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Water administration of glucose and amino acids attenuates changes in intestinal structure and lesion scores in PRRSv and PEDv co-infected pigs
Porcine epidemic diarrhea virus (PEDv) infection causes enterocyte loss and villus atrophy, which results in reduced performance and, if severe enough, mortality. Therefore, our objective was to examine whether water delivery of nutrients (glucose and amino acids) could alleviate changes in intestinal structure and function in growing pigs co-infected with Porcine Reproductive and Respiratory Syndrome virus (PRRSv) and PEDv. Thirty gilts (16.6 ± 1.8 kg BW) were allocated to one of three treatments for 21 d. Treatments included: 1) Control, healthy, PRRSv, and PEDv naïve gilts (n=6), 2) PRRSv+PEDv co-infection (n=12; PRP) and 3) PRRSv+PEDv co-infection + water delivery of nutrients (n=12; PRPD). Treatments 2 and 3 were inoculated with a live PRRSv at d 0, then with PEDv at 14 dpi. Water supplementation which consisted of glucose syrup, monosodium glutamate, betaine, glycine and alanine was delivered at 15-30 g/d solids for 21 d. At d21 all pigs were euthanized, jejunum samples were collected and histological samples were assessed for lesions, including villus atrophy, crypt depth, inflammation, and brush border digestive enzyme activities. Control pigs remained negative for PEDv and PRRSv by qPCR and as expected, the challenged pigs were positive for both PEDv and PRRSv. PRP and PRPD treatments reduced villus height versus the control (264, 289 and 422 µm, P < 0.001, respectively). Crypt depth tended to be altered due to treatment (280, 317 and 255 µm; control, PRP and PRPD respectively, P = 0.056). Irrespective of challenge, villi:crypt ratio was reduced compared to the control (P < 0.05). However, PRPD gilts tended to have a higher villi:crypt ratio compared to the PRP treatment (P = 0.10). Histologic lesions were scored on a scale of increasing severity from 1-5. Compared to the control (0), the jejunum lesion scores were increased (P < 0.01) with PRP treatment (4.42). However, compared to the PRP, PRPD numerically attenuated this score (3.58, P > 0.05). Brush border digestive enzyme activities for sucrase and aminopeptidase were not altered by treatment. However, both the PRP and PRPD treatments reduced maltase and lactase activities by 50% compared to the control (P < 0.05). Overall, nutrient supplementation by supplemented water during a PRRSv and PEDv co-infection reduced jejunum lesion scores, but did not influence digestive enzymes.
Keywords: co-infection, intestinal structure, intestinal function