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CORD-19:12b030be66b617bec99c12d770c89cb59c3773a9 JSONTXT 7 Projects

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Id Subject Object Predicate Lexical cue
T1 0-115 Sentence denotes Changes in nonstructural protein 3 are associated with attenuation in avian coronavirus infectious bronchitis virus
T2 117-125 Sentence denotes Abstract
T3 126-350 Sentence denotes Full-length genome sequencing of pathogenic and attenuated (for chickens) avian coronavirus infectious bronchitis virus (IBV) strains of the same serotype was conducted to identify genetic differences between the pathotypes.
T4 351-760 Sentence denotes Analysis of the consensus full-length genome for three different IBV serotypes (Ark, GA98, and Mass41) showed that passage in embryonated eggs, to attenuate the viruses for chickens, resulted in 34.75-43.66% of all the amino acid changes occurring in nsp 3 within a virus type, whereas changes in the spike glycoprotein, thought to be the most variable protein in IBV, ranged from 5.8 to 13.4% of all changes.
T5 761-921 Sentence denotes The attenuated viruses did not cause any clinical signs of disease and had lower replication rates than the pathogenic viruses of the same serotype in chickens.
T6 922-1229 Sentence denotes However, both attenuated and pathogenic viruses of the same serotype replicated similarly in embryonated eggs, suggesting that mutations in nsp 3, which is involved in replication of the virus, might play an important role in the reduced replication observed in chickens leading to the attenuated phenotype.
T7 1231-1354 Sentence denotes Avian coronavirus infectious bronchitis virus (IBV) causes a highly contagious upper respiratory tract disease in chickens.
T8 1355-1523 Sentence denotes Live attenuated vaccines are used against the virus but the disease is difficult to control because cross-protection does not usually occur between different serotypes.
T9 1524-1689 Sentence denotes The respiratory disease caused by this virus can be mild to moderate and can vary depending on the breed of chicken infected as well as the strain of the virus [1] .
T10 1690-2131 Sentence denotes The virus is worldwide in distribution, and in addition to chickens, IBV has been isolated from peafowl (Galliformes) and other Electronic supplementary material The online version of this article (doi:10.1007/s11262-011-0668-7) contains supplementary material, which is available to authorized users. gamma-coronaviruses have been isolated from teal (Anas crecca), geese (Anserinae), pigeons (Columbiformes), and ducks (Anserfiformes) [2] .
T11 2132-2440 Sentence denotes Coronaviruses are enveloped viruses in the order Nidovirales and are classified based on genome organization and antigenic characteristics as alpha (previously group 1), beta (previously group 2), and gamma (previously group 3)-coronaviruses with the avian coronaviruses belonging to the gamma-coronaviruses.
T12 2441-2681 Sentence denotes Subgroups within each group have been reported, and recently, comparative full-length genome analysis placed a novel coronavirus from a beluga whale in subgroup 3b and three new coronavirus isolates from passerine birds in subgroup 3c [3] .
T13 2682-2796 Sentence denotes Infectious bronchitis virus and related isolates as well as turkey coronavirus (TCoV) are assigned to subgroup 3a.
T14 2797-2931 Sentence denotes Coronaviruses have a single-stranded positive-sense RNA genome ranging in size from 27 to 30 kb, with a 5 0 cap and a 3 0 poly-A tail.
T15 2932-3071 Sentence denotes Transcription occurs through a leader-primed RNA synthesis mechanism that results for IBV in six 3 0 co-terminal subgenomic mRNA molecules.
T16 3072-3211 Sentence denotes Four structural proteins-spike (S), envelope (E), membrane (M), and nucleocapsid (N)-along with the viral RNA make up the enveloped virion.
T17 3212-3293 Sentence denotes The N protein binds to the viral RNA forming the ribonucleoprotein (RNP) complex.
T18 3294-3386 Sentence denotes The E and the M protein are membrane bound proteins that play a role in virus assembly [4] .
T19 3387-3638 Sentence denotes The S glycoprotein on the surface of the virus mediates attachment to the host cell, is responsible for fusion of the host cell membrane and viral envelope, and in IBV, it contains epitopes that define serotype and induce neutralizing antibodies [5] .
T20 3639-3802 Sentence denotes The S glycoprotein of IBV is post-translationally cleaved into S1 and S2 subunits, and the S1 subunit is reported to have three hypervariable regions [6] [7] [8] .
T21 3803-3982 Sentence denotes Mutations, insertions, deletions, and recombination in S contribute to the genetic diversity of IBV, which is recognized as different genetic or serologic types of the virus [5] .
T22 3983-4138 Sentence denotes Two polyproteins 1a and 1ab account for approximately two-thirds of the viral genome-coding region and make up the replication transcription complex (RTC).
T23 4139-4269 Sentence denotes The polyprotein 1ab is translated through a-1 frame-shift translation mechanism that occurs approximately 20-40% of the time [9] .
T24 4270-4501 Sentence denotes The IBV 1a and 1ab polyproteins are post-translationally cleaved into 15 nonstructural proteins (nsps), nsps 2 through 16 by a papain-like protease (PLP) and the main protease (Mpro), also referred to as the 3C-like protease [10] .
T25 4502-4574 Sentence denotes IBV does not have an nsp 1 equivalent found in some other coronaviruses.
T26 4575-4656 Sentence denotes The PLP contained within nsp 3 is divided into PL1 and PL2 papain-like proteases.
T27 4657-4786 Sentence denotes The PL1 protease, present in other coronaviruses, is truncated and nonfunctional in IBV, thus PL2 cleaves nsps 2, 3, and 4 [11] .
