Oral Administration of Coronavirus Spike Protein Provides Protection to Newborn Pigs When Challenged with PEDV.

Magdalena Maj,John A Howard,Ryan Saltzman,John H Walker,Gina M Fake

doi:10.3390/vaccines9121416

Magdalena Maj, John A Howard + Show 3 more

Open Access

https://doi.org/10.3390/vaccines9121416

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Abstract

To investigate whether oral administration of maize-produced S antigen can provide passive immunity to piglets against porcine epidemic diarrhea virus (PEDV), 16 pregnant sows were randomly assigned to one of four treatments: (1) injection of PEDV vaccine (INJ), (2) maize grain without S protein (CON), (3) maize grain containing low dose of S antigen (LOV) and (4) maize grain containing a high dose of S antigen (HOV). Vaccines were administered on days 57, 85 and 110 of gestation. Sows’ serum and colostrum were collected at farrowing and milk on day 6 post-challenge to quantify neutralizing antibodies (NABs) and cytokines. Piglets were challenged with PEDV 3–5 d after farrowing, and severity of disease and mortality assessed on day 11 post-challenge. Disease severity was lower in LOV and INJ compared with HOV and CON, whereas the survival rate increased in piglets from LOV sows compared with HOV and CON (p ≤ 0.001). Higher titers of NABs and lower levels of cytokine granulocyte-macrophage colony-stimulating factor in sows’ milk were positively correlated with piglet survivability (p ≤ 0.05). These data suggest that feeding S protein in corn to pregnant sows protects nursing piglets against PEDV.

Highlights

Coronaviruses have become a major problem for both human and animal welfare and are a continuing threat for the future
Expression of S1 protein was targeted to the corn embryo, which enabled the S1 antigen to be concentrated by enriching for the germ fraction using a CIM-8-MIS pin mill (Munson; Utica, NY, USA), DP650-14 roller mill (Roskamp; Waterloo, I), and a LS18S55 separator (SWECO; Florence, KY, USA)
Using a 5% significance level, we found piglet body weight, milk granulocyte-macrophage colonystimulating factor (GM-CSF), and milk neutralizing antibodies (NABs) significantly correlated with pig survival (p ≤ 0.05; Table 3)

Summary

Introduction

Coronaviruses have become a major problem for both human and animal welfare and are a continuing threat for the future. Porcine epidemic diarrhea virus (PEDV) is a positive strand enveloped RNA virus of family Coronaviridae with a genome of 28 kb. The virus infects swine, resulting in major losses to the industry in the U.S and worldwide [1,2]. The disease was first identified in Europe in the early 1970s, in Asia in 2010 and in the United States in 2013, and it continues to be a major problem in the swine industry worldwide [2,5]. The conditionally approved vaccines in North America from Harrisvaccines (Ames, IA, USA) and Zoetis (Parsippany, NJ, USA) are based on RNA or inactivated virus but are only marginally effective [6,7]. There is an urgent need for a more effective vaccine for PEDV

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