11 results on '"Meng, Xiang-Jin"'
Search Results
2. Efficacy and future prospects of commercially available and experimental vaccines against porcine circovirus type 2 (PCV2)
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Beach, Nathan M. and Meng, Xiang-Jin
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CIRCOVIRUSES , *VIRAL vaccines , *VIRUS diseases in swine , *DRUG efficacy , *VIRAL genetics , *IMMUNE response , *DRUG development - Abstract
Abstract: 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. [Copyright &y& Elsevier]
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- 2012
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3. Porcine circoviruses: a minuscule yet mammoth paradox.
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Ramamoorthy, Sheela and Meng, Xiang-Jin
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VIRUS diseases in swine , *PORK industry , *SWINE diseases , *VIRAL vaccines , *EPIDEMICS - Abstract
Porcine circovirus type 2 (PCV2) is the primary causative agent for porcine circovirusassociated disease (PCVAD). PCVAD has been the cause of considerable economic losses to the pork industry worldwide. The disease is primarily characterized by wasting, enlarged lymph nodes, jaundice and weight loss in affected weanling pigs. Several other complex syndromes involving reproductive failure, enteritis, pneumonia and necrotizing dermatitis have also been associated with PCV2 infection. Lymphoid depletion, which is the hallmark lesion of PCVAD, predisposes the host to immunosuppression. Disease progression is further complicated by co-infections with other bacterial and viral pathogens. Despite the availability of effective vaccines for the last 2 years, newly emerging strains of the virus have been reported to cause more severe outbreaks in parts of the USA and Canada. While knowledge of the biology and pathogenesis of PCV2 has progressed considerably over the last 12 years since the disease was recognized, many questions still remain to be answered. [ABSTRACT FROM AUTHOR]
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- 2009
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4. Spread like a wildfire—The omnipresence of porcine circovirus type 2 (PCV2) and its ever-expanding association with diseases in pigs
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Meng, Xiang-Jin
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CIRCOVIRUSES , *VETERINARY virology , *VIRUS diseases in swine , *DETECTION of microorganisms , *EPIDEMIOLOGY , *VIRUS disease transmission , *IMMUNOLOGY , *DRUG development - Abstract
Abstract: The discovery of porcine circovirus type 2 (PCV2) in 1998 initiated intensive research on arguably the most economically important pathogen facing the global swine industry today. PCV2 infection is now widespread worldwide, and increasing numbers of disease conditions have been linked to PCV2 infection in pigs. In this special issue of Virus Research, leading experts in the field review the history, epidemiology, transmission, clinical and pathological features, immunology, pathogenesis, molecular biology and vaccine development of PCV2 and porcine circovirus associated disease (PCVAD). In addition, circovirus-like DNA sequences recently identified from humans and other animal species and their biological significances are also reviewed. The articles in this special issue identify gaps in current PCV2 research and offer insights for the direction of future research. [Copyright &y& Elsevier]
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- 2012
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5. Markedly different immune responses and virus kinetics in littermates infected with porcine circovirus type 2 or porcine parvovirus type 1.
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Opriessnig, Tanja, Gerber, Priscilla F., Matzinger, Shannon R., Meng, Xiang-Jin, and Halbur, Patrick G.
