Component of Antiplague Molecular Vaccine
Y.pestis V Antigen - the Main Component of New Generation Antiplague Molecular Vaccine: Animal Studies of Positive and Negative Side Effects
Tech Area / Field
3 Approved without Funding
Institute of Bioorganic Chemistry (Branch), Russia, Moscow reg., Puschino
- Institute of Immunological Engineering, Russia, Moscow reg., Lyubuchany
- University of Turku / Finnish-Russian Joint Biotechnology Laboratory, Finland, Turku
Project summaryThe aim of the proposed project is to study side effects (both positive and negative) of recombinant Yersinia pestis V antigen - the main component of new generation antiplague molecular vaccine.
Yersinia pestis, the causative agent of bubonic plague, produce a range of virulence proteins, encoded by a 70 kb plasmid, which are essential for infection, and also form a part of a contact-dependent virulence mechanism. One of the plasmid-encoded proteins, V antigen, is considered to be a protective antigen [Leary S.E. et al., Microb. Pathog., 1999, V. 26, P. 159] and the most promising candidate for preparation of molecular vaccine against plague. In addition to its protective properties, V antigen attracts considerable interest as an agent possessing immunosuppressive activity due to its stimulatory effect on IL-10 production [Nedialkov Y.A. et al., Infect. Immun., 1997, V. 65, P. 1196; Sing A. et al., J. Immunol., 2002, V. 168, P. 1315]. This cytokine is known to down-regulate proinflammatory cytokines required for expression of cell-mediated immunity and therefore is a promising agent for treatment of such autoimmune diseases as multiple sclerosis, rheumatoid arthritis etc. IL-10 and another immunosuppressive cytokine, TGF-β, due to their ability to inhibit antigen-presenting cell function and to mediate direct anti-proliferative effect on T cells have potential therapeutic value for organ-specific autoimmune diseases. They have been shown to ameliorate clinical manifestations in animal models for multiple sclerosis and rheumatoid arthritis (experimental autoimmune encephalomyelitis, EAE, and collagen-induced arthritis, CIA, respectively) [Zargarova T.A. et al., Immunology (Moscow), 1999, V. 5, P. 9; Joosten L.A.B. et al., Arthritis Rheum., 1997, V. 40,P. 249].
On the other hand, V antigen being used as a component of anti-plague vaccine can exert one or another toxic effect, specifically, due to its immunosuppressive properties. Immunosuppressive agents can have an adverse effect in inpiduals with immunodeficiency states associated, for instance, with cancer and aging. Numerous immunological studies have demonstrated that there is a concurrent decrease in cellular and humoral immunity with increasing age. Cancer patients have decreased immunological reactivity against their tumors, in addition, treatment with radiotherapy and chemotherapy is often accompanied by high incidence of infection resulted from decreased T-cell reactivity. Immunosuppression can also augment risk of tumor formation in predisposed inpiduals.
Thus, V antigen as a stimulator of IL-10 production can have two type side effects when used for vaccination against plague: positive, resulting in amelioration of autoimmune disorders; and negative, resulting in depression of host immune response to invading microbes, tumors etc. Therefore, it is reasonable to study these plausible side effects in a whole body level, using animal models for autoimmune disorders, tumor-bearing and aged animals.
The scientists from the Institute of Immunological engineering have created the E.coli strain producing recombinant V antigen (rVag) in amounts sufficient for extensive functional in vivo studies. The researchers from the Branch of Shemyakin and Ovchinnikov Institute of Bioorganic Chemistry of the Russian Academy of Sciences (Biological testing laboratory) over a period of years are engaged in preclinical safety evaluation studies using animals and development of animal models for various human disorders for testing potential therapeutic agents.
In the frames of the proposed project we intend to study a plausible therapeutic effect of recombinant V antigen in treatment for autoimmune disease - multiple sclerosis using an established rat model for this disorder – EAE. In parallel, we intend to test a gene therapy approach to treatment for EAE using rat fibroblasts transduced with human TGFβ1 precursor gene. This approach offers a significant advantage over the systemic TGFβ1 administration: the latent precursor will be activated directly in the sites of inflammation by enzymes and/or acidification in macrophages, thus avoiding undesirable side effects. Finally, we shall test in the above-mentioned animal model a novel promising approach – combination therapy – using TGFβ1-producing cells in combination with rVag injections.
During execution of the project we shall also study a possible toxic effect of rVag vaccination. The following safety evaluation studies using specific pathogen free animals will be carried out: acute and delayed toxicity, immunotoxicity in adult and aged animals, allergenicity, reproductive toxicity. The effect of rVag injection on tumor growth and mean survival time of tumor-bearing mice will be investigated as well.
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