La réaction d'immunofluorescence dans le sérodiagnostic des brucelloses humaines

Risk of infection by Brucella melitensis for people living near infected goats

Taking advantage of a local outbreak of brucellosis in a herd of goats, we have assessed the risk of infection for people living nearby. By means of serological tests we have shown that such a risk is small provided that direct contact with contaminated tissues or secretions of goats is avoided.

Immunization by an insoluble fraction extracted from Brucella melitensis: immunological and chemical characterization of the active substances

A peptidoglycan-containing fraction called fraction P.I. (phenol insoluble), extracted from Brucella melitensis and previously described by some of us, had immunogenic and protective properties and did not produce any allergic reactions. Since it is well known that bacterial peptidoglycans studied so far have immunoadjuvant properties, the isolation of the active factor(s) of Brucella was undertaken. By successive enzymatic and chemical treatments, a new, much more purified fraction, called "4A" (approximately 5% of fraction P.I.), is obtained, retaining the same properties as P.I. and giving better protection against infection by Brucella. Immunogenicity, immunoadjuvant activity, allergizing capacity, and specific and nonspecific protective effects of fractions P.I. and 4A are compared. Chemically, fraction 4A is constituted by a lipoprotein covalently linked to peptidoglycan and by a few (lipo)proteins that could be solubilized by hot sodium dodecyl sulfate. Intrinsic properties of peptidoglycan could not be studied, but it does not seem to be essential for the activity. In conclusion, fractions P.I. and 4A are not agglutinogenic and, since fraction 4A induces better protection against infection by Brucella, it could advantageously replace fraction P.I. as a vaccine for humans.