The Experts below are selected from a list of 6372 Experts worldwide ranked by ideXlab platform
Xiangjin Meng - One of the best experts on this subject based on the ideXlab platform.
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porcine Circovirus type 2 pcv2 pathogenesis and interaction with the immune system
Annual Review of Animal Biosciences, 2013Co-Authors: Xiangjin MengAbstract:Porcine Circovirus type 2 (PCV2) is the primary causative agent of porcine Circovirus–associated disease (PCVAD). The virus preferentially targets the lymphoid tissues, which leads to lymphoid depletion and immunosuppression in pigs. The disease is exacerbated by immunostimulation or concurrent infections with other pathogens. PCV2 resides in certain immune cells, such as macrophage and dendritic cells, and modulates their functions. Upregulation of IL-10 and proinflammatory cytokines in infected pigs may contribute to pathogenesis. Pig genetics influence host susceptibility to PCV2, but the viral genetic determinants for virulence remain unknown. PCV2 DNA and proteins interact with various cellular genes that control immune responses to regulate virus replication and pathogenesis. Both neutralizing antibodies and cell-mediated immunity are important immunological correlates of protection. Despite the availability of effective vaccines, variant strains of PCV2 continue to emerge. Although tremendous progr...
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efficacy and future prospects of commercially available and experimental vaccines against porcine Circovirus type 2 pcv2
Virus Research, 2012Co-Authors: Nathan M Beach, Xiangjin MengAbstract:Porcine Circovirus type 2 (PCV2) is the causative agent of an economically significant collection of disease syndromes in pigs, now known as porcine Circovirus associated diseases (PCVADs) in the United States or porcine Circovirus diseases (PCVDs) in Europe. Inactivated and subunit vaccines based on PCV2a genotype are commercially available and have been shown to be effective at decreasing mortality and increasing growth parameters in commercial swine herds. Since 2003, there has been a drastic global shift in the predominant prevalence of PCV2b genotype in swine populations, concurrently in most but not all cases with increased severity of clinical disease. Although the current commercial vaccines based on PCV2a do confer cross-protection against PCV2b, novel experimental vaccines based on PCV2b genotype such as modified live-attenuated vaccines are being developed and may provide a superior protection and reduce vaccine costs. In this review, we discuss the current understanding of the impact of PCV2 infection on the host immune response, review the efficacy of the currently available commercial PCV2 vaccines in experimental and field conditions, and provide insight into novel experimental approaches that are useful in the development of next generation vaccines against PCV2.
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replacement of the replication factors of porcine Circovirus pcv type 2 with those of pcv type 1 greatly enhances viral replication in vitro
Journal of Virology, 2010Co-Authors: Nathan M Beach, Nicole M Juhan, Laura Cordoba, Xiangjin MengAbstract:Porcine Circovirus type 1 (PCV1), originally isolated as a contaminant of PK-15 cells, is nonpathogenic, whereas porcine Circovirus type 2 (PCV2) causes an economically important disease in pigs. To determine the factors affecting virus replication, we constructed chimeric viruses by swapping open reading frame 1 (ORF1) (rep) or the origin of replication (Ori) between PCV1 and PCV2 and compared the replication efficiencies of the chimeric viruses in PK-15 cells. The results showed that the replication factors of PCV1 and PCV2 are fully exchangeable and, most importantly, that both the Ori and rep of PCV1 enhance the virus replication efficiencies of the chimeric viruses with the PCV2 backbone.
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Porcine Circovirus Type 2 and Porcine Circovirus-Associated Disease
Journal of Veterinary Internal Medicine, 2009Co-Authors: J. Gillespie, Tanja Opriessnig, Xiangjin Meng, K. Pelzer, Virginia Buechner-maxwellAbstract:Porcine Circovirus type 2 (PCV2) belongs to the viral family Circoviridae and to the genus Circovirus. Circoviruses are small, single-stranded nonenveloped DNA viruses that have an unsegmented circular genome. PCV2 is the primary causative agent of several syndromes collectively known as porcine Circovirus-associated disease (PCVAD). Many of the syndromes associated with PCVAD are a result of coinfection with PCV2 virus and other agents such as Mycoplasma and porcine reproductive and respiratory syndrome virus. PCV2 infection is present in every major swine-producing country in the world, and the number of identified cases of PCVAD is rapidly increasing. In the United States, the disease has cost producers an average of 3-4 dollars per pig with peak losses ranging up to 20 dollars per pig. The importance of this disease has stimulated investigations aimed at identifying risk factors associated with infection and minimizing these risks through modified management practices and development of vaccination strategies. This paper provides an overview of current knowledge relating to PCV2 and PCVAD with an emphasis on information relevant to the swine veterinarian.