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IMMUNE response , *CIRCOVIRUSES , *PARVOVIRUSES , *DNA viruses , *VIRUS diseases in swine , *VIREMIA , *DIAGNOSIS - Abstract
Porcine parvovirus type 1 (PPV1) and porcine circovirus type 2 (PCV2) are small single-stranded DNA viruses with high prevalence in the global pig population. The aim of this study was to compare and contrast PCV2 and PPV1 infections in high-health status pigs and to describe PCV2 long-term infection dynamics. Six caesarian-derived colostrum-deprived pigs were randomly divided into two groups and were experimentally infected with PCV2 or PPV1 at 5 weeks of age. All pigs had detectable viremia by day (D) 3 post-infection. Pigs infected with PPV1 had a detectable INF-α response by D3 followed by a high IFN-γ response by D6. The PPV1 pigs developed antibodies against PPV1 by D6 resulting in decreasing virus titers until PPV1 DNA became undetectable from D28 until D42. In contrast, PCV2-infected pigs had no detectable INF-α or IFN-γ response after PCV2 infection. PCV2-infected pigs had no detectable anti-PCV2 humoral response until D49 and had a sustained high level of PCV2 DNA for the duration of the study. While PPV1-infected pigs were clinically normal, PCV2-infected pigs developed severe clinical illness including fatal systemic porcine circovirus associated disease (PCVAD) by D28, fatal enteric PCVAD by D56 and chronic PCVAD manifested as decreased weight gain and periods of diarrhea. Microscopically, all three PCV2-infected pigs had lymphoid lesions consistent with PCVAD and associated with low (chronic disease) to high (acute disease) levels of PCV2 antigen. Under the study conditions, there was a lack of early IFN-γ and INF-α activation followed by a delayed and low humoral immune response and persisting viremia with PCV2 infection. In contrast, PPV1-infected pigs had IFN-γ and INF-α activation and an effective immune response to the PPV1 infection. [ABSTRACT FROM AUTHOR]
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- 2017
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6. A commercial porcine circovirus (PCV) type 2a-based vaccine reduces PCV2d viremia and shedding and prevents PCV2d transmission to naïve pigs under experimental conditions.
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Opriessnig, Tanja, Xiao, Chao-Ting, Halbur, Patrick G., Gerber, Priscilla F., Matzinger, Shannon R., and Meng, Xiang-Jin
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CIRCOVIRUS diseases , *VIRAL vaccines , *VACCINE effectiveness , *VIRAL disease prevention , *SWINE diseases , *VIRUS diseases in swine , *COMPARATIVE studies , *INFECTIOUS disease transmission , *SWINE - Abstract
Porcine circovirus type 2 (PCV2) vaccination has been effective in protecting pigs from clinical disease and today is used extensively. Recent studies in vaccinated populations indicate a major PCV2 genotype shift from the predominant PCV2 genotype 2b towards 2d. The aims of this study were to determine the ability of the commercial inactivated PCV2a vaccine Circovac® to protect pigs against experimental challenge with a 2013 PCV2d strain and prevent transmission. Thirty-eight pigs were randomly divided into four groups with 9–10 pigs per group: NEG (sham-vaccinated, sham-challenged), VAC (PCV2a-vaccinated, sham-challenged), VAC + CHAL (PCV2a-vaccinated and PCV2d-challenged), and CHAL (sham-vaccinated, PCV2d-challenged). Vaccination was done at 3 weeks of age using Circovac® according to label instructions. The CHAL and VAC + CHAL groups were challenged with PCV2d at 7 weeks of age and all pigs were necropsied 21 days post-challenge (dpc). The VAC-CHAL pigs seroconverted to PCV2 by 21 days post vaccination (dpv). At PCV2d challenge on 28 dpv, 3/9 VAC and 1/9 VAC + CHAL pigs were seropositive. NEG pigs remained seronegative for the duration of the study. Vaccination significantly reduced PCV2d viremia (VAC + CHAL) at dpc 14 and 21, PCV2d fecal shedding at dpc 14 and 21 and PCV2d nasal shedding at dpc 7, 14 and 21 compared to CHAL pigs. Vaccination significantly reduced mean PCV2 antigen load in lymph nodes in VAC + CHAL pigs compared to CHAL pigs. When pooled serum or feces collected from VAC + CHAL and CHAL pigs at dpc 21 were used to expose single-housed PCV2 naïve pigs, a pooled fecal sample from CHAL pigs contained infectious PCV2 whereas this was not the case for VAC + CHAL pigs suggesting reduction of PCV2d transmission by vaccination. Under the study conditions, the PCV2a-based vaccine was effective in reducing PCV2d viremia, tissue loads, shedding and transmission indicating that PCV2a vaccination should be effective in PCV2d-infected herds. [ABSTRACT FROM AUTHOR]
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- 2017
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7. Broadening the Heterologous Cross-Neutralizing Antibody Inducing Ability of Porcine Reproductive and Respiratory Syndrome Virus by Breeding the GP4 or M genes.
