Download or read book Molecular and Phylogenetic Analysis of Porcine Reproductive and Respiratory Syndrome Virus Prrsv and Porcine Circovirus Type 2 Pcv2 written by Yick-Yeung Li and published by Open Dissertation Press. This book was released on 2017-01-27 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: This dissertation, "Molecular and Phylogenetic Analysis of Porcine Reproductive and Respiratory Syndrome Virus (PRRSV) and Porcine Circovirus Type 2 (PCV2)" by Yick-yeung, Li, 李亦揚, was obtained from The University of Hong Kong (Pokfulam, Hong Kong) and is being sold pursuant to Creative Commons: Attribution 3.0 Hong Kong License. The content of this dissertation has not been altered in any way. We have altered the formatting in order to facilitate the ease of printing and reading of the dissertation. All rights not granted by the above license are retained by the author. Abstract: Abstract of thesis entitled MOLECULAR AND PHYLOGENETIC ANALYSIS OF PORCINE REPRODUCTIVE AND RESPIRATORY SYNDROME VIRUS (PRRSV) AND PORCINE CIRCOVIRUS TYPE 2 (PCV2) Submitted by Yick Yeung LI for the Degree of Master of Philosophy (MPhil) at The University of Hong Kong in November 2003 Porcine reproductive and respiratory syndrome virus (PRRSV) and postweaning multisystemic wasting syndrome (PMWS) have caused a huge economical loss in the global swine industry. The aim of this study is to characterize the prevalence and phylogenetic relationship of local PRRSV and porcine circovirus type 2 (PCV2, causative agent of PMWS), and to develop a DNA vaccine against PRRSV. In this study, PRRSV (26% of tested pigs) and PCV2 (15% of tested pigs) were identified in local swineherds. Phylogenetic analysis on eighteen local PRRSVs from different pig farms demonstrated the existence of both European (45%) and North American (55%) genotypes. Also, the local European typed virus and North American typed virus showed that the amino acid identity of nucleocapsid protein ranged from 89.1% to 95.3% and 94.4% to 98.4% when compared to their respective prototypes. However, the average pairwise genetic distances of the European genotype and North American genotype were found to be 0.047 and 0.065, respectively, suggesting that the PRRSVs with North American genotype was more diverse than those with European genotype. In addition, two sub-branches of European typed PRRSVs and at least four sub-branches of North American typed PRRSVs were identified in local pig farms. Using the phylogenetic tree analysis on the basis of complete nucleotide sequence of local PCV2 viruses and PCV2 isolates around the world, the nucleotide homology of local viruses ranged from 96.1% to 99.9% whereas the nucleotide homology of that with other PCV2 strains ranged from 94.2% to 99.9%. Also, the amino acid identity of the capsid protein of the 10 local PCV2 ranged from 93.2% to 99.6%. Besides, eight PCV2 infected pigs were found to be co-infected with PRRSV. Among them, six were co-infected with North American PRRSV genotypes, one with European genotype and one with both genotypes. To summarize, at least three different PCV2 sub-branches were identified and co-infection with both PRRSV and PCV2 were found in Hong Kong. Apart from the phylogenetic analysis of the two viruses, four mutants with truncated putative signal sequence (Δ 5.4, Δ 5.5, Δ5.6 and Δ5.7) were constructed, based on the hydropathy profile of the PRRSV (strain AV), for DNA vaccine development against PRRSV. Among all mutants, only mutants Δ5.6 and Δ5.7 demonstrated a high level of expression in E. coli. when compared to the full-length (ORF5) construct and were expressed in transfected COS-7 cell lines. Both mutants triggered humoral responses in immunized mice and pigs. In mice, the antibody titer peaked at week 3 and was sustained for at least another three weeks while serum neutralizing antibody was detected in pigs at week 4 and maintained until week 8 at variable levels. Therefore, these two deletion mutants are potential candidates for DNA vaccine development. DOI: 10.5353/th_b2929710 Subjects: Swine - Virus diseases - Genetic aspects DNA vaccines

Download or read book Molecular and Phylogenetic Analysis of Porcine Reproductive and Respiratory Syndrome Virus PRRSV and Porcine Circovirus Type 2 PCV2 written by Yick-yeung Li and published by . This book was released on 2003 with total page 242 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Molecular Epidemiology and Characterization of the Receptor Binding of Porcine Circovirus Type 2 Pcv2 written by Ching-Man Ma and published by . This book was released on 2017-01-27 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: This dissertation, "Molecular Epidemiology and Characterization of the Receptor Binding of Porcine Circovirus Type 2 (PCV2)" by Ching-man, Ma, 馬靜雯, was obtained from The University of Hong Kong (Pokfulam, Hong Kong) and is being sold pursuant to Creative Commons: Attribution 3.0 Hong Kong License. The content of this dissertation has not been altered in any way. We have altered the formatting in order to facilitate