relationships of S/POutbreak and S/PVx with performance at the commercial (vaccinated crossbred sows) and nucleus level (non-infected and PRRSV-infected purebred sows), respectively, and tested the effect of previously identified SNP for these indicator traits. Antibody response was measured on 541 Landrace sows ~54 d after the start of a PRRSV outbreak, and on 906 F1 (Landrace × Large White) gilts ~50 d after vaccination with a commercial PRRSV vaccine. Reproductive performance was recorded for 711 and 428 Landrace sows before and during the PRRSV outbreak, respectively, and for 811 vaccinated F1 animals. The estimate of the genetic correlation (rg) of S/POutbreak with S/PVx was 0.72 ± 0.18. The estimates of rg of S/POutbreak with reproductive performance in vaccinated crossbred sows were low to moderate, ranging from 0.05 ± 0.23 to 0.30 ± 0.20. The estimate of rg of S/PVx with reproductive performance in non-infected purebred sows was moderate and favorable with number born alive (0.50 ± 0.23) but low (0 ± 0.23 to -0.11 ± 0.23) with piglet mortality traits. The estimates of rg of S/PVx were moderate and negative (-0.38 ± 0.21) with number of mummies in PRRSV-infected purebred sows and low with other traits (-0.30 ± 0.18 to 0.05 ± 0.18). Several significant associations (P0 > 0.90) of previously reported SNP for S/P ratio (ASGA0032063 and H3GA0020505) were identified for S/P ratio and performance in non-infected purebred and PRRSV-exposed purebred and crossbred sows. Genomic regions harboring the major histocompatibility complex class II region significantly contributed to the genetic correlation of antibody response to PRRSV with most of the traits analyzed. These results indicate that selection for antibody response in purebred sows following a PRRSV outbreak in the nucleus and for antibody response to PRRSV vaccination measured in commercial crossbred sows are expected to increase litter size in purebred and commercial sows.
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http://dx.doi.org/10.1093/jas/skab097DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8118356PMC
May 2021

Gut microbiome associations with outcome following co-infection with porcine reproductive and respiratory syndrome virus (PRRSV) and porcine circovirus type 2 (PCV2) in pigs immunized with a PRRS modified live virus vaccine.

Vet Microbiol 2021 Mar 16;254:109018. Epub 2021 Feb 16.

Department of Diagnostic Medicine/Pathobiology, College of Veterinary Medicine, Kansas State University, 1800 Denison Avenue, Manhattan, Kansas 66506, United States. Electronic address:

Porcine reproductive and respiratory syndrome virus (PRRSV) and porcine circovirus type 2 (PCV2) are two of the most significant pathogens affecting swine. Co-infections are common and result in respiratory disease and reduced weight gain in growing pigs. Although PRRS modified live virus (MLV) vaccines are widely used to decrease PRRS-associated losses, they are generally considered inadequate for disease control. The gut microbiome provides an alternative strategy to enhance vaccine efficacy and improve PRRS control. The objective of this study was to identify gut microbiome characteristics associated with improved outcome in pigs immunized with a PRRS MLV and co-challenged with PRRSV and PCV2b. Twenty-eight days after vaccination and prior to co-challenge, fecal samples were collected from an experimental population of 50 nursery pigs. At 42 days post-challenge, 20 pigs were retrospectively identified as having high or low growth outcomes during the post-challenge period. Gut microbiomes of the two outcome groups were compared using the Lawrence Livermore Microbial Detection Array (LLMDA) and 16S rDNA sequencing. High growth outcomes were associated with several gut microbiome characteristics, such as increased bacterial diversity, increased Bacteroides pectinophilus, decreased Mycoplasmataceae species diversity, higher Firmicutes:Bacteroidetes ratios, increased relative abundance of the phylum Spirochaetes, reduced relative abundance of the family Lachnospiraceae, and increased Lachnospiraceae species C6A11 and P6B14. Overall, this study identifies gut microbiomes associated with improved outcomes in PRRS vaccinated pigs following a polymicrobial respiratory challenge and provides evidence towards the gut microbiome playing a role in PRRS vaccine efficacy.
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http://dx.doi.org/10.1016/j.vetmic.2021.109018DOI Listing
March 2021

Quantification of soya-based feed ingredient entry from ASFV-positive countries to the United States by ocean freight shipping and associated seaports.

Transbound Emerg Dis 2021 Jul 30;68(4):2603-2609. Epub 2020 Oct 30.

Pipestone Applied Research, Pipestone Veterinary Services, Pipestone, MN, USA.

