Broad spectrum pyrogenic antagonists and vaccines directed against pyrogenic exotoxins

Abstract

The invention relates to peptides comprising an amino acid sequence homologous to the amino sequence of a fragment of a pyrogenic exotoxin, and functional derivatives of said peptides, capable of eliciting protective immunity against toxic shock induced by a pyrogenic exotoxin or by a mixture of pyrogenic exotoxins. Preferred peptides comprise an amino acid sequence homologous to the amino acid sequence of a fragment of Staphylococcal aureus enterotoxin B (SEB). The invention also relates to broad spectrum pharmaceutical compositions for the treatment, protection against or short-term prophylaxis of toxin-mediated activation of T cells, comprising as active ingredient at least one peptide according to the invention or derivative thereof, and to broad spectrum vaccines for conferring long-term immunity against toxic shock induced by at least one pyrogenic exotoxin are provided. The vaccines comprise as active ingredient at least one peptide according to the invention, or derivative thereof.

Description

INTRODUCTION [0001] The invention relates to peptides structurally related to protein domains in pyrogenic exotoxins that are capable of antagonizing the activation of T cells that is mediated by said exotoxins and of eliciting protective immunity against the toxic shock that is induced by said exotoxins. The invention further relates to pharmaceutical preparations containing said peptides, for the treatment or prophylaxis of toxic shock and to vaccines containing said peptides that are capable of eliciting protective immunity against the toxic shock induced by said exotoxins. BACKGROUND OF THE INVENTION [0002] A family of pyrogenic exotoxins, also known as superantigenic toxins, is produced by Staphylococcus aureus and Streptococcus pyogenes. The exotoxins comprised of the S. aureus enterotoxins (SEs) cause the majority of human food poisoning cases manifested by vomiting and diarrhea after ingestion (Schlievert, J Infect Dis 167:997 (1993)). S. aureus is found widespread in nature...

AI Technical Summary

Benefits of technology

[0020] In a first aspect, the present invention relates to an isolated and purified peptide having an amino acid sequence homologous to an amino acid sequence of a domain of a pyrogenic exotoxin, which domain forms a central turn in the exotoxin starting within β-strand 7 and connecting the β-strand 7, via short β-strand 8, to α-helix 4, and ending within α-helix 4, based on the domain numbering of SEB, and any functional fragments or derivatives of said peptide, wherein said isolated peptide does not have toxin agonist activity and is capable of antagonizing toxin-mediated activation of T lymphocytes, and / or of eliciting protective immunity against toxic shock induced by a pyrogenic exotoxin or by a mixture of pyrogenic exotoxins and protecting against toxic shock induced by a pyrogenic exotoxin or by a mixture of pyrogenic exotoxins.

[0022] The isolated and purified peptides of the invention and their derivatives are capable of antagonizing toxin-mediated activation of T cells and of protecting against toxic shock induced by a pyrogenic exotoxin or by a mixture of pyrogenic exotoxins.

[0032] In addition, a pharmaceutical composition is provided, for the treatment or short-term prophylaxis of toxin-mediated activation of T cells, comprising as active ingredient a therapeutically effective amount of at least one peptide according to the invention or a derivative thereof. The peptides of the invention are capable of protecting against toxic shock induced by a pyrogenic exotoxin or by a mixture of pyrogenic exotoxins.

[0040] In yet a further aspect, the invention relates to an antiserum containing antibodies directed against at least one peptide of the invention, which peptide can elicit the production of the antibodies. The antiserum is capable of alleviating toxic shock induced by a pyrogenic exotoxin.

Problems solved by technology

However, through its exquisite ability to induce vomiting and diarrhea, SEB is also an incapacitating agent that could severely impair the effectiveness of a fighting force, even temporarily, thereby enhancing vulnerability to conventional military means.

Needless to say, the harmful effects of SEB need to be generally attacked, and not only in connection with the military aspect.

The toxicity of SEB and related exotoxins is thought to be related to the capacity of these molecules to stimulate the rapid and excessive production of cytokines, especially of IL-2, IFN-γ and tumor necrosis factors (TNFs).

14:3292 (1995)) and are thought to cause a rapid drop in blood pressure leading to toxic shock.

While investigation has produced a plausible explanation for the vast stimulation of T cells by SEs, it is not yet clear why these toxins are also strongly immunosuppressive.

Such deletions have not been detected in humans, making them far more vulnerable.

Despite the urgency of this need, methods of protection or treatment have been lacking.

This finding limits the use of SEB toxoids as vaccine, in view of the danger of eliciting certain SEB-sensitizing antibodies that could not only fail to confer protective immunity but would lead to significant exacerbation of the toxic responses in SEB-exposed persons.

That effort failed to yield an effective or specific inhibitory response.

Moreover, currently, there is no prophylaxis available against SEB or any other pyrogenic exotoxin, nor treatment of exposed persons.

In addition, currently there is no way by which to assess the efficacy of vaccination of humans against pyrogenic toxins, since humans cannot be challenged with the toxin in order to check whether they have been conferred the desired immunity.

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