T28 4787-4846 Sentence denotes The Mpro contained within nsp 5 cleaves nsps 5 through 16 .
T29 4847-4960 Sentence denotes The biological characteristics of many nsps have been previously reported [9, 10, [12] [13] [14] [15] [16] [17] .
T30 4961-5147 Sentence denotes In addition to nsps 3 and 5, which contain proteases PL2 and Mpro, respectively, nsps 2, 4, and 6 contain hydrophobic residues predicted to play a role in anchoring the RTC to the Golgi.
T31 5148-5229 Sentence denotes Nonstructural proteins 7, 8, 9, and 10 are reported to have RNA-binding activity.
T32 5230-5416 Sentence denotes Nonstructural protein 11/12 is the RNA-dependent RNA-polymerase, nsp 13 is a RNA helicase, nsp 14 is an exoribonuclease, nsp 15 is an endoribonuclease, and nsp 16 is a methyltransferase.
T33 5417-5576 Sentence denotes Adaptation of IBV to different hosts has been associated with changes in the S glycoprotein, suggesting that spike plays a key role in pathogenicity [18, 19] .
T34 5577-5776 Sentence denotes However, the ectodomain of the S glycoprotein from the Beaudette strain of IBV, an attenuated laboratory strain, was replaced with an S from a pathogenic strain (Mass 41 strain) of the same serotype.
T35 5777-5971 Sentence denotes This chimeric virus was shown to induce an immune response but remained nonpathogenic in chickens, indicating that the S glycoprotein is not solely responsible for pathogenicity of IBV [2, 20] .
T36 5972-6179 Sentence denotes In another study, a chimeric IBV was created with the replicase genes 1a and 1ab from the attenuated Beaudette strain, and all of the structural genes from the pathogenic Mass 41 strain including the S gene.
T37 6180-6328 Sentence denotes This chimeric virus was not pathogenic in chickens, indicating that the replicase proteins also appear to be determinants of IBV pathotype [2, 21] .
T38 6329-6539 Sentence denotes Genetic differences reported in 1a and S between virulent and avirulent strains of IBV also led others to suggest that the replicase proteins, in addition to S, are involved in the pathotype of the virus [22] .
T39 6540-6809 Sentence denotes To examine the sequence changes in individual genes associated with attenuation of IBV for chickens, we sequenced and compared the full-length consensus genomes of pathogenic IBV viruses and egg-passaged attenuated (for chickens) viruses from three different serotypes.
T40 6810-6997 Sentence denotes We also examined the replication of pathogenic and attenuated viruses in embryonated eggs and in chickens to determine whether there are differences in growth rate between the pathotypes.
T41 6998-7106 Sentence denotes Pathogenic and attenuated (for chickens) IBV strains from three different serotypes were used in this study.
T42 7107-7238 Sentence denotes The pathogenic Arkansas-Delmarva Poultry Industry Ark/Ark-DPI/81 and the Massachusetts strain Mass/Mass41/41 were obtained from Dr.
T43 7239-7241 Sentence denotes J.
T44 7242-7289 Sentence denotes Gelb, Jr. (University of Delaware, Newark, DE).
T45 7290-7391 Sentence denotes The pathogenic Georgia 98 virus, GA98/CWL0470/98 virus, was isolated in our laboratory in 1998 [23] .
T46 7392-7575 Sentence denotes The pathogenic viruses were propagated in 10-day-old embryonated chicken eggs (Ark/Ark-DPI/81 pass 6, Mass/Mass41/41 pass 8, and GA98/CWL0470/98 pass 8) as previously described [24] .
T47 7576-7775 Sentence denotes The attenuated viruses of the same strain and serotype were obtained from Intervet and were designated Ark-attenuated (Mildvac-Ark), Mass41-attenuated (Mildvac-H), and GA98attenuated (Mildvac-Ga-98).
T48 7776-7953 Sentence denotes Whole-genome nucleotide and deduced amino acid sequence analysis Viral RNA extraction, RT-PCR, library construction, and sequencing were conducted as previously described [25] .
T49 7954-8094 Sentence denotes Briefly, the viruses were filtered through a 0.8-lm filter then through a 0.22-lm filter (Millipore, Billerica, MA) prior to RNA extraction.
T50 8095-8290 Sentence denotes Viral RNA was purified using the high pure RNA isolation kit according to the manufacturer's recommendation (Roche Diagnostic Corporation, Foster City, CA) and re-suspended in DEPC-treated water.
T51 8291-8587 Sentence denotes Reverse transcription (RT) and polymerase chain reaction (PCR) amplification were performed with the Takara RNA LA PCR kit (Takara Bio Inc., Otsu, Shiga, Japan) using a random primer and an amplification primer in a strand displacement amplification reaction following the manufacture's protocol.
T52 8588-8873 Sentence denotes The sequence of the random reverse transcription primer was 5 0 -AGC GGG GGT TGT CGA ATG TTT GAN NNN N-3 0 , and the amplification primer sequence, which is designed to anneal to the complement of the conserved region on the random primer, was 5 0 -AGC GGG GGT TGT CGA ATG TTT GA-3 0 .
T53 8874-8957 Sentence denotes Both primers were obtained from Integrated DNA Technologies, Inc. (Coralville, IA).
T54 8958-9270 Sentence denotes For the RT reaction, a master mix was prepared, which included MgCl 2 (5 mM), 109 RNA PCR buffer (19) , dNTP mixture (1 mM), RNase inhibitor (1 units/ll), reverse transcriptase (0.25 units/ll), 5 0 degenerate primer (2.5 lM), and RNA (5.75 ll/reaction) then 10 ll per sample was aliquoted in a thermocycler tube.
