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Content available Immunoprofilaktyka w parazytologii
In the paper chosen problems of immunoprophylaxis against parasitoses were presented, as well as an extensive review of references concerning the vaccines, either being already produced or being under examination in laboratories, aga.inst parasitic Protozoa and Metazoa.
The term adjuvant is derived from the Latin word adjuvare, which means to help. In veterinary medicine the most popular adjuvants are aluminium hydroxide and oil adjuvants, but these chemical adjuvants may cause many adverse reactions. Saponins from various herbs are mentioned among potential adjuvants. To date, saponins with adjuvant activity have been identified, among others, in Panax ginseng Astragalus species, Cochinchina momordica, Quillaja saponaria, Polygala senega, Chenopodium quinoa, and Acacia concinna. The mechanisms of immune-stimulating action of saponins have not been clearly understood. It is probable that saponins enhance cross-presentation of exogenous antigens into MHC class I pathway, thereby promoting the cellular response. Moreover, they are likely to increase the permeability of the mucosal epithelium and facilitate the entry of antigens into the bloodstream or the interaction between the mucosal-associated lymphoid tissue and antigens. Saponins induce a mixed Th₁/Th₂ response, which stimulates the production of typical cytokines (INF-γ, IL-4 or IL-10). Data presented in this article indicate clearly that saponins possess strong adjuvant properties and do not cause adverse reactions. However, a great deal of research is still needed to explain the mechanism of fitoadjuvant activity.
Efforts at devising new vaccinations against fish disease involve using antigens which are comprised of compounds contained in the cell membrane of bacteria or extracellular compounds excreted by them. The compounds which are the subject of this type of research are lipopolisaccharides (LPS), polysaccharides (EPS), protein layer A (А-layer), protein regulating the collection of iron substances from the medium, as well as protein ECP extra-cellularly excreted by bacteria. Research is also being conducted into finding an immunogenic compound through using biotechnological methods. One example is obtaining an immunogenic gluco- protein typical for virus 1HN in insect cells, into which the IHNV gene which codes this protein has been previously introduced by use of a vector. As a result of the fact that the most immunologically active atnino- -acid sequence in the IHN glucoprotein virus is 336-444, an attempt has been made to create a vaccination which would contain this sequence. The latter has been synthesised in Escherichia coli plasmodia into which the appropriate gene of the IHN virus has been introduced. Attempts have also been made to inoculate fish with IHN glucoprotein synthesised in-vitro. The article also presents new methods of attenuating bacteria and virus antigens. Attenuation of Aeromonas salmonicida has been achieved through depriving it of protein A and of antigen О in LPS or through removing gene AroA from its genome. Further examples of new methods of attenuation have concerned Renibacterium salmoninarium. Protein p57 has been degraded in the cellular membrane of this bacteria. Attenuation of IHN virus has been achieved by its mutation caused by cultivating it in the presence of neutralising antibodies. The attenuation of herpes virus CCV has also been achieved by depriving it of the tymidine kinase gene. The paper additionally reviews the first research into creating a genetic vaccination for fish.
The aim of the work was to prepare an inactivated vaccine against ovine campylobacteriosis and evaluate its immunogenic properties. For the vaccine production there was used 4 strains of Campylobacter fetus subsp. fetus, serotype B, isolated from the fetus of an aborted sheep. The prepared vaccine was first tested on laboratory animals and later administered intramuscularly at a dose of 4 ml (0.38 X 10¹¹ bacteria per 1 ml) to 61 sheep being in the second month of pregnancy. The level of neutralizing antibodies was tested 6 times. It was found that vaccination elicited a high level of specific antibodies whose titers were rising especially between 4 and 6 weeks after vaccination. A high level of antibodies persisted up to the end of pregnancy.
The main purpose cf the studies was to evaluate the possibility to replace alive monovalent vaccines with a combined one possessing a wide spectrum of activity. The experiments were carried out on calves (16 animals) in two periods, i.e. in autumn-winter season (group I and Ia) and in spring-summer season (group II and IIa). The group I was given the combined vaccine twice at intervals of 10 days intramuscularly, and group II apart from the vaccine received levamisole 4 times, i.e. before vaccination and at day 3, 10 and 17 after the first dose of the vaccine. The combined vaccine contained an inactivated suspension of the Trichophyton verrucosum and T. mentagrophytes var. granulosum strains, prepared separatelly according to the method described previously (61) and inactivated with formaldehyde. It was found that the combined vaccine elicited a distinct immune response of cellular type. At week 4 after the first dose of the vaccine there was found in all the animals except one a positive result of leukocyte migration inhibition (from 22% to 54%). The increased values of the test lasted for the next two weeks. After 8 weeks they decreased especially in the group of animals that had not received levamisole. A delayed type of hypersensitivity accompanied the positive reactions assessed by the cell migration inhibition test. A drop of lymphocytes producing rosettes took place at day 3 after vaccination, however, at day 10, particularly in the group treated with levamisole, there was observed an increase of the percentage of T lymphocytes (p ≤ 0.001). With the both groups of calves the percentage of T lymphocytes forming E rosettes came back to the state before vaccination at day 17. Fungicidal activity of leukocytes, determined in the same periods of time increased at day 3 following vaccination. However, at day 10 there was observed not only a drop of fungicidal activity but a growth stimulation of the fungus. After 4 weeks fungicidal activity attained the level before vaccination. The challenge trial performed at week 6 after the first dose of the vaccine confirmed a distinct resistance of the animals immunised (tab. 4). The calves treated with the combined vaccine possessed a congenial immunity against the two species of Trichophyton which had been used for experimental infection.
The introduction of genetic or "naked DNA" vaccines may open a new era in vaccinology. DNA vaccination is a relatively simple process: a recombinant vector containing cDNA of the potentially protective pathogen antigen, is delivered to a host organism under the control of a strong promoter. It has been demonstrated that the introduced DNA remains stable as an episome for a long time and does not integrate into a genome of vaccinated organism. The type of immune response elicited by DNA vaccination depends very much on the antigen used and on the way of the vaccine delivery. Generally, DNA vaccination induces Tol-dependent rather than Th2-dependent immune response. DNA vaccines present many advantages over "traditional" ones. Firstly, it is easier to obtain a considerable amount of DNA than similar quantities of purified protective antigen protein. Secondly, the antigenic proteins synthesised within the host cell possess an appropriate molecular structure and undergo a posttranslational modifications specific for the native protein. The posttranslational modifications, for example glycosylation, cannot be introduced during expression of the recombinant protein antigens in bacterial hosts.
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