Drug – bio-affecting and body treating compositions – Enzyme or coenzyme containing – Hydrolases
Reexamination Certificate
1995-06-07
2001-09-11
Saidha, Tekchand (Department: 1652)
Drug, bio-affecting and body treating compositions
Enzyme or coenzyme containing
Hydrolases
C435S201000, C435S069100, C435S252300, C435S320100, C536S023200, C536S023500, C536S023400, C530S350000
Reexamination Certificate
active
06287559
ABSTRACT:
FIELD OF THE INVENTION
The present invention is directed to nucleic acids encoding vespid venom allergens, in particular venom enzymes such as phospholipase and hyaluronidase, or fragments thereof, recombinant vectors comprising such nucleic acids, and host cells containing the recombinant vectors. The invention is further directed to expression of such nucleic acids to produce a recombinant vespid venom enzyme, such as phospholipase or hyaluronidase, or recombinant fragments thereof. Such an allergen and fragments thereof are useful for diagnosis of allergy and for therapeutic treatment of allergy.
BACKGROUND OF THE INVENTION
Biochemical Aspects of Insect Venom Allergens
Insect sting allergy to bees and vespids is of common occurrence. The vespids include hornets, yellowjackets and wasps (Golden, et al., 1989, Am. Med. Assoc. 262:240). Susceptible people can be sensitized on exposure to minute amounts of venom proteins; as little as 2-10 &mgr;g of protein is injected into the skin on a single sting by a vespid (Hoffman and Jacobson, 1984, Ann. Allergy. 52:276).
There are many species of hornets (genus Dolichovespula), yellowjackets (genus Vespula) and wasp (genus Polistes) in North America (Akre, et al., 1980, “Yellowjackets of America North of Mexico,” Agriculture Handbook No. 552, US Department of Agriculture). The vespids have similar venom compositions (King, et al., 1978, Biochemistry 17:5165; King, et al., 1983, Mol. Immunol. 20:297; King, et al., 1984, Arch. Biochem. Biophys. 230:1; King, et al., 1985, J. Allergy and Clin. Immunol. 75:621; King, 1987, J. Allergy Clin. Immunol. 79:113; Hoffman, 1985, J. Allergy and Clin. Immunol. 75:611). Their venom each contains three major venom allergens, phospholipase (37 kD), hyaluronidase (43 kD) and antigen 5 (23 kD) of as yet unknown biologic function.
In addition to the insect venom allergens described above, the complete amino acid sequence of several major allergens from different grass (Perez, et al., 1990, J. Biol. Chem. 265:16210; Ansari, et al., 1989, Biochemistry 26:8665; Silvanovich, et al., 1991, J. Biol. Chem. 266:1204), tree pollen (Breiteneder, 1989, EMBO J. 8:1935; Valenta, et al., 1991, Science, 253:557), weed pollen (Rafnar, et al., 1991, J. Biol. Chem. 266:1229; Griffith, et al., 1991, Int. Arch. Allergy Appl. Immunol. 96:296), mites (Chua, et al., 1988, J. Exp. Med. 167:175), cat dander (Griffith, et al., 1992, Gene. 113:263), and mold (Aruda, et al., 1990, J. Exp. Med. 172:1529; Han, et al., 1991, J. Allergy Clin. Immunol. 87:327) have been reported in the past few years. These major allergens are proteins of 10-40 kD and they have widely different biological functions. Nearly all allergens of known sequences have a varying extent of sequence similarity with other proteins in our environment.
T and B Cell Epitopes of Allergens
Antibody responses to proteins require the collaboration of T helper and B lymphocytes and antigen presenting cells (APC). The antigen receptors of B cells are the membrane-bound antibody (Ab) molecules, which recognize and bind immunogens directly. The antigen receptors of T cells (TCR) only recognize and bind complexes of antigenic peptide-MHC class II molecule. Immunogens are first processed by APC into peptides that are presented on the surface of APC in association with the MHC class II molecules (Unanue, 1992, Current Opinion in Immunol 4:63). As MHC molecules are highly polymorphic in individuals, they have different specificity of binding antigenic peptides (Rothbard and Gefter, 1991, Ann. Rev. Immunol. 9:527). This is one mechanism for genetic control of immune response.