T55 9271-9503 Sentence denotes The reaction conditions for the RT reaction were 10 min at 30°C for the primer annealing then an hour at 50°C for extension followed by a five-minute incubation at 99°C for inactivation of the enzyme and a five-minute period at 5°C.
T56 9504-9770 Sentence denotes A PCR master mix-which included at the final concentrations MgCl 2 (2.5 mM), 109 LA PCR Buffer (19) , sterilized distilled water (32.25 ll), Takara LA Taq (1.25U/50 ll), and 5 0 primer (0.2 lM)-was prepared and 10 ll of the RT reaction was added to 40 ll of the mix.
T57 9771-9907 Sentence denotes The amplification reaction consisted of a 94°C step for 2 min followed by 30 cycles of 94°C for 30 s, 60°C for 30 s, and 72°C for 3 min.
T58 9908-10092 Sentence denotes Ten PCR were combined for each virus and purified using the QIAquick PCR purification kit (QIAGEN, Foster City, CA) and then run on a 1% agarose gel to visualize the amplified product.
T59 10093-10191 Sentence denotes The PCR products were size selected by cutting out amplicons between 500 and 1500 bp from the gel.
T60 10192-10269 Sentence denotes The amplicons were purified using the QIAquick (QIAGEN) gel purification kit.
T61 10270-10447 Sentence denotes The TOPO cloning kit (Invitrogen, Life Technologies, Carlsbad CA) was used to clone the PCR products into the pCR-XL-TOPO vector according to the manufacturer's recommendations.
T62 10448-10712 Sentence denotes Then, One Shot TOPO Electrocompetent Escherichia coli cells (Invitrogen) were transformed using 30 ll of competent cells mixed with 2 ll of the ligation reaction and electroporated with settings at 20 kV and 200 X using a BioRad (BioRad Gene Pulser, Hercules, CA).
T63 10713-10828 Sentence denotes The electroporated cells were incubated at 37°C in 480 ll of Super Optimal broth medium for 1 h on a rotary shaker.
T64 10829-11039 Sentence denotes The cultures were mixed with 70% glycerol and frozen in -80°C until plated on Q-trays (Genetix, Boston, MA) containing liquid broth agar CAT#3002-032 (MP Biomedicals, LLC, Solon, Oh) with 50 lg/ml of kanamycin.
T65 11040-11242 Sentence denotes The Q-trays were pre-warmed at 37°C before the entire culture (approximately 500 ll) was spread on the plates and incubated overnight at 37°C, then robotically picked with a Q-BOT (Genetix, Boston, MA).
T66 11243-11495 Sentence denotes Plasmid DNA from the libraries of cloned cDNA fragments for each virus was isolated using an alkaline lysis method modified for the 96-well format, and incorporating both Hydra and Tomtek robots (http://www.intl-pag.org/ 11/abstracts/P2c_P116_XI.html).
T67 11496-11688 Sentence denotes Cycle sequencing reactions were performed using the BigDye TM Terminator Ò Cycle Sequencing kit Version 3.1 (Applied Biosystems, Foster City, CA) and MJ Research (Watertown, MA) thermocyclers.
T68 11689-11803 Sentence denotes Finished reactions were filtered through Sephadex filter plates into Perkin-Elmer MicroAmp Optical 96-well plates.
T69 11804-11918 Sentence denotes A 1/12-strength sequencing reaction on an ABI 3730 was used to sequence each clone from both the 5 0 and 3 0 ends.
T70 11919-11981 Sentence denotes Each viral genome was sequenced to approximately 109 coverage.
T71 11982-12081 Sentence denotes The accuracy of the sequence was ensured by generating data in both the 5 0 and the 3 0 directions.
T72 12082-12247 Sentence denotes Gaps and areas with less than 29 coverage were identified and specific primers were synthesized (IDT) for RT-PCR amplification and sequencing of the ambiguous areas.
T73 12248-12492 Sentence denotes The RT-PCR was conducted as described above, and the reaction conditions were 42°C for 60 min, 95°C for 5 min, then 10 cycles of 94°C for 30 s, 50°C for 30 s, 68°C for 90 s, followed by 25 cycles of 94°C for 30 s, 50°C for 30 s, 68°C for 90 s ?
T74 12493-12509 Sentence denotes 5 s/cycle added.
T75 12510-12597 Sentence denotes The final elongation step was 68°C for 7 min, and then, the reaction was cooled to 4°C.
T76 12598-12816 Sentence denotes The PCR products were sequenced in both directions using the ABI Prism BigDye Terminator v3.0 (Applied Biosystems, Foster City, CA) and the specific primers that were used for amplification at a concentration of 15 ng.
T77 12817-12962 Sentence denotes The amount of cDNA added to the reaction ranged from 20 to 30 ng, and the sequencing reactions were analyzed on an ABI 3730 (Applied Biosystems).
T78 12963-13129 Sentence denotes Chromatogram files and trace data were read and assembled using SeqMan Pro, and genome annotation was conducted with SeqBuilder (DNASTAR, Inc., v.8.0.2, Madison, WI).
T79 13130-13249 Sentence denotes Low-quality segments and vector sequence were trimmed from the ends of each sequence and removed from further analysis.
T80 13250-13430 Sentence denotes Full-length genomes were uploaded to the National Center for Biotechnology Information (NCBI) open reading frame (ORF) finder (http://www.ncbi. nlm.nih.gov/gorf/) to identify ORFs.
