University of Khartoum

Trials for Development of a Vaccine Against Caseous Lymphadenitis in Sheep

Trials for Development of a Vaccine Against Caseous Lymphadenitis in Sheep

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Title: Trials for Development of a Vaccine Against Caseous Lymphadenitis in Sheep
Author: BAKRI, MOHAMED
Abstract: A survey of 9884 sheep (6560 live at animal markets and 3324 slaughtered in Nyala slaughterhouse ) and 4634 goats (4450 live at animal markets and 184 slaughtered in Nyala slaughterhouse) was carried out in South Darfur State, west Sudan, to determine the prevalence of caseous lymphadenitis which was 0.6% in live and 1.7% in slaughtered sheep, whereas it was 0.6% in live and 2.7% in slaughtered goats. The distribution of 141 lesions in lymph nodes of slaughtered and live sheep was 50.4 % in prescapular, 14.9 % in parotid, 11.3% in precrural, 5.7% in mandibular, 3.5% in supramammary, 0.7% in mediastinal, and 0.7% in mesenteric lymph nodes. Lesions in other parts of the body were 11.3% subcutaneous abscesses, 0.7% abscess in a liver, and 0.7% abscess in lung. The distribution of 44 lesions in lymph nodes of live and slaughtered goats was 43.2 % in prescapular, 27.3% in parotid, 11.4 % in mandibular and 9.1% in precrural lymph nodes. In other parts 9.1% subcutaneous abscesses were noted in goats. Mass culture of a local strain of Corynebacterium pseudotuberculosis CP41 N was obtained using IBT bioreactor at pH 8, temperature 31 ℃ and dilution rate of 0.02 h -1 . The harvest was used to prepare five types of v vaccines; The first a cell wall vaccine containing 6mg/ 1 ml of protein, the second a whole cell vaccine containing 16mg/ 1ml of bacterial dry weight, the third a toxoid vaccine containing 8 mg/1 ml of protein the fourth a cell wall + toxoid vaccine (6mg/ 1ml+ 8mg/1ml) and the fifth a whole cell + toxoid vaccine (16mg/1ml + 8 mg/1ml). Saponin and aluminum hydroxide adjuvants were added in a concenteration of 1mg/1ml to each of the different vaccines. A dose of 0.5 ml from the three first vaccines and of 1ml from the fourth and fifth ones were injected subcutaneously to each one of 5 groups of sheep of 7 animals, and a sixth group was left as unvaccinated control. All animals were bled at weekly intervals. After one month a booster doses of the vaccines were given to the animals which were bled weekly for serological monitoring by the agglutination test. All animals were challenged subcutaneously with 5.1X10 8 CFU Corynebacterium pseudotuberculosis CP41 N one month after the second dose of vaccine. The animals were then slaughtered one month later to determine the number of abscesses in the carcasses.The results showed that the vaccine which consisted of whole cells + toxoid was the best of the five vaccines with a significant reduction (p< 0.05) in mean abscesses numbers in vaccinated animals after challenge with C.pseudotuberculosis. The percentage of protection of the group vaccinated with the whole cell+ toxoid was 75% vi compared with 32.3%, 37.5%, 37.5% and 45.3% for the groups vaccinated with cell wall, whole cell, toxoid and the cell wall + toxoid vaccines, respectively Sixty- six isolates of Corynebacterium pseudotuberculosis from the sheep and goats were tested for their sensitivity to 16 antimicrobial agents. The isolates were found highly sensitive to nitrofurantoin, chloramphenicol, rifampacin, cotrimoxazole, erythromycin, and ampicillin. Moderately sensitive to methicillin, kanamycin, gentamycin and tetracycline, but were resistant to nalidixic acid, colistin, novobiocin, penicillin, cloxacillin and streptomycin. PCR technique was used to examine 28 of the local isolates of Corynebacterium pseudotuberculosis using the primer targeting the 16S rRNA gene. The results showed homogeneity of the isolates with the molecular size of this gene. The study showed that caseous lymphadenitis is prevalent in South Darfur State, which is an important area for sheep production in the country. A vaccine consisting of whole cell+toxoid appears to be promising for protection against the disease, examination of this vaccine under field conditions is recommended
URI: http://khartoumspace.uofk.edu/handle/123456789/9154
Date: 2015-04-21


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