ANALYSIS OF IMMUNOGLOBULIN CLASSES AND SUBCLASSES IN RESPONSE TO INFECTION OF BALB CJ AND C57BL/6J MICE WITH COXIELLA-BURNETII/

In order to establish defined immunological parameters for Q fever inf ection models, a microtitre enzyme-linked immunosorbent fluorescence a ssay (ELISA) was used for the first time to analyse the humoral immune response of Balb/cJ and C57BL/6J mice after experimental infection wi th Coxiella burnetii strain 'Nine Mile' in phase I. The experimental i nfection evoked a seroconversion in all mice within 10 days. Typically , the immune response measured against the whole-cell antigen showed a n early increase of immunoglobulin (Ig) M followed by a later increase of the IgG subclasses. The IgA was low during the entire investigatio n period. Within the IgG subclasses only IgG2a and IgG2b gained higher values, whereby C57BL/6J mice produced high IgG2b titres and signific antly lower IgG2a titres. In contrast, Balb/cJ mice developed IgG2a an d IgG2b al equal levels. The use of partial antigens of C. burnetii de monstrated that the dominating IgG2b reaction of the C57BL/6J mice was directed against the lipopolysaccharide (LPS) of C. burnetii. This re action was al-nest absent in Balb/cJ mice. In contrast, the SP27 prote in antigen did not evoke different IgG2b reactions within the two bree ds. No significant influence was observed within the two breeds in reg ard to sex or between hormone synchronized and non-hormone synchronize d animals.