Development and validation of a serological potency test for the release of Leptospira vaccines--requirements in the European Union.

Both European Pharmacopoeia Monograph 01/2008:0447 "Canine Leptospirosis vaccine (inactivated)" and the more recent Monograph 01/2008:1939 "Bovine Leptospirosis vaccine (inactivated)" explicitly allow for a sero-response test to assess batch potency. Test setup and requirements for in vivo and in vitro validation are described. Furthermore, the two main strategies to assess batch potency and their specific demands are addressed.

[Investigation of the endotoxin content of veterinary vaccines]

Vaccines composed of gram-negative bacteria contain endotoxin in considerable amounts. This may result in adverse effects after vaccination of sensitive animals. For reasons of safety and animal welfare the endotoxin level of veterinary vaccines should be limited. The limulus amebocyte lysate test is suitable to check the endotoxin content in most vaccines. Safety tests in animals should only be performed if the results of the limulus test are satisfactory.

[Investigation about development of alternative efficacy verifications of swine erysipelas vaccines]

Vaccination is the most effective prophylaxis against swine erysipelas. Vaccines are usually tested for efficacy by a challenge of vaccinated and untreated pigs. Up to now the efforts to replace the infection test by a serological method have been limited to the potency test in laboratory animals. Here we provide evidence that the measurement of antibodies by an enzyme-linked immunosorbent assay (ELISA) after vaccination and challenge is also possible in the target species. Pig sera were tested for titre development after a single and repeated vaccination in clinical trials. The efficacy of the vaccines was confirmed by a challenge, which demonstrated that all immunized pigs survived with no signs of disease whereas all control animals became severely ill. The ELISA was also used to measure erysipelas antibodies after immunization of pigs with several vaccines in a field trial. The ELISA may be a suitable alternative to replace the challenge methods currently used for testing of erysipelas vaccines.