the ease of printing and reading of the dissertation. All rights not granted by the above license are retained by the author. Abstract: Abstract of thesis entitled MOLECULAR EPIDEMIOLOGY AND CHARACTERIZATION OF THE RECEPTOR BINDING OF PORCINE CIRCOVIRUS TYPE 2 (PCV2) Submitted by Ching Man MA for the degree of Master of Philosophy at The University of Hong Kong in November 2006 Porcine circovirus type 2 (PCV2) belongs to the family Circoviridae, which is the causative agent of postweaning multisystemic wasting syndrome (PMWS) in pigs. To investigate the evolution and pathogenicity of PCV2, molecular epidemiology was studied using a bioinformatic approach. In addition, receptor binding of PCV2 was studied using cell-binding assays. Classification of worldwide PCV2 strains designated five major PCV2 lineages (I-V) following phylogenetic analysis. It was found the local and worldwide strains were mainly originated from sub-lineage Ia. Evidences for recombination was shown in PCV2 strains from Hong Kong and mainland China. Molecular dating of PCV2 sub-lineage Ia using Bayesian Monte Carlo Markov chain (BMCMC) approach estimated that the emergence time of the most recent common ancestor (TMRCA) was around 1995. To study the receptor binding of PCV2, both cap genes (ORF2) of PCV1 and PCV2 without the nuclear localization signal (NLS) were expressed as glutathione S-transferase (GST)-fusion proteins in a bacterial expression system. The recombinant proteins GST-1.2-XNLS and GST-2.2-XNLS were demonstrated to bind to the porcine monocytic cell line 3D4/31 in a dose-dependent and specific manner. Both GST-1.2-XNLS and GST-2.2-XNLS showed reduced bindings in trypsin pre-treated cells and post-binding NaCl washing at different levels. Binding of GST-2.2-XNLS could not be significantly inhibited by GST-1.2-XNLS. Interestingly, both recombination proteins bound to all eight mammalian cell lines investigated, suggesting PCV1 and PCV2 use ubiquitous receptor(s) for cell attachment. However, different receptors might be responsible for successive infection. The current study provides information on evolution, receptor usage and pathogenicity of PCV2. DOI: 10.5353/th_b3822720 Subjects: DNA virus - Receptors Swine - Virus diseases - Genetic aspects Viral genetics Molecular epidemiology

Download or read book Molecular Epidemiology and Evolution of Type 2 Porcine Reproductive and Respiratory Syndrome Virus in Ontario Canada written by Manreetpal Singh Brar and published by Open Dissertation Press. This book was released on 2017-01-26 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: This dissertation, "Molecular Epidemiology and Evolution of Type 2 Porcine Reproductive and Respiratory Syndrome Virus in Ontario, Canada" by Manreetpal Singh, Brar, was obtained from The University of Hong Kong (Pokfulam, Hong Kong) and is being sold pursuant to Creative Commons: Attribution 3.0 Hong Kong License. The content of this dissertation has not been altered in any way. We have altered the formatting in order to facilitate the ease of printing and reading of the dissertation. All rights not granted by the above license are retained by the author. Abstract: Recently, progress was made in collecting, classifying, and characterizing the genetic diversity of type 2 porcine reproductive and respiratory syndrome virus (PRRSV) using all known and publically available sequencing information. Despite this voluminous attempt, these analyses were largely na?ve of the Canadian contribution to circulating viruses. This represented a vital omission in the study of molecular epidemiology due to the fact that Canada had recorded the earliest evidence of the existence of type 2 PRRSV. To this end, the genetic diversity and evolutionary aspects of PRRSVs distributed in the Province of Ontario in Canada were characterized to abridge this existing knowledge gap on type 2 PRRSV. Genotyping of type 2 strains is primarily based on either a phylogenetic or restriction fragment length polymorphism (RFLP) approach. Classification of Ontario PRRSV field isolates (n = 505) from 1999 to 2010, based on a global type 2 PRRSV ORF5 phylogenetic framework, revealed genetic diversity comparable to PRRSV in the USA, with sequences assigned to five of nine lineages (1, 2, 5, 8 and 9). A majority ( 85%) of these isolates were typed to the first two lineages (1 and 2). Despite a relatively smaller sample size to the USA, the topology of the phylogenetic tree indicated Canadian origins of these two lineages. Mapping RFLP patterns of Ontario isolates onto the phylogenetic tree revealed numerous examples of different patterns located within the same phylogenetic cluster. Examples of the non-specificity of RFLP patterns to any particular lineage or sub-lineage were abound. Statistical analysis showed occurrences where similar RFLP patterns masked diverse genetic distances and instances of close genetic proximity with divergent RFLP patterns. An examination of the most abundant 15 RFLP patterns revealed that the discrepancy between RFLP typing and genetic distances was