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Zhou, Lei, Ni, Yan-Yan, Piñeyro, Pablo, Cossaboom, Caitlin M., Subramaniam, Sakthivel, Sanford, Brenton J., Dryman, Barbara A., Huang, Yao-Wei, and Meng, Xiang-Jin
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PORCINE reproductive & respiratory syndrome , *VIRUS diseases in swine , *VIRAL vaccines , *NUCLEOTIDE sequence , *VETERINARY virology , *VETERINARY microbiology , *RECOMBINANT DNA - Abstract
Porcine reproductive and respiratory syndrome virus (PRRSV) is one of the most economically important swine pathogens, which causes reproductive failure in sows and respiratory disease in piglets. A major hurdle to control PRRSV is the ineffectiveness of the current vaccines to confer protection against heterologous strains. Since both GP4 and M genes of PRRSV induce neutralizing antibodies, in this study we molecularly bred PRRSV through DNA shuffling of the GP4 and M genes, separately, from six genetically different strains of PRRSV in an attempt to identify chimeras with improved heterologous cross-neutralizing capability. The shuffled GP4 and M genes libraries were each cloned into the backbone of PRRSV strain VR2385 infectious clone pIR-VR2385-CA. Three GP4-shuffled chimeras and five M-shuffled chimeras, each representing sequences from all six parental strains, were selected and further characterized in vitro and in pigs. These eight chimeric viruses showed similar levels of replication with their backbone strain VR2385 both in vitro and in vivo, indicating that the DNA shuffling of GP4 and M genes did not significantly impair the replication ability of these chimeras. Cross-neutralization test revealed that the GP4-shuffled chimera GP4TS14 induced significantly higher cross-neutralizing antibodies against heterologous strains FL-12 and NADC20, and similarly that the M-shuffled chimera MTS57 also induced significantly higher levels of cross-neutralizing antibodies against heterologous strains MN184B and NADC20, when compared with their backbone parental strain VR2385 in infected pigs. The results suggest that DNA shuffling of the GP4 or M genes from different parental viruses can broaden the cross-neutralizing antibody-inducing ability of the chimeric viruses against heterologous PRRSV strains. The study has important implications for future development of a broadly protective vaccine against PRRSV. [ABSTRACT FROM AUTHOR]
- Published
- 2013
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8. A PCV2 vaccine based on genotype 2b is more effective than a 2a-based vaccine to protect against PCV2b or combined PCV2a/2b viremia in pigs with concurrent PCV2, PRRSV and PPV infection
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Opriessnig, Tanja, O’Neill, Kevin, Gerber, Priscilla F., de Castro, Alessandra M.M.G., Gimenéz-Lirola, Luis G., Beach, Nathan M., Zhou, Lei, Meng, Xiang-Jin, Wang, Chong, and Halbur, Patrick G.
