Chemistry: molecular biology and microbiology – Micro-organism – tissue cell culture or enzyme using process... – Recombinant dna technique included in method of making a...
Patent
1996-07-12
2000-02-15
Caputa, Anthony C.
Chemistry: molecular biology and microbiology
Micro-organism, tissue cell culture or enzyme using process...
Recombinant dna technique included in method of making a...
4353201, 435325, 514 44, 536 237, C12P 2106, C12N 1500, C12N 500, C07H 2104
Patent
active
060251646
DESCRIPTION:
BRIEF SUMMARY
TECHNICAL FIELD
The present invention provides recombinant polypeptides which constitute Helicobacter pylori antigens, said antigens being expressed on the surface of both dividing (bacillary) forms as well as resting (coccoid) forms of H. pylori, and giving rise to both systemic and local (mucosal) production of antibodies. The invention furthermore provides nucleic acid molecules coding for the said polypeptides, as well as vectors and host cells comprising such nucleic acid molecules. The said recombinant polypeptides are useful for the diagnosis of H. pylori infections and for the manufacture of vaccine compositions which will elicit a protective immune response against such infections, said vaccine compositions being suitable for both therapeutic and prophylactic use.
BACKGROUND ART
The gram-negative bacterium Helicobacter pylori is an important human pathogen, involved in several gastroduodenal diseases. Colonization of gastric epithelium by the bacterium leads to active inflammation and progressive chronic gastritis, with a greatly enhanced risk of progression to peptic ulcer disease.
In order to colonize the gastric mucosa, H. pylori uses a number of virulence factors. Such virulence factors comprise several adhesins, with which the bacterium associates with the mucus and/or binds to epithelial cells; ureases which helps to neutralize the acid environment; and proteolytic enzymes which makes the mucus more fluid.
Despite a strong apparent host immune response to H. pylori, with production of both local (mucosal) as well as systemic antibodies, the pathogen persists in the gastric mucosa, normally for the life of the host. The reason for this is probably that the spontaneously induced immune-response is inadequate or directed towards the wrong epitopes of the antigens.
In order to understand the pathogenesis and immunology of H. pylori infections, it is of great importance to define the antigenic structure of this bacterium. In particular, there is a need for characterization of surface-exposed like adhesins) and secreted proteins which, in many bacterial pathogens, have been shown to constitute the main virulence factors, and which can be useful for the diagnosis of H. Pylori and in the manufacture of vaccine compositions.
Cloning of the gene hpaA, which codes for a 20 kDa receptor-binding subunit of the N-acteylneuraminyllactose-binding fibrillar hemagglutinin (NLBH) of H. pylori, has been disclosed by Evans et al. (1993) J. Bacteriol. 175, 674-683.
Monoclonal antibodies (MAbs) against membrane preparations of H. pylori have been disclosed by Bolin et al. (1995) J. Clin. Microbiol. 33, 381-384. One of these MAbs, designated HP30-1:1:6, reacted with a 30 kDa protein which was shown to be exposed on the surface of intact bacteria and to have properties like that of an adhesin.
Whenever stressed or threatened, the H. pylori cell transforms from a bacillary to a coccoid form. In the coccoid form, the H. pylori cell is much less sensitive to antibiotics and other anti-bacterial agents. Circumstantial evidence indicate the H. pylori might be transmitted between individuals in this form, possibly via water or direct contact. An efficient vaccine composition should therefore elicit an immune response towards both the coccoid and the bacillary form of H. pylori. Since systemic immunity probably only plays a limited role in protection against mucosal infections, it is also important that the vaccine composition will enhance protective immune mechanisms locally in the stomach.
PURPOSE OF THE INVENTION
The purpose of this invention is to provide an antigenic H. pylori polypeptide which can be useful i.a. for eliciting a protective immune response against, and for diagnosis of, H. pylori infection. This purpose has been achieved by the recombinant cloning of a H. pylori gene which encodes a surface-exposed protein. The nucleic acid sequence of this gene is similar to the sequence of the hpaA gene as published by Evans et al. (1993) in the Journal of Bacteriology, vol. 175, 674-683. However, while the hp
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Bolin Ingrid
Svennerholm Ann-Mari
Astra Aktiebolag
Caputa Anthony C.
Navarro Mark
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