not attributable to a single or few patterns but was rather a permeating feature. Importantly, the tree topology also indicated a Canadian ancestry for the highly virulent MN184-related strains that first emerged in 2001 in the USA. Selective pressure analyses highlighted a handful of positively selected sites most of which were located in the ORF5 ectodomains of outbreak strains, implicating the host immune system as the possible selective agent. This was in contrast to the closely-related Ontario strains which were subject to strong purifying selection. A broader survey of transmission dynamics in North America unveiled a higher virus flow from Canada to the USA with the primary targets being the Lake States and Corn Belt. In turn, these regions served to disseminate viruses to other swine production regions in the USA. Virus flow from the USA to Canada occurred on a much smaller scale. Collectively, extensive genetic diversity prevails in type 2 PRRSV in one region of the North American swine industry and it is not described adequately by RFLP typing which might have some value in differentiating strains at the local farm level, instead. For diagnostic and research purposes, phylogenetic typing should be the preferred method. Finally, stronger surveillance needs to be adopted to minimize cross-border virus transmission. DOI: 10.5353/th_b4716692 Subjects: Porcine reproductive and respiratory syndrome - Molecula

Download or read book Molecular Detection Genetic Diversity and Prevalence of Major Porcine Viral Pathogens written by Yin Wang and published by . This book was released on 2020 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Infectious diseases of food animals have major impacts on economic returns and public health. Effective surveillance and control of animal diseases are very important, in which rapid and accurate detection of etiological agents play a critical role. Molecular diagnostics have been developed and used extensively. Because of its high sensitivity, high specificity, high-throughput and short turnaround time, molecular diagnostics is considered a powerful tool for detection and identification of infectious agents. Several molecular assays have been developed and validated for major swine virus detections in this dissertation. In Chapter 2.1, a multiplex quantitative real-time PCR assay (mqPCR) was developed to detect and differentiate two porcine circoviruses (PCV) associated with the diseases of similar clinical signs: the novel PCV type 3 (PCV3) and the well-known economically important PCV type 2 (PCV2). In Chapter 2.2, a mqPCR assay was developed and validated for detection and differentiation of three PCV2 genotypes, PCV2a, PCV2b and PCV2d, the most frequently circulating genotypes in the US. In Chapter 2.3, a real-time RT-PCR (RT-qPCR) assay of Seneca Valley virus 1 (SVV-1) was developed and multiplexed with the published foot-and-mouth virus (FMDV) assays to differentiate the two viruses, which cause clinically similar vesicular diseases in swine. In Chapter 2.4, a real-time PCR assay was developed for rapid detection of African swine fever virus (ASFV). Its current spread in Asia and Europe resulted in significant economic losses on the global swine industry. In Chapter 2.5, the Luminex xTAG assay was developed to detect type 2 porcine reproductive and respiratory syndrome virus (PRRSV-2), one of most economically significant viruses in the US. The multiplexing assay allowed to differentiation of the field strains from the vaccine strains. In the design of the molecular assays described above, the most recent sequence databases were built to obtain high strain coverages. The analytical and diagnostic analyses showed high sensitivities and specificities. Subsequent evaluation of clinical samples of different sample types indicated good diagnostic applicability. Finally, addition of the internal controls helped to monitor extractions and amplification efficiencies and to avoid false negative results. Genetic diversity and prevalence of PCV3 and PCV2 were investigated (Chapter 3.1). It showed high prevalence of PCV3 and PCV2 in the swine herds of the Midwestern region of the US in 2016-2018. The phylogenetic analysis indicated low genetic diversity of PCV3, but high genetic diversity of PCV2. A new genotype, PCV2i, was proposed and the genotypes, PCV2a, PCV2b and PCV2d, were indicated as those circulating in the region. Finally, genetic diversity analysis of Rotavirus C (RVC) was conducted (Chapter 3.2). Thirty-one complete genomes were sequenced with next generation sequencing technology and analyzed with all available published reference sequences. Based on the phylogenetic analysis, several new genotypes were defined here, G18-G31 for VP7, P[22]-P[26] for VP4, R5 for VP1, A9-A12 for NSP1, N9-N10 for NSP2, T7-T9 for NSP3 and E6-E8 for NSP4. Genotyping of the 31 complete genomes indicated reassortment existed in 7 segments, VP7, VP4, VP6, VP2, NSP1, NSP2 and NSP3. The study updated the genotypes of RVC strains to help understand its diversity and evolution.