African swine fever virus (ASFV) can survive in soya-based products for 30 days with T ½ ranging from 9.6 to 12.9 days in soya bean meals and soya oil cake. As the United States imports soya-based products from several ASFV-positive countries, knowledge of the type and quantity of these specific imports, and their ports of entry (POE), is necessary information to manage risk. Using the data from the International Trade Commission Harmonized Tariff Schedule website in conjunction with pivot tables, we analysed imports across air, land and sea POE of soya-based products from 43 ASFV-positive countries to the United States during 2018 and 2019. In 2018, 104,366 metric tons (MT) of soya-based products, specifically conventional and organic soya bean meal, soya beans, soya oil cake and soya oil were imported from these countries into the United States via seaports only. The two largest suppliers were China (52.7%, 55,034 MT) and the Ukraine (42.9%, 44,775 MT). In 2019, 73,331 MT entered the United States and 54.7% (40,143 MT) came from the Ukraine and 8.4% (6,182 MT) from China. Regarding POE, 80.9%-83.2% of soya-based imports from China entered the United States at the seaports of San Francisco, CA, and Seattle, WA, while 89.4%-100% entered from the Ukraine via the seaports of New Orleans, LA, and Charlotte, NC. Analysis of five-year trends (2015-2019) of the volume of soya imports from China indicated reduction over time (with a noticeably sharp decrease between 2018 and 2019), and seaport utilization was consistent. In contrast, volume remained high for Ukrainian soya imports, and seaport utilization was inconsistent. Overall, this exercise introduced a new approach to collect objective data on an important risk factor, providing researchers, government officials and industry stakeholders a means to objectively identify and quantify potential channels of foreign animal disease entry into the United States.
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http://dx.doi.org/10.1111/tbed.13881DOI Listing
July 2021

Genetic Analysis of Antibody Response to Porcine Reproductive and Respiratory Syndrome Vaccination as an Indicator Trait for Reproductive Performance in Commercial Sows.

Front Genet 2020 11;11:1011. Epub 2020 Sep 11.

Department of Animal Science, Iowa State University, Ames, IA, United States.

We proposed to investigate the genomic basis of antibody response to porcine reproductive and respiratory syndrome (PRRS) virus (PRRSV) vaccination and its relationship to reproductive performance in non-PRRSV-infected commercial sows. Nine hundred and six F1 replacement gilts (139 ± 17 days old) from two commercial farms were vaccinated with a commercial modified live PRRSV vaccine. Blood samples were collected about 52 days after vaccination to measure antibody response to PRRSV as sample-to-positive (S/P) ratio and for single-nucleotide polymorphism (SNP) genotyping. Reproductive performance was recorded for up to 807 sows for number born alive (NBA), number of piglets weaned, number born mummified (MUM), number of stillborn (NSB), and number of pre-weaning mortality (PWM) at parities (P) 1-3 and per sow per year (PSY). Fertility traits such as farrowing rate and age at first service were also analyzed. BayesC0 was used to estimate heritability and genetic correlations of S/P ratio with reproductive performance. Genome-wide association study (GWAS) and genomic prediction were performed using BayesB. The heritability estimate of S/P ratio was 0.34 ± 0.05. High genetic correlations ( ) of S/P ratio with farrowing performance were identified for NBA P1 (0.61), PWM P2 (-0.70), NSB P3 (-0.83), MUM P3 (-0.84), and NSB PSY (-0.90), indicating that genetic selection for increased S/P ratio would result in improved performance of these traits. A quantitative trait locus was identified on chromosome 7 (∼25 Mb), at the major histocompatibility complex (MHC) region, explaining ∼30% of the genetic variance for S/P ratio, mainly by SNPs ASGA0032113, H3GA0020505, and M1GA0009777. This same region was identified in the bivariate GWAS of S/P ratio and reproductive traits, with SNP H3GA0020505 explaining up to 10% (for NBA P1) of the genetic variance of reproductive performance. The heterozygote genotype at H3GA0020505 was associated with greater S/P ratio and NBA P1 ( = 0.06), and lower MUM P3 and NSB P3 ( = 0.07). Genomic prediction accuracy for S/P ratio was high when using all SNPs (0.67) and when using only those in the MHC region (0.59) and moderate to low when using all SNPs excluding those in the MHC region (0.39). These results suggest that there is great potential to use antibody response to PRRSV vaccination as an indicator trait to improve reproductive performance in commercial pigs.
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http://dx.doi.org/10.3389/fgene.2020.01011DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7516203PMC
September 2020

An evaluation of additives for mitigating the risk of virus-contaminated feed using an ice-block challenge model.

Transbound Emerg Dis 2021 Mar 6;68(2):833-845. Epub 2020 Aug 6.

Department of Veterinary and Biomedical Sciences, South Dakota State University, Brookings, South Dakota, USA.

The role of animal feed as a vehicle for the transport and transmission of viral diseases was first identified during the porcine epidemic diarrhoea virus (PEDV) epidemic in North America. Since that time, various feed additives have been evaluated at the laboratory level to measure their effect on viral viability and infectivity in contaminated feed using bioassay piglet models. While a valid first step, the conditions of these studies were not representative of commercial swine production. Therefore, the purpose of this study was to evaluate the ability of feed additives to mitigate the risk of virus-contaminated feed using a model based on real-world conditions. This new model used an 'ice-block' challenge, containing equal concentrations of porcine reproductive and respiratory syndrome virus (PRRSV), Senecavirus A (SVA) and PEDV, larger populations of pigs, representative commercial facilities and environments, along with realistic volumes of complete feed supplemented with selected additives. Following supplementation, the ice block was manually dropped into designated feed bins and pigs consumed feed by natural feeding behaviour. After challenge, samples were collected at the pen level (feed troughs, oral fluids) and at the animal level (clinical signs, viral infection, growth rate, and mortality) across five independent experiments involving 15 additives. In 14 of the additives tested, pigs on supplemented diets had significantly greater average daily gain (ADG), significantly lower clinical signs and infection levels, and numerically lower mortality rates compared to non-supplemented controls. In conclusion, the majority of the additives evaluated mitigated the effects of PRRSV 174, PEDV and SVA in contaminated feed, resulting in improved health and performance.
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http://dx.doi.org/10.1111/tbed.13749DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8247034PMC
March 2021

Mitigating the risk of African swine fever virus in feed with anti-viral chemical additives.

