scholarly journals Harnessing the Genetic Plasticity of Porcine Circovirus Type 2 to Target Suicidal Replication

Viruses ◽  
2021 ◽  
Vol 13 (9) ◽  
pp. 1676
Author(s):  
Agm Rakibuzzaman ◽  
Pablo Piñeyro ◽  
Angela Pillatzki ◽  
Sheela Ramamoorthy
Keyword(s):  
Viral Replication ◽  
Body Weight Loss ◽  
Neutralizing Antibody ◽  
Porcine Circovirus Type ◽  
Porcine Circovirus Type 2 ◽  
Mutation Rates ◽  
Porcine Circovirus ◽  
Emerging Viruses ◽  
Weanling Piglets

Porcine circovirus type 2 (PCV2), the causative agent of a wasting disease in weanling piglets, has periodically evolved into several new subtypes since its discovery, indicating that the efficacy of current vaccines can be improved. Although a DNA virus, the mutation rates of PCV2 resemble RNA viruses. The hypothesis that recoding of selected serine and leucine codons in the PCV2b capsid gene could result in stop codons due to mutations occurring during viral replication and thus result in rapid attenuation was tested. Vaccination of weanling pigs with the suicidal vaccine constructs elicited strong virus-neutralizing antibody responses. Vaccination prevented lesions, body-weight loss, and viral replication on challenge with a heterologous PCV2d strain. The suicidal PCV2 vaccine construct was not detectable in the sera of vaccinated pigs at 14 days post-vaccination, indicating that the attenuated vaccine was very safe. Exposure of the modified virus to immune selection pressure with sub-neutralizing levels of antibodies resulted in 5 of the 22 target codons mutating to a stop signal. Thus, the described approach for the rapid attenuation of PCV2 was both effective and safe. It can be readily adapted to newly emerging viruses with high mutation rates to meet the current need for improved platforms for rapid-response vaccines.

scholarly journals Studies on Porcine Circovirus Type 2 Vaccination of 5-Day-Old Piglets

2011 ◽  
Vol 18 (11) ◽  
pp. 1865-1871 ◽  
Author(s):  
K. C. O'Neill ◽  
H. G. Shen ◽  
K. Lin ◽  
M. Hemann ◽  
N. M. Beach ◽  
...  
Keyword(s):  
Neutralizing Antibodies ◽  
Neutralizing Antibody ◽  
Porcine Circovirus Type ◽  
Positive Control ◽  
Porcine Circovirus Type 2 ◽  
Porcine Circovirus ◽  
Respiratory Syndrome Virus ◽  
Control Group ◽  
Associated Lesions

ABSTRACTPorcine circovirus type 2 (PCV2) vaccines have become widely used since they became available in 2006. It is not uncommon for producers to use PCV2 vaccines in pigs younger than what is approved by manufacturers. The objective of this study was to determine the efficacy of a chimeric and a subunit PCV2 vaccine administered at 5 or 21 days of age. Forty-eight PCV2-naïve piglets were randomly divided into six groups of eight pigs each. Vaccination was done at day 5 or day 21, followed by triple challenge with PCV2, porcine parvovirus (PPV), and porcine reproductive and respiratory syndrome virus (PRRSV) at day 49. Vaccinated pigs seroconverted to PCV2 approximately 14 days postvaccination and had a detectable neutralizing antibody response by 21 days postvaccination regardless of age at vaccination. At day 49, the pigs vaccinated with the chimeric vaccine had significantly higher levels of neutralizing antibodies than the pigs vaccinated with the subunit vaccine. After challenge, vaccinated pigs had significantly decreased levels of PCV2 viremia and a decreased prevalence and severity of microscopic lesions compared to the positive-control group, which had severe lymphoid lesions associated with abundant PCV2 antigen, compatible with PCV-associated disease. The results of this study indicate that, under the conditions of this study, vaccination of PCV2-naïve pigs at day 5 or day 21 resulted in development of a detectable humoral immune response and provided reduction or complete protection against PCV2 viremia and PCV2-associated lesions after triple challenge with PCV2, PPV, and PRRSV.

scholarly journals Influence of Maternal Antibodies on Efficacy of Porcine Circovirus Type 2 (PCV2) Vaccination To Protect Pigs from Experimental Infection with PCV2

2007 ◽  
Vol 15 (3) ◽  
pp. 397-401 ◽  
Author(s):  
T. Opriessnig ◽  
A. R. Patterson ◽  
J. Elsener ◽  
X. J. Meng ◽  
P. G. Halbur
Keyword(s):  
Clinical Signs ◽  
Neutralizing Antibody ◽  
Antibody Test ◽  
Porcine Circovirus Type ◽  
Porcine Circovirus Type 2 ◽  
Maternal Antibodies ◽  
Porcine Circovirus ◽  
Group Designation ◽  
Pcv2 Vaccination

ABSTRACT Due to the ubiquitous nature of porcine circovirus type 2 (PCV2) in the pig population and the increasing use of PCV2 vaccines in breeding herds, the majority of dams have been exposed to field PCV2 or PCV2 vaccines, resulting in piglets with varied levels of passively acquired PCV2 maternal antibodies. The objective of the current research was to investigate the influence of passively acquired anti-PCV2 antibodies on PCV2 vaccine efficacy. Sixty 26-day-old pigs were divided into four groups: vaccinated pigs with no maternal PCV2 antibodies at the time of vaccination (VAC-NEG; n = 9), vaccinated pigs with maternal PCV2 antibodies at the time of vaccination (VAC-POS; n = 21), nonvaccinated pigs with no maternal antibodies at the time of challenge (NVAC-CNEG; n = 15), and nonvaccinated pigs with maternal antibodies at the time of challenge (NVAC-CPOS; n = 15). Vaccinations and challenges were performed on trial days 0 and 28, respectively, according to group designation. The pigs were monitored for clinical signs of disease daily and weighed weekly, and blood was collected weekly. All pigs were necropsied on trial day 49, and tissues were evaluated for macroscopic and microscopic lesions. Serum was evaluated using PCV2 immunoglobulin G (IgG) and PCV2 IgM enzyme-linked immunosorbent assays, quantitative PCV2 PCR, and a serum PCV2 neutralizing antibody test. In comparison to NVAC-CPOS pigs, VAC-POS animals had significantly (P < 0.01) less severe microscopic PCV2-associated lymphoid lesions and significantly (P < 0.04) reduced PCV2 genomic copies in serum following PCV2 challenge. These results indicate that vaccination with Suvaxyn PCV2 One Dose reduces viremia and prevents microscopic lesions associated with PCV2 in the presence of maternal antibodies.

scholarly journals Porcine MKRN1 Modulates the Replication and Pathogenesis of Porcine Circovirus Type 2 by Inducing Capsid Protein Ubiquitination and Degradation

2018 ◽  
Vol 92 (11) ◽  
Author(s):  
Tongtong Wang ◽  
Qian Du ◽  
Xingchen Wu ◽  
Yingying Niu ◽  
Lijuan Guan ◽  
...  
Keyword(s):  
Viral Replication ◽  
Capsid Protein ◽  
Virus Replication ◽  
Ring Finger ◽  
Porcine Circovirus Type ◽  
Porcine Circovirus Type 2 ◽  
Pcv2 Infection ◽  
Porcine Circovirus ◽  
Lysine Residues

