The effect of porcine reproductive and respiratory syndrome virus and porcine epidemic diarrhea virus challenge on growing pigs II: Intestinal integrity and function1

Abstract

The objective of this study was to determine if intestinal function and integrity is altered due to porcine reproductive and respiratory syndrome (PRRS) virus and porcine epidemic diarrhea (PED) virus infection in growing pigs. Forty-two gilts (16.8 ± 0.6 kg BW), naïve for PRRS and PED, were selected and randomly assigned to 1 of 4 treatments: 1) a control (CON; = 6), 2) PRRS virus challenge only (PRRS; = 12), 3) PED virus challenge only (; = 12), or 4) coinfection of PRRS + PED viruses (PRP; = 12). Treatments 2 and 4 were inoculated with a live field strain of PRRS virus on d 0 after inoculation. Treatments 3 and 4 were inoculated with PED virus on 14 d after inoculation (dpi) and all pigs were euthanized 7 d later (21 dpi). Infection with PRRS virus was determined by viremia and seroconversion. Fecal quantitative PCR was used to confirm PED virus infection. Control pigs remained PRRS and PED virus negative throughout the study. Compared with the CON, intestinal morphology was unaffected by PRRS. As expected, PED and PRP treatments resulted in duodenum, jejunum, and ileum villus atrophy compared with the CON treatment ( < 0.01). Ex vivo transepithelial electrical resistance (TER) did not differ between CON and PRRS pigs (P < 0.05) but was reduced by 40% in PED alone ( < 0.01). Interestingly, TER was increased ( < 0.01) in the PRP pigs. Active transport of glucose was increased in PRRS pigs over CON pigs ( < 0.01), whereas PED had pigs increased ( < 0.01) active glutamine transport over the CON pigs. Jejunum GLUT2 mRNA abundance and sucrase, maltase, and Na+/K+ adenosine triphosphatase activities tended to be increased in PRRS pigs compared with CON pigs ( < 0.06). The jejunum AA transporter, SLC6A14, and mucin 2 mRNA abundance tended to be increased in PED-only pigs ( < 0.10). These data suggest that PRRS infection supports a higher affinity for glucose uptake, whereas PED favors glutamine uptake. Interestingly, digestive machinery during PED challenge remained intact. Altogether, PED but not PRRS challenges alter intestinal morphology and integrity in growing pigs.

Porcine epidemic diarrhea virus reduces feed efficiency in nursery pigs

“…Previous work reported that PEDV detected by IHC is most abundant at dpi 5 and this coincides with increased crypt stem cell proliferation, DNA fragmentation, and active glutamine transport in the jejunum ( Curry et al, 2017b ). In agreement with this study, it has been well characterized that during peak infection PEDV reduces VH ( Stevenson et al, 2013 ; Madson et al, 2014 ) and that PEDV increases villus fusion as well as immune cell infiltrates ( Schweer et al, 2015a ). Crypt stem cell proliferation has been assessed using Ki67 IHC, and PEDV-inoculated pigs have been shown to have increased Ki67-positive cells in small intestinal crypts ( Jung et al, 2015 ; Curry et al, 2017b ).…”

“…Total RNA was isolated from LD muscle as previously described ( Schweer et al, 2015a ). Total protein was set relative to total RNA to assess protein synthesis efficiency, which has previously been published ( Pringle et al, 1993 ).…”

Impact of viral disease hypophagia on pig jejunal function and integrity

“…Adverse health events and the accompanying hypophagia results in economically significant losses in pig growth performance worldwide. However, it is unclear how an adverse health event such as PRRSV challenge directly, or indirectly via hypophagia, impacts small intestinal function and integrity [8]. Moreover, little is known about how much disease hypophagia contributes to attenuated pig performance and modulations in small intestinal function and integrity.…”

“…Reductions in intestinal integrity and function have been documented under a variety of stressors, including heat stress [3,4], weaning stress [5,6], and enteric disease challenges such as with Porcine Epidemic Diarrhea Virus [PEDV; 7,8,9]. However, reduced nutrient intake is often reported in accompaniment of these stressors, which alone can modulate intestinal integrity and function [10][11][12].…”

Swine enteric coronavirus disease: A review of 4 years with porcine epidemic diarrhoea virus and porcine deltacoronavirus in the United States and Canada

“…The long‐term impact of PEDV and potentially PDCoV on performance may be due to the systemic inflammatory effects on feed intake and utilization, localized effects on enterocyte health and function, or a combination of the two. For example, infection with PEDV results in apoptosis of epithelial cells, increased gastrointestinal permeability, disruption of tight and adherens junctions of enterocytes, and reduced goblet cells present in the small intestine (Jung, Eyerly, Annamalai, Lu, & Saif, ; Jung & Saif, ; Kim & Lee, ; Schweer, Pearce et al., ). These disruptions to normal gastrointestinal anatomy and physiology likely impact digestive capacity and function.…”