Transiently produced IgGs enable infection-blocking vaccine efficacy assessment

Area of Science:

• Veterinary immunology
• Vaccinology
• Serological diagnostics

Background:

• Current vaccines are often assessed by symptom prevention, not infection blocking, hindering control of asymptomatic spread.
• Evaluating vaccine efficacy (VE) for infection-blocking requires precise methods to track protection duration and detect subclinical infections.

Purpose of the Study:

• To develop a serology-based strategy for detecting asymptomatic infections and quantifying infection-blocking vaccine protection.
• To establish a framework for data-driven re-vaccination schedules and future VE trials focused on infection blocking.

Main Methods:

• Utilized porcine circovirus 2 (PCV2) vaccines as a model system.
• Differentiated serological responses: transient anti-peptide IgGs post-infection vs. persistent anti-Capsid protein IgGs.
• Developed a digital microarray index (DMI) based on anti-peptide IgG patterns to quantify protection duration.

Main Results:

• Distinct IgG responses identified new infections post-vaccination.
• The DMI successfully quantified and ranked the infection-blocking efficacy of five commercial PCV2 vaccines.
• DMI analysis, combined with vaccination records, accurately assessed herd immunity and guided re-vaccination strategies on farms.

Conclusions:

• Introduced a serological platform for detecting asymptomatic infections and measuring infection-blocking protection.
• The DMI provides high-resolution immune surveillance, enabling timely re-vaccination decisions.
• This approach supports future VE trials aimed at pathogen elimination and controlling transmission.