Id |
Subject |
Object |
Predicate |
Lexical cue |
T319 |
0-4 |
Sentence |
denotes |
6.1. |
T320 |
5-87 |
Sentence |
denotes |
CoVs Utilize SAs and SA Linkages as Attachment and Entry Sites to Human Host Cells |
T321 |
88-207 |
Sentence |
denotes |
Several β-CoV genera such as BCoV bind to O-acetylated SAs and bear an acetylesterase enzyme to act as a host cell RDE. |
T322 |
208-343 |
Sentence |
denotes |
Certain α-CoV and γ-CoV are deficient for the comparable acetylesterase enzyme but have a preference to NeuAc or NeuGc type SA species. |
T323 |
344-436 |
Sentence |
denotes |
Infectious bronchitis virus (IBV) and transmissible gastroenteritis virus are such examples. |
T324 |
437-538 |
Sentence |
denotes |
Additionally, both α-CoV and γ-CoV also include sub-members deficient of any SA-recognizing activity. |
T325 |
539-626 |
Sentence |
denotes |
During evolution, some subtypes of SARS-CoV and HCoV-229E acquired SA-binding capacity. |
T326 |
627-739 |
Sentence |
denotes |
The SA-binding activities of BCoV, transmissible gastroenteritis coronavirus (TGEV) and IBV are well known [60]. |
T327 |
741-761 |
Sentence |
denotes |
6.1.1. α-Coronavirus |
T328 |
762-865 |
Sentence |
denotes |
In α-CoVs such as TGEV, HA-activity is attributed to the SA-recognizing activity to α2,3-NeuGc [61,62]. |
T329 |
866-952 |
Sentence |
denotes |
The SA-binding site is present on the N-terminal region of the S-glycoprotein of TGEV. |
T330 |
953-1009 |
Sentence |
denotes |
TGEV has two types with enteric and respiratory tropism. |
T331 |
1010-1108 |
Sentence |
denotes |
The respiratory TGEV has the porcine aminopeptidase N (pAPN)-binding domain and SA-binding domain. |
T332 |
1109-1265 |
Sentence |
denotes |
Nucleotide 655 of the S gene is essential for enteric tropism and the S219A mutation of the S glycoprotein confers the enteric to respiratory tropism shift. |
T333 |
1266-1434 |
Sentence |
denotes |
In addition, a 6-nucleotide insertional mutation at nucleotide 1124, which yields the Y374-T375insND shift of the S glycoprotein, causes enhanced enteric tract tropism. |
T334 |
1435-1594 |
Sentence |
denotes |
TGEV interacts with SA species on mucin-like glycoprotein (MGP), a highly glycosylated protein, in an SA-dependent manner, on mucin-secreting goblet cells [6]. |
T335 |
1595-1679 |
Sentence |
denotes |
MGP SA-binding allows virus entry via the mucus layer to the intestinal enterocytes. |
T336 |
1680-1834 |
Sentence |
denotes |
Different from TGEV, the S glycoprotein of porcine CoV has no hemagglutination activity due to deletion of the SA-binding site of the S glycoprotein [61]. |
T337 |
1835-1912 |
Sentence |
denotes |
The loss of SA-binding activity is correlated to the non-enteropathogenicity. |
T338 |
1913-2102 |
Sentence |
denotes |
SAs function as HA-mediated entry determinants for TGEV, causing the enteropathogenic outcome of the virus, and SA-recognition activity is also responsible for virus amplification in cells. |
T339 |
2103-2212 |
Sentence |
denotes |
SA-binding activity-deficient TGEV can propagate in cells through pAPN, known as CD13, as a receptor [62,63]. |
T340 |
2213-2299 |
Sentence |
denotes |
The SA-binding activity potentiates infection and is crucial for intestinal infection. |
T341 |
2301-2321 |
Sentence |
denotes |
6.1.2. β-Coronavirus |
T342 |
2322-2433 |
Sentence |
denotes |
In β-CoV, HE mediates viral attachment to O-Ac-SAs and its function relies on the combined CBD and RDE domains. |
T343 |
2434-2551 |
Sentence |
denotes |
Most β-CoVs target 9-O-Ac-SAs (type I), but certain strains switched to alternatively targeting 4-O-Ac-SAs (type II). |
T344 |
2552-2701 |
Sentence |
denotes |
For example, the SA-acetylesterase enzyme in BCoVs and HCoV-OC43 is known to have hemagglutinizing activities as a type of SA-9-O-acetylesterase [8]. |
T345 |
2702-2763 |
Sentence |
denotes |
The SA-acetylesterase is the HE surface glycoprotein in BCoV. |
T346 |
2764-2847 |
Sentence |
denotes |
The three-dimensional structure of BCoV HE is similar to other viral esterases [9]. |
T347 |
2848-2893 |
Sentence |
denotes |
The HE gene is found only in the β-CoV genus. |
T348 |
2894-3065 |
Sentence |
denotes |
The acetylesterase of murine CoVs differs in its substrate binding specificity from that of BCoV and HCoV-OC43, which is specific for O-acetyl residue release from SA C-9. |
T349 |
3066-3119 |
Sentence |
denotes |
Murine CoVs prefer to esterize 4-O-acetyl-NeuAc [64]. |
T350 |
3120-3229 |
Sentence |
denotes |
The β-CoV acetylesterase destroys the receptors and this specificity is similar to that of influenza viruses. |
