Dissertação
Verificação de desempenho do ensaio de neutralização viral para detecção de anticorpos para o vírus da Febre Aftosa
Fecha
2019-02-15Autor
Valdenia Lopes da Silva Gonçalves
Institución
Resumen
Brazil is one of the countries with the greatest international prominence in
agribusiness, due to the increase of exports in this sector of the economy. A disease
of great impact for national livestock farming is Foot-and-Mouth Disease (FMD), which
has great social and economic importance. FMD is a highly infectious, highly
disseminated viral disease that affects split cloven-hoofed animals, causing fever,
lameness, vesicular lesions on the paws, tongue, snout and teats. It is a sanitary barrier
to international trade, and demands high investments for control and prevention. Footand-Mouth disease virus (FMDV) has seven serotypes, which are immunologically
distinct, O, A, C, SAT-1, SAT-2, SAT-3 and Asia 1, serotypes that are not uniformly
distributed throughout the world. O, A and C serotypes have the highest distribution
and are responsible for outbreaks, especially in Brazil. Serological methods for
diagnosis and evaluation of FMDV, such as the viral neutralization test (NV), are
essential for the diagnosis of the infection and evaluation of the efficacy of the vaccines
used. The objective of this work was to verify the performance of the NV method, based
on the evaluation of samples of bovine sera vaccinated with the FMD vaccine produced
in Brazil. The samples were collected, after 28 days of vaccination and 28 days after
booster vaccination. It was possible to verify the performance of the virus neutralization
method of antibodies to the foot-and-mouth disease virus satisfactorily. The results of
measurement uncertainty, repeatability and reproducibility were within the expected
limits of evaluation, proving the effectiveness and guaranteeing the quality of the test
method. The pilot test for the evaluation of the potency of the Foot-and-Mouth disease
vaccine, performed by ELISA, reached a Percent Protection Expectancy (EPP) above
99% for the three vaccine serotypes, proving the efficacy of the vaccine used. Values
of r1 and EPP, evaluating the combination of viral serotypes of the vaccines and the
field isolates, the results of r1 showed that the serotype C isolate had the highest
antigenic similarity to the vaccine strain, and the O and A isolates had less antigenic
similarity to the vaccine viral strains. The EPP results showed that the vaccine
serotypes have greater antigenic similarity with the evaluated viral isolates.