Tanja Opriessnig - One of the best experts on this subject based on the ideXlab platform.
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Novel Circovirus species identified in farmed pigs designated as Porcine Circovirus 4, Hunan province, China.
Transboundary and emerging diseases, 2019Co-Authors: Hui-hui Zhang, Tian-ning Liu, Ji‐yong Zhou, Chao-ting Xiao, Tanja OpriessnigAbstract:In pigs, three Circovirus species within the genus Circovirus have been identified so far, including the non-pathogenic Porcine Circovirus 1 (PCV1), the pathogenic Porcine Circovirus 2 (PCV2) and the recently identified Porcine Circovirus 3 (PCV3). In April 2019, a new Circovirus with a distinct relationship to other Circoviruses was identified in several pigs with severe clinical disease in Hunan province, China. The size of the viral genome, tentatively designated as porcine Circovirus type 4 (PCV4), is 1,770 nucleotides (nt). PCV4 shows the highest genomic identity to mink Circovirus (66.9%) and has identities of 43.2%-51.5% to the other PCV genomes. Two major genes, a replicase (Rep) gene spanning 891 nt and a capsid (Cap) gene spanning 687 nt, were predicted. Furthermore, a TaqMan® real-time polymerase chain reaction (PCR) targeting the replicase gene was developed to investigate the prevalence of PCV4 in 187 clinical samples from Hunan province, China. The results revealed an overall PCV4 prevalence of 12.8%, with the highest positive rates in nasal swabs (28.5%, 6/21) followed by serum samples (13.4%, 11/82). The clinical significance and pathogenesis of this virus needs further investigation.
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concurrent infections are important for expression of porcine Circovirus associated disease
Virus Research, 2012Co-Authors: Tanja Opriessnig, Patrick G HalburAbstract:Porcine Circovirus type 2 (PCV2) is the essential component of porcine Circovirus disease (PCVD) as the disease syndrome is referred to in Europe and porcine Circovirus associated disease (PCVAD) as it is referred to in North America. Singular PCV2 infection rarely results in clinical disease; however, PCVAD is often accelerated in onset, enhanced in severity and prolonged in duration by concurrent viral or bacterial infections. Due to its effect on the immune system, PCV2 has also been shown to enhance protozoal, metazoal, and fungal infections. Several retrospective or cross-sectional studies have investigated the presence and prevalence of various infectious agents associated with PCVAD under field conditions. Experimental models confirm that PCV2 replication and associated lesions can be enhanced by concurrent infection with other viruses or bacteria. The exact mechanisms by which concurrent pathogens upregulate PCV2 are unknown. Co-infections may promote PCV2 infection by increasing immune host cell replication and accumulation in tissues thereby enhancing targets for PCV2 replication. It has also been proposed that co-infections interfere with PCV2 clearance by alteration of cytokine production and profiles. The outcome of differences in timing of co-infections in PCV2-infected pigs is also likely very important and is an area where more research is needed. Given the current knowledge base, it is important that veterinarians do a thorough diagnostic investigation on herds where PCVAD is a recurrent problem in order to implement the most appropriate and cost effective intervention strategies.
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Porcine Circovirus Type 2 and Porcine Circovirus-Associated Disease
Journal of Veterinary Internal Medicine, 2009Co-Authors: J. Gillespie, Tanja Opriessnig, Xiangjin Meng, K. Pelzer, Virginia Buechner-maxwellAbstract:Porcine Circovirus type 2 (PCV2) belongs to the viral family Circoviridae and to the genus Circovirus. Circoviruses are small, single-stranded nonenveloped DNA viruses that have an unsegmented circular genome. PCV2 is the primary causative agent of several syndromes collectively known as porcine Circovirus-associated disease (PCVAD). Many of the syndromes associated with PCVAD are a result of coinfection with PCV2 virus and other agents such as Mycoplasma and porcine reproductive and respiratory syndrome virus. PCV2 infection is present in every major swine-producing country in the world, and the number of identified cases of PCVAD is rapidly increasing. In the United States, the disease has cost producers an average of 3-4 dollars per pig with peak losses ranging up to 20 dollars per pig. The importance of this disease has stimulated investigations aimed at identifying risk factors associated with infection and minimizing these risks through modified management practices and development of vaccination strategies. This paper provides an overview of current knowledge relating to PCV2 and PCVAD with an emphasis on information relevant to the swine veterinarian.
Annette Mankertz - One of the best experts on this subject based on the ideXlab platform.
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interaction of the replication proteins and the capsid protein of porcine Circovirus type 1 and 2 with host proteins
Virology, 2009Co-Authors: Tim Finsterbusch, Tobias Steinfeldt, Kai Doberstein, Claudia Rodner, Annette MankertzAbstract:Porcine Circovirus type 2 (PCV2) is an important pathogen in swine, whereas porcine Circovirus type 1 (PCV1) is apathogenic. To analyze the interactions between PCV and its host, we have used a yeast two-hybrid assay to identify cellular proteins interacting with Cap and Rep proteins of both PCV genotypes. Six cellular proteins were found to interact with Cap (MKRN1, gC1qR, Par-4, NAP1, NPM1 and Hsp40) and three with Rep (ZNF265, TDG and VG5Q). These interactions were confirmed by co-immunoprecipitation. Investigation of the localisation of the proteins by immunofluorescence revealed in some cases only limited spatial overlapping with Cap, while in others a clear co-localisation and prominent protein redistribution was observed. The nine cellular proteins are associated with distinct aspects of viral lifecycle and our data is likely to support future research in the field of PCV2 pathogenesis.
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identification of a protein essential for replication of porcine Circovirus
Journal of General Virology, 1998Co-Authors: Annette Mankertz, Joachim Mankertz, Katarina Wolf, H J BuhkAbstract:The largest open reading frame of porcine Circovirus (ORF 4) encodes a protein of 312 amino acids. The predicted gene product of ORF 4 shows similarities to Rep proteins of other plant Circoviruses and geminiviruses. Three motifs have been identified that are characteristic for proteins involved in rolling circle replication and the consensus sequence for a putative dNTP-binding box (GKS) has been found. In this paper, experimental evidence is presented which indicates that ORF 4 encodes the replication protein of porcine Circovirus. After cloning of the ORF 4 gene product, it was supplied in trans in a transient replication assay. The ORF 4 gene product promoted the replication of plasmid pOP11, which carries the origin of DNA replication of porcine Circovirus. Since pOP11 itself is unable to replicate in virus-free porcine kidney cells, the ORF 4 gene product must be essential for replication of porcine Circovirus.
Daniel Todd - One of the best experts on this subject based on the ideXlab platform.
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Journal of General Virology (1997), 78, 221–227. Printed in Great Britain Sequence of porcine Circovirus DNA: affinities with plant Circoviruses
2013Co-Authors: Brian M. Meehan, Julie L. Creelan, Stewart M. Mcnulty, Daniel ToddAbstract:The complete nucleotide sequence (1759 nt) of the ssDNA genome of porcine Circovirus (PCV) was determined from a cloned dsDNA replicative form isolated from PCV-infected cells. Sequence analysis detected no significant nucleic acid or protein similarity with another animal Circovirus, chicken anaemia virus (CAV) but, surprisingly, the highest protein similarity was obtained between the product of the largest predicted PCV ORF (ORF1; encoding a potential protein of 35�7 kDa) and a putative protein encoded by the plant Circovirus banana bunchy top virus (BBTV). High protein similarity was also detected with the other plant Circoviruses subterranean clover stunt virus (SCSV) and coconut foliar decay virus (CFDV). This region of protein identity corresponds with the putative plant Circovirus replication-associated protein (Rep). The presence of a nonanucleotide sequence at the apex of a potential-stem loop structure, identical to that found in the plant Circoviruses CFDV and SCSV and similar (one mismatch) to that found in the plant Circovirus BBTV and in the geminiviruses, suggests that rolling-circle replication may operate during PCV DNA replication. These findings show that PCV is unique in that it bridges the gap between animal and plant Circoviruses. The taxonomic relationship of PCV with other members of the Circoviridae is discussed
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Genome Sequence Determinations and Analyses of Novel Circoviruses from Goose and Pigeon
Virology, 2001Co-Authors: Daniel Todd, D. Soike, Jonathan Weston, Joan A SmythAbstract:The genomes of novel Circoviruses from goose and pigeon, which were isolated using degenerate primer and inverse primer PCR methods, were cloned and sequenced. Comparative nucleotide (nt) sequence analyses showed that the goose Circovirus (GCV) and pigeon Circovirus (PiCV) possessed genomes which were 1821 and 2037 or 2036 nt, respectively, and which had features in common with the genomes of porcine Circoviruses types 1 and 2 (PCV1, PCV2) and psittacine beak and feather disease virus (BFDV), such that they can now be assigned to the genus Circovirus of the family Circoviridae. Common features include the possession of (i) a potential stem-loop/nonanucleotide motif with which the initiation of rolling circle replication of the virus DNA is associated; (ii) two major ORFs, located on the virus (V1 ORF) and complementary (C1 ORF) strands, which encode the replication-associated protein (Rep) and capsid protein, respectively; (iii) high levels of amino acid identity (41.2--58.2%) shared with other Circovirus Rep proteins; and (iv) direct/inverted repeat sequences within the putative intergenic region. On the basis of nt and amino acid sequence identities, GCV is substantially less closely related to BFDV than PiCV is to BFDV.