Transbound Emerg Dis 2021 Mar 11;68(2):477-486. Epub 2020 Jul 11.

Department of Diagnostic Medicine/Pathobiology, College of Veterinary Medicine, Kansas State University, Manhattan, KS, USA.

African swine fever (ASF) is currently considered the most significant global threat to pork production worldwide. Disease caused by the ASF virus (ASFV) results in high case fatality of pigs. Importantly, ASF is a trade-limiting disease with substantial implications on both global pork and agricultural feed commodities. ASFV is transmissible through natural consumption of contaminated swine feed and is broadly stable across a wide range of commonly imported feed ingredients and conditions. The objective of the current study was to investigate the efficacy of medium-chain fatty acid and formaldehyde-based feed additives in inactivating ASFV. Feed additives were tested in cell culture and in feed ingredients under a transoceanic shipment model. Both chemical additives reduced ASFV infectivity in a dose-dependent manner. This study provides evidence that chemical feed additives may potentially serve as mitigants for reducing the risk of ASFV introduction and transmission through feed.
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http://dx.doi.org/10.1111/tbed.13699DOI Listing
March 2021

The risk of viral transmission in feed: What do we know, what do we do?

Transbound Emerg Dis 2020 Nov 10;67(6):2365-2371. Epub 2020 Jul 10.

Swine Health Information Center, Ames, IA, USA.

The role of animal feed as a vehicle for the transport and transmission of viral diseases was first identified in 2014 during the porcine epidemic diarrhoea virus epidemic in North America. Since the identification of this novel risk factor, scientists have conducted numerous studies to understand its relevance. Over the past few years, the body of scientific evidence supporting the reality of this risk has grown substantially. In addition, numerous papers describing actions and interventions designed to mitigate this risk have been published. Therefore, the purpose of this paper is to review the literature on the risk of feed (what do we know) and the protocols developed to reduce this risk (what do we do) in an effort to develop a comprehensive document to raise awareness, facilitate learning, improve the accuracy of risk assessments and to identify knowledge gaps for future studies.
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http://dx.doi.org/10.1111/tbed.13606DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7754325PMC
November 2020

Stability of classical swine fever virus and pseudorabies virus in animal feed ingredients exposed to transpacific shipping conditions.

Transbound Emerg Dis 2020 Jul 9;67(4):1623-1632. Epub 2020 Feb 9.

Department of Diagnostic Medicine/Pathobiology, College of Veterinary Medicine, Kansas State University, Manhattan, KS, USA.

Classical swine fever virus (CSFV) and pseudorabies virus (PRV) are two of the most significant trade-limiting pathogens affecting swine worldwide. Both viruses are endemic to China where millions of kilograms of feed ingredients are manufactured and subsequently imported into the United States. Although stability and oral transmission of both viruses through contaminated pork products has been demonstrated as a risk factor for transboundary spread, stability in animal feed ingredients had yet to be investigated. The objective of this study was to determine the survival of CSFV and variant PRV in 12 animal feeds and ingredients exposed to environmental conditions simulating a 37-day transpacific shipment. Virus was detected by PCR, virus isolation and nursery pig bioassay. CSFV and PRV nucleic acids were stable throughout the 37-day period in all feed matrices. Infectious CSFV was detected in two ingredients (conventional soybean meal and pork sausage casings) at 37 days post-contamination, whereas infectious PRV was detected in nine ingredients (conventional and organic soybean meal, lysine, choline, vitamin D, moist cat and dog food, dry dog food and pork sausage casings). This study demonstrates the relative stability of CSFV and PRV in different feed ingredients under shipment conditions and provides evidence that feed ingredients may represent important risk factors for the transboundary spread of these viruses.
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http://dx.doi.org/10.1111/tbed.13498DOI Listing
July 2020

Investigating the relationship between vaginal microbiota and host genetics and their impact on immune response and farrowing traits in commercial gilts.

J Anim Breed Genet 2020 Jan 25;137(1):84-102. Epub 2019 Nov 25.

Department of Animal Science, Iowa State University, Ames, Iowa.

Our objectives were to evaluate the interaction between host genetics and vaginal microbiota and their relationships with antibody (Ab) response to porcine reproductive and respiratory syndrome virus (PRRSV) vaccination and farrowing performance in commercial gilts. The farrowing performance traits were number born alive, number weaning (NW), total number born, number born dead, stillborn, mummies and preweaning mortality (PWM). The vaginal microbiota was collected on days 4 (D4) and 52 (D52) after vaccination for PRRSV. Blood samples were collected on D52 for Ab measurement. Actinobacteria, Bacterioidetes, Firmicutes, Proteobacteria and Tenericutes were the most abundant Phyla identified in the vaginal microbiota. Heritability ranged from ~0 to 0.60 (Fusobacterium) on D4 and from ~0 to 0.63 (Terrisporobacter) on D52, with 43 operational taxonomic units (OTUs) presenting moderate to high heritability. One major QTL on chromosome 12 was identified for 5 OTUs (Clostridiales, Acinetobacter, Ruminococcaceae, Campylobacter and Anaerococcus), among other 19 QTL. The microbiability for Ab response to PRRSV vaccination was low for both days (<0.07). For farrowing performance, microbiability varied from <0.001 to 0.15 (NW on D4). For NW and PWM, the microbiability was greater than the heritability estimates. Actinobacillus, Streptococcus, Campylobacter, Anaerococcus, Mollicutes, Peptostreptococcus, Treponema and Fusobacterium showed different abundance between low and high Ab responders. Finally, canonical discriminant analyses revealed that vaginal microbiota was able to classify gilts in high and low Ab responders to PRRSV vaccination with a misclassification rate of <0.02. Although the microbiota explained limited variation in Ab response and farrowing performance traits, there is still potential to explore the use of vaginal microbiota to explain variation in traits such as NW and PWM. In addition, these results revealed that there is a partial control of host genetic over vaginal microbiota, suggesting a possibility for genetic selection on the vaginal microbiota.
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http://dx.doi.org/10.1111/jbg.12456DOI Listing
January 2020

