[Efficacy of Spirolept vaccine against human leptospirosis as estimated by passive protection of laboratory rodents].

OBJECTIVE

This study had for aim to assess the serological response induced by the Spirolept vaccine against human leptospirosis.

METHOD: A serological follow-up was made on 31 patients at a risk of occupational exposure. The antibody titers of vaccinated patients were assessed by MAT and ELISA. In a second step, vaccinal protection was studied in vivo by checking the seroprotective effect of the human sera injected in an animal model (Meriones unguiculatus) naturally susceptible to the disease. The passive protection was studied by comparing the death rate on five batches of animals to which the bacterium was inoculated. Thus, four batches of animals were injected subcutaneously with a pooled sera of vaccinated people sampled at D0, D15, D135, and D320 after Spirolept vaccination. One control batch was given PBS. One day after injection, the latter batch was inoculated with the homologous strain Verdun of Leptospira interrogans ss icterohemorrhagiae (serogroup Icterohemorrhagiae) used to make the vaccine.

RESULTS

The death rate was significantly decreased as soon as D15 after the first injection, even with pooled sera of vaccinated people negative for the MAT.

COMMENTS: The Spirolept vaccine induces a protective response against icterohemorrhagiae, which can be transmitted to the animal model and thus is linked to a humoral response.