ABSTRACT Porcine circovirus type 2 (PCV2) capsid protein (Cap) is a unique structure protein that plays pivotal roles in the process of viral replication and pathogenesis. Herein, we characterized a putative porcine Makorin RING finger protein 1 (pMKRN1) variant, an N-terminal-truncated variant of putative full-size porcine MKRN1 which has a unique expression pattern resulting from the porcine mkrn1 gene and which interacts with PCV2 Cap. A domain mapping assay showed that the C terminus of pMKRN1 and fragments (amino acids 108 to 198) of Cap are required for this interaction. PCV2 transiently upregulated pMKRN1 in PK-15 cells, but persistent viral infection downregulated pMKRN1 in major pathological tissues of PCV2-infected piglets. Overexpression of pMKRN1 significantly inhibited the generation of progeny PCV2 via ubiquitination and degradation of Cap, whereas knockout of pMKRN1 blocked Cap degradation and promoted progeny virus replication. pMKRN1 specifically targeted PCV2 Cap lysine residues 164, 179, and 191 to induce polyubiquitination and subsequent degradation. Mutation of either of the three lysine residues in the Cap protein or mutation of the histidine at residue 243 within the RING finger domain of pMKRN1 abrogated the E3 ligase activity of pMKRN1, rendering cells incapable of inducing Cap ubiquitination and degradation. Consistent with this finding, a Cap ubiquitination-deficient PCV2 strain showed enhanced virus replication and produced severe histological lesions in the lung and lymph node tissues compared with wild-type PCV2. Taken together, the results presented here suggest that PCV2 downregulates the pMKRN1 variant to avoid pMKRN1-mediated Cap ubiquitination and degradation, thus promoting viral replication and pathogenesis in its targeted tissues. IMPORTANCE Porcine circovirus type 2 is the pathogen to which pigs are the most susceptible, causing immense economic losses in the global swine industry, but whether host cells have developed some strategies to prevent viral replication is still unclear. Here, we found that porcine MKRN1 (pMKRN1) was upregulated in the early stage of PCV2 infection and mediated the polyubiquitination and degradation of Cap protein to block PCV2 replication, yet persistent PCV2 infection downregulated pMKRN1 levels to avoid degradation, promoting viral replication and pathogenesis in its targeted tissues. These data present new insight into the molecular mechanisms underlying the antiviral effects of pMKRN1 E3 ligase during PCV2 infection and also suggest potential new control measures for PCV2 outbreaks.

scholarly journals Characterization of a Previously Unidentified Viral Protein in Porcine Circovirus Type 2-Infected Cells and Its Role in Virus-Induced Apoptosis

2005 ◽  
Vol 79 (13) ◽  
pp. 8262-8274 ◽  
Author(s):  
Jue Liu ◽  
Isabelle Chen ◽  
Jimmy Kwang
Keyword(s):  
Viral Replication ◽  
Caspase 3 ◽  
Porcine Circovirus Type ◽  
Porcine Circovirus Type 2 ◽  
Porcine Circovirus ◽  
Caspase 8 ◽  
Infected Cells ◽  
Apoptotic Activity ◽  
Induced Apoptosis

ABSTRACT Porcine circovirus type 2 (PCV2) is the causative agent of postweaning multisystemic wasting syndrome in pigs. In this study, transcription and translation of a novel viral gene (termed ORF3 here) was detected during productive infection of PCV2 in PK15 cells. The results of infection with ORF3-deficient PCV2 by site-directed mutagenesis indicated that the protein is not essential for viral replication. To investigate the underlying mechanism of cell death caused by replication of PCV2, apoptosis characterized by chromosomal condensation and fragmentation, formation of apoptotic bodies, and significant increase in hypodiploids were detected in infected cells. We further demonstrated that PCV2-induced apoptosis required the activation of caspase-8 but not caspase-9. The activation of caspase-8 results in the activation of caspase-3 as shown by an increase in the cleavage of the caspase substrate in the infected cells. To determine whether ORF3 protein could trigger apoptosis, ORF3 as well as ORF1 and ORF2 genes were transiently expressed in PK15 and Cos-7 cells for apoptotic activity assay. Transfection of cells with the ORF3 alone induced apoptosis using a pathway similar to that described in the context of viral infection. This is further confirmed by a significant decrease in apoptotic activity of infected cells in the absence of the ORF3 expression, suggesting that the protein plays a major role in the induction of virus-induced apoptosis. Altogether, these results indicate that ORF3 is a novel PCV2 protein that is not essential for viral replication in cultured cells but is involved in PCV2-induced apoptosis by activating caspase-8 and caspase-3 pathways.

A nine-base nucleotide sequence in the porcine circovirus type 2 (PCV2) nucleocapsid gene determines viral replication and virulence

2012 ◽  
Vol 164 (1-2) ◽  
pp. 90-99 ◽  
Author(s):  
Steven Krakowka ◽  
Gordon Allan ◽  
John Ellis ◽  
Alexander Hamberg ◽  
Catherine Charreyre ◽  
...  
Keyword(s):  
Nucleotide Sequence ◽  
Viral Replication ◽  
Porcine Circovirus Type ◽  
Porcine Circovirus Type 2 ◽  
Porcine Circovirus ◽  
Nucleocapsid Gene
Sign in / Sign up

Export Citation Format

Share Document