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Swine plays a very particular role in FMD epizootiology. It is, therefore, absolutely necessary to have highly effective vaccines available for this species at all times. They have to ensure early buildup of long-lasting strong immunity even after one single application. Since the effectiveness of conventional adsorbate vaccines had proved to be insufficient, monovalent and trivalent oil emulsion vaccines were specifically developed of swine, using a GDR-made oil adjuvant. Stable immunity is very soon induced by them to endangered pig stock even against the immunologically problematic sub-types O1 and A5 after one single subcutaneous (s.c.) application of 2 ml (monovalent) or 5 ml (trivalent). Application establishes in s.c. connective tissue an oil emulsion depot that leads to formation of a vaccination granuloma. The immunocompetent cells identified in the latter are morphologically correlated to adjuvant action.

Coupled synthetic peptides, representing the sequences of amino acids 130-160, 141-160 and 145-160 of foot-and-mouth disease virus O1K protein VP1, induced virus-binding and virus-neutralizing antibody response in guinea pigs, rabbits, and pigs. We also detected antibody response in guinea pigs after immunization with uncoupled peptides and in cattle with 21 aa-peptide-Keyhole-limpet hemocyanin (-KLH). The best results were obtained from 21 aa-peptide-KLH and 31 aa-peptide with or without KLH or thyroglobulin as carrier. Our preliminary results show the induction of virus-neutralizing antibodies to be obviously influenced by length of the peptide as well as by the kind of carrier and coupling.

Three peptides of main epitope of FMD virus O1-Kaufbeuren, VP1 (16, 21, 31), were found to induce in the 130-160 sequence range, in free and/or carrier-bonded form, virus-neutralising antibodies in guinea pig, rabbit, mouse, swine, and cattle. Five carrier proteins were tested, with thyroglobulin, next to keyhole limpet hemocyanin (KLH), being most effective for 16-peptides (145-160) and 21-peptides (141-160 Tyr161). To protect guinea pig from FMD, minimum dosage of 21-peptide was found to be 2 x 8 micrograms. The immunogenic spectrum of peptides and conjugates proved to be broader than that of monovalent vaccines of inactivated virus. Free peptides were found to be also capable in vitro of inhibiting virus infection.

Riems FMD two-component oil emulsion vaccine was subcutaneously applied (5 ml) under field conditions to 855 store pigs of different age groups (trivalent--O1, A5, C). It produced early onset of lasting strong immunity against the three above FMD virus types. General condition of the animals and their body weight development were not adversely affected. Pea-size to walnut-size vaccination granulomas were recorded on slaughter as locally delimited reactions in 15 to 20 percent of vaccinated animals and were found to be morphologically correlated to adjuvant action. They were easily removed from the carcasses by excision of the vaccination point, with only minor loss of slaughter substance.

The GDR in 1977 had been the first country to introduce a laboratory method for potency testing of FMD vaccines on the basis of secured correlations between titres of virus-neutralising serum antibodies of immunised cattle, on the one hand, and their probit-transformed protection against FMD, on the other. This is now the only state-registered method for potency testing. The method has ever since worked well all over the place. An evaluation of results obtained between 1982 and 1988 revealed seasonal variations of anti-FMD immunogenesis in cattle. FMD immunisations from February to July proved more effective than those performed in the rest of the year, in that higher antibody titres were built up within 14 days from vaccination. These results were confirmed by rates of protection of cattle recorded from direct potency testing of immunised animals, between 1969 and 1977.

An analysis is made of the latest developments and importance of immunoprophylaxis against FMD, with reference to the epizootiological situation of the disease and its bearings, today, on industrialized livestock production. Comprehensive immunoprophylactic action (vaccination of all cattle every year) has been taken first by the GDR and later on by more European countries, as well. As a result of such action the disastrous impact of FMD and its associated high loss rate have been considerably mitigated. A decisive role, in that context, has been played by the development of effective inactivated vaccines for swine. An FMD live vaccine has been devised in GDR for after-care of swine. It is not only harmless to the animal, but, as well known, it provides numerous advantages over adsorbate vaccines. FMD immunoprophylaxis for full success depends primarily on the proper selection of virus strains suitable for vaccine produktion, vaccine quality, avoidance of post-vaccination damage or disease, and the availability of an efficient concept for vaccine application. The above problems are expounded in this paper, and derived from them are substantive conclusions for further studies, with the view to improving FMD immunoprophylaxis.

At all 3 studied FMD-viruses typs O2, A5 and C we could show the 73S unit in the analytical ultracentrifuge and in the electron microscope. 73S unit is found in the normal cycle of purification of virus and by density gradient centrifugation separated and purified. In CsCl pH 7.6 its density is 1.308 +/- 0,005 g/ml. Its sedimentation coefficient has a value of 72.7 +/- 1,5S. In electron microscope it show itself as a empty virus capsid. Its diameter is in partial purified preparations with 25 +/- 1 nm the same as of the virion. Its wall diameter is 2 to 3 nm. Further purification induced defiguration of particles and increase of its diameter. 73S unit dissociates in 19S and 12S units and shows a typical protein-UV-absorption spectrum with a maximum at 276 to 278 nm and a minimum at 250 nm. Emax/Emin is 2.3. Extinction coefficient E276nm is 1,4 mg/cm2. By sucrose density gradient centrifugation and titration of fractions in the complement fixation test it was detected, that croude virus solution contained already the 73S unit.

29 pigs (meat type of German Landrace) were kept in groups in a confined space (0.48 m2 a head; group E), in a normal area (1.2 m2 a head; group N) or in a normal area plus daily exercise (group L). After having been kept under these conditions for specified periods, the pigs were made to run on a band moving at 1.1 metres a second for 2 km. During exercise the heart rate increased to 275 beats a minute in group E and only 180 in group L. In group L the recovery pulse rate was greater and the absolute and relative heart weight smaller than in group L; rectal temperature after exercise was also higher than in group L. Values for group N lay between those of groups E and L. The relationship of respiration rate to rectal temperature after exercise was greater in group L than in groups E and N. Physical fitness of groups E and N was inferior to that of group L.