[Fundamental studies on rapid detection of Haemophilus influenzae by enzyme-linked immunosorbent assay (ELISA)]

To establish a rapid method for detection of Haemophilus influenzae, an antiserum against H. influenzae (Anti-HibOMP) was prepared by immunization of rabbits with crude outer membrane proteins (OMP) of H. influenzae type b. Various isolates of H. influenzae including typable and nontypable strains and other species were tested by ELISA and Western blot assay with Anti-HibOMP. The results are as follows: 1. Anti-HibOMP reacted to all of the OMPs from 18 H. influenzae isolates which contained typable and nontypable strains by Western blot assay. Molecular weights of these OMPs were about 24, 27, 31, 34, 39 and 45 kilo-dalton. This result suggests that all H. influenzae isolates have identical antigenic proteins on their outer membranes. 2. It was found that 172 out of 179 (96%) culture suspensions of H. influenzae isolates including 66 typable and 113 nontypable showed positive result by ELISA with Anti-HibOMP. 3. To define the cross-reactivity of Anti-HibOMP, 20 species (111 isolates) other than H. influenzae were tested by the ELISA. All isolates were negative with exception of a portion of H. parainfluenzae and Staphylococcus aureus producing Protein A. The cross-reactions to H. parainfluenzae and S. aureus were removed by absorption of Anti-HibOMP with formalinized cells of H. parainfluenzae and reduction of the antibody to F(ab)2 with pepsin digestion respectively.(ABSTRACT TRUNCATED AT 250 WORDS)