Download or read book Understanding the Pathogenesis of Porcine Circovirus Type 2 PCV2 associated Diseases written by Tanja Ilse Opriessnig and published by . This book was released on 2006 with total page 634 pages. Available in PDF, EPUB and Kindle. Book excerpt: Porcine circovirus type 2 (PCV2) is associated with several disease manifestations in pigs including postweaning multisystemic wasting syndrome (PMWS). The hallmark microscopic lesions of PCV2-infection are lymphoid depletion or granulomatous lymphadentitis (or both) and the presence of PCV2 antigen or nucleic acids associated with the lymphoid lesions. PCV2 alone is limited in its ability to induce the full spectrum of disease and lesions associated with PMWS in pigs. PCV2 is widespread in the global swine population and in order to establish a PCV2 model in conventional pigs it was necessary to identify a method to derive pigs free of PCV2 or anti-PCV2 antibodies. We obtained more than 500 PCV2-free pigs from six seropositive breeding herds and demonstrated that segregated early weaning is an effective technique to derive PCV2-free pigs from positive breeding herds for research or for commercial production. We determined that vaccination with commercially available adjuvanted bacterins enhances PCV2 replication and PCV2-associated lesions. We also found that timing of vaccination in relationship to PCV2 infection is important in the outcome of vaccine-induced enhancement of PCV2 replication and PCV2-associated lesions. Field reports indicated that PCV2-infection may also decrease the efficacy of vaccines used at the time of PCV2 infection. When we vaccinated pigs with a modified-live porcine reproductive and respiratory syndrome virus (PRRSV) vaccine 14 days post PCV2 inoculation we found that PCV2 infection significantly decreased the efficacy of the PRRSV vaccine as measured by gross and microscopic lesions. It is thought that coinfections may be an important trigger for progression of PCV2 to PMWS and other PCV2-associated diseases. We experimentally confirmed that PCV2 and porcine parvovirus coinfection resulted in clinical PMWS in conventional pigs whereas singular infection does not. Coinfecting conventional pigs with PCV2 and Mycoplasma hyopneumoniae resulted in severe respiratory disease, reduced average daily gain, and severe lung and lymphoid lesions associated with PCV2-antigen in dual-infected pigs implying that M. hyopneumoniae potentiates the severity of PCV2-associated lung and lymphoid lesions and increases the incidence of PMWS. Host and virus differences may also be important in the outcome of PCV2 infection. In our conventional pig model, we found a predisposition of Landrace pigs to PCV2-associated lesions and disease when compared to Duroc and Large White pigs. Finally, we were the first to experimentally confirm that PCV2-field isolates differ significantly in virulence in our conventional pig model.

Download or read book Prrsv Webtool written by Lai-Yin Charles Wong and published by . This book was released on 2017-01-26 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: This dissertation, "PRRSV-webtool: a Web-based Database and Phylogenetic Tool to Study Molecular Epidemiology and Evolution of Porcine Reproductive and Respiratory Syndrome Virus, and Related Tool and Algorithm" by Lai-yin, Charles, Wong, 王禮賢, was obtained from The University of Hong Kong (Pokfulam, Hong Kong) and is being sold pursuant to Creative Commons: Attribution 3.0 Hong Kong License. The content of this dissertation has not been altered in any way. We have altered the formatting in order to facilitate the ease of printing and reading of the dissertation. All rights not granted by the above license are retained by the author. Abstract: Porcine Reproductive and Respiratory Syndrome virus (PRRSV) causes the disease - Porcine Reproductive and Respiratory Syndrome (PRRS) which is one of the most economically important diseases for pig farmers. Since it was discovered in the United States and Europe, it has quickly affected the swine industry all over the world. Studying and controlling PRRSV has become an important issue in swine industry and scientific community, and has raised the concerns of governments like US and China. By using different bioinformatics and phylogenetics tools, scientists could understand the epidemiology and evolution of PRRSV from genomic data. However, a well-designed database for PRRSV sequence and relevant meta-information are generally required for the tools to produce insightful results. Therefore, I would like to introduce an easily accessible web platform for PRRSV analysis - PRRSV-Webtool. The core component of PRRSV-Webtool is phylogenetic reconstruction. Instead of using traditional phylogenetic reconstruction, a new method of reconstruction was introduced - Reconstruction by Addition of Taxon (RAT). RAT could build a phylogenetic tree from known existing phylogeny. Simulation tests were performed to evaluate the accuracies of RAT using PRRSV dataset. The percentages of correct branch reconstruction are 73.81% for type 1 PRRSV dataset and 80.68% for type 2 PRRSV dataset. Another important function of PRRSV-Webtool is genotyping. RAT could correctly identify the genotype of all sequences in the testing datasets. PRRSV-Webtool combined three main components: database, phylogenetic tool and World Wide Web. By using PRRSV-Webtool, the users can study their own PRRSV genome data easily via the web browser. Tools in PRRSV-Webtool can allow users to know more about their PRRSV isolates related to other field samples. With our PRRSV-Webtool, scientists and veterinaries can help to improve their understanding of PRRSV and help to control the virus by accelerating the process of virus surveillance and field sampling. DOI: 10.5353/th_b5053426 Subjects: Porcine reproductive and respiratory syndrome - Epidemiology Viruses - Phylogeny Swine - Virus diseases

