HUMAN IMMUNE-RESPONSE AGAINST OUTER-MEMBRANE PROTEINS OF MORAXELLA (BRANHAMELLA) CATARRHALIS DETERMINED BY IMMUNOBLOTTING AND ENZYME-IMMUNOASSAY

The role of Moraxella (Branhamella) catarrhalis as a respiratory tract pathogen is increasingly recognized. We looked at the human immune re sponse against individual outer membrane proteins of M. catarrhalis an d against the 81-kDa CopB protein, which has previously been shown to be a target far protective antibodies. Paired serum samples from six e lderly patients with pneumonia were tested by Western blot (immunoblot ) analysis by using outer membrane vesicles of M. catarrhalis 035E as antigen. All of the six convalescent-phase serum samples reacted with a protein which migrated at the position of the CopB protein and with a high-molecular-weight protein of M. catarrhalis; three serum samples also reacted with a 34-kDa outer membrane protein. Paired serum sampl es from 18 patients, 10 of which had M. catarrhalis infection on the b asis of previous serology results, were tested by enzyme immunoassay ( EIA) with the CopB protein and whole cells of M. catarrhalis 035E as a ntigens. Nine patients showed a significant rise in EIA titer between acute- and convalescent-phase sera when whole bacterial cells were use d as antigens. Six (67%) patient samples that were positive by the EIA with the whole-cell antigen were also positive by the EIA with the Co pB antigen, and six of nine patient samples negative by the EIA with t he whole-cell antigen were also negative by the EIA with the CopB anti gen. These results suggest that both the CopB and a high-molecular-wei ght protein are major targets of the immune response against M. catarr halis, and further studies with greater amounts of patient materials a re needed to elucidate the usefulness of CopB as an antigen in etiolog ic studies.