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VIREMIA , *VIRUS diseases in swine , *CIRCOVIRUSES , *PARVOVIRUS diseases , *PORCINE reproductive & respiratory syndrome , *SWINE vaccination , *HUMORAL immunity , *VIRAL replication - Abstract
Abstract: The predominant genotype of porcine circovirus (PCV) in the pig population today is PCV2b yet PCV2a-based commercial vaccines are considered effective in protecting against porcine circovirus associated disease. The objective of this study was to compare the ability of PCV2a- and PCV2b-based vaccines to control PCV2b viremia in a challenge model that mimics the U.S. field situation. Sixty-three pigs were randomly assigned to one of eight groups. Sixteen pigs were vaccinated with an experimental live-attenuated chimeric PCV1-2a vaccine based on genotype 2a and another 16 pigs with a chimeric PCV1-2b vaccine based on genotype 2b. Challenge was done 28 days post vaccination (dpv) using PCV2b (or a combination of PCV2a and PCV2b), porcine reproductive and respiratory syndrome virus (PRRSV), and porcine parvovirus (PPV) to mimic what commonly occurs in the field. The experiment was terminated 21 days post challenge (dpc) or 49dpv. Pigs vaccinated with the chimeric PCV1-2b vaccine had significantly higher levels of PCV1-2b viremia and shedding of the PCV1-2b vaccine virus in feces and nasal secretions but also a more robust humoral immune response as evidenced by significantly higher ELISA S/P ratios compared to the PCV1-2a vaccination. Regardless of challenge, the PCV1-2b vaccination significantly reduced the prevalence and amount of PCV2 viremia compared to the PCV1-2a vaccination. Interestingly, in the non-vaccinated pigs concurrent PCV2a infection resulted in clinical disease and increased macroscopic lung lesions compared to pigs challenged with PCV2b alone, further supporting the idea that concurrent PCV2a/PCV2b infection is necessary for optimal PCV2 replication. [Copyright &y& Elsevier]
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- 2013
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9. ORF1 but not ORF2 dependent differences are important for in vitro replication of PCV2 in porcine alveolar macrophages singularly or coinfected with PRRSV
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Sinha, Avanti, Lin, Kathy, Hemann, Michelle, Shen, Huigang, Beach, Nathan M., Ledesma, Carmen, Meng, Xiang-Jin, Wang, Chong, Halbur, Patrick G., and Opriessnig, Tanja
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PORCINE reproductive & respiratory syndrome , *ALVEOLAR macrophages , *OPEN reading frames (Genetics) , *VIRAL replication , *ENZYME-linked immunosorbent assay , *MESSENGER RNA , *CYTOKINES , *VIRUS diseases in swine , *VIRUSES - Abstract
Abstract: The objective of this study was to investigate cytokine expression and in vitro replication of porcine circovirus type 2 (PCV2) and porcine reproductive and respiratory syndrome virus (PRRSV) in pulmonary alveolar macrophages (PAMs) emphasizing PCV2 open-reading frame (ORF) origin (PCV2a or PCV2b) and PRRSV strain. Chimeric PCV2 viruses composed of different combinations of ORF1 and ORF2 of PCV2a or PCV2b (chimera PCV2a–2b and chimera PCV2b–2a) were constructed and five different PRRSV isolates were utilized: Type 1 (SD 01-08) or type 2 (NC16845b, VR-2332, MN-184, JA-142). PAMs were infected singularly or with combinations of PCV2b, PCV2a, chimera PCV2a–2b, and chimera PCV2b–2a, and one of the five PRRSV isolates. Real-time PCR was used to test PAMs (PCV2 mRNA) and supernatants (PRRSV RNA, PCV2 DNA, PCV2 mRNA) harvested at 24, 48, 72 and 96h post inoculation (hpi). Levels of IFN-γ, TNF-α and IL-10 were determined by quantitative ELISAs. PCV2 replication in PAMs was limited to groups inoculated with PCV2 strains containing ORF1 of PCV2a (PCV2a, chimera PCV2a–2b). Furthermore, in supernatants, PCV2 mRNA was only detected in groups coinfected with PRRSV regardless of strain at 48hpi supporting an enhancing effect of PRRSV on PCV2 infection. Changes in cytokine levels were minimal and associated with PRRSV strain for TNF-α. In summary, in vitro differences in PCV2 replication in PAMs inoculated with different PCV2–PRRSV combinations were independent of PCV2 ORF2 origin with minimal effects of concurrent PRRSV infection perhaps indicating that PCV2-specific changes in ORF1 may be more important than those in ORF2. [Copyright &y& Elsevier]
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- 2012
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10. The prevalence of Torque teno sus virus (TTSuV) is common and increases with the age of growing pigs in the United States
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Xiao, Chao-Ting, Giménez-Lirola, Luis, Huang, Yao-wei, Meng, Xiang-Jin, Halbur, Patrick G., and Opriessnig, Tanja
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TORQUE teno virus , *VIRUS diseases in swine , *AGE , *SWINE , *EPIDEMIOLOGY , *BLOOD testing , *DIAGNOSTIC use of polymerase chain reaction - Abstract
Abstract: Infection with the Torque teno sus virus (TTSuV) is believed to be common yet limited information is available on the epidemiology of TTSuV. The objectives of this study were to develop novel and improve existing diagnostic methods for TTSuV infection and to investigate the prevalence of TTSuV species 1 (TTSuV1) and 2 (TTSuV2) in the USA. Three hundred and four blood or fetal thoracic fluid samples were collected from pigs on 40 US farms in 12 States. Samples were collected from fetuses and in pre-suckle neonates (n =73), suckling pigs (1–20 days of age; n =27), nursery pigs (21–55 days of age; n =60), finisher pigs (8–25 weeks of age; n =90) and adults (>25 weeks of age; n =54). Samples were tested by a new quantitative differential real-time PCR for TTSuV1 and TTSuV2 DNA and by ELISA for detection of anti-TTSuV2-antibodies. The prevalence of TTSuV1 DNA ranged from 8.2% (fetuses and neonates) to 81% (finisher pigs) and the prevalence of TTSuV2 DNA ranged from 3.7% (suckling pigs) to 67% (finisher pigs). Evidence of fetal TTSuV infection was minimal. Mixed infection of TTSuV1 and TTSuV2 was seen in 6.7% of the nursery pigs, 52.2% of the finisher pigs, and 22.2% of the mature pigs. The prevalence of TTSuV1 was higher than that of TTSuV2. Anti-TTSuV2 antibodies were not detected in the fetuses and neonates and the seroprevalence of TTSuV2 was between 3.8% and 100% in growing pigs. The results of this study indicate that vertical transmission may not be a main route of TTSuV transmission in pigs in the USA. [Copyright &y& Elsevier]
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- 2012
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11. Intergenotypic chimeric hepatitis E viruses (HEVs) with the genotype 4 human HEV capsid gene in the backbone of genotype 3 swine HEV are infectious in pigs
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Feagins, Alicia R., Córdoba, Laura, Sanford, Brent J., Dryman, Barbara A., Huang, Yao-Wei, LeRoith, Tanya, Emerson, Suzanne U., and Meng, Xiang-Jin
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HEPATITIS E , *MIRIDAE , *VIRUS diseases in swine , *EXPERIMENTAL design , *GENOMICS , *VIRAL replication , *VIRUS diseases - Abstract
Abstract: Genotypes 1 and 2 hepatitis E virus (HEV) infect only humans whereas genotypes 3 and 4 HEV infect both humans and pigs. To evaluate the mechanism of cross-species HEV infection between humans and swine, in this study we constructed five intergenotypic chimeric viruses and tested for their infectivity in vitro and in pigs. We demonstrated that chimeric viruses containing the ORF2 capsid gene either alone or in combination with its adjacent 5′ junction region (JR) and 3′ noncoding region (NCR) from a genotype 4 human HEV in the backbone of a genotype 3 swine HEV are replication-competent in Huh7 cells and infectious in HepG2/C3A cells and in pigs, and thus supporting the hypothesis that genotypes 3 and 4 human HEV are of swine origin. However, chimeric viruses containing the JR+ORF2+3′ NCR of genotypes 3 or 4 HEV in the backbone of genotype 1 human HEV failed to infect pigs, suggesting that other genomic regions such as 5′ NCR and ORF1 may also be involved in HEV cross-species infection. The results from this study provide the first experimental evidence of the exchangeability of the capsid gene between genotype 3 swine HEV and genotype 4 human HEV, and have important implications for understanding the mechanism of HEV cross-species infection. [Copyright &y& Elsevier]
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- 2011
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