What are recombinant allergens?
Allergy caused by immunoglobulin (Ig) E is a common hypersensitivity condition throughout the world. In general, two approaches are followed for allergy treatment: the first is medications that are used to reduce allergic symptoms, and the second approach involves the use of allergen-specific immunotherapies (AITs). Pharmacotherapy is often used to reduce allergic symptoms and inflammation; however, these drugs can cause adverse effects, there is low clinical efficacy, and the effects diminish after discontinuation of therapy. High cost and lack of disease-modifying effects are other disadvantages of traditional pharmacotherapy.
AIT-based interventions involve the identification of disease-causing allergens, allergen avoidance strategies, and prescription of targeted immunotherapy. Treatment is based on the administration of the allergens recombinant causing the disease in order to induce a protective immune response. Although the approach involves a longer treatment time frame, the effects of the treatment are long-lasting. AIT also confers disease-modifying effects that stop the progression of mild to severe manifestations. The treatment is relatively inexpensive and can also be used for the prevention of allergic sensitization.
The quality of allergen extracts from natural sources is a major bottleneck for AIT. Instability and variable amounts of allergens, contamination and poor immunogenicity of allergens are the main obstacles. Natural allergen extracts do not meet the requirements of regulatory authorities for the manufacture of allergy vaccines. Furthermore, the administration of such allergens can induce serious and life-threatening side effects and thus require cumbersome dosing schedules with multiple injections and hospitalization.
The application of recombinant technologies for the production of recombinant allergens for AIT has opened new avenues for the treatment of allergic diseases. With the advancement of research, allergen-encoding complementary DNA (cDNA) has been isolated for most clinically relevant allergens. This has led to the production of recombinant forms of allergens in large quantities and with consistent quality. The first recombinant allergen for the dust mite allergen Der p 1 was discovered in 1988.
Recombinant allergens in the elucidation of structures.
Allergens occur naturally as a mixture of various isoforms, and separation of the isoforms is a difficult task. Also, some allergens are present in very low concentrations; therefore, it is cumbersome to obtain a sufficient amount of the purified allergen for crystallization. Recombinant allergens have helped elucidate the crystal and solution structures of allergens.
Recombinant allergens in diagnostic tests
Because natural allergens can only be isolated in small amounts from natural sources, recombinant allergens have become an alternative for allergy diagnosis. Molecular diagnostic tests help elucidate a patient’s sensitization patterns at the molecular level. This procedure increases diagnostic accuracy, distinguishes genuine sensitization from sensitization due to cross-reactivity, helps assess the risk and type of allergic reaction, and facilitates the selection of eligible patients and appropriate allergens for allergen-specific immunotherapy.
Recombinant allergens in vaccine production
The use of recombinant technologies in vaccine production has led to the production of well-characterized, uncontaminated vaccines with well-defined biological activity. Genetic engineering techniques allow the development of allergen derivatives with reduced IgE reactivity, reduced risk of triggering undesirable allergic reactions while retaining immunogenic activity.
Much progress has been made in the field of development and application of recombinant allergens. These advances can be applied to improve basic scientific research, diagnosis, and therapy of human allergic diseases.