[The PRRSV-serumneutralization test detects gaps in herd immunity].

Area of Science:

• Veterinary Virology
• Immunology
• Swine Health

Context:

• Porcine Reproductive and Respiratory Syndrome Virus (PRRSV) poses significant challenges to swine production globally.
• Two main genotypes, European (EU) and United States (US), exist, with available attenuated live-vaccines for both.
• Understanding herd immunity is crucial for effective PRRSV control strategies.

Purpose:

• To evaluate the level of neutralizing antibodies against PRRSV genotypes in Bavarian sow herds.
• To assess the correlation between vaccination status, PRRSV genotype detection, and antibody titers.
• To determine the diagnostic value of ELISA and serum neutralization tests (SNT) in assessing herd immunity.

Summary:

• A cross-sectional study analyzed sera from 38 Bavarian sow herds, categorizing them by vaccination status (EU, US, or non-vaccinated).
• EU-vaccinated sows exhibited the highest EU-SNT titers, suggesting the EU-SNT effectively reflects herd immunity against the EU vaccine virus.
• ELISA showed high reactivity in US-vaccinated herds with EU-PRRSV detection, but its value is limited to certifying PRRSV-free herds, while EU-SNT indicates herd immunity gaps.

Impact:

• The EU-SNT is a valuable tool for assessing herd immunity levels against PRRSV, particularly identifying deficiencies in protection.
• ELISA's utility is primarily for confirming PRRSV-free status rather than assessing active immunity.
• Findings contribute to optimizing PRRSV vaccination and management strategies in swine herds.