Serological survey for bovine herpesvirus 1 in cattle from different regions in the state of Bahia, Brazil

Inglés. The presence of antibodies against BHV-1 was evaluated in young bovines from fifteen different counties distributed along North, South and Central regions of the state of Bahia. Bovines with age ranged from 1 to 4 years old, non-vaccinated against BHV-1 and without diagnostic of BHV-1 infection were chosen for blood collection. A total of 558 serum samples were collected equivalent to 10% of the population in each farm. The sera were submitted to ELISA (HerdCheck-IDDEX) and Microserum neutralization (MSN) tests. The MSN was performed in monolayers of MDBK cells in microplates using Los Angeles BHV-1 strain. The results of serum samples by ELISA showed that 56% (314/558) were positive and 44% (244/558) were negative. The sera assayed by MSN showed that 48% (269/558) were negative and 52% (289/558) were positive. These positive sera demonstrated that 54% had serumneutralization titer between 4-16, 35% between 32-64 and 11% > or = 64. Our results suggest that the virus is circulating actively in herds. Furthermore, the high diffusion of the BHV-1 in young bovines could represent a constant source of viral infection in the herd.

Portugués. A presença de anticorpos contra Herpesvírus Bovino tipo 1 (HBV-1) foi avaliada em bovinos jovens provenientes de quinze municípios diferentes, distribuídos nas regiões Norte, Sul e Central do estado da Bahia. Foram coletadas amostras de sangue de bovinos de 1 a 4 anos de idade, não vacinados contra HBV-1 e sem prévio diagnóstico de infecção pelo vírus HBV-1. O total de amostras correspondeu a 558 soros, equivalente a 10% da população bovina de cada fazenda. Os 558 soros foram submetidos à técnica de Microssoroneutralização (MSN) em microplacas, utilizando-se monocamadas de células MDBK e a cepa de HBV-1 Los Angeles, e ao teste de ELISA comercialmente adquirido: HerdCheck-IDDEX. Os resultados da amostragem feito pelo teste de ELISA mostraram que 56% (314/558) dos soros foram positivos e 44% (244/558), negativos. A técnica de MSN mostrou que 48% (269/558) dos soros foram negativos e 52% (289/558) foram positivos. Destes soros positivos, 54% tiveram títulos soroneutralizantes entre 4-16, 35% entre 32-64, e 11% > ou = 64. Os resultados sugerem que o HBV-1 esteja circulando ativamente na população bovina jovem. Por outra parte, a alta difusão do vírus em animais jovens representaria uma fonte contínua de infecção viral para o rebanho.