T helper cells are activated when the antigen receptor binds the peptide-MHC complex on the surface of APC. Activated T cells secrete lymphokines. In mice (Street and Mosmann, 1991, FASEB J. 5:171) and apparently in humans (Wierenga, et al., 1990, J. Immunol. 144:4651; Parronchi, et al., 1991, Proc. Natl. Acad. Sci. USA. 88:4538) the T helper cells can be divided into different types on the basis of their patterns of lymphokine production. Primarily, T helper cells divide into two groups: TH1 cells producing IL-2 and IFN-&ggr;, and TH2 cells producing IL-4 and IL-5. These lymphokines in turn influence the antigen-activated B cells to differentiate and proliferate into plasma cells secreting Abs of different isotypes. IL-4 is one lymphokine known to influence IgE synthesis (Finkelman, et al., 1990, Ann. Rev. Immunol. 8:303).
It is believed that the entire accessible surface of a protein molecule can be recognized as epitopes by the antigen receptors of B cells, although all epitopes are not necessarily recognized with equal likelihood (Benjamin, et al., 1984, Ann. Rev. Immunol. 2:67). B cell epitopes of a protein are of two types: topographic and linear. The topographic type consists of amino acid residues which are spatially adjacent but may or may not be sequentially adjacent. The linear type consists of only sequentially adjacent residues. X-ray crystallographic data of Ag-Ab complexes indicate the size of their complementary binding region to have 16-17 amino acid residues (Amit, et al., 1986, Science 233:747), but peptide mapping suggests that less than about 8 residues contribute significantly to the binding process of a linear epitope (Appel, et al., 1990, J. Immunol. 144:976).
Allergens, like other protein antigens, can have both types of B cell epitopes or only one. For example, vespid antigen 5s have both types. Bee venom melittin appears to have only one B cell epitope of linear type (King, et al., 1984, J. Immunol. 133:2668).
T cell epitopes of proteins consist of only the linear type since they are peptides that have been processed in the lysosomes of APC by proteases of unknown specificity (Unanue, 1992, Curr. Op. Immunol. 4:63). Analysis of naturally processed antigenic peptides bound to MHC class II molecules indicates that their size ranges from about 13 to 17 amino acid residues, but analysis of synthetic peptide-MHC class II molecule complex for their T cell proliferate response suggests a minimal size of about 8 amino acid residues (Cf. Rudensky et al., 1991, Nature 353:622). Studies suggest that T cell epitopes are distributed throughout the entire protein molecule, and they may function as major or minor determinants depending on the MHC haplotype of the immunized host (Roy, et al., Science 244:572; Gammon, et al., 1987, Immunol. Rev. 98:53; O'Hehir et al., 1991, Ann. Rev. Immunol. 9:67).
Hypersensitivity of the immediate type is known to be caused by the presence of allergen-specific IgE. IgE is found in the circulation and bound to specific IgE-Fc receptors on mast cells and basophils. Cross-linking of cell-bound IgE by allergens leads to release of histamine, leukotrienes and other chemical mediators that cause the allergic symptoms. IgE is one of the different isotypes of immunoglobulins. As pointed out above, lymphokines secreted by T cells influence isotype switch events in B cells.
Because of the central role of TH2 cells in determining the isotypes switch event of B cells, the T cell epitopes of several allergens have been mapped (Cf. O'Hehir et al., supra). These allergens include ragweed Amb &agr; III, rye grass Lol p I, cat Fel d I, mouse urine Mus m I, midge Chi t I, bee venom phospholipase A
2
(Dhillon, et al., 1992, J. Allergy Clin. Immunol. 90:42) and melittin (Fehlner, et al., 1991, J. Immunol. 146:799). The data do not reveal any unusual or common structural features. However, any conclusion from these data is qualified as these data are collected from humans and mice of different haplotypes.
Modulation of T and B Cell Responses
Normally hosts are tolerant to the dominant B and T cell epitopes of self proteins by clonal deletion and anergy. However this tolerance can be broken under certain circumstances (Gammon, et al., 1991, Immunol. Today. 12:193; Basten, et al., 1991, Immunol. Rev. 122:5). It has been suggested that self-tolerance is broken in autoimmune diseases through encounters with foreign proteins that are similar to host proteins. Therefore the sequen
Darby & Darby
Saidha Tekchand
The Rockefeller University
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