الفهرس 
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Abstract
In this study, serological survey was applied on 200 serum samples collected from calves { 150 apparently healthy & 50 had respiratory manifestation} aged between 2-8 months from different localities in Egypt for
determination the prevalence of antibodies against N. somnus.
Tube agglutination test was applied on serum samples for detection of
antibodies against Haemophilus somnus. The results revealed that 70% of examined calves, which suffered from respiratory manifestation, had
agglutinating antibody titers for Haemophilus somnus in which 51.3% of
positive seroreactive had agglutinating antibody titers ranged from 200 to 800 for H. somnus. While 64.6% of apparently healthy calves that used in this
survey had agglutinating antibody titers for H. somnus and 80.3% of positive seroreactive had agglutinating antibody titers ranged between 25-100 for H.
S011111US.
Mouse protection test was applied on serum samples collected from respiratory diseased and apparently healthy calves whose blood serum samples containing antibodies for Haemophilus somnus to clarified the
protective role of such antibodies.
The result revealed that the agglutinating antibody titer in serum
samples was 400 obtained from either respiratory diseased or apparently healthy calves gave passive protective % {100%} for mice against experimental challenge with 50 LD so of Haemophilus somnus.
In this study, enzyme assisted immunoelectrobloting (Western Blotting) was applied by using serum samples collected from respiratory diseased calves and had protected mice against experimental challenge with 5OLD50 to determined the major proteins that antibodies were elicited against it, it was revealed that Haemophilus somnus OMP of 40-KDa was given strong reaction with that serum samples.
The 40-KDa outer membrane protein of Haemophilus somnus was
isolated and purified using Gel filtration chromatography to be used as a subunit vaccine.
In this work, three types of vaccines were prepared including subunit Haemophilus somnus vaccine; Bivalent Clostridium chauvoei & Clostridium
septicum vaccine, and combined subunit Haemophilus somnus & Bivalent clostridia! vaccine.
Fifteen male Holstein Frisian calves of 4-6 months age were divided to four groups:
Group (1): vaccinated with subunit Haemophilus somnus vaccine. Group (2): vaccinated with Bivalent C. chauvoei & C. septicum vaccine.
Group (3): vaccinated with combined subunit H. somnus & Bivalent Clostridial vaccine.
Group (4) kept animals as non vaccinated control.
The different prepared vaccines were safe as neither disease nor adverse reaction occurred with the dosage used.
In the groups (1)&(3), calves had elicited antibodies against H. somnus from day-14 post vaccination with agglutinating titer 70.71 and 59.46 for both vaccines respectively with gradually elevated of agglutinating titers till reached to its peak at day-60 post vaccination for both vaccines with agglutinating titer 1959.59 and 1872.27respectively. The agglutinating titers then began to decline for both vaccines to reach the titer of 336.35 and 282.84 at day-150 that still able to protect calves, after that the agglutinating titers were declined to be unable to protect calves. There was no significant difference in antibody titers of H. somnus between calves vaccinated with subunit H. somnus or combined vaccines. The agglutinating antibody titers of H. somnus had significant elevation from day-30 up to day-150 post vaccination in both groups of vaccinated calves.
Mouse protection test was applied by using serum samples collected from vaccinated calves with subunit H. somnus vaccine and combined vaccine; it was revealed that mice passively protected by serum samples collected from vaccinated calves from day-45 up to day-120 gave highest protection percentage (100%). The passive protection percentage of inoculated mice was (75%) by serum samples obtained from vaccinated calves at day-30 and at day-150 post vaccination for both vaccines.
It was revealed that calves vaccinated with bivalent clostridia’ and combined vaccines had no difference in antitoxin titers for C. septicum in both groups. The pattern of antitoxin titers for C. septicum during period of study revealed that there was significant elevation from day-14 up to day-150 post vaccination in both groups.
It was revealed that the agglutinating antibody titers for C. chauvoei in calves vaccinated with either bivalent clostridial vaccine or combined vaccine had no significant difference between them, But the pattern of agglutinating antibody titers for C. chauvoei in both groups of calves showed that there was significant elevation in agglutinating antibody titers during period from day-30 up to day-150 post vaccination. ,
Comparing the results of ELISA test for measuring antibody titers with that obtained by tube agglutination test, slide agglutination test, and serum neutralization test; the results of these tests were pass parallel with each other as all tests gave almost the same pattern during entire period of the study.