Infection of porcine precision cut intestinal slices by transmissible gastroenteritis coronavirus demonstrates the importance of the spike protein for enterotropism of different virus strains

Abstract

TGEV is a coronavirus that is still widely spread in pig farming. On molecular level this virus has been studied in detail. However, studying TGEV infection within the complexity of the porcine intestinal epithelium reveals difficulties due to limiting infection models. Here we established a new ex vivo model to analyze the enterotropism of TGEV in porcine intestinal tissue. Precision cut intestinal slices (PCIS) were produced and ATP level was measured to proof vitality of the slices. ATP measurements and HE staining revealed living tissue in culture for up to 24h. PCIS were infected with three different TGEV strains. TGEV PUR 46-MAD is a commonly used TGEV strain that is known to be attenuated. TGEV Miller was passaged in piglets several times to reveal high infection. Finally, TGEV GFP is a recombinant strain that obtained its main body from TGEV PUR 46-MAD, but its spike protein from TGEV PUR-C11 that showed high mortality in piglets in vivo. Our results were in complete consensus of these statements. TGEV Miller mildly and TGEV GFP extensively infected the cells in the jejunum based on the amount of positive stained epithelial cells. However, for TGEV PUR 46-MAD no nucleocapsid protein was detected in the epithelial cells of the tissue. This shows that differences in TGEV strains and their infectious potential are highly dependent on their S protein.

Keywords: Coronavirus; Porcine gastroenteritis; Porcine jejunum; Precision cut intestinal slices; Spike protein; TGEV.