T81 13431-13619 Sentence denotes Nucleotide and deduced amino acid alignments were generated using ClustalW, and phylogenetic trees with 1,000 bootstrap replicates were constructed in the MegAlign program (DNASTAR, Inc.).
T82 13620-13736 Sentence denotes Hydrophilicity analysis using Hopp-Woods and Kyte-Doolittle were conducted with the Protean program (DNASTAR, Inc.).
T83 13737-13903 Sentence denotes The viruses were titrated in 10 day of incubation embryonated eggs to obtain a 50% embryo infectious dose (EID 50 ) according to previously published procedures (24).
T84 13904-14026 Sentence denotes Two-week-old chickens were given 1 9 10 4 EID 50 of virus in 100 ll of PBS equally divided intraocularly and intranasally.
T85 14027-14111 Sentence denotes Due to isolator availability, different numbers of birds were tested for each virus.
T86 14112-14306 Sentence denotes Six birds were given Ark/ Ark-DPI/81, 20 birds were given Ark attenuated, 10 birds each were given Mass/Mass41/41, Mass attenuated, and GA98 attenuated, and 12 birds were given GA98/ CWL0470/98.
T87 14307-14365 Sentence denotes Each of the negative control groups consisted of 10 birds.
T88 14366-14516 Sentence denotes Clinical signs and lesions were recorded, and tracheal swabs were collected and placed in 1 ml of ice-cold PBS (pH 7.4) at 5 days post-exposure [26] .
T89 14517-14626 Sentence denotes The presence of virus in the tracheal swab supernatant was determined by quantitative real-time RT-PCR [27] .
T90 14627-14782 Sentence denotes Tracheas were collected in 10% neutral buffered formalin, routinely processed into paraffin, and 5-lm sections were cut for hematoxylin and eosin staining.
T91 14783-14949 Sentence denotes Epithelial hyperplasia, lymphocyte infiltration, and the severity of epithelial deciliation were scored for each trachea with 1 being normal and 4 being severe [28] .
T92 14950-15108 Sentence denotes As a measure of adaptation, we examined the growth of the Ark/Ark-DPI/81, Ark attenuated, Mass/Mass41/41 and Mass41-attenuated in embryonated eggs and chicks.
T93 15109-15207 Sentence denotes Because of limited isolator availability, we did not include the GA 98 viruses in this experiment.
T94 15208-15367 Sentence denotes Virus growth in embryonated eggs was examined by inoculating 1 9 10 5 EID 50 of each virus into 30 eggs at 10 days of incubation via the chorioallantoic route.
T95 15368-15479 Sentence denotes For each virus, allantoic fluid was harvested from five eggs at 12, 24, 36, 48, 72, and 96 h after inoculation.
T96 15480-15611 Sentence denotes The amount of virus present in fresh (not previously frozen) allantoic fluid was determined by quantitative real-time RT-PCR [27] .
T97 15612-15773 Sentence denotes To examine virus growth in chicks, 1 9 10 5 EID 50 of each virus was inoculated into 30 specific pathogen-free chicks at 1 day of age via the ocular/nasal route.
T98 15774-15922 Sentence denotes Tracheal swabs were collected from each of five birds at 12, 24, 36, 48, 72, and 96 h after inoculation and placed in 1 ml of ice-cold PBS (pH 7.4).
T99 15923-15985 Sentence denotes Once the birds were swabbed, they were removed from the study.
T100 15986-16131 Sentence denotes The amount of virus present in the fresh (not previously frozen) tracheal swab supernatant was determined by quantitative real-time RT-PCR [27] .
T101 16132-16237 Sentence denotes Sequences generated in this study were submitted to GenBank and assigned the following accession numbers:
T102 16238-16409 Sentence denotes Ark/Ark-DPI/81 (GQ504720); Ark-attenuated (GQ504721); GA98/CWL0470/98 (GQ504722); GA98-attenuated (GQ50 4723); Mass/Mass41/41 (GQ504724); and Mass41-attenuated (GQ504725).
T103 16410-16704 Sentence denotes The consensus sequence of the full-length genomes of Ark/ Ark-DPI/81, Ark-attenuated, GA98/CWL0470/98, GA98attenuated, Mass/Mass41/41, and Mass41-attenuated were sequenced, and the genome sizes were found to be 27,651 nt, 27,620 nt, 27,638 nt, 27,621 nt, 27,475 nt, and 27,451 nt, respectively.
T104 16705-16918 Sentence denotes The genome organization consisting of a 5 0 untranslated region (UTR), polyproteins 1a and 1ab, spike, 3a, 3b, envelope, membrane, 4b, 5a, 5b, nucleocapsid, and 3 0 UTR was the same for all six viruses (Table 1) .
T105 16919-16987 Sentence denotes Gene locations for the nsps in ORF 1a and 1ab are shown in Table 2 .
T106 16988-17141 Sentence denotes The 4b protein, previously recognized in M41 [21] , is 94 amino acids long and located downstream from the membrane protein in all the viruses sequenced.
T107 17142-17301 Sentence denotes A BLAST search was conducted, and we found the protein to have 96% sequence identity with the 4b protein from TCoV (TCoV, GenBank accession number EU022526.1).
T108 17302-17459 Sentence denotes In addition, a 6b protein downstream of the nucleocapsid protein was similar to the predicted 6b ORF reported for TCoV (GenBank accession number EU022526.1).
T109 17460-17545 Sentence denotes The 6b ORF was identified in the Ark and GA98 viruses but not in the Mass 41 viruses.
T110 17546-17831 Sentence denotes Alignment and phylogenetic analysis of the full-length genomes show that Ark/Ark-DPI/81 has 99.1% sequence identity with Ark-attenuated, GA98/CWL0470/98 has 97.1% sequence identity with GA98-attenuated, and Mass/ Mass41/41 has 92.3% sequence similarity with Mass41attenuated (Fig. 1) .
T111 17832-17960 Sentence denotes Nucleotide and amino acid sequence differences were identified between each of the pathogenic and attenuated viruses (Table 3) .
T112 17961-18336 Sentence denotes When the genome sequences are compared, there are 249 nucleotide (nt) changes resulting in 62 amino acid changes in the coding regions between the Ark viruses, 629 nt changes resulting in 268 amino acid changes between the GA98 viruses, and 1,805 nt changes resulting in 462 amino acid changes between the Mass 41 viruses (see Table 3 and Supplemental data Tables 5 and 6 ).
T113 18337-18403 Sentence denotes The size of the 5 0 UTR is 528 nt for all the viruses ( Table 1 ).
T114 18404-18502 Sentence denotes The number of nt differences between the Ark viruses for the 5 0 UTR was 25 with a 95.6% identity.
T115 18503-18654 Sentence denotes The GA98 viruses have 6 nt differences with 98.9% identity, and the Mass viruses have 12 nt differences with 98.3% identity in the 5 0 UTR ( Table 3 ).
T116 18655-18920 Sentence denotes The leader junction sequence, nucleotides 57-64 (5 0 -CTTAACAA), were found to be identical for the Ark and Mass viruses, whereas the GA98/CWL0470/98 pathogenic virus leader junction sequence is 5 0 -CTCAACAA and the GA98 attenuated virus sequence is 5 0 -CTTTACAA.
T117 18921-19095 Sentence denotes The transcriptional regulatory sequences (TRS) were identical in all of the viruses and were 5 0 -CTGAACAA-3 0 for mRNAs 2 and 3, and 5 0 -CTTAACAA-3 0 for mRNAs 4, 5, and 6.
T118 19096-19303 Sentence denotes The size of the 3 0 UTRs is 273 nt for Ark/Ark-DPI/81 pathogenic and Ark-attenuated, 276 nt for GA98/ CWL0470/98, 244 nt for GA98-attenuated, and 322 nt for Mass/Mass41/41, and Mass41-attenuated ( Table 1 ).
T119 19304-19398 Sentence denotes The number of nt differences within the 3 0 UTRs for the Ark viruses is 6 with 98.5% identity.
T120 19399-19562 Sentence denotes The GA98 viruses have 9 nt differences resulting in 97.1% identity, and the Mass viruses have 2 nt differences with 99.4% identity within the 3 0 UTRs ( Table 3) .
T121 19563-19687 Sentence denotes The 3 0 UTRs contain the S2M motif, which is 41 nt long with a sequence identity of 92.7% or higher between the six viruses.
T122 19688-19955 Sentence denotes Analysis of the locations and number of sequence differences between pathogenic and attenuated viruses of the same serotype for individual nsps in polyproteins 1a and 1a/b (Table 3) shows that nsp 3 has the highest number of amino acid differences among all the nsps.
T123 19956-20072 Sentence denotes In addition, nsp 3 has the greatest number of differences when coding regions across the entire genome are compared.
T124 20073-20181 Sentence denotes A schematic representation of nsp 3 and number of amino acid changes in each domain is presented in Fig. 2 .
T125 20182-20802 Sentence denotes The nsp 3 ORF has 43.66% of all amino acid differences observed between Ark/Ark-DPI/81 and Ark-attenuated (including a ten amino acid deletion in the attenuated virus at positions 789-798), 34.75% of all amino acid differences observed between GA98/CWL0470/98 and GA98-attenuated (including an eight amino acid deletion in the pathogenic virus at positions 901-908 and a three amino acid deletion in the pathogenic virus at positions 950-952), and 37.08% of all amino acid differences observed between Mass/Mass41/41 and Mass-attenuated (including a ten amino acid deletion in the attenuated virus at positions 797-806).
T126 20803-20934 Sentence denotes These changes represent 1.96, 5.18, and 11.06 differences per 100 amino acids within nsp 3 for Ark, GA98 and Mass 41, respectively.
T127 20935-21107 Sentence denotes We also found a virus subpopulation within the Ark/Ark-DPI/81 strain, which had a ten amino acid deletion in nsp 3 at positions 789-798 similar to the Ark-attenuated virus.
T128 21108-21355 Sentence denotes The catalytic triad of the PL2 protease, amino acids Cys623, Hys786, Asp802 [29] was conserved among all of the viruses, and a hydrophobicity plot of nsp 3 predicted fours transmembrane regions between amino acids 1,000 and 1,300 (data not shown).
T129 21356-21518 Sentence denotes The fewest amino acid changes for the nsps between pathogenic and attenuated viruses within a serotype are found in nsps 7-10, which are the RNA-binding proteins.
T130 21519-21840 Sentence denotes The polyprotein 1ab-1 frame-shift slippery sequence (5 0 -UUUAAAC) is conserved among all six viruses but the location was found at nt 12,328 for Ark/Ark-DPI/81, nt 12,298 for Ark-attenuated, nt 12,321 for GA98/CWL0470/ 98, nt 12,360 for GA98-attenuated, nt 12,391 for Mass/ Mass41/41 and nt 12,327 for Mass41-attenuated.
T131 21841-21986 Sentence denotes The percent amino acid identity for the S glycoprotein is 97.8% for Ark viruses, 96.6% for GA98 viruses, and 97.2% for Mass 41 viruses (Fig. 3) .
T132 21987-22163 Sentence denotes The number of amino acid differences within the S glycoprotein between pathogenic and attenuated viruses are 7, 33, and 27 for Ark, GA98, and Mass 41, respectively ( Table 3 ).
T133 22164-22356 Sentence denotes The S glycoprotein for the Ark viruses had 9.86% (0.60 differences/100 amino acids) of all amino acid differences, which is the third most variable ORF in the entire genome after nsp 3 and 12.
T134 22357-22556 Sentence denotes For the GA98 viruses, the S glycoprotein has 13.36% (2.82 differences/100 amino acids) of all amino acid differences, which is the third most variable ORF in the entire genome after nsp 3 and ORF 6b.
T135 22557-22758 Sentence denotes The S glycoprotein for the Mass 41 viruses has 5.77% of all amino acid differences (2.31 differences/100 amino acids), which was the fourth most variable ORF in the entire genome after nsp 3, 2, and 4.
T136 22759-22927 Sentence denotes ORF 3b has the fewest number of differences with no differences observed between the Ark viruses, whereas the GA98 and Mass viruses each have one amino acid difference.
T137 22928-23136 Sentence denotes For ORF 4b, no amino acid differences are observed for the Ark viruses, 16 amino acid differences are observed between the GA98 viruses, and 17 amino acid differences are observed between the Mass 41 viruses.
T138 23137-23369 Sentence denotes The Ark virus 6b proteins have only one amino acid mutation and are 99.9% similar to each other, whereas the GA98 virus 6b proteins have 43 amino acid mutations, 3 amino acid deletions, and 1 substitution and are only 41.9% similar.
T139 23370-23663 Sentence denotes Because this protein has not been previously recognized in IBV, a nucleotide BLAST search rather than an amino acid search was conducted and showed that the GA98/CWL0470/98 virus has 98% identity with Mass H120 (FJ888351) and the GA98-attenuated virus has 98% identity with Ark-DPI (EU418976).
T140 23664-24043 Sentence denotes To determine whether the GA98-attenuated virus 6b sequence was a subpopulation within the GA98/CWL0470/98 virus, two forward primers (GA98A #1 5 0 -TCACGCTCAAGTTCAAGACCTG-3 0 , and GA98A #3 5 0 -CAGCTTTAGGTGAGAATGAACT-3 0 ) and two reverse primers (GA98A #2 5 0 -TACGATAAAACAA ACTAATGAGAA-3 0 , and GA98A #4 5 0 -TTGATAGGAA AGCACAGAAATAG-3 0 ) specific for the GA98-attenuated 1M
T141 24044-24375 Sentence denotes a Positions are based on 1ab from TCoV (accession number YP_001941164) and presented as the residue position with 1 being the methionine at the beginning of ORF 1a and 1ab followed by the single letter code for the amino acid at that position 6b sequence were used in combination in an RT-PCR assay, but no amplicons were observed.
T142 24376-24976 Sentence denotes The data on pathogenicity of the viruses in 2-week-old SPF chicks are presented in Table 4 . a Birds were given 1 9 10 4 50% embryo infectious doses intraocularly/intranasally and examined for clinical signs, virus, and lesions at 5 days post-inoculation b Virus was detected in tracheal swabs by real-time RT-PCR as previously described Callison et al. [27] c Epithelial hyperplasia, lymphocyte infiltration, and the severity of epithelial deciliation were scored for each trachea with one being normal and four being severe d A representative control group from one of the experiments is presented.
T143 24977-25051 Sentence denotes All of the data from the negative control groups were the same (Fig. 4a) .
T144 25052-25464 Sentence denotes The Ark-attenuated virus, which is adapted to embryonated eggs, only killed Chicks inoculated with virus at 1 day of age showed statistical differences (P B 0.1) in the amount of virus detected in the trachea between the Ark/Ark-DPI/81 and Ark-attenuated viruses at 24, 48, 72, and 96 h post-inoculation with the pathogenic Ark/Ark-DPI/81 having the higher amount of virus at each of the sample times (Fig. 4b) .
T145 25465-25679 Sentence denotes Although not statistically different, the chicks given the pathogenic Ark/Ark-DPI/81 virus also had more virus detected in the trachea than the chicks given the Ark-attenuated virus at 12 and 36 h post-inoculation.
T146 25681-25925 Sentence denotes Many studies have examined sequence changes in the structural proteins of IBV and found that most of the changes associated with adaptation to a particular host or with a particular virus pathotype occur in the spike glycoprotein [18, 19, 30] .
T147 25926-26062 Sentence denotes But only a few studies have examined changes across the entire genome associated with biological characteristics of the virus [22, 31] .
T148 26063-26299 Sentence denotes Ammayappan et al. [22] found a total of 17 amino acid changes between the genomes of Ark DPI 11, a pathogenic virus and Ark DPI 101 an attenuated virus, with four amino changes in nsp 3 and six amino acid changes in the S1 glycoprotein.
T149 26300-26446 Sentence denotes Based on that data, it was suggested that changes in the replicase sequence in addition to structural proteins might play a role in pathogenicity.
T150 26447-26701 Sentence denotes Fang et al. [31] found 53.06% of all amino acid substitutions across the entire genome were located in the spike glycoprotein following adaptation of an attenuated avian coronavirus to primate cells, suggesting that spike plays a role in host adaptation.
T151 26702-27023 Sentence denotes In this study, we analyzed the consensus full-length genome for the pathogenic and attenuated viruses of three different IBV types and showed that within a virus type, 34.75 to 43.66% of all the amino acid changes between the pathotypes occurred in nsp 3, whereas changes in spike ranged from 5.8 to 13.4% of all changes.
T152 27024-27203 Sentence denotes It should be noted, however, that spike had the highest number of differences between different serotypes of the virus, which is consistent with previous reports [5] [6] [7] [8] .
T153 27204-27361 Sentence denotes A high percentage of differences between pathogenic and attenuated viruses within a serotype in nsp 3 suggests this region plays a key role in pathogenicity.
T154 27362-27481 Sentence denotes The nsp 3 is a complex protein with multiple domains making it an attractive target for antiviral drug design [9, 32] .
T155 27482-27677 Sentence denotes It is approximately 1,600 amino acid residues in length and consists of an acidic domain, an ADP-ribose 1 phosphatase, the PL2 protease (a deubiquitinating protease), Y and transmembrane domains.
T156 27678-27869 Sentence denotes The acidic domain is of unknown function, however; there is some evidence that it possesses nucleic acid binding activity because it is consistently co-purified with singlestranded RNA [33] .
T157 27870-28014 Sentence denotes Previous studies with other organisms indicate that electrostatic interactions from this type of domain play a key role in ligand binding [34] .
T158 28015-28175 Sentence denotes Influenza A viruses also contain a polymerase acidic protein (PA) that is required for the transcription and replication activity of the viral polymerase [34] .
T159 28176-28360 Sentence denotes Differences between pathogenic and attenuated IBV strains within a serotype, including deletions in Ark and Mass41 viruses, were in and around the acidic domain within nsp 3 (Fig. 2) .
T160 28361-28514 Sentence denotes Thus, it is likely that the acidic domain plays a role in attenuation in chickens but the exact function(s) of the amino acids in this domain is unclear.
T161 28515-28718 Sentence denotes It was interesting that we observed an eight and a three amino acid deletion in the pathogenic virus GA98/CWL0470/98 at positions 901-908 and 950-952, respectively, compared to the GA98-attenuated virus.
T162 28719-28955 Sentence denotes Since sequence insertions are not likely to occur during the attenuation process, the GA98-attenuated virus possibly represents a minor undetected subpopulation in the pathogenic virus, which was selected by passage in embryonated eggs.
T163 28956-29075 Sentence denotes The ADP-ribose-1 phosphatase domain within nsp 3 is relatively conserved between the pathogenic and attenuated strains.
T164 29076-29211 Sentence denotes This domain has been shown in the Beaudette laboratory attenuated strain of IBV not to function as an ADP-ribose binding protein [35] .
T165 29212-29413 Sentence denotes However, the triple glycine sequence that forms part of the ADP-ribose binding site (Gly47-Gly48-Gly49), which was not conserved in Beaudette, is conserved in all of the viruses sequenced herein [35] .
T166 29414-29611 Sentence denotes This suggests that the ADP-ribose-1 protein may be functional in the pathogenic and attenuated IBV viruses and is consistent with the results of the Mass 41-X domain as reported by Xu et al. [14] .
T167 29612-29851 Sentence denotes The ADP-ribose-1 phosphatase may be important in pathogenicity of IBV because it has been shown to play a role in ADP ribosylation, a post-translational protein modification involved in DNA damage repair and transcription regulation [14] .
T168 29852-30083 Sentence denotes In addition, it was reported that the ADP-ribose-1 is dispensable for viral replication in tissue culture, suggesting that this domain is involved in regulation of viral replication rather than the actual replication process [36] .
T169 30084-30191 Sentence denotes The PL2 domain is a papain-like protease that is responsible for the cleavage of the nsp 2/3 and 3/4 sites.
T170 30192-30316 Sentence denotes Most coronaviruses have two papain-like proteases; however, in IBV the PL1 protease is truncated and is nonfunctional [16] .
T171 30317-30415 Sentence denotes The structure of the PL2 protease domain was determined to be a ''thumb-palm-finger'' motif [37] .
T172 30416-30731 Sentence denotes This domain has also been shown to be a potent IFN antagonist by inhibiting the phosphorylation and nuclear translocation of interferon regulatory factor 3 (IRF-3) causing a disruption in the activation of the type I IFN response through Toll-like receptor 3 (TLR 3) or retinoic acid-inducible gene I (RIG-I) [38] .
T173 30732-31000 Sentence denotes Although the catalytic triad of the PL2 protease is conserved, amino acid changes between the pathogenic and attenuated viruses are observed in the PL2 protease, which could affect the efficiency of this IFN antagonist leading to altered viral replication in the cell.
T174 31001-31144 Sentence denotes The disruption of IFN signaling has been shown in many viral infections, including SARS-CoV, dengue virus, and paramyxoviruses [39] [40] [41] .
T175 31145-31257 Sentence denotes The IBV PL2 viral protease was also shown to have characteristics similar to ubiquitin-specific proteases [42] .
T176 31258-31505 Sentence denotes Deubuquitinating proteases, which remove ubiquitin from proteins that have been marked by cellular mechanisms for ATP-dependent degradation, could be a potential mechanism by which the virus can alter the cellular environment favoring replication.
T177 31506-31749 Sentence denotes The Y domain, containing transmembrane domains at its N-terminus, was originally described by Gorbalenya et al. [43] and has been predicted to consist of three domains Y1, Y2, and Y3, which may act together to form an enzymatic function [32] .
T178 31750-31938 Sentence denotes The transmembrane domain is inserted into the endoplasmic reticulum (ER) membrane co-translationally and plays an important scaffolding role for the replication transcription complex [9] .
T179 31939-32185 Sentence denotes Recently, it was shown that three transmembrane domains were predicted for the SARS-CoV nsp 3 but only two were found to span the ER membrane orienting the protease domain of nsp 3 on the cytoplasmic side where viral replication occurs [13, 15] .
T180 32186-32381 Sentence denotes In murine hepatitis virus (MHV), five transmembrane domains were predicted but only two domains were found to span the membrane, also locating the protease domain on the cytoplasm side [13, 15] .
T181 32382-32457 Sentence denotes Our sequence data for IBV predicts four transmembrane domains within nsp 3.
T182 32458-32612 Sentence denotes Assuming the protease domain is located on the cytoplasm side of the membrane, we predict that either two or all four transmembrane domains would be used.
T183 32613-32893 Sentence denotes A chimera IBV containing the replicase genes 1a and 1a/b from the attenuated Beaudette strain and the structural genes from the pathogenic Mass 41 strain was not pathogenic in chickens, indicating that the replicase proteins appear to be determinants of pathotype in IBV [2, 21] .
T184 32894-33010 Sentence denotes Our data strongly support these studies and further indicate that changes in nsp 3 play a key role in IBV pathotype.
T185 33011-33202 Sentence denotes It should also be emphasized that pathogenicity in avian coronaviruses is likely polygenic, since we and others [22] observed amino acid substitutions in other viral proteins including spike.
T186 33203-33326 Sentence denotes The 6b ORF detected in TCoV (GenBank accession numbers ACB87503 and ACB87504) is identified in Ark and GA98 viruses herein.
T187 33327-33499 Sentence denotes Only one amino acid difference was observed between the Ark viruses, but 43 differences as well as 3 amino acid deletions and 1 insertion are observed between GA98 viruses.
T188 33500-33628 Sentence denotes An attempt to identify a subpopulation in the GA98/CWL0470/98 pathogenic virus with the GA98attenuated gene 6b was unsuccessful.
T189 33629-33781 Sentence denotes It is not clear why gene 6b is so variable between the GA98 viruses but it appears recombination rather than mutations over time may have played a role.
T190 33782-34009 Sentence denotes A nucleotide blast analysis indicated that the GA98/CWL040/98 virus was 98% similar to Mass H120 a vaccine virus and the GA98-attenuated virus was 98% similar to Ark-DPI a pathogenic virus, suggesting an origin for those genes.
T191 34010-34114 Sentence denotes Nonetheless, assuming the 6b ORF is expressed, it apparently does not play a role in defining pathotype.
T192 34115-34216 Sentence denotes Interestingly, we find differences between pathogenic and attenuated viruses in the 5 0 and 3 0 UTRs.
T193 34217-34309 Sentence denotes The 5 0 and 3 0 UTRs play key roles in transcription and replication of coronaviruses [44] .
T194 34310-34547 Sentence denotes However, the differences between the Ark and Mass viruses, which are 25 nt and 12 nt, respectively, for the 5 0 UTR, and 6 nt and 2 nt, respectively, for the 3 0 UTR did not appear to affect replication as determined in embryonated eggs.
T195 34548-34714 Sentence denotes The TRS sequences for generation of the subgenomic mRNAs were identical in all of the viruses; however, the leader junction sequences were different for GA98 viruses.
T196 34715-34872 Sentence denotes Different leader junction sequences could be important for attenuation since efficiency of subgenomic mRNA production would affect growth of the virus [45] .
T197 34873-34982 Sentence denotes Differences are observed in the amount of virus detected in chickens given viruses with different pathotypes.
T198 34983-35258 Sentence denotes When the same amount of virus was administered, birds given the attenuated virus compared to birds given the homologous pathogenic virus had less virus detected in the trachea at all sampling times and the difference was statistically significant for most of the time points.
T199 35259-35396 Sentence denotes Thus, it appears that the amount of IBV replication in the trachea correlates with the ability of the virus to cause disease in chickens.
T200 35397-35620 Sentence denotes Attachment and entry, and replication of the attenuated virus (for chickens) were not impaired because it grew to the same titer (with the exception of one time point) as the pathogenic virus in 10-day-old embryonated eggs.
T201 35621-35719 Sentence denotes Inefficient attachment and entry into chicken host cells in vivo could be due to changes in spike.
T202 35720-35936 Sentence denotes And decreased replication of the attenuated viruses could be due to the inability of the virus to overcome some as yet unidentified innate defense mechanism(s) in chicken cells that is not present in embryonic cells.
T203 35937-36066 Sentence denotes Domains within nsp 3 associated with the deubiquitinating protease or IFN antagonists are likely candidates for further research.
T204 36067-36286 Sentence denotes In summary, we find that most changes associated with attenuation of IBV for chickens are located within nsp 3 and that the attenuated viruses have reduced replication in chickens but not in 10-day-old embryonated eggs.
T205 36287-36512 Sentence denotes Changes in spike suggest that attachment and entry may have been affected and changes in nsp 3 suggest that the attenuated virus lost the ability to overcome some innate host cell defense mechanism in the mature chicken cell.
T206 36513-36810 Sentence denotes The exact mechanism(s) surrounding the interaction of virus and host processes affecting virus replication have yet to be determined for IBV, but identifying the sequence changes in the virus responsible for reduced replication and attenuation is an important step in elucidating those mechanisms.
T207 36811-36957 Sentence denotes Finally, changes observed in nsp 3 and spike as well as in other viral genes support the polygenic nature of pathogenicity in avian coronaviruses.