Download or read book Evolution of Porcine Reproductive and Respiratory Syndrome Virus written by Manreetpal Singh Brar and published by . This book was released on 2017-01-26 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: This dissertation, "Evolution of Porcine Reproductive and Respiratory Syndrome Virus" by Manreetpal Singh, Brar, was obtained from The University of Hong Kong (Pokfulam, Hong Kong) and is being sold pursuant to Creative Commons: Attribution 3.0 Hong Kong License. The content of this dissertation has not been altered in any way. We have altered the formatting in order to facilitate the ease of printing and reading of the dissertation. All rights not granted by the above license are retained by the author. Abstract: Porcine reproductive and respiratory syndrome virus (PRRSV) is one of the leading swine pathogens causing tremendous economic loss to the global swine industry. Since its recognition in the late 1980s, PRRSV has continued to expand in genetic diversity which poses problems for management and eradication. As a result, tracing and tracking the evolving diversity of PRRSV is critical to all stakeholders. In 2010, a phylogenetic framework was proposed to classify all type 2 PRRSV ORF5 sequences (n ≈ 8,000). Since then a further build-up of sequences (n ≈ 5,000) prompted questions on the robustness of the 2010 system in typing new sequences and what new insights on PRRSV diversity could be gauged. Phylogenetic classification of new sequences did not lead to the discovery of new evolutionary lineages but enriched the diversity of existing lineages. Importantly, lineages 1 and 9 revealed widening divergence of PRRSV isolates over time with genetic distance peaking at >= 10% at present. The growing genetic disparity between viruses and commercial vaccines over time was equally evident. Seven out of the nine lineages had evolutionary origins in North America while the remaining two originated from East Asia. Lineages 1, 5, 8, and 9 viruses were the dominant circulating strains in the field, accounting for > 97% of the dataset. The USA was the country most impacted from the circulation of a diverse set of viruses with isolation of strains of almost every lineage. However, Canada exhibited the greatest heterogeneity in viral diversity despite having rarely experienced foreign introductions. Asian countries also displayed significant diversity but the burden of type 2 PRRSV in Europe was limited. While intra-country diversity levels were more or less comparable across the USA, the same was highly skewed among Canadian provinces. Overall, the inferred burden of vaccine-related viruses on circulating strains was approximately 5%. To date, the majority of PRRSV diversity studies have focused on limited regions of the genome which incompletely characterize evolutionary mechanisms shaping the viral genome as a whole. A methodology of sequencing near complete-length PRRSV genomes was developed to obtain genomic sequences of a diverse set of 16 Hong Kong isolates. Genome assemblies and phylogenetic typing indicated the co-circulation of strains of both genotypes (type 1and type 2) with varying Nsp2 deletion patterns and distinct evolutionary lineages ("High Fever"-like and local endemic type). Recombination analyses revealed genomic breakpoints in structural and non-structural regions of genomes of both genotypes with evidence of many recombination events originating from common ancestors. Additionally, the high fold of coverage per nucleotide allowed the characterization of minor variants arising from the intra-strain heterogeneity. Overall, 0.56-2.83% of sites were polymorphic with respect to cognate consensus genomes. The distribution of minor variants across each genome was not uniform, indicating the influence of selective forces. The proportion of variants causing an amino acid change in their respective codons ranged between 25-67% with many predicted to be non-deleterious. Low frequency deletion variants were also detected, providing one possible mechanism for their sudden emergence as cited in previous reports. DOI: 10.5353/th_b5387949 Subjects: Porcine reproductive and respirator

Download or read book It Ain t Necessarily So written by Richard Lewontin and published by New York Review of Books. This book was released on 2001-09-30 with total page 404 pages. Available in PDF, EPUB and Kindle. Book excerpt: Is our nature—as individuals, as a species—determined by our evolution and encoded in our genes? If we unravel the protein sequences of our DNA, will we gain the power to cure all of our physiological and psychological afflictions and even to solve the problems of our society? Today biologists—especially geneticists—are proposing answers to questions that have long been asked by philosophy or faith or the social sciences. Their work carries the weight of scientific authority and attracts widespread public attention, but it is often based on what the renowned evolutionary biologist Richard Lewontin identifies as a highly reductive misconception: "the pervasive error that confuses the genetic state of an organism with its total physical and psychic nature as a human being." In these nine essays covering the history of modern biology from Darwin to Dolly the sheep, all of which were originally published in The New York Review of Books, Lewontin combines sharp criticisms of overreaching scientific claims with lucid expositions of the exact state of current scientific knowledge—not only what we do know, but what we don't and maybe won't anytime soon. Among the subjects he discusses are heredity and natural selection, evolutionary psychology and altruism, nineteenth-century naturalist novels, sex surveys, cloning, and the Human Genome Project. In each case he casts an ever-vigilant and deflationary eye on the temptation to look to biology for explanations of everything we want to know about our physical, mental, and social lives. These essays—several of them updated with epilogues that take account of scientific developments since they were first written—are an indispensable guide to the most controversial issues in the life sciences today. The second edition of this collection includes new essays on genetically modified food and the completion of the Human Genome Project. It is an indispensable guide to the most controversial issues in the life sciences today.

