A critical review speculating on the protective efficacies of autogenous bacterins as used in Europe.

Background: is a major porcine pathogen causing high morbidity worldwide. This includes well-managed herds with high hygiene standards. In Europe, no licensed vaccine is available. As practitioners are obliged to reduce the use of antibiotics, autogenous vaccines have become very popular in Europe.

Main Body: Autogenous vaccines (AV) are generally neither tested for safety, immunogenicity nor protective efficacy, which leads to substantial uncertainties regarding control of disease and return on investment. Here, publications are reviewed that include important data on epidemiology, pathologies and bacterin vaccination relevant for the use of AV in the field. Differences between herds such as the porcine reproductive and respiratory syndrome virus infection status and the impact of specific pathotypes are probably highly relevant for the outcome of immunoprophylaxis using autogenous bacterins. Thus, a profound diagnosis of the herd status is crucial for management of expectations and successful implementation of AV as a tool to control disease. Induction of opsonizing antibodies is an in vitro correlate of protective immunity elicited by bacterins. However, opsonophagocytosis assays are difficult to include in the portfolio of diagnostic services.

Conclusion: Autogenous bacterins are associated with limitations and risks of failure, which can partly be managed through improvement of diagnostics.