Assessment of the immunogenicity of porcine Circovirus 2 (PCV2) vaccines : a prototype vaccine and a lambda display vaccine
Bibliographic record
Abstract
Porcine Circovirus 2 (PCV2) associated diseases (PCVAD) cause economic loss to the global swine industry.Control measures for PCVAD largely depend on the use of PCV2 vaccines.The available commercial PCV2 vaccines contain either inactivated whole virus particles or recombinant PCV2 capsid protein.These preparations most likely contain varying amounts of immune-irrelevant proteins that can cause adverse injection site reactions, with compromised efficacy due to alteration of protective immune epitopes arising during the viral inactivation process.Other constraints include high production cost attributed to propagation of slow growing virus and expression and extraction of recombinant proteins, a requirement for adjuvants, and the induction of a Th2-biased immune response.Hence, development of new PCV2 vaccines is necessary.There are two recommended PCV2 vaccination strategies.They are i.vaccinating sows, which relies on the passive transfer of maternal immunity to offspring, and ii.immunizing young piglets to induce an active immune response.The piglet vaccination has been shown to confer better protection from mortality.Maternal antibody interference to the induction of an active immune response is an obstacle when piglets are vaccinated at an early age.Can we sidestep this maternal antibody interference?To address this issue, I investigated whether a prototypical PCV2 vaccine, parenterally administered, could override maternally-derived PCV2 antibodies in seropositive piglets.The results of this study were not conclusive.However, they laid the foundation for future studies based upon using varying levels of vaccine antigen with different adjuvants, and administered to piglets with defined maternally derived PCV2 antibodies.Subsequently, I examined if a new PCV2 vaccine candidate comprised of bacteriophage lambda particles displaying part of the PCV2 capsid protein could induce anti-PCV2 immunity.Initial experiments showed that pigs do not have pre-existing anti-lambda antibodies and thus will not neutralize display particles used as a vaccine at primary vaccination.I produced and characterized lambda phage particles displaying four immunodominant regions of porcine circovirus 2 (PCV2) capsid protein fused to the lambda capsid protein D i.e., D-CAP, phage display particles.Expression of D-CAP in Escherichia coli (E.coli) and its presence in the vaccine preparation was shown by ELISA and Western blots using anti-PCV2 polyclonal antiserum from a gnotobiotic pig.The vaccine, lambda particles displaying PCV2 capsid protein iii immunogenic epitopes fused to lambda D protein (LDP-D-CAP), administered without an adjuvant induced both humoral and cellular immunity to PCV2 in conventional pigs, as shown by ELISA, Western blots, virus neutralization assay and delayed type hypersensitivity (DTH)reactions.This work produced the first potential phage vaccine to PCV2.In order to further investigate the feasibility of using the lambda display technology.I produced and characterized two additional lambda display particle preparations, LDP-D-FLAG and LDP-D-GFP, displaying a FLAG tag and the green fluorescent proteins, respectively.
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How this classification was reachedexpand
Full frame machine prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. The Gemma side is a direct model label for every work in the frame, read from the title-only record. The Codex side is a classifier learned from the 10,348 direct Codex labels and calibrated to design-weighted sample rates; fields without enough sample support carry no Codex call. Candidate is the union of the two sides; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels.
Distilled classifier scores by category (both heads)
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.001 | 0.000 |
| Meta-epidemiology (narrow) | 0.001 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.000 | 0.000 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.001 | 0.001 |
| Insufficient payload (model declined to judge) | 0.001 | 0.000 |
Machine scores (provisional)
The two teacher heads of the student model, read on this work. A score orders the frame for review; it never asserts a category, and the validation status ships verbatim with every row.
Baseline scores from an immature model (maturity gate not passed, 7 training rounds). Scores rank; they never assert a category.
score_only:v0-immature-baseline · verbatim from the scoring run: score_only means the number may rank works, and no category label ships from itClassification
machine, unvalidatedMachine predicted; a candidate call from one source (direct Gemma or distilled Codex), not a consensus.
How this classification was reached, model by model and score by score, is at the end of the page under "How this classification was reached".