scholarly journals Minimum Determinants of Transmissible Gastroenteritis Virus Enteric Tropism Are Located in the N-Terminus of Spike Protein

Pathogens ◽  
2019 ◽  
Vol 9 (1) ◽  
pp. 2 ◽  
Author(s):  
Carlos M. Sanchez ◽  
Alejandro Pascual-Iglesias ◽  
Isabel Sola ◽  
Sonia Zuñiga ◽  
Luis Enjuanes
Keyword(s):  
Sialic Acid ◽  
Transmissible Gastroenteritis Virus ◽  
High Morbidity ◽  
S Protein ◽  
Binding Domains ◽  
Gastroenteritis Virus ◽  
Sialic Acid Binding ◽  
Transmissible Gastroenteritis ◽  
Enteric Tract

Transmissible gastroenteritis virus (TGEV) is an enteric coronavirus causing high morbidity and mortality in porcine herds worldwide, that possesses both enteric and respiratory tropism. The ability to replicate in the enteric tract directly correlates with virulence, as TGEVs with an exclusive respiratory tropism are attenuated. The tissue tropism is determined by spike (S) protein, although the molecular bases for enteric tropism remain to be fully characterized. Both pAPN and sialic acid binding domains (aa 506–655 and 145–155, respectively) are necessary but not sufficient for enteric tract infection. Using a TGEV infectious cDNA and enteric (TGEV-SC11) or respiratory (TGEV-SPTV) isolates, encoding a full-length S protein, a set of chimeric recombinant viruses, with a sequential modification in S protein amino terminus, was engineered. In vivo tropism, either enteric, respiratory or both, was studied by inoculating three-day-old piglets and analyzing viral titers in lung and gut. The data indicated that U655>G change in S gene (S219A in S protein) was required to confer enteric tropism to a respiratory virus that already contains the pAPN and sialic acid binding domains in its S protein. Moreover, an engineered virus containing U655>G and a 6 nt insertion at position 1124 (Y374-T375insND in S protein) was genetically stable after passage in cell cultures, and increased virus titers in gut by 1000-fold. We postulated that the effect of these residues in enteric tropism may be mediated by the modification of both glycosaminoglycan binding and S protein structure.

scholarly journals Recombinant dimeric small immunoproteins neutralize transmissible gastroenteritis virus infectivity efficiently in vitro and confer passive immunity in vivo

2007 ◽  
Vol 88 (1) ◽  
pp. 187-195 ◽  
Author(s):  
Marco Bestagno ◽  
Isabel Sola ◽  
Eliana Dallegno ◽  
Patricia Sabella ◽  
Monica Poggianella ◽  
...  
Keyword(s):  
Passive Immunization ◽  
Transmissible Gastroenteritis Virus ◽  
Virus Infectivity ◽  
Single Chain ◽  
Variable Regions ◽  
Chain Molecules ◽  
Gastroenteritis Virus ◽  
Transmissible Gastroenteritis

Small immunoproteins (SIPs) are single-chain molecules comprising the variable regions of an antibody assembled in a single polypeptide (scFv) and joined to the immunoglobulin heavy-chain dimerizing domain. To investigate the potential of these molecules to provide protection against enteric infections when supplied orally, SIPs were generated against Transmissible gastroenteritis virus (TGEV), a highly pathogenic porcine virus. Different variants of TGEV-specific SIPs were created, of ε and α isotypes, by exploiting the dimerizing domains εCH4 and αCH3 of human and swine origin. Transfected cells secreted these recombinant mini-antibodies efficiently, mainly as dimers stabilized covalently by inter-chain disulphide bridges. The specificity and functionality of the recombinant TGEV-specific SIPs were determined by in vitro binding, neutralization and infection-interference assays. The neutralization indices of the TGEV-specific SIPs were all very similar to that of the original TGEV-specific mAb, thus confirming that the immunological properties have been preserved in the recombinant SIPs. In vivo protection experiments on newborn piglets have, in addition, demonstrated a strong reduction of virus titre in infected tissues of animals treated orally with TGEV-specific SIPs. It has therefore been demonstrated that it is possible to confer passive immunization to newborn pigs by feeding them with recombinant SIPs.

scholarly journals Binding of Transmissible Gastroenteritis Coronavirus to Cell Surface Sialoglycoproteins

2002 ◽  
Vol 76 (12) ◽  
pp. 6037-6043 ◽  
Author(s):  
Christel Schwegmann-Weßels ◽  
Gert Zimmer ◽  
Hubert Laude ◽  
Luis Enjuanes ◽  
Georg Herrler
Keyword(s):  
Sialic Acid ◽  
Cell Surface ◽  
Molecular Mass ◽  
Cultured Cells ◽  
Binding Activity ◽  
High Molecular Mass ◽  
Parental Virus ◽  
Transmissible Gastroenteritis Virus ◽  
Sialic Acid Binding ◽  
Transmissible Gastroenteritis

ABSTRACT The surface glycoprotein S of transmissible gastroenteritis virus (TGEV) has two binding activities. (i) Binding to porcine aminopeptidase N (pAPN) is essential for the initiation of infection. (ii) Binding to sialic acid residues on glycoproteins is dispensable for the infection of cultured cells but is required for enteropathogenicity. By comparing parental TGEV with mutant viruses deficient in the sialic acid binding activity, we determined the contributions of both binding activities to the attachment of TGEV to cultured cells. In the presence of a functional sialic acid binding activity, the amount of virus bound to two different porcine cell lines was increased sixfold compared to the binding of the mutant viruses. The attachment of parental virus was reduced to levels observed with the mutants when sialic acid containing inhibitors was present or when the cells were pretreated with neuraminidase. In virus overlay binding assays with immobilized cell surface proteins, the mutant virus only recognized pAPN. In addition, the parental virus bound to a high-molecular-mass sialoglycoprotein. The recognition of pAPN was sensitive to reducing conditions and was not dependent on sialic acid residues. On the other hand, binding to the sialic acid residues of the high-molecular-mass glycoprotein was observed regardless of whether the cellular proteins had been separated under reducing or nonreducing conditions. We propose that binding to a surface sialoglycoprotein is required for TGEV as a primary attachment site to initiate infection of intestinal cells. This concept is discussed in the context of other viruses that use two different receptors to infect cells.

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