ABSTRACT
Bovine tuberculosis (bTB) control programs generally rely on intradermal tuberculin tests for the antemortem diagnosis of Mycobacterium bovis infection in cattle, but these tests detect only a portion of the infected animals. The aim of the present study was to evaluate the diagnostic coverage of a combination of the bTB antemortem techniques known as the comparative intradermal tuberculin test (CITT) and an ELISA based on a recombinant chimera of ESAT-6/MPB70/MPB83 as the antigen in cattle. The results were compared to postmortem findings based on M. bovis culturing and PCR. Paired comparisons of all data (n=92) demonstrated that ELISA and LST results compared to the culturing results did not present significant differences (P=0.27 on McNemar's test and P=0.12 on Fisher's exact test, respectively). Using culturing as the gold standard, the sensitivity and specificity of ELISA were 79.5% (95% CI: 64.5-89.2%) and 75.5% (95% CI: 62.4-85.1%), respectively, whereas LST demonstrated 100% sensitivity (95% CI: 91.03-100%) and 92.5% specificity (95% CI: 82.1-97.0%). The ELISA results did not reveal significant differences in relation to the LST results (P>0.99 on Fisher's exact test). Using the latter as the gold standard, the sensitivity and specificity of ELISA were 79.1% (95% CI: 64.8-88.6%) and 79.6% (95% CI: 66.4-88.5%), respectively. The use of ELISA with the recombinant chimera of ESAT-6/MPB70/MPB83 as the antigen complements the diagnostic coverage provided by CITT and increases the removal of infected animals from herds.
Subject(s)
Antigens, Bacterial/genetics , Bacterial Proteins/genetics , Cattle Diseases/diagnosis , Enzyme-Linked Immunosorbent Assay/veterinary , Membrane Proteins/genetics , Tuberculosis, Bovine/diagnosis , Animals , Cattle , Enzyme-Linked Immunosorbent Assay/methods , Mycobacterium bovis , Recombinant Fusion Proteins/geneticsABSTRACT
Foi comparado o nível de anticorpos de ovelhas imunizadas com uma ou duas doses de bacterina oleosa produzida com a sorovariedade Hardjo, tipo Hardjoprajitno, estirpe Norma, isolada da urina de bovino no Brasil. Culturas de 2x10(8) leptospiras/mL foram inativadas com formalina a 0,3 por cento, à concentração final e emulsionada em óleo Emulsigen® 12 por cento. A dose da vacina foi padronizada para a concentração de 1x10(8) leptospiras/mL. Quarenta ovinos adultos, da raça Santa Inês, de um rebanho livre de leptospirose por exames clínicos e sorológicos durante um ano foram escolhidos para o experimento. O grupo A (n=15) recebeu duas doses de 3,0mL da vacina por via subcutânea, com intervalo de 30 dias. O grupo B (n=15) recebeu dose única de 3,0mL, via subcutânea e o grupo C (controle) recebeu uma dose subcutânea de 3,0mL de solução 0,85 por cento de cloreto de sódio. Os títulos de anticorpos pós-vacinação foram mensurados pelo teste de soroaglutinação microscópica (SAM) e um teste imunoenzimático (ELISA) a cada 30 dias durante 120 dias. Os títulos dos grupos A e B na primeira colheita variaram de 80 a 160. No grupo A, após a segunda dose, os títulos aumentaram duas a quatro vezes, até 3.200, enquanto no grupo B os títulos de aglutininas foram menores que 160 e diminuíram uma a duas vezes após 60 dias da vacinação. Utilizando-se dose única, os anticorpos persistiram por somente 30 dias e, com duas doses, com 30 dias de intervalo, os anticorpos foram detectáveis por 60 dias por meio do teste de SAM e 120 dias no teste de ELISA. Assim, o teste de SAM detectou títulos de IgM vacinal somente por 60 dias, enquanto o teste de ELISA foi capaz de detectar anticorpos durante os 120 dias. No grupo controle negativo, ocorreram no ELISA reações inespecíficas de títulos até 80, porém no SAM os títulos dos mesmos animais se mantiveram em zero. O teste de ELISA pode ser utilizado para medir anticorpos vacinais para a sorovariedade Hardjo, tipo Hardjoprajitno, estirpe Norma em ovinos.
It was compared the level of antibodies of sheep immunized with one or two doses of an oil bacterin produced with serovar Hardjo, type Hardjoprajitno, strain Norma, isolated from cattle urine in Brazil. Cultures of 2x10(8) leptospires/mL were inactivated with formalin 0.3 percent, final concentration and emulsified in oil Emulsigen® 12 percent. The vaccine dose was standardized to the concentration of 1x10(8) leptospires/mL. Forty adult sheep, Santa Inês breed from a herd free of leptospirosis by clinical and serological examinations during one year were chosen for the experiment. Group A (n=15) received two subcutaneous 3.0 mL vaccine dose, interval of 30 days. Group B (n=15) received one subcutaneous 3.0 mL vaccine dose. Group C (control) received one subcutaneous dose of 3.0 mL of 0.85 percent sodium chloride solution. Post vaccination antibody titers were measured by microscopic agglutination test (MAT) and an in house enzyme linked immunosorbent assay (ELISA) every 30 days during 120 days. At 30 days post-vaccination, the titers of the groups A and B ranged from 80 to 160. In group A, after the booster dose, the titers increased two to four times until 3,200, while in the group B the titers were lower than 160 and decreased by one to two times after 60 days after vaccination. Using a single dose, the antibodies persisted for only 30 days, and with two doses with 30 days of interval, the antibodies were detectable for 60 days through the MAT test and 120 days through the ELISA. The MAT test detected IgM titers of vaccine only for 60 days, while the ELISA was able to detect antibodies during the 120 days. In the negative control group, nonspecific reactions occurred in the ELISA up to titer 80, however titers in the MAT of the same animals remained at zero. The ELISA test can be used to assess anti leptospire vaccinal antibody level to the serovar Hardjo, type Hardjoprajitno, strain Norma in sheep.