Effect of dietary medium-chain fatty acids on nursery pig growth performance, fecal microbial composition, and mitigation properties against porcine epidemic diarrhea virus following storage.

J Anim Sci 2020 Jan;98(1)

Department of Animal Science, College of Agricultural Sciences and Natural Resources, University of Nebraska, Lincoln, NE.

An experiment was conducted to evaluate the effect of dietary medium-chain fatty acid (MCFA) addition on nursery pig growth performance, fecal microbial composition, and mitigation of porcine epidemic diarrhea virus (PEDV) following storage. A total of 360 pigs (DNA 400 × 200, Columbus, NE; initially 6.7 ± 0.07 kg) were randomized to pens (5 pigs per pen) on the day of weaning (approximately 20 d of age), allowed a 6-d acclimation, blocked by BW, and randomized to dietary treatment (9 pens per treatment). All MCFA (Sigma-Aldrich, St. Louis, MO) were guaranteed ≥98% purity, including hexanoic (C6:0), octanoic (C8:0), and decanoic (C10:0) acids. Treatment diets were formulated in 2 phases (7 to 11 and 11 to 23 kg BW) and formulated to meet or exceed NRC requirement estimates. Treatments (n = 8) were a dose response including 0%, 0.25%, 0.5%, 1.0%, and 1.5% added MCFA blend (1:1:1 ratio C6:0, C8:0, and C10:0), as well as treatments with individual additions of 0.5% C6:0, C8:0, or C10:0. Fecal samples were collected from pigs fed control and 1.5% MCFA blend diets on days 0 and 14 and analyzed using 16s rDNA sequencing. Following feed manufacture, feed was stored in bags at barn temperature and humidity for 40 d before laboratory inoculation with PEDV. Subsamples of retained feed were inoculated with PEDV to achieve a titer of 104 TCID50/g and separate sample bottles were analyzed on 0 and 3 d post-inoculation (dpi). Overall, ADG and ADFI were increased (linear, P ≤ 0.010) and feed efficiency (G:F) improved (linear, P = 0.004) with increasing MCFA blend. Pigs fed 0.5% C8:0 had greater (P = 0.038) ADG compared with pigs fed the control diet, and G:F was improved (P ≤ 0.024) when pigs were fed 0.5% C6:0, 0.5% C8:0, or 0.5% C10:0 compared with control. An inclusion level × day interaction was observed (quadratic, P = 0.023), where PEDV Ct values increased (quadratic, P = 0.001) on 0 dpi with increasing levels of MCFA blend inclusion and also increased on 3 dpi (linear, P < 0.001). Fecal microbial diversity and composition were similar between control and 1.5% MCFA blend. In summary, the use of MCFA in nursery pig diets improves growth performance, provides residual mitigation activity against PEDV, and does not significantly alter fecal microbial composition.
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http://dx.doi.org/10.1093/jas/skz358DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6978897PMC
January 2020

Half-Life of African Swine Fever Virus in Shipped Feed.

Emerg Infect Dis 2019 12 17;25(12):2261-2263. Epub 2019 Dec 17.

African swine fever virus is transmissible through animal consumption of contaminated feed. To determine virus survival during transoceanic shipping, we calculated the half-life of the virus in 9 feed ingredients exposed to 30-day shipment conditions. Half-lives ranged from 9.6 to 14.2 days, indicating that the feed matrix environment promotes virus stability.
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http://dx.doi.org/10.3201/eid2512.191002DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6874236PMC
December 2019

Infectious Dose of African Swine Fever Virus When Consumed Naturally in Liquid or Feed.

Emerg Infect Dis 2019 05 17;25(5):891-897. Epub 2019 May 17.

African swine fever virus (ASFV) is a contagious, rapidly spreading, transboundary animal disease and a major threat to pork production globally. Although plant-based feed has been identified as a potential route for virus introduction onto swine farms, little is known about the risks for ASFV transmission in feed. We aimed to determine the minimum and median infectious doses of the Georgia 2007 strain of ASFV through oral exposure during natural drinking and feeding behaviors. The minimum infectious dose of ASFV in liquid was 10 50% tissue culture infectious dose (TCID), compared with 10 TCID in feed. The median infectious dose was 10 TCID for liquid and 10 TCID for feed. Our findings demonstrate that ASFV Georgia 2007 can easily be transmitted orally, although higher doses are required for infection in plant-based feed. These data provide important information that can be incorporated into risk models for ASFV transmission.
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http://dx.doi.org/10.3201/eid2505.181495DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6478231PMC
May 2019

Fecal microbiota transplantation as a tool to treat and reduce susceptibility to disease in animals.

Vet Immunol Immunopathol 2018 Dec 3;206:65-72. Epub 2018 Nov 3.

Department of Diagnostic Medicine/Pathobiology, College of Veterinary Medicine, Kansas State University, USA. Electronic address:

Fecal microbiota transplantation (FMT) is the process by which fecal microbiota are donated from a healthy individual and subsequently transplanted into a diseased or young individual. The mechanism by which FMT is effective is believed to be due to enhanced beneficial microbes, increased microbiome diversity, and restored normal flora. Beneficial gut microorganisms not only play a role in maintaining an intestinal barrier and metabolizing nutrients, but importantly, these microbes help regulate local and systemic immune function. Although FMT has been described for several centuries, only recently has it been utilized as a mainstream therapy in humans and significantly considered for applications in other species. In humans and animals, gastrointestinal diseases are by far the most widely accepted FMT-treatable conditions; however, recent research has shown exceptional promise for FMT being used to treat or prevent other conditions, including those outside of the gastrointestinal tract. Overall, FMT is likely an underutilized, widely-available, and inexpensive tool for improving the health and response to disease in animals. In this review, the effects of FMT on veterinary diseases and potential applications for FMT in animals are discussed.
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http://dx.doi.org/10.1016/j.vetimm.2018.11.002DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7173282PMC
December 2018

Double-stranded viral RNA persists in vitro and in vivo during prolonged infection of porcine reproductive and respiratory syndrome virus.

Virology 2018 11 27;524:78-89. Epub 2018 Aug 27.

Department of Diagnostic Medicine and Pathobiology, Kansas State University, Manhattan, KS, USA; Department of Veterinary and Biomedical Sciences, South Dakota State University, Brookings, SD, USA. Electronic address:

In order to study the mechanism of PRRSV persistence, an in vitro model of persistence was developed by serially passaging PRRSV-infected MARC-145 cells 109 times. Viral persistence was detected to be associated with increased double-stranded (dsRNA) in the infected cells. In PRRSV infected pigs, reduced ratio of plus to minus strands of viral RNA was observed in lymphoid tissues from PRRSV persistent pigs at 52 days post infection. Viral dsRNA was mostly detected in the germinal center during persistent infection compared to the localization of dsRNA in the inter-follicular zones during acute infection. RNA array analysis of antiviral cytokines in persistently infected lymph nodes showed that the presence of dsRNA did not stimulate antiviral immunity. These results suggest that PRRSV dsRNA functions as a mediator for viral persistence. The localization of PRRSV dsRNA in the germinal center of lymphoid tissues reveals a novel mechanism for PRRSV persistence.
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http://dx.doi.org/10.1016/j.virol.2018.08.006DOI Listing
November 2018

Fecal Microbiota Transplantation Is Associated With Reduced Morbidity and Mortality in Porcine Circovirus Associated Disease.

Front Microbiol 2018 23;9:1631. Epub 2018 Jul 23.

Department of Diagnostic Medicine/Pathobiology, College of Veterinary Medicine, Kansas State University, Manhattan, KS, United States.

Porcine circovirus associated disease (PCVAD) is a term used to describe the multi-factorial disease syndromes caused by porcine circovirus type 2 (PCV-2), which can be reproduced in an experimental setting through the co-infection of pigs with PCV-2 and porcine reproductive and respiratory syndrome virus (PRRSV). The resulting PCVAD-affected pigs represent a subpopulation within the co-infected group. In co-infection studies, the presence of increased microbiome diversity is linked to a reduction in clinical signs. In this study, fecal microbiota transplantation (FMT) was investigated as a means to prevent PCVAD in pigs co-infected with PRRSV and PCV-2d. The sources of the FMT material were high-parity sows with a documented history of high health status and robust litter characteristics. The analysis of the donated FMT material showed the absence of common pathogens along with the presence of diverse microbial phyla and families. One group of pigs ( = 10) was administered the FMT while a control group ( = 10) was administered a sterile mock-transplant. Over the 42-day post-infection period, the FMT group showed fewer PCVAD-affected pigs, as evidenced by a significant reduction in morbidity and mortality in transplanted pigs, along with increased antibody levels. Overall, this study provides evidence that FMT decreases the severity of clinical signs following co-infection with PRRSV and PCV-2 by reducing the prevalence of PCVAD.
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http://dx.doi.org/10.3389/fmicb.2018.01631DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6064930PMC
July 2018

Evaluation of the effects of flushing feed manufacturing equipment with chemically treated rice hulls on porcine epidemic diarrhea virus cross-contamination during feed manufacturing.

J Anim Sci 2018 Sep;96(10):4149-4158

Department of Diagnostic Medicine/Pathobiology, College of Veterinary Medicine, Kansas State University, Manhattan, KS.

