• Korean Journal of Veterinary Research
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• v.11 no.1
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• pp.1-39
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• 1971

The purpose of present study was to investigate the possibility to immunize guineapigs and swine against Metastrongylus apri infection by the administration of irradiated infective larvae. Four main experiments were undertaken. Firstly, three groups of infective larvae irradiated at $3{\times}10^4r$, $4{\times}10^4r$, and $5{\times}10^4r$ respectively were inoculated to guineapigs and their immunogenic effects were examined from the clinical, anatomical, and serological viewpoints to decide the optimal dose of X-ray for the atenuation of them. Secondly, the migratory behavior of the larvae irradiated at the optimal dose was compared with that of normal infective larvae. Thirdly, pigs were inoculated with each 5,000 infective larvae irradiated at the optimal dose and the clinical, anatomical and serological responses of them before and after challenge were examined. Fourthly, the heated extract of adult M. apri which had been used as an antigen in the serological examinations was analyzed and compared with that of adult Ascaris suis and of adult Trichuris suis by immunoelectrophoretic method. The results obtained are summerized as follows: 1) The optimal dose of X-ray for the atenuation of the infective larvae which can minimize the pathogenecity but keep the antigenecity of the infective larvae was $5{\times}10^4r$. 2) Guineapigs could become completely resistant to subsequent challenge infection by the administration of 1,000 infective larvae irradiated at $5{\times}10^4r$, without showing any symptom of disease before and after the challenge. 3) There were some indication that guineapigs could acquire complete immunity after they overcome the infection with normal infective larvae. 4) It was shown that, in guineapigs, the $5{\times}10^4r$-irradiated larvae can migrate to the large intestine and mesenteric lymph node within a day, where they stay for as long as 16 days to stimulate the host's immunity. 5) It also was shown that, in guineapigs, the normal infective larvae challenged to resistant guineapigs can migrate to the large intestine and mesenteric lymph node, where they are affected by the immune mechanism of host within 10 days without further migration. 6) Pigs could become partially resistant to subsequant challenge by the administration of 5,000 infective larve irradiated at $5{\times}10^4r$; no clinical symptom occurred after the administration, but milder symptoms of parasitic bronchitis were observable after the challenge infection and fewer number of worms were detected from the lungs at autopsy compared with severe symptoms and much number of worms in control pigs. 7) It was shown that, in pigs, a few of the $5{\times}10^4r$-irradiated larvae can migrate to the lungs, where they stay for as long as 104 days in stunted and sterile states; their body-lengths were short and their uteri developted no eggs. 8) There was evidence that the male larvae were more susceptible to X-ray than the female larvae. 9) Antibodies relating to the administration with $5{\times}10^4r$-irradiated or normal larvae were detected from the sera of both guineapigs and pigs by means of indirect haemagglutination and agar diffusion precipitin tests. Relatively higher antibody titers were recorded by the former test, but precipitin bands were demonstrable only when the positive sera were concentrated in one tenth of original volume in the later one. 10) The antibody titers of pig sera began to rose on 14 days, kept their peak during the period from 14 th day to 21st day, and fell to a low level on 28 days after the administration of $5{\times}10^4r$ or normal infective larvae. 11) A slight increase in gamma globublin of the pig sera occurred following the administration. The gamma globulin level showed a tendency to fluctuate in acordance with the antibody level. 12) A marked eosionophilia occurred in pigs on 7 or 14 days following the administration. The eosinophil count showed the same tendency to fluctuate as the gamma globulin did. 13) It was shown that the serum antibodies detected by the heated extract of adult Metastrongylus apri react crossly with the heated extract of adult Ascaris suis but not with that of adult Trichuris suis in indirect haemagglutination and agar diffusion preciption reactions. 14) The heated extract of adult Metastrongylus apri could he divided into 9 antigenic components by immunoelectrophoresis, one (arc 4) of which was shown to be common to both extracts of adult Ascaris suis and adult Trichuris suis, and the other one (arc 9) to only the extract of adult Ascaris suis.