Identification of a genetic determinant of pathogenicity in chicken anaemia virus

Yamaguchi, Shigeo; Imada, Tadao; Kaji, Noriyuki; Mase, Masaji; Tsukamoto, Kenji; Tanimura, Nobuhiko; Yuasa, N.

doi:10.1099/0022-1317-82-5-1233

Cited by 76 publications

(62 citation statements)

References 27 publications

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“…Hence, the balancing control of efficient replication of dengue 4 virus in either mosquito or Vero cells was maintained by a single amino acid change. Within the Circoviridae family, a single amino acid mutation in the VP1 capsid protein of chicken anemia virus was found to be responsible for the pathogenicity of the virus in chickens (36). Taken together, the results from this study suggested that the P110A and R191S mutations are likely responsible for the attenuation of PCV2 VP120 in pigs and for the enhanced growth ability of PCV2 in PK-15 cells.…”

Section: Discussionmentioning

confidence: 54%

Two Amino Acid Mutations in the Capsid Protein of Type 2 Porcine Circovirus (PCV2) Enhanced PCV2 Replication In Vitro and Attenuated the Virus In Vivo

Fenaux

Opriessnig

Halbur

et al. 2004

J Virol

103

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Porcine circovirus type 2 (PCV2) is the primary causative agent of postweaning multisystemic wasting syndrome (PMWS) in pigs. To identify potential genetic determinants for virulence and replication, we serially passaged a PCV2 isolate 120 times in PK-15 cells. The viruses harvested at virus passages 1 (VP1) and 120 (VP120) were biologically, genetically, and experimentally characterized. The PCV2 VP120 virus replicated in PK-15 cells to a titer similar to that of the PK-15 cell line-derived nonpathogenic PCV1 but replicated more efficiently than PCV2 VP1 with a difference of about 1 log unit in the titers. The complete genomic sequences of viruses at passages 0, 30, 60, 90, and 120 were determined. After 120 passages, only two nucleotide mutations were identified in the entire genome, and both were located in the capsid gene: the mutations were located at nucleotide positions 328 (C328G) and 573 (A573C). The C328G mutation, in which a proline at position 110 of the capsid protein changed to an alanine (P110A), occurred at passage 30 and remained in the subsequent passages. The second mutation, A573C, resulting in a change from an arginine to a serine at position 191 (R191S), appeared at passage 120. To experimentally characterize the VP120 virus, 31 specific-pathogen-free pigs were randomly divided into three groups. Ten pigs in group 1 received phosphate-buffered saline as negative controls. Each pig in group 2 (11 pigs) was inoculated intramuscularly and intranasally with 10 4.9 50% tissue culture infective doses (TCID 50 ) of PCV2 VP120. Each pig in group 3 (10 pigs) was similarly inoculated with 10 4.9 TCID 50 of PCV2 VP1. Viremia was detected in 9 of 10 pigs in the PCV2 VP1 group with a mean duration of 3 weeks, but in only 4 of 11 pigs in the PCV2 VP120 group with a mean duration of 1.6 weeks. The PCV2 genomic copy numbers in serum in the PCV2 VP1 group were significantly higher than those in the PCV2 VP120 group (P < 0.0001). Gross and histopathologic lesions in pigs inoculated with PCV2 VP1 were more severe than those inoculated with PCV2 VP120 at both day 21 and 42 necropsies (P ‫؍‬ 0.0032 and P ‫؍‬ 0.0274, respectively). Taken together, the results from this study indicated that the P110A and R191S mutations in the capsid of PCV2 enhanced the growth ability of PCV2 in vitro and attenuated the virus in vivo. This finding has important implications for PCV2 vaccine development.

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Section: Discussionmentioning

confidence: 54%

Two Amino Acid Mutations in the Capsid Protein of Type 2 Porcine Circovirus (PCV2) Enhanced PCV2 Replication In Vitro and Attenuated the Virus In Vivo

Fenaux

Opriessnig

Halbur

et al. 2004

J Virol

103

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“…This finding indicated that these amino acid changes, which were selected by multiple cell culture passages and which result in reduced reactivity with MAb 2A9, may be responsible for the attenuation exhibited by highly passaged Cux-1 CAV. This research and that by Yamaguchi et al (10), who showed that VP1 amino acid 394 was a determinant of the pathogenicity exhibited by Japanese CAV isolates, may allow the development of highly attenuated viruses, which may be worthy of evaluation as live attenuated vaccines.…”

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confidence: 53%

Molecular Basis of the Attenuation Exhibited by Molecularly Cloned Highly Passaged Chicken Anemia Virus Isolates

Todd¹,

Scott

Ball³

et al. 2002

J Virol

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Chimeric virus experiments indicated that the pathogenicity and monoclonal antibody reactivity differences between two molecularly cloned, highly passaged chicken anemia virus isolates could be attributed to the VP1 amino acid change at residue 89. The introduction of this change into a pathogenic cloned low-passage isolate was not sufficient to cause attenuation.Chicken anemia virus (CAV) has a circular, single-stranded 2.3-kb DNA genome contained within an icosahedral capsid, 25 nm in diameter (9), and is the only member of the genus Gyrovirus of the virus family Circoviridae (6). The virus genome encodes 1 structural (VP1) and 2 nonstructural (VP2 and VP3) proteins ( Fig. 1a) (5). To date, all naturally occurring CAV isolates belong to the same serotype, and all are pathogenic when tested experimentally (2). We previously reported that molecularly cloned virus isolates that were selected from the Cuxhaven-1 (Cux) CAV isolate, which had received 310 cell culture passages (P310) in MDCC-MSB1 cells, showed variation with regard to pathogenicity and reactivity with a neutralizing monoclonal antibody (MAb), 2A9 (7,8). Of these, the attenuated P310-cloned isolate 34, which reacts weakly with MAb 2A9, differed from the pathogenic P310-cloned isolate 33, which reacts strongly with MAb 2A9, at two amino acid residues, namely, VP1 residue 89 and VP3 residue 41. In this study the significance of the VP1 amino acid change at residue 89 as a determinant of pathogenicity was investigated by producing and biologically characterizing chimeric and in-vitromutagenized viruses.The cloned low-passage Cux isolate and the P310-cloned isolates 33 and 34 were produced as described previously (4, 7). Indirect immunofluorescence (IIF) was used to determine the reactivities of the cloned, mutated, and chimeric CAV isolates with CAV-specific MAb 2A9 (7). Chimeric CAV replicative form (RF) DNAs were constructed from BamHI-PstI (BP), PstI-StuI (PS), and StuI-BamHI (SB) restriction fragments, which were produced by restricting cloned P310 RF 33 and 34 DNAs and were purified from agarose gel after electrophoretic fractionation. Following ligation, mixtures containing approximately equimolar amounts of the three fragments were used to transfect MDCC-MSB1 cells to generate the chimeric and reconstructed cloned isolate 34 (Fig. 1a and b). An additional chimeric virus isolate was produced by ligating the SB fragment derived from P310 RF 34 to the complementary BS fragment, derived from the recombinant CAV plasmid pCAA5 (4), which specifies the pathogenic cloned low-passage Cux isolate (Fig. 1c). In this case, PCR methods were used to amplify the BS and SB fragments prior to ligation and transfection. The PCR-ligation-PCR method was used to introduce a site-specific mutation by which amino acid 89 in VP1 of the cloned low-passage Cux isolate was changed from threonine to alanine to produce the VP1 aa89 Cux mutant (1). Experimental infections of 1-day-old specific-pathogen-free chicks were used to evaluate the pathogenicities of chimeric and muta...

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“…In cells infected with CAV, VP1, VP2 and VP3 are expressed, but its capsid contains only the VP1 protein. Yamaguchi et al [67] found that a single amino acid change of VP1, glutamine 394 to histidine, was crucial for the pathogenicity of CAV. In the CAV system, cells expressing either VP1 or VP2 alone were not recognised by neutralising antibody, suggesting that the non-structural protein VP2 might act as a scaffold protein in virion assembly [68].…”

Section: Proteins Of Ttv and Cavmentioning

confidence: 99%

Torque teno virus (TTV): current status

Hino

Miyata

2006

Reviews in Medical Virology

168

133

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Torque teno virus (TTV), currently classified into the family Circoviridae, genus Anellovirus, was first found in a patient with non-A-E hepatitis. TTV has a single stranded circular DNA of approximately 3.8 kb. TTVs are extraordinarily diverse, spanning five groups including SANBAN and SEN viruses. Torque teno mini virus (TTMV) with approximately 2.9 kb genome also has wide variants. Recently, two related 2.2- and 2.6-kb species joined this community. Recombinations between variants are frequent. This extensive TTV diversity remains unexplained; it is unclear how TTVs could be viable, and why they require such genetic variation. An unequivocal culture system is still not available. TTVs are ubiquitous in > 90% of adults worldwide but no human pathogenicity of TTV has been fully established. Epidemiological surveys need to specify the variants being studied and clinical targets, and must calibrate the sensitivity of the assay used. Potentially interesting observations include a higher viral load in patients with severe idiopathic inflammatory myopathies, cancer and lupus. Active replication was also found in infants with acute respiratory diseases. TTV/TTMV-related viruses were found in chimpanzees, apes, African monkeys and tupaias, and also in chickens, pigs, cows, sheep and dogs. Experimentally, rhesus monkeys were persistently infected by TTV, but only 1/53 chimpanzees. TTV transcribes three species of mRNAs, 3.0-, 1.2- and 1.0-kb in the ratio of 60:5:35. Recently, at least three mRNAs were shown in chicken anaemia virus. The genomic region -154/-76 contains a critical promoter. TTV seems to have at least three proteins; however, the definite functions of these proteins await further research work.

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Identification of a genetic determinant of pathogenicity in chicken anaemia virus

Cited by 76 publications

References 27 publications

Two Amino Acid Mutations in the Capsid Protein of Type 2 Porcine Circovirus (PCV2) Enhanced PCV2 Replication In Vitro and Attenuated the Virus In Vivo

Two Amino Acid Mutations in the Capsid Protein of Type 2 Porcine Circovirus (PCV2) Enhanced PCV2 Replication In Vitro and Attenuated the Virus In Vivo

Molecular Basis of the Attenuation Exhibited by Molecularly Cloned Highly Passaged Chicken Anemia Virus Isolates

Torque teno virus (TTV): current status

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