Various strategies have been proposed to mitigate potential risk of porcine epidemic diarrhea virus (PEDV) transmission via feed and feed ingredients. Wet disinfection has been found to be the most effective decontamination of feed mill surfaces; however, this is not practical on a commercial feed production scale. Another potential mitigation strategy would be using chemically treated rice hulls flushed through the feed manufacturing equipment. Therefore, the objective of this study was to determine the effects of medium-chain fatty acids (MCFA) or formaldehyde-treated rice hull flush batches as potential chemical mitigation strategies for PEDV during feed manufacturing. Feed without evidence of PEDV RNA contamination was inoculated with PEDV. Based on polymerase chain reaction analysis, this feed had a cycle threshold (Ct) = 30.2 and was confirmed infective in bioassay. After manufacturing the PEDV-positive feed, untreated rice hulls, formaldehyde-treated rice hulls, 2% MCFA- (a 1:1:1 blend of hexanoic, octanoic, and decanoic acid) treated rice hulls, or 10% MCFA-treated rice hulls were flushed through laboratory scale mixers. For the untreated rice hulls, 3 of 6 samples had detectable PEDV RNA, whereas 1 of 6 formaldehyde-treated rice hull flush samples and 2 of 6 of the 2% MCFA rice hull flush samples had detectable PEDV RNA. However, PEDV RNA was not detected in any of the 10% MCFA rice hull flush samples. Then, rice hulls treated with 10% MCFA were mixed and discharged through a production scale mixer and bucket elevator following PEDV-positive feed. No rice hull flush or feed samples from the mixer following chemically treated rice hull flush had detectible PEDV RNA. However, one 10% MCFA rice hull sample collected from the bucket elevator discharge spout had detectible PEDV RNA. Dust collected following mixing of PEDV contaminated feed had detectable PEDV RNA (Ct = 29.4) and was infectious. However, dust collected immediately after the 10% MCFA rice hull flush batch had a reduced quantity of PEDV RNA (Ct = 33.7) and did not cause infection. Overall, the use of rice hull flushes effectively reduced the quantity of detectible RNA present after mixing a batch of PEDV-positive feed. Chemical treatment of rice hulls with formaldehyde or 10% MCFA provided additional reduction in detectible RNA. Finally, dust collected after manufacturing PEDV-inoculated feed has the potential to serve as a vector for PEDV transmission.
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http://dx.doi.org/10.1093/jas/sky295DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6162582PMC
September 2018

Survival of viral pathogens in animal feed ingredients under transboundary shipping models.

PLoS One 2018 20;13(3):e0194509. Epub 2018 Mar 20.

Animal Disease Research and Diagnostic Laboratory, Department of Veterinary and Biomedical Sciences, South Dakota State University, Brookings, South Dakota, United States of America.

The goal of this study was to evaluate survival of important viral pathogens of livestock in animal feed ingredients imported daily into the United States under simulated transboundary conditions. Eleven viruses were selected based on global significance and impact to the livestock industry, including Foot and Mouth Disease Virus (FMDV), Classical Swine Fever Virus (CSFV), African Swine Fever Virus (ASFV), Influenza A Virus of Swine (IAV-S), Pseudorabies virus (PRV), Nipah Virus (NiV), Porcine Reproductive and Respiratory Syndrome Virus (PRRSV), Swine Vesicular Disease Virus (SVDV), Vesicular Stomatitis Virus (VSV), Porcine Circovirus Type 2 (PCV2) and Vesicular Exanthema of Swine Virus (VESV). Surrogate viruses with similar genetic and physical properties were used for 6 viruses. Surrogates belonged to the same virus families as target pathogens, and included Senecavirus A (SVA) for FMDV, Bovine Viral Diarrhea Virus (BVDV) for CSFV, Bovine Herpesvirus Type 1 (BHV-1) for PRV, Canine Distemper Virus (CDV) for NiV, Porcine Sapelovirus (PSV) for SVDV and Feline Calicivirus (FCV) for VESV. For the remaining target viruses, actual pathogens were used. Virus survival was evaluated using Trans-Pacific or Trans-Atlantic transboundary models involving representative feed ingredients, transport times and environmental conditions, with samples tested by PCR, VI and/or swine bioassay. SVA (representing FMDV), FCV (representing VESV), BHV-1 (representing PRV), PRRSV, PSV (representing SVDV), ASFV and PCV2 maintained infectivity during transport, while BVDV (representing CSFV), VSV, CDV (representing NiV) and IAV-S did not. Notably, more viruses survived in conventional soybean meal, lysine hydrochloride, choline chloride, vitamin D and pork sausage casings. These results support published data on transboundary risk of PEDV in feed, demonstrate survival of certain viruses in specific feed ingredients ("high-risk combinations") under conditions simulating transport between continents and provide further evidence that contaminated feed ingredients may represent a risk for transport of pathogens at domestic and global levels.
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http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0194509PLOS
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5860775PMC
July 2018

Genomic regions associated with host response to porcine reproductive and respiratory syndrome vaccination and co-infection in nursery pigs.

BMC Genomics 2017 Nov 13;18(1):865. Epub 2017 Nov 13.

Department of Animal Science, Iowa State University, Ames, IA, 50011, USA.

Background: The WUR1000125 (WUR) single nucleotide polymorphism (SNP) can be used as a genetic marker for host response to porcine reproductive and respiratory syndrome (PRRS), PRRS vaccination, and co-infection with porcine circovirus type 2b (PCV2b). Objectives of this study were to identify genomic regions other than WUR associated with host response to PRRS vaccination and PRRSV/PCV2b co-infection and regions with a different effect on host response to co-infection, depending on previous vaccination for PRRS.

Methods: Commercial crossbred nursery pigs were pre-selected for WUR genotype (n = 171 AA and 198 AB pigs) where B is the dominant and favorable allele. Half of the pigs were vaccinated for PRRS and 4 weeks later, all pigs were co-infected with PRRS virus and PCV2b. Average daily gain (ADG) and viral load (VL) were quantified post vaccination (Post Vx) and post co-infection (Post Co-X). Single-SNP genome-wide association analyses were then conducted to identify genomic regions associated with response to vaccination and co-infection.

Results: Multiple SNPs near the major histocompatibility complex were significantly associated with PCV2b VL (-log P ≥ 5.5), regardless of prior vaccination for PRRS. Several SNPs were also significantly associated with ADG Post Vx and Post Co-X. SNPs with a different effect on ADG, depending on prior vaccination for PRRS, were identified Post Vx (-log P = 5.6) and Post Co-X (-log P = 5.5). No SNPs were significantly associated with vaccination VL (-log P ≤ 4.7) or PRRS VL (-log P ≤ 4.3). Genes near SNPs associated with vaccination VL, PRRS VL, and PCV2b VL were enriched (P ≤ 0.01) for immune-related pathways and genes near SNPs associated with ADG were enriched for metabolism pathways (P ≤ 0.04). SNPs associated with vaccination VL, PRRS VL, and PCV2b VL showed overrepresentation of health QTL identified in previous studies and SNPs associated with ADG Post Vx of Non-Vx pigs showed overrepresentation of growth QTL.

Conclusions: Multiple genomic regions were associated with PCV2b VL and ADG Post Vx and Post Co-X. Different SNPs were associated with ADG, depending on previous vaccination for PRRS. Results of functional annotation analyses and novel approaches of using previously-reported QTL support the identified regions.
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http://dx.doi.org/10.1186/s12864-017-4182-8DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5682865PMC
November 2017

Increased microbiome diversity at the time of infection is associated with improved growth rates of pigs after co-infection with porcine reproductive and respiratory syndrome virus (PRRSV) and porcine circovirus type 2 (PCV2).

Vet Microbiol 2017 Sep 18;208:203-211. Epub 2017 Aug 18.

Department of Diagnostic Medicine/Pathobiology, College of Veterinary Medicine, Kansas State University,1800 Denison Avenue, Manhattan, KS 66506, USA; Kansas State Veterinary Diagnostic Laboratory, Kansas State University,1800 Denison Avenue, Manhattan, KS 66506, USA. Electronic address:

Porcine reproductive and respiratory syndrome virus (PRRSV) and porcine circovirus type 2 (PCV2) are two of the most important pathogens affecting the swine industry worldwide. Co-infections are common on a global scale, resulting in pork production losses through reducing weight gain and causing respiratory disease in growing pigs. Our initial work demonstrated that the fecal microbiome was associated with clinical outcome of pigs 70days post-infection (dpi) with PRRSV and PCV2. However, it remained uncertain if microbiome characteristics could predispose response to viral infection. The purpose of this study was to determine if microbiome characteristics present at the time of virus exposure were associated with outcome after co-infection. Using the Lawrence Livermore Microbial Detection Array, we profiled the microbiome in feces prior to infection from pigs identified retrospectively as having high or low growth rates after co-infection. High growth rate pigs had less severe interstitial pneumonia, reduced virus replication, and a significant increase in average daily weight gain throughout the study. At the level of the fecal microbiome, high growth rate pigs had increased microbial diversity on both a family and species level. Shifts in the microbiome composition of high growth rate pigs included reduced Methanobacteriaceae species, increased Ruminococcaceae species, and increased Streptococcaceae species when compared to low growth rate pigs. The results indicate that both microbiome diversity and composition at the time of virus exposure may play a role in the subsequent response of pigs to PRRSV/PCV2 co-infection.
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http://dx.doi.org/10.1016/j.vetmic.2017.06.023DOI Listing
September 2017

Role of the microbiome in swine respiratory disease.

Vet Microbiol 2017 Sep 2;209:97-106. Epub 2017 Mar 2.

Department of Diagnostic Medicine/Pathobiology, College of Veterinary Medicine, Kansas State University, 1800 Denison Avenue, Manhattan, KS 66506, USA; Kansas State Veterinary Diagnostic Laboratory, Kansas State University, 1800 Denison Avenue, Manhattan, KS 66506, USA. Electronic address:

Microbiome is a term used to describe the community of microorganisms that live on the skin and mucosal surfaces of animals. The gastrointestinal microbiome is essential for proper nutrition and immunity. How the gastrointestinal microbiome impacts primary respiratory or systemic infections is an emerging area of study. Porcine reproductive and respiratory syndrome (PRRS) is caused by a systemic virus infection with primary lung pathology and continues to be the most costly disease of swine worldwide. Recent studies have demonstrated that improved outcome after experimental infection with PRRS virus and porcine circovirus type 2 (PCV2) is associated with increased fecal microbiome diversity and the presence of non-pathogenic Escherichia coli. In this review, we will discuss the factors that influence microbiome development in swine, associations of the microbiome with growth and immunity during infection with respiratory pathogens, and the role of the microbiome in PRRS. Taken together, modulation of the microbiome may be an alternative tool in the control of PRRS due to its intricate role in digestion of nutrients, systemic immunity, and response to pulmonary infections.
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http://dx.doi.org/10.1016/j.vetmic.2017.02.017DOI Listing
September 2017

Tissue localization, shedding, virus carriage, antibody response, and aerosol transmission of Porcine epidemic diarrhea virus following inoculation of 4-week-old feeder pigs.

J Vet Diagn Invest 2016 Nov 3;28(6):671-678. Epub 2016 Oct 3.

Department of Diagnostic Medicine/Pathobiology, College of Veterinary Medicine, Kansas State University, Manhattan, KS (Niederwerder, Nietfeld, Bai, Peddireddi, Kerrigan, Oberst, Rowland, G. Anderson, Hesse)Kansas State Veterinary Diagnostic Laboratory, College of Veterinary Medicine, Kansas State University, Manhattan, KS (Niederwerder, Nietfeld, Bai, Peddireddi, Breazeale, J. Anderson, An, Oberst, G. Anderson, Hesse)National Animal Disease Center, United States Department of Agriculture-Agricultural Research Service, Ames, IA (Crawford, Lager)Department of Veterinary Diagnostic and Production Animal Medicine, Iowa State University, Ames, IA (Madson).

We determined tissue localization, shedding patterns, virus carriage, antibody response, and aerosol transmission of Porcine epidemic diarrhea virus (PEDV) following inoculation of 4-week-old feeder pigs. Thirty-three pigs were randomly assigned to 1 of 3 groups for the 42-day study: inoculated (group A; n = 23), contact transmission (group B; n = 5), and aerosol transmission (group C; n = 5). Contact transmission occurred rapidly to group B pigs whereas productive aerosol transmission failed to occur to group C pigs. Emesis was the first clinical sign noted at 3 days postinoculation (dpi) followed by mild to moderate diarrhea lasting 5 more days. Real-time PCR detected PEDV in fecal and nasal swabs, oral fluids, serum, and gastrointestinal and lymphoid tissues. Shedding occurred primarily during the first 2 weeks postinoculation, peaking at 5-6 dpi; however, some pigs had PEDV nucleic acid detected in swabs collected at 21 and 28 dpi. Antibody titers were measurable between 14 and 42 dpi. Although feces and intestines collected at 42 dpi were PEDV negative by PCR and immunohistochemistry, respectively, small intestines from 70% of group A pigs were PCR positive. Although disease was relatively mild and transient in this age group, the results demonstrate that 4-week-old pigs are productively infected and can sustain virus replication for several weeks. Long-term shedding of PEDV in subclinically affected pigs should be considered an important source for PEDV transmission.
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http://dx.doi.org/10.1177/1040638716663251DOI Listing
November 2016

Is There a Risk for Introducing Porcine Reproductive and Respiratory Syndrome Virus (PRRSV) Through the Legal Importation of Pork?

Food Environ Virol 2017 03 2;9(1):1-13. Epub 2016 Sep 2.

Department of Diagnostic Medicine/Pathobiology, College of Veterinary Medicine, Kansas State University, 1800 Denison Avenue, Manhattan, KS, 66506, USA.

Since the appearance of porcine reproductive and respiratory syndrome virus (PRRSV) in the late 1980s, the virus has become endemic throughout the world, with only the countries of Sweden, Switzerland, Finland, Norway, Australia, and New Zealand historically free of PRRS virus. Biosecurity is maintained largely through restrictions on the importation of pigs and semen. The risk for a PRRSV outbreak via the legal importation of fresh/chilled/frozen pork from PRRSV-positive countries remains controversial. However, examination of the historical record shows that countries retained a PRRSV-negative status during the importation of more than 500,000 tons of fresh/chilled/frozen pork from PRRSV-positive trading partners. This review describes some of the unique properties of PRRSV, including the poor stability of the virus in the environment, the low probability for airborne transmission, and the inability to sustain infections in feral swine, which make PRRSV a poor candidate for disease introduction through the legal importation of pork.
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http://dx.doi.org/10.1007/s12560-016-9259-zDOI Listing
March 2017

Microbiome associations in pigs with the best and worst clinical outcomes following co-infection with porcine reproductive and respiratory syndrome virus (PRRSV) and porcine circovirus type 2 (PCV2).

Vet Microbiol 2016 May 11;188:1-11. Epub 2016 Mar 11.

Department of Diagnostic Medicine/Pathobiology, College of Veterinary Medicine, Kansas State University, 1800 Denison Avenue, Manhattan, KS 66506, USA.

On a world-wide basis, co-infections involving porcine reproductive and respiratory syndrome virus (PRRSV) and porcine circovirus type 2 (PCV2) are common and contribute to a range of polymicrobial disease syndromes in swine. Both viruses compromise host defenses, resulting in increased susceptibility to infections by primary and secondary pathogens that can affect growth performance as well as increased morbidity and mortality. An experimental population of 95 pigs was co-infected with PRRSV and PCV2. At 70days post-infection (dpi), 20 representative pigs were selected as having the best or worst clinical outcome based on average daily gain (ADG) and the presence of clinical disease. Worst clinical outcome pigs had prolonged and greater levels of viremia as measured by qPCR. Serum, lung and fecal samples collected at 70 dpi were analyzed using a comprehensive DNA microarray technology, the Lawrence Livermore Microbial Detection Array, to detect over 8000 microbes. Bacterial species, such as Bacillus cereus, were detected at a higher rate in the serum of worst performing pigs. At the level of the fecal microbiome, the overall microbial diversity was lower in the worst clinical outcome group. The results reinforce the importance of pathogen load in determining clinical outcome and suggest an important role of microbial diversity as a contributing factor in disease.
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http://dx.doi.org/10.1016/j.vetmic.2016.03.008DOI Listing
May 2016
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