ABSTRACT
The present objective was to investigate the presence of anti-equine viral encephalomyelitis (EVE) antibodies and the possible risk factors for its dissemination in horses raised in the East and West Potiguar mesoregions of the state of Rio Grande do Norte, Brazil. Serological diagnosis for neutralizing antibodies against Eastern (EEEV), Western (WEEV) and Venezuelan (VEEV). Equine viral encephalomyelitis was performed using a seroneutralization technique on 811 blood samples from horses from ninety properties and sixteen municipalities between July 2018 and February 2019. Factors associated with EVE were evaluated using an investigative epidemiological questionnaire, and the data were statistically analyzed using the Epi Info 3.5.2 software with a confidence level of 95%. The seroprevalence of anti-EVE antibodies was 14.2% (115), with 10.36% (84) for EEEV, 6.9% (56) for WEEV, and null for EVE. When analyzing risk factors, it can be concluded that horses raised in properties that do not clean installations and/or rent out their pasture are more likely to have anti-EVE antibodies. These results show evidence that horses raised in the East and West Potiguar mesoregions were exposed to EEEV and WEEV, thus reinforcing the importance of vaccination and serological survey of nonvaccinated horses as a means of monitoring the disease.
Subject(s)
Animals , Encephalomyelitis, Equine/epidemiology , Horse Diseases/diagnosis , Horses/virology , Brazil , Seroepidemiologic Studies , Encephalitis, Viral/veterinaryABSTRACT
Aiming to investigate in vitro alternatives, a test for neutralizing antibody detection using cell culture was developed. This test was more sensitive than previous animal models, allowing for detection of substantially lower alpha toxin and anti-alpha toxin titers. Titers observed during in vivo and in vitro seroneutralization had a correlation of 99.12 percent, indicating that cell culture is a viable alternative in the evaluation of vaccine potency, screening of vaccinal seeds, and Clostridium septicum alpha toxin titration.
Padronizou-se um teste para detecção de anticorpos neutralizantes in vitro, em cultura de células. O modelo in vitro mostrou-se mais sensível que os testes com animais, permitindo a detecção de títulos de toxina e antitoxina alfa mais baixos. Os títulos observados na soroneutralização in vivo e in vitro, apresentaram correlação de 99,12 por cento, demonstrando ser a cultura de células uma alternativa viável na avaliação da potência de vacinas, triagem de sementes vacinais e titulação de toxina alfa de Clostridium septicum.
Subject(s)
Animals , Clostridium septicum/immunology , Toxoids , Serologic Tests/methods , VaccinesABSTRACT
O herpesvírus bovino 5 (BoHV-5) é o agente da menigoencefalite herpética bovina. A doença neurológica, associada à infecção pelo BoHV-5, apresenta altas taxas de letalidade em bovinos jovens e está disseminada no Brasil. A prevenção das perdas causadas pela infecção pelo herpesvírus está baseada, principalmente, na imunização dos animais. Nesse sentido, foi delineada uma comparação entre isolados de BoHV-5, buscando selecionar o isolado mais antigênico para a formulação de vacinas. As formulações inativadas foram produzidas com os isolados ISO9898292, SV507, SV163, 1807 e EVI145 e administradas a cinco grupos de 10 ovelhas cada, que receberam duas doses vacinais por via intramuscular com intervalo de 21 dias. Foram realizadas coletas de sangue para análise de presença de anticorpos por soroneutralização e acompanhamento dos animais até o 63° dia após a primo-vacinação. Foram observados dois picos na curva de anticorpos, o primeiro no dia 14, após a vacinação, quando os títulos médios de anticorpos variaram entre 23,1 e 138,6. O segundo pico foi observado 14 dias após a revacinação, quando os títulos médios variaram entre 301,3 e 1017,5. No 42° dia após a revacinação, foi observada variação de título entre 82,4 e 305,9. A diferença entre as médias de títulos de anticorpos de cada grupo de animais sugere uma menor antigenicidade do isolado ISO9898292 em relação aos demais, demonstrando uma possível variação antigênica entre os isolados. Todos os isolados, com exceção do ISO9898292, mostraram-se imunogênicos para a indução de anticorpos.
Herpesvirus bovine 5 (BoHV-5) is the agent of bovine herpetic menigoencephalitis. The neurological disease associated with the infection is highly lethal in young cattle and it is widespread in Brazil. Control of the clinical signs caused by herpesviruses is based mainly on the immunization of cattle. A comparative study was performed among Brazilian BoHV-5 isolates to select the more antigenic virus. Inactivated vaccines were formulated using isolates ISO9898292, SV507, SV163, 1807 and EVI145 and administered to five groups of 10 sheep, each animal receiving two intramuscular doses with a 21 days interval. Blood collection for serology by virusneutralization were performed until the 63rd day after the first vaccination, two peaks in the curve of antibodies were observed, the first on day 14, ranged from 23.l to 138.6. The second peak was observed 14 days after the booster, and ranged from 301.3 to 1017.5. In the 42nd day after the booster, it was observed a titer variation from 82.4 to 305.9. The differences among antibody titers of each group of suggests a lower antigenicity of isolate ISO9898292 in comparison with the others, demonstrating a possible antigenic variation among the isolates. Thus, all isolates, with exception of ISO9898292, were immunogenic for the induction of neutralizing antibodies.