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Sequence of porcine Circovirus DNA: affinities with plant Circoviruses
Journal of General Virology, 1997Co-Authors: Brian M. Meehan, Julie L. Creelan, M. S. Mcnulty, Daniel ToddAbstract:The complete nucleotide sequence (1759 nt) of the ssDNA genome of porcine Circovirus (PCV) was determined from a cloned dsDNA replicative form isolated from PCV-infected cells. Sequence analysis detected no significant nucleic acid or protein similarity with another animal Circovirus, chicken anaemia virus (CAV) but, surprisingly, the highest protein similarity was obtained between the product of the largest predicted PCV ORF (ORF1; encoding a potential protein of 35.7 kDa) and a putative protein encoded by the plant Circovirus banana bunchy top virus (BBTV). High protein similarity was also detected with the other plant Circoviruses subterranean clover stunt virus (SCSV) and coconut foliar decay virus (CFDV). This region of protein identity corresponds with the putative plant Circovirus replication-associated protein (Rep). The presence of a nonanucleotide sequence at the apex of a potential-stem loop structure, identical to that found in the plant Circoviruses CFDV and SCSV and similar (one mismatch) to that found in the plant Circovirus BBTV and in the geminiviruses, suggests that rolling-circle replication may operate during PCV DNA replication. These findings show that PCV is unique in that it bridges the gap between animal and plant Circoviruses. The taxonomic relationship of PCV with other members of the Circoviridae is discussed.
Nathan M Beach - One of the best experts on this subject based on the ideXlab platform.
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efficacy and future prospects of commercially available and experimental vaccines against porcine Circovirus type 2 pcv2
Virus Research, 2012Co-Authors: Nathan M Beach, Xiangjin MengAbstract:Porcine Circovirus type 2 (PCV2) is the causative agent of an economically significant collection of disease syndromes in pigs, now known as porcine Circovirus associated diseases (PCVADs) in the United States or porcine Circovirus diseases (PCVDs) in Europe. Inactivated and subunit vaccines based on PCV2a genotype are commercially available and have been shown to be effective at decreasing mortality and increasing growth parameters in commercial swine herds. Since 2003, there has been a drastic global shift in the predominant prevalence of PCV2b genotype in swine populations, concurrently in most but not all cases with increased severity of clinical disease. Although the current commercial vaccines based on PCV2a do confer cross-protection against PCV2b, novel experimental vaccines based on PCV2b genotype such as modified live-attenuated vaccines are being developed and may provide a superior protection and reduce vaccine costs. In this review, we discuss the current understanding of the impact of PCV2 infection on the host immune response, review the efficacy of the currently available commercial PCV2 vaccines in experimental and field conditions, and provide insight into novel experimental approaches that are useful in the development of next generation vaccines against PCV2.
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replacement of the replication factors of porcine Circovirus pcv type 2 with those of pcv type 1 greatly enhances viral replication in vitro
Journal of Virology, 2010Co-Authors: Nathan M Beach, Nicole M Juhan, Laura Cordoba, Xiangjin MengAbstract:Porcine Circovirus type 1 (PCV1), originally isolated as a contaminant of PK-15 cells, is nonpathogenic, whereas porcine Circovirus type 2 (PCV2) causes an economically important disease in pigs. To determine the factors affecting virus replication, we constructed chimeric viruses by swapping open reading frame 1 (ORF1) (rep) or the origin of replication (Ori) between PCV1 and PCV2 and compared the replication efficiencies of the chimeric viruses in PK-15 cells. The results showed that the replication factors of PCV1 and PCV2 are fully exchangeable and, most importantly, that both the Ori and rep of PCV1 enhance the virus replication efficiencies of the chimeric viruses with the PCV2 backbone.