Venezuelan field trials of vaccines against brucellosis in swine
Lord, V.R.; Cherwonogrodzky, J.W.; Schurig, G.G.; Lord, R.D.; Marcano, M.J.; Meléndez, G.E.
American Journal of Veterinary Research 59(5): 546-551
1998
ISSN/ISBN: 0002-9645 PMID: 9582954 Document Number: 486206
The efficacy of live attenuated Brucella abortus RB51, killed B. suis cells, O-polysaccharide (OPS) from B. abortus 1119-3 and OPS from B. suis 1330, in protecting pigs against B. suis was examined by challenge exposure under farm conditions. 10 infected boars, 160 unvaccinated control sows and their 1040 progeny and 610 vaccinated sows and their 6600 progeny were used. 45- to 65-day-old or 4- to 6-month-old gilts were either vaccinated or left unvaccinated. Mature gilts were mated with 4 infected boars, then serological reaction to Brucella spp., results of bacteriological culture of vaginal secretions, presence of abortion and litter size were assessed. Various tissues obtained from aborted fetuses were analysed for Brucella spp. About 40% of unvaccinated control gilts seroconverted to Brucella spp., 27% were positive for OPS by use of agar gel immunodiffusion, 23% aborted their fetuses, and the remaining gilts had litters of 5 to 8 pigs. Of the pigs vaccinated with killed B. suis cells, 25% were seropositive, 5% had positive results from agar gel immunodiffusion, 5% aborted, and the remaining gilts had litters of 7 to 8 pigs. In gilts that received live RB51 or OPS vaccine, serological reactions were always negative, abortion did not occur and litter size was 10 to 12 pigs. Live attenuated B. abortus RB51 or purified OPS effectively protected gilts against B. suis infections. Dose (106 to 109 cells, 100 to 500 micro g, respectively), number of doses (1 or 3), or route (i.m. or oral administration) made little difference to efficacy.