Ciência Rural (Feb 2005)
Anticorpos neutralizantes contra o vírus da Diarréia Viral Bovina (BVDV): comparação entre um imunógeno experimental atenuado e três vacinas comerciais inativadas Vaccination-induced neutralizing antibodies against bovine viral diarrhea virus (BVDV): comparison between an experimental modified-live vaccine and three comercial inactivated vaccines
Abstract
Os títulos e duração de anticorpos neutralizantes contra o vírus da Diarréia Viral Bovina (BVDV) induzidos por uma vacina experimental atenuada (vacina A: dose única) foram comparados com os induzidos por três vacinas comerciais inativadas (B, C e D: duas doses com intervalo de 30 dias). Trinta dias após a vacinação (vacina A) ou após a segunda dose (vacinas B, C e D), anticorpos neutralizantes contra o BVDV-1 foram detectados em todos os animais (12/12) do grupo A (título médio geométrico GMT=1612,7); em 32 de 36 animais do grupo B (GMT=14,3); 22 de 28 do grupo C (GMT=25,1); e em 16 de 30 do grupo D (GMT=40,0). Anticorpos frente ao BVDV-2 foram detectados em todos os animais do grupo A (GMT=151,0); em 27 de 36 do grupo B (GMT=10,0); 12 de 28 do grupo C (GMT=11,5) e em 10 de 30 animais do grupo D (GMT=10,0). No dia 180 após a vacinação, o número de animais que ainda apresentava anticorpos contra o BVDV-1 e os GMTs para cada grupo foram: vacina A (12/12, GMT=905,0); vacina B (30/36, GMT=28,3); vacina C (20/28, GMT=28,3); vacina D (14/30, GMT=16,1); e contra o BVDV-2 foram: vacina A (12/12, GMT=56,6); vacina B (18/36, GMT=16,8); vacina C (10/28, GMT=21,6) e vacina D (6/30, GMT=16,1). Os títulos médios (GMTs) induzidos pela vacina A foram significativamente superiores aos demais, tanto para o BVDV-1 (PThe titers and duration of neutralizing antibodies against bovine viral diarrhea virus (BVDV) induced by an experimental attenuated vaccine (vaccine A: one dose) were compared to those induced by three commercial inactivated ones (B, C and D: two doses at a 30 day interval). Thirty days after vaccination (vaccine A) or the second dose (vaccines B, C and D), neutralizing antibodies to BVDV-1 were detected in all calves (12/12) from group A (mean geometric titer GMT=1612.7); in 32 out of 36 from group B (GMT=14.3); 22/28 from group C (GMT=25.1); 16/30 from group D (GMT=40.0). Antibodies reacting with BVDV-2 were detected in all animals from group A (GMT=151.0); 27/36 from group B (GMT=10.0); 12/28 from group C (GMT=11.5) and in 10 out of 30 animals of group D (GMT=10.0). At day 180 post-vaccination, the number of animals reacting to BVDV-1 and the GMTs were: vaccine A (12/12, GMT=905.0); vaccine B (30/36, GMT=28.3); vaccine C (20/28, GMT=28.3); vaccine D (14/30, GMT=16.1); and against BVDV-2: vaccine A (12/12, GMT=56.6); vaccine B (18/36, GMT=16.8); vaccine C (10/28, GMT=21.6) and vaccine D (6/30, GMT=16.1). The geometric mean titers (GMTs) induced by vaccine A were significantly higher than those induced by the other vaccines (BVDV-1: P<0.0001) and (BVDV-2: P=0.01) in all days of testing. Cross-neutralization tests revealed that the antibodies induced by vaccine A cross-reacted to higher titers also with three Brazilian BVDV-1 and one BVDV-2 isolates. These results demonstrate that the experimental attenuated vaccine induced neutralizing antibodies in higher titers, duration and spectