Source 1primary paper2025MED
Toolkit/hemagglutination inhibition assay
hemagglutination inhibition assay
Also known as: hemagglutination inhibition, HI
Taxonomy: Technique Branch / Method. Workflows sit above the mechanism and technique branches rather than replacing them.
Summary
Blood samples were collected on day 21 to measure hemagglutination inhibition (HI) and virus-neutralizing (VN) antibody responses.
Usefulness & Problems
Why this is useful
HI is used here to quantify antibody responses after FPV VLP vaccination. It serves as one of the immunogenicity endpoints measured on day 21.; measuring vaccine-induced antibody responses
Source:
HI is used here to quantify antibody responses after FPV VLP vaccination. It serves as one of the immunogenicity endpoints measured on day 21.
Source:
measuring vaccine-induced antibody responses
Problem solved
It provides a serologic measure of vaccine response before challenge. This helps compare vaccinated groups with PBS controls.; providing an immunogenicity readout after vaccination
Source:
It provides a serologic measure of vaccine response before challenge. This helps compare vaccinated groups with PBS controls.
Source:
providing an immunogenicity readout after vaccination
Problem links
providing an immunogenicity readout after vaccination
LiteratureIt provides a serologic measure of vaccine response before challenge. This helps compare vaccinated groups with PBS controls.
Source:
It provides a serologic measure of vaccine response before challenge. This helps compare vaccinated groups with PBS controls.
Published Workflows
Objective: Produce FPV VP2-based virus-like particles using a recombinant baculovirus expression system and evaluate their immunogenicity and protective efficacy in cats.
Why it works: The workflow first generates and confirms assembled FPV VLPs, then tests whether those particles induce antibody responses and protect cats from virulent challenge. The paper frames this as a route to a safer and more efficient alternative to current vaccines.
VP2-based self-assembly into virus-like particlesinduction of HI and virus-neutralizing antibody responsesrecombinant baculovirus expression in Sf9 cellsprotein purification by ultrafiltration and SECparticle characterization by DLS and TEManimal immunization and virulent challenge
Stages
- 1.VLP production and purification(library_build)
This stage generates the FPV VP2 material needed to form the vaccine candidate before characterization and animal testing.
Selection: Expression of VP2 in Sf9 insect cells followed by purification of VP2 material.
- 2.Particle assembly confirmation(functional_characterization)
This stage verifies that the expressed and purified VP2 formed virus-like particles before proceeding to animal immunization.
Selection: Confirmation of VLP assembly by DLS and TEM.
- 3.Cat immunization and serologic readout(secondary_characterization)
This stage tests whether the VLP vaccine induces measurable antibody responses in the target animal species before challenge.
Selection: Comparison of HI and VN antibody responses between vaccinated and PBS control cats.
- 4.Virulent challenge validation(confirmatory_validation)
This stage confirms whether vaccination translates into protection against virulent FPV infection in cats.
Selection: Protection from clinical signs and maintenance of white blood cell counts after virulent FPV strain 708 challenge.
Steps
- 1.Express VP2 in Sf9 insect cells using recombinant baculovirusengineered vaccine material being produced
Generate FPV VP2 protein for VLP formation.
VP2 expression is required before purification, assembly confirmation, and animal testing can occur.
- 2.Purify VP2 material by ultrafiltration and SECvaccine material being purified
Obtain purified VP2/VLP material for downstream assembly confirmation and immunization.
Purification follows expression so that the material can be characterized and used as vaccine input.
- 3.Confirm VLP assembly by DLS and TEMvaccine construct being characterized
Verify that the purified VP2 material formed virus-like particles.
Assembly confirmation is performed before animal immunization to ensure the intended VLP product was generated.
- 4.Immunize cats with three VLP dose levels and collect day-21 blood samplesvaccine administered to animals
Test dose-dependent immunization in cats and prepare for serologic assessment.
Animal dosing must precede antibody measurement and challenge testing.
- 5.Measure HI and VN antibody responsesassays used to evaluate vaccine response
Assess immunogenicity of the FPV VLP vaccine before challenge.
Serologic testing follows immunization and provides a pre-challenge readout of vaccine-induced antibody responses.
- 6.Challenge the 15 bcg dose group with virulent FPV strain 708 and monitor disease outcomesvaccine previously administered to challenged animals
Determine whether vaccination protects cats from virulent FPV disease.
Challenge is performed after immunization and serologic assessment to test whether the vaccine confers functional protection.
Taxonomy & Function
Primary hierarchy
Technique Branch
Method: A concrete measurement method used to characterize an engineered system.
Mechanisms
hemagglutination inhibitionTechniques
Functional AssayTarget processes
No target processes tagged yet.
Implementation Constraints
cofactor dependency: cofactor requirement unknownencoding mode: genetically encodedimplementation constraint: context specific validationoperating role: sensor
The abstract indicates that blood samples are required from vaccinated cats. No further protocol details are provided in the abstract.; requires blood sampling from immunized animals
The abstract does not indicate that HI alone establishes protection mechanism or long-term immunity. It also does not provide assay standardization details.; abstract does not provide protocol details or positivity thresholds
Validation
Cell-freeBacteriaMammalianMouseHumanTherapeuticIndep. Replication
Observations
successLarge Animalapplication democat
serology
Inferred from claim c2 during normalization. Immunization with the FPV VLP vaccine produced significantly higher HI and VN antibody titers than PBS control in cats. Derived from claim c2. Quoted text: Immunized cats exhibited significantly higher HI and VN antibody titers compared to controls.
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Supporting Sources
Ranked Claims
PBS control cats developed severe symptoms and significant leukopenia after virulent FPV challenge, unlike vaccinated cats.
In contrast, control cats developed severe symptoms and experienced significant leukopenia.
An FPV VLP vaccine was produced using a recombinant baculovirus system expressing VP2 in Sf9 insect cells, and VLP assembly was confirmed by DLS and TEM.
Sf9 insect cells were infected with recombinant baculovirus to express VP2 protein. The VP2 protein was purified using ultrafiltration and size-exclusion chromatography (SEC). Dynamic light scattering (DLS) and transmission electron microscopy (TEM) confirmed the assembly of VLPs.
Immunization with the FPV VLP vaccine produced significantly higher HI and VN antibody titers than PBS control in cats.
Immunized cats exhibited significantly higher HI and VN antibody titers compared to controls.
The FPV VLP vaccine protected challenged cats from clinical disease and leukopenia after virulent FPV strain 708 challenge.
Cats in the 15 bcg dose group were challenged with virulent FPV strain 708 on day 21, and clinical signs and white blood cell counts were monitored for 10 days. After challenge, vaccinated cats showed no clinical signs of disease, and their white blood cell counts remained stable.
challenge monitoring duration 10 days
Approval Evidence
1 source1 linked approval claimfirst-pass slug hemagglutination-inhibition-assay
Blood samples were collected on day 21 to measure hemagglutination inhibition (HI) and virus-neutralizing (VN) antibody responses.
Source:
immunogenicitysupports
Immunization with the FPV VLP vaccine produced significantly higher HI and VN antibody titers than PBS control in cats.
Immunized cats exhibited significantly higher HI and VN antibody titers compared to controls.
Source:
Comparisons
Source-stated alternatives
The same study also uses a virus-neutralizing assay as a second antibody readout.
Source:
The same study also uses a virus-neutralizing assay as a second antibody readout.
Source-backed strengths
explicitly used as a day-21 serologic readout in vaccinated cats
Source:
explicitly used as a day-21 serologic readout in vaccinated cats
Compared with virus-neutralizing assay
The same study also uses a virus-neutralizing assay as a second antibody readout.
Shared frame: source-stated alternative in extracted literature
Strengths here: explicitly used as a day-21 serologic readout in vaccinated cats.
Relative tradeoffs: abstract does not provide protocol details or positivity thresholds.
Source:
The same study also uses a virus-neutralizing assay as a second antibody readout.
Ranked Citations
- 1.