Download or read book Molecular Characterization and Co Infection of North American and European Porcine Reproductive and Respiratory Syndrome Virus in Hongkong written by Yick-Yeung Li and published by Open Dissertation Press. This book was released on 2017-01-27 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: This dissertation, "Molecular Characterization and Co-infection of North American and European Porcine Reproductive and Respiratory Syndrome Virus in HongKong" by 李亦揚, Yick-yeung, Li, was obtained from The University of Hong Kong (Pokfulam, Hong Kong) and is being sold pursuant to Creative Commons: Attribution 3.0 Hong Kong License. The content of this dissertation has not been altered in any way. We have altered the formatting in order to facilitate the ease of printing and reading of the dissertation. All rights not granted by the above license are retained by the author. Abstract: Abstract of thesis entitled MOLECULAR CHARACTERIZATION AND CO-INFECTION OF NORTH AMERICAN AND EUROPEAN PORCINE REPRODUCTIVE AND RESPIRATORY SYNDROME VIRUS IN HONG KONG Submitted by Yick Yeung LI for the Degree of Doctor of Philosophy at The University of Hong Kong in March 2008 Porcine reproductive and respiratory syndrome (PPRS), one of the most problematic swine diseases, has been widely spread in most of the swine-producing countries. This disease, characterized by respiratory weakness and reproductive failure was identified in Hong Kong and a previous study revealed the existence of both North American (NA) and European (EU) genotypes in local pig farms, which is rare elsewhere. Therefore, an in-depth study on molecular epidemiology, genomic characterization, prevalence of NA/EU coinfection as well as the possibility of inter-type recombination was carried out. In an epidemiological study, a total of 124 PRRSV strains in which 71 of NA lineage and 53 of EU lineage, were identified between 2001 and 2006 from 54 local pig farms and phylogenetic analysis revealed multiple distinctive clusters existed in both genotypes, possibly due to the multiple introductions of infected swine and purchasing of contaminated frozen semen. In addition, eight full-length genomic sequences (4 NA and 4 EU) of Hong Kong (HK) isolates were analysed and the genomic size of HKNA isolates was characterized to contain 15,411 nucleotides, of which the HKEU isolates have deviated into two sizes: 15,098 and 15,074, where the shortened genome consists of a 24-nucleotide deletion in the hypervariable region located at ORF3/4 overlapping region. Phylogenetic analysis based on ORF3 gene further indicated that the deletion mutants possibly emerged from the non-deleted strains in Hong Kong. It was revealed that 37 tested farms have been coinfected with NA/EU PRRSV from 2001 to 2006, thus characterization of both NA/EU PRRS viruses within a coinfected farm was performed. Among the 35 selected pigs tested, seroconversion was observed but there were no cross-protection detected from heterologous infection. Moreover, the localization of NA and EU PRRS viruses from a persistently coinfected pig was further analyzed by immuno-histochemistry (IHC) and in situ hybridization (ISH). NA/EU coinfection was demonstrated within left cranial and caudal lobe of the lung, but single-cell coinfection was not detected. In this study, the emergence of deletion mutants of EU lineage was identified in Hong Kong pig farms. Together with the full-length sequence analysis, valuable data were provided towards the European PRRS virus genomic characterization which is still very much lacking around the world. Furthermore, cases of NA/EU coinfection have been identified within single pig, suggesting that the infection of one genotype would not exclude the infection of another genotype. In addition, localization of NA and EU PRRS viruses in coinfected tissues, together with negative detection of single-cell coinfection suggested the possibility of the generation of an inter-type recombinant virus in nature is low. However, the interaction of both genotypes on the entry pathway as well as the effects on host immune system remains to be elucidated. DOI: 10.5353/th_b3955817 Subjects: Porcine reproduct

Download or read book Porcine Reproductive And Respiratory Syndrome New Insights for the Healthcare Professional 2011 Edition written by and published by ScholarlyEditions. This book was released on 2012-01-09 with total page 27 pages. Available in PDF, EPUB and Kindle. Book excerpt: Porcine Reproductive And Respiratory Syndrome: New Insights for the Healthcare Professional: 2011 Edition is a ScholarlyPaper™ that delivers timely, authoritative, and intensively focused information about Porcine Reproductive And Respiratory Syndrome in a compact format. The editors have built Porcine Reproductive And Respiratory Syndrome: New Insights for the Healthcare Professional: 2011 Edition on the vast information databases of ScholarlyNews.™ You can expect the information about Porcine Reproductive And Respiratory Syndrome in this eBook to be deeper than what you can access anywhere else, as well as consistently reliable, authoritative, informed, and relevant. The content of Porcine Reproductive And Respiratory Syndrome: New Insights for the Healthcare Professional: 2011 Edition has been produced by the world’s leading scientists, engineers, analysts, research institutions, and companies. All of the content is from peer-reviewed sources, and all of it is written, assembled, and edited by the editors at ScholarlyEditions™ and available exclusively from us. You now have a source you can cite with authority, confidence, and credibility. More information is available at http://www.ScholarlyEditions.com/.

