Outer membrane protein D15 is conserved among Haemophilus influenzae species and may represent a universal protective antigen against invasive disease.

Abstract

We have cloned and sequenced the d15 gene from two strains of Haemophilus influenzae type b (Hib) and two strains of nontypeable H. influenzae (NTHI). The nucleotide and deduced protein sequences of d15 are highly conserved, with only a small variable region identified near the carboxyl terminus of the protein. Analysis of upstream sequences revealed that the H. influenzae d15 gene may be part of a large potential operon of closely spaced open reading frames, including one with significant homology to the Escherichia coli cds gene encoding CDP-diglyceride synthetase. Southern blot analysis demonstrated that the d15 gene is also present in H. influenzae types a, c, d, e, and f and in Haemophilus parainfluenzae. A recombinant D15 (rD15) protein was expressed in good quantity in E. coli from the inducible T7 promoter, and monospecific anti-rD15 antibodies were raised. Immunoblot analysis of H. influenzae serotypes a, b, c, d, e, and f, NTHI, and H. parainfluenzae lysates revealed that they all expressed a cross-reactive D15-like protein. Purified rD15 was found to be highly immunogenic in mice, guinea pigs, and rabbits, and passive transfer of anti-rD15 antibodies protected infant rats from challenge with H. influenzae type b or type a in infant rat models of bacteremia. Thus, D15 is a highly conserved antigen that is protective in animal models and it may be a useful component of a universal subunit vaccine against Haemophilus infection and disease.

• Authors: S M Loosmore, Y P Yang, D C Coleman, J M Shortreed, D M England, M H Klein
• Journal: Infection and immunity (Infect Immun) Vol. 65 Issue 9 Pg. 3701-7 (Sep 1997) ISSN: 0019-9567 [Print] United States
• PMID: 9284140 (Publication Type: Journal Article)

Chemical References

• Antigens, Bacterial
• Bacterial Outer Membrane Proteins
• D15 antigen, bacteria
• Recombinant Proteins

Topics

• Amino Acid Sequence
• Animals
• Antigens, Bacterial (chemistry)
• Bacterial Outer Membrane Proteins (chemistry, immunology)
• Base Sequence
• Blotting, Western
• Cloning, Molecular
• Escherichia coli
• Guinea Pigs
• Haemophilus influenzae (chemistry, genetics, immunology)
• Mice
• Mice, Inbred BALB C
• Molecular Sequence Data
• Rabbits
• Recombinant Proteins (immunology)
• Sequence Alignment
• Sequence Homology, Amino Acid
• Serotyping