Vaccine against Gram-negative bacterial infections

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS According to the present invention, a non-covalent, polyvalent complex between purified, detoxified LPS ("DLPS") derived from E.
coli and purified outer membrane protein derived from N.
meningitidis is provided which, when injected into a host subject, actively immunizes the host subject against Gram-negative bacteria and LPS-mediated pathology.
Post-immune serum or plasma from the host subject, or specific polyclonal antibody purified from these fluids, can be administered to a second subject, passively immunizing the second subject against infection by Gram-negative bacteria and LPS-induced pathology.
The preferred strain of E.
coli from which to prepare purified and detoxified LPS endotoxin is an E.
coli J5 (Rc chemotype) strain.
Native J5 LPS may be purchased from List Biological Labs, Inc.
, Campbell, Calif.
For purification purposes it is preferred that the LPS preparation contain less than about 1% protein and less than about 1% nucleic acid.
By "purified E.
coli LPS" is meant LPS suitable for use in the invention vaccine prepared by sonicating native LPS in an alkaline solution, heating the solution at 65° C.
, neutralizing the cooled solution to pH 7.
0, removing released fatty acids and remaining native LPS by Sephadex G-50 chromatography, and collecting the purified, detoxified DLPS.
As determined in a standard rabbit pyrogenicity test, this method reduces the pyrogenicity of LPS preparations, and thus are also referred to as DLPS.
An embodiment of this procedure is described in Example 1 below.
A preferred strain of meningococcus is N.
meningitidis group B.
The outer membrane protein therefrom (hereinafter "GBOMP") is prepared as described in Zollinger et al.
, J.
Clin.
Invest.
63:836 (1079), and U.
S.
Pat.
No.
4,707,543 (1987), the contents of which are incorporated herein by reference.
Briefly, meningococcal group B cells are warmed to about 55 to 60° C.
for a brief period, and disrupted in a shearing device such as OMNIMIX, sold by DuPont Instruments (Newtown, Conn