Download or read book Characterization of the Antibody Response to Vaccination and Or Infection with Porcine Circovirus Type 2 and Identification and Characterization of a Decoy Epitope in the Capsid Protein written by Benjamin Ralph Trible and published by . This book was released on 2021 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: Chapter 1: Porcine circovirus-associated disease (PCVAD) encompasses a group of complex, multi-factorial syndromes, which are dependent on infection with porcine circovirus type 2 (PCV2). Current strains of PCV2 circulating in the field are phylogenically classified into two groups, termed PCV2a and 2b. Outbreaks of severe PCVAD in North America in 2005 are linked with a shift in the predominant circulating genotype, from PCV2a to PCV2b. Therefore genotype specific differences in pathogenesis and antigenicity have been suggested. Overall, evidence suggests pathogenicity is a function of the specific PCV2 isolate, regardless of genotype. In addition, only minor antigenic differences have been reported. In terms of immunopathogenisis, a genotypically conserved immune decoy epitope, located in the C-terminal region of the capsid protein, provides an explanation for the inability to identify pathogenic differences between genotypes. Finally, genetic variation of PCV2 and the resulting consequences with respect to vaccination and diagnostics is discussed. Chapter 2: Open reading frame 2 (ORF2) of porcine circovirus type 2 (PCV2) codes for the 233 amino acid capsid protein (CP). Baculovirus-based vaccines that express only ORF2 are protective against clinical disease following experimental challenge or natural infection. The goal of this study was to identify regions in CP preferentially recognized by sera from experimentally infected and vaccinated pigs, and compare these responses to pigs diagnosed with porcine circovirus-associated disease (PCVAD), including porcine multi-systemic wasting syndrome (PMWS) and porcine dermatitis and nephropathy syndrome (PDNS). The approach was to react porcine sera with CP polypeptide fragments followed by finer mapping studies using overlapping oligopeptides that covered amino acids 141-200. The results showed that vaccinated pigs preferentially recognized only the largest CP(43-233) polypeptide fragment. A subset of experimentally infected pigs and pigs with PDNS showed strong reactivity against a CP oligopeptide, 169-STIDYFQPNNKR-180. Alanine scanning identified Y-173, F-174, Q-175 and K-179 as important for antibody recognition. The results from this study support the notion of PCV2 modulation of immunity, including antibody responses that may represent a precursor for disease. The recognition of CP(169-180) and other polypeptides provide opportunities to devise diagnostic tests for monitoring the immunological effectiveness of vaccination. Chapter 3: Porcine circovirus associated disease (PCVAD) encompasses a group of syndromes linked to infection with porcine circovirus type 2 (PCV2). Based on the hypothesis that the immune response to vaccination versus infection are quantitatively and qualitatively different, the objective of this study was to evaluate immunity, virus replication and disease protection in pigs vaccinated with PCV2 capsid protein (CP) and natural infection. The disease model included dual infection with PCV2 and porcine reproductive and respiratory syndrome virus (PRRSV), a factor known to enhance disease progression and severity. The principal effect of PRRSV infection was to increase peak PCV2 viremia by almost 40-fold; however, PCV2 failed to show a reciprocal effect on PRRSV. In vaccinated pigs, there was no evidence of disease or PCV2 replication following dual virus challenge. Immunity following vaccination favored neutralizing antibody; whereas, PCV2 infection produced high levels of non-neutralizing antibody, primarily directed against a polypeptide in the C-terminal region of CP. These results support the notion that the magnitude of the total antibody response cannot be used as a measure of protective immunity. Furthermore, protection versus disease lies in the immunodominance of specific epitopes. Epitope specificity should be taken into consideration when designing PCV2 vaccines. Chapter 4: Porcine circovirus type 2 (PCV2) capsid protein (CP) is the only protein necessary for the formation of the virion capsid and recombinant CP spontaneously forms virus-like particles (VLPs). Located within a single CP subunit is an immunodominant epitope, CP(169-180), which is exposed on the surface of the subunit; but, in the structural context of the