Respuesta serológica y protección en terneras revacunadas con cepa 19 en dosis reducida
From 8 dairy farms having more than 20% of brucellosis prevalence, 247 heifer-calves were selected after 2 to 6 months of the traditional immunization withBrucella abortus Strain 19 (S19). Two groups were established in each farm and a total number of 157 animals received a revaccination with 4.5 x 109 CFU of S19 through the conjunctival route, while 90 animals remained unvaccinated.All the animals were bled at days 45, 90, 180, 360, 540 and 720 after revaccination and the sera were tested by SAT and RBT. The reactors to one or both of these tests were retested by a double immunodiffusion test (ID) using aB. abortus polysaccharide antigen to discard the vaccine response and detect a possible natural infecction. No significative differences (p > 0.05) between the control and revaccinated groups were found respect to SAT and/or RBT reactors. It is noticeable that the number of reactors decreased until the day 360 and increased slowly in the 540 and 720 sampling days, concurrent with the appearence of ID reactors. It is concluded that the effect of revaccination proposed did not enhanced the protection of animals during the period of study. At the same time is was showed that the traditional use of S19 did not protect efficiently because some animals became reactors to ID test after 2 to 2 1/2 years of being vaccinated.
| Main Authors: | , , , , , |
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| Format: | Digital revista |
| Language: | spa |
| Published: |
Universidad de Chile. Facultad de Ciencias Veterinarias y Pecuarias
1992
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| Online Access: | https://avancesveterinaria.uchile.cl/index.php/ACV/article/view/10423 |
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| Summary: | From 8 dairy farms having more than 20% of brucellosis prevalence, 247 heifer-calves were selected after 2 to 6 months of the traditional immunization withBrucella abortus Strain 19 (S19). Two groups were established in each farm and a total number of 157 animals received a revaccination with 4.5 x 109 CFU of S19 through the conjunctival route, while 90 animals remained unvaccinated.All the animals were bled at days 45, 90, 180, 360, 540 and 720 after revaccination and the sera were tested by SAT and RBT. The reactors to one or both of these tests were retested by a double immunodiffusion test (ID) using aB. abortus polysaccharide antigen to discard the vaccine response and detect a possible natural infecction. No significative differences (p > 0.05) between the control and revaccinated groups were found respect to SAT and/or RBT reactors. It is noticeable that the number of reactors decreased until the day 360 and increased slowly in the 540 and 720 sampling days, concurrent with the appearence of ID reactors. It is concluded that the effect of revaccination proposed did not enhanced the protection of animals during the period of study. At the same time is was showed that the traditional use of S19 did not protect efficiently because some animals became reactors to ID test after 2 to 2 1/2 years of being vaccinated. |
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