T351 |
3230-3355 |
Sentence |
denotes |
Acetylesterase activity can be inhibited by diisopropyl fluorophosphate and this agent decreases viral infection levels [65]. |
T352 |
3356-3511 |
Sentence |
denotes |
As deduced from the SA acetylesterase of HCoV-OC43 [8], the 9-O-Ac-SA species is a receptor binding determinant for erythrocytes and entry into cells [59]. |
T353 |
3512-3579 |
Sentence |
denotes |
The BCoV HE protein has dual activity of acetylesterase and HA [9]. |
T354 |
3580-3701 |
Sentence |
denotes |
BCoV widely agglutinates erythrocytes and purified HE only agglutinates Neu5,9Ac2-enriched erythrocytes of rats and mice. |
T355 |
3702-3784 |
Sentence |
denotes |
BCoV and HCoV-OC43 can agglutinate chicken erythrocytes, while purified HE cannot. |
T356 |
3785-3972 |
Sentence |
denotes |
In contrast to the HE protein, purified S glycoprotein can agglutinate chicken erythrocytes [52], indicating that the major HA is the S protein which acts as the major SA-binding protein. |
T357 |
3973-4148 |
Sentence |
denotes |
However, the role of O-Ac-SAs is not certain to be essential in receptors, and SA-binding activity may be essential only to the HE protein, but not to the S glycoprotein [54]. |
T358 |
4150-4170 |
Sentence |
denotes |
6.1.3. γ-Coronavirus |
T359 |
4171-4275 |
Sentence |
denotes |
In γ-CoVs, IBV strains, known as poultry respiratory infectious pathogens, can agglutinate erythrocytes. |
T360 |
4276-4377 |
Sentence |
denotes |
IBV prefers to recognize α2,3-NeuAc and the SA functions as a host entry receptor for infection [66]. |
T361 |
4378-4556 |
Sentence |
denotes |
Glycosylation of IBV M41 S1 protein RBD is crucial for interaction with chicken trachea tissue and RBD N-glycosylation confers receptor specificity and enables virus replication. |
T362 |
4557-4615 |
Sentence |
denotes |
The heavy glycosylated M41 RBD has 10 glycosylation sites. |
T363 |
4616-4671 |
Sentence |
denotes |
N-glycosylation of IBV determines receptor specificity. |
T364 |
4672-4722 |
Sentence |
denotes |
However, the host receptor has not yet been found. |
T365 |
4723-4809 |
Sentence |
denotes |
NA treatment reduces the binding of soluble S to kidney and tracheal epithelial cells. |
T366 |
4810-4881 |
Sentence |
denotes |
The IBV S protein recognizes epithelial cells in a SA-dependent manner. |
T367 |
4882-5011 |
Sentence |
denotes |
The SA-binding ability of IBV is necessary for infection of tracheal epithelial cells and lung respiratory epithelial cells [67]. |
T368 |
5012-5127 |
Sentence |
denotes |
The SA-binding site is located on S1 of the IBV S protein, although the IBV-specific protein receptor is not known. |
T369 |
5128-5179 |
Sentence |
denotes |
In contrast to BCoV or HCoV-OC43, IBV lacks an RDE. |
T370 |
5180-5258 |
Sentence |
denotes |
SA binding of IBV is likely more essential than in other viruses such as TGEV. |
T371 |
5260-5266 |
Sentence |
denotes |
6.1.4. |
T372 |
5267-5276 |
Sentence |
denotes |
Torovirus |
T373 |
5277-5417 |
Sentence |
denotes |
In torovirus, which belongs to the family Coronaviridae, the toroviruses are grouped into the Torovirinae subfamily and the Torovirus genus. |
T374 |
5418-5533 |
Sentence |
denotes |
The known toroviruses can infect four species of hosts, constituting bovine, equine, porcine and human toroviruses. |
T375 |
5534-5640 |
Sentence |
denotes |
They mildly infect swine and cattle through the HE protein, which is similar to the β-CoV HE protein [68]. |
T376 |
5641-5734 |
Sentence |
denotes |
The HE protein is a class I membrane glycoprotein which forms homodimers with a MW of 65 kDa. |
T377 |
5735-5810 |
Sentence |
denotes |
The RDE protein HE reversibly binds to glycans [15] through binding to SAs. |
T378 |
5811-5860 |
Sentence |
denotes |
The acetyl-esterase activity disrupts SA binding. |
T379 |
5861-6016 |
Sentence |
denotes |
HE hemagglutinates mouse erythrocytes and cleaves the acetyl-ester linkage of glycans and acetylated synthetic substrate p-nitrophenyl acetate (pNPA) [69]. |
T380 |
6017-6180 |
Sentence |
denotes |
Similar to CoV, torovirus HE is an acetylesterase type, which cleaves the O-acetyl group from the SA C-9 position using Neu5,9Ac2 and N-acetyl-7(8),9-O-NeuAc [64]. |
T381 |
6181-6433 |
Sentence |
denotes |
However, torovirus HE exhibits a restricted specificity for the Neu5,9Ac2 substrate, but not for the Neu5,7(8),9Ac3 substrate, with a unique SA-binding site generated by a single amino acid difference in porcine Thr73 and bovine Ser64 for each HE [70]. |