VLP, the epitope is buried and inaccessible to antibody. High levels of anti-CP(169-180) activity are associated with porcine circovirus-associated disease (PCVAD). The purpose of this study was to investigate the role of the immune response to monomer CP in the development of PCVAD. The approach was to immunize pigs with CP monomer followed by challenge with PCV2 and porcine reproductive and respiratory syndrome virus (PRRSV). To maintain the CP immunogen as a stable monomer, CP(43-233) was fused to ubiquitin (Ub-CP). Size exclusion chromatography showed that Ub-CP was present as a single 33 kDa protein. Pigs immunized with Ub-CP developed a strong antibody response to PCV2, including antibodies against CP(169-180). However, only low levels of virus neutralizing activity were detected and viremia was similar to non-immunized pigs. As a positive control, immunization with baculovirus-expressed CP (Bac-CP) resulted in high levels of virus neutralizing activity, low amounts of anti-CP(169-180) activity, and the absence of viremia in pigs following virus challenge. The data support the role of CP(169-180) as an immunological decoy and illustrate the importance of the structural form of the CP immunogen in determining the outcome following infection.

Download or read book Molecular Characterization of the Chinese Isolates of Porcine Reproductive and Respiratory Syndrome Virus Prrsv and the Construction and Characterization of the DNA Vaccines written by Knowledge by Design Yue-Ling Wong and published by Open Dissertation Press. This book was released on 2017-01-27 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: This dissertation, "Molecular Characterization of the Chinese Isolates of Porcine Reproductive and Respiratory Syndrome Virus (PRRSV) and the Construction and Characterization of the DNA Vaccines" by Yue-ling, Wong, 王如玲, was obtained from The University of Hong Kong (Pokfulam, Hong Kong) and is being sold pursuant to Creative Commons: Attribution 3.0 Hong Kong License. The content of this dissertation has not been altered in any way. We have altered the formatting in order to facilitate the ease of printing and reading of the dissertation. All rights not granted by the above license are retained by the author. DOI: 10.5353/th_b3122689 Subjects: Swine - Virus diseases Viral proteins DNA vaccines

Download or read book Porcine Reproductive And Respiratory Syndrome New Insights for the Healthcare Professional 2012 Edition written by and published by ScholarlyEditions. This book was released on 2012-12-10 with total page 34 pages. Available in PDF, EPUB and Kindle. Book excerpt: Porcine Reproductive And Respiratory Syndrome: New Insights for the Healthcare Professional / 2012 Edition is a ScholarlyPaper™ that delivers timely, authoritative, and intensively focused information about Porcine Reproductive And Respiratory Syndrome in a compact format. The editors have built Porcine Reproductive And Respiratory Syndrome: New Insights for the Healthcare Professional / 2012 Edition on the vast information databases of ScholarlyNews.™ You can expect the information about Porcine Reproductive And Respiratory Syndrome in this eBook to be deeper than what you can access anywhere else, as well as consistently reliable, authoritative, informed, and relevant. The content of Porcine Reproductive And Respiratory Syndrome: New Insights for the Healthcare Professional / 2012 Edition has been produced by the world’s leading scientists, engineers, analysts, research institutions, and companies. All of the content is from peer-reviewed sources, and all of it is written, assembled, and edited by the editors at ScholarlyEditions™ and available exclusively from us. You now have a source you can cite with authority, confidence, and credibility. More information is available at http://www.ScholarlyEditions.com/.

Download or read book Interactions of Porcine Circovirus Type 2 and Porcine Reproductive and Respiratory Syndrome Virus written by Avanti Sinha and published by . This book was released on 2011 with total page 215 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Epidemic status and prevention of swine infectious diseases written by Zhou Mo and published by Frontiers Media SA. This book was released on 2023-04-04 with total page 116 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Molecular diagnostics for infectious diseases Novel approaches clinical applications and future challenges written by Xiaogang Xu and published by Frontiers Media SA. This book was released on 2023-03-31 with total page 193 pages. Available in PDF, EPUB and Kindle. Book excerpt: