Antitoxins and methods for making antitoxins

Drug – bio-affecting and body treating compositions – Immunoglobulin – antiserum – antibody – or antibody fragment,...

Reexamination Certificate

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C424S157100, C424S164100, C424S804000

Reexamination Certificate

active

06613326

ABSTRACT:

This invention was made with government support. The Government has certain rights in the invention.
1. Field of the Invention
This invention relates to a method of antitoxin production, and in particular, antibodies to naturally-occurring plant and/or bacterial toxins.
2. Background of the Invention
The present invention relates to antitoxins suitable for treatment of humans and animals as well as for analytical use.
I. Venoms
A toxin is a single protein or peptide that has deleterious effects in man or animals. A venom comprises a plurality of toxins; they are relatively complex mixtures of proteins and peptides that can cause considerable morbidity and mortality in humans and animals.
The chemical actions of and biological reactions to venoms are as diverse as their sources. Depending on the nature of the venoms, their toxic effects may be evident in the cardiovascular, hematologic, nervous, and/or respiratory systems.
Each region of the world has its own particularly troublesome venomous species. Within Eukarvota (see Table 1), some specific venom sources from the Animalia kingdom are most notable.
A. Eukaryota
i) Chordata. A number of Chordata classes are sources of venoms (e.g., Amphibians, Fish, Reptiles). Among Reptiles, the most significant order is snakes. Snake venom is a relatively complex mixture of enzymes, non-enzymatic proteins and peptides, and as yet unidentified compounds. W. A. Wingert and J. Wainschel, S. Med. J. 68:1015 (1975). D. C. Christopher and C. B. Rodning, S. Med. J. 79:159 (1986). While there are some chemical similarities, the.venom.of each species exhibits its own characteristic toxicity. M. J. Ellenhorn and D. G. Barceloux, Medical Toxicology, Ch.39 (Elsevier Press 1988).
TABLE 1
Phylogeny of Toxin- and Venom-Producing Organisms
SUPERKINGDOM:
PROKARYOTA
KINGDOM:
MONERA
DIVISION:
BACTERIA
SUPERKINGDOM:
EUKARYOTA
KINGDOM:
FUNGI
KINGDOM:
PLANTAE
KINGDOM:
ANIMALIA
PHYLUM:
CHORDATA
CLASSES:
Amphibia
Reptilia
Pisces
PHYLUM:
ARTHROPODA
CLASSES:
Arachnida
Insecta
Myriapoda
PHYLUM:
COELENTERATA
PHYLUM:
MOLLUSCA
Of the over 100 species of snakes in the United States, approximately 10% are poisonous. H. M. Parrish, Public Health Rpt. 81:269 (1966). The majority of these are from the family Crotalidae. The venomous species include the rattlesnakes (Crotalus), cottonmouths and copperheads (Agkistrodon), and pigmy and massassauga rattlesnakes (Sistrurus). There are also poisonous members of the Elapidae family, the coral snakes (Micruroides). F. E. Russell et al., JAMA 233:341 (1975).
ii) Arthropoda. In the Arthropoda phylum, an important class is Arachnida. Among Arachnida, scorpions (Order Scorpiones) produce the most significant venoms. While scorpion venoms are also complex mixtures, there has been some success identifying their active agents. Approximately thirty different protein neurotoxins, each having a molecular weight of about 7000 daltons, have been isolated. M. E. Ayeb and P. Delori, In: Handbook of Natural Toxins, Vol.2, Insect Poisons, Allergens, and Other Invertebrate Venoms, (Anthony T. Tu, Ed.)(Marcel Dekker 1984), Chapter 18 (pp. 607-638). Of the approximately 650 scorpion species, the most dangerous belong to the Buthidae family and the genuses Tityus (North and South America), Centruroides (U.S. and Mexico), Centrurus (Mexico), Androctonus (Mediterranean/North Africa), Buthacus (Mediterranean/North Africa), Leiurus (Mediterranean/North Africa), Buthotus (Mediterranean/North Africa), Buthus (Mediterranean/North Africa), and Parabuthus (South Africa). F. Hassan, In: Handbook of Natural Toxins, Vol.2, Insect Poisons, Allergens, and Other Invertebrate Venoms, (Anthony T. Tu, Ed.)(Marcel Dekker 1984), Chapter 17 (pp. 577-605).
iii) Coelenterata. In the Coelenterata phylum, jelly fish are an important venomous species; the venom from
Chironex fleckeri
is among the most potent and medically significant. In the waters off Northern Australia, about one fatality occurs each year. J. Lumley et al., Med. J. Aust. 148, 527 (1988). Several toxic fractions have been characterized from
C. fleckeri
venom including two high molecular weight myotoxins (R. Endean, Toxicon 25, 483 (1987)) and several low molecular weight toxins having hemolytic or dermonecrotic properties (C. E. Olson et al., Toxicon 22, 733 (1984); E. H. Baxter and A. G. M. Marr, Toxicon 7, 195 (1969)).
iv) Mollusca. In the Mollusca phylum, the most significant venomous members are the coneshells (Conidae) which produce potent myotoxins that can be fatal. G. G. Habermehl, Venomous Animals and Their Toxins (Springer-Verlag, Berlin 1981). Little is known about the structure of the molluscan myotoxins.
B. Prokaryota
Prokaryotes are an important source of toxins. Most bacterial toxins, for example, are well known. Among species of bacteria, the most notorious toxin sources are certainly
Clostridum botulinum
and
Clostridium Parabotulinum
. The species produce the neurogenic toxin known as botulinus toxin. While a relatively rare occurrence in the United States, involving only 355 cases between 1976 and 1984 (K. L. MacDonald et al., Am J. Epidemiology 124, 794 (1986)), the death rate due to the botulism toxin is 12% and can be higher in particular risk groups. C. O. Tacket et al., Am. J. Med. 76, 794 (1984).
Many other bacteria produce protein toxins of significance to humans, including
Bacillus anthracis, Bordetella pertussis
(diptheria),
Pasteurella pestis, Pseudomonas aeruginosa, Streptococcos pyrogenes, Bacillus cereus,
E. coli
, Shigella,
Staphylococcus aureus, Vibrio cholerae
, and
Clostridium tetani
. Thorne and Gorbach, Pharmacology of Bacterial Toxins, In: International Encyclopedia of Pharmacology and Therapeutics, F. Dorner and J. Drews (eds.), Pergamon Press, Oxford (1986), pp. 5-16.
II. Treatment
As noted above, a toxin is defined as a single protein or peptide and a venom is defined as comprising a plurality of toxins. Both toxin and venom have been used as antigen for treatment.
Exposure to most venoms in humans does not result in protective immunity. Furthermore, all attempts to create protective immunity against venoms with vaccines have failed. F. E. Russell, JAMA 215:1994 (1971) (rattlesnake venom). By contrast, there has been success creating protective immunity against individual toxins, including diptheria (F. Audibert et al., Proc. Natl. Acad. Sci USA 79:5042 (1982)) and tetanus vaccines. J. E. Alouf, Ann Inst. Pasteur/Microbiol. 136B, 309 (1985).
A. Active Immunization
Tetanus toxoid injections provide an effective protection because they elicit a low level of circulating antibody and establish immunological memory. When exposed to a low dose of the tetanus organism and toxin, the immunized animal can neutralize the organism and toxin before the infection develops.
In the case of animal venoms, such prophylactic measures have not been feasible. First, many animal venoms are too difficult or too expensive to obtain to immunize a population where a relatively small percentage of that population will be exposed to the animal venom. Second, even if they can be obtained, animal venoms, unless detoxified, may cause more morbidity when administered to a large population than would be caused by the venomous animals themselves. Third, even if the venom is affordable, obtained in sufficient quantity, and detoxified, it is extremely difficult to achieve the titer of circulating antibody necessary to neutralize the infusion of what can be a large amount of venom (up to one gram of animal venom as compared with nanogram or picogram amounts of tetanus toxin). Finally, even with successful immunization, immunological memory is too slow to respond to the immediate crisis of envenomation.
Although active immunization with venoms has the above-named problems, some investigators have chosen to pursue research in this area rather than in the area of passive immunization, arguing that passive immunization is too long and expensive. These investigators have made some progress in the method of immunization by using liposomes. R. R. C. New et al., New Eng. J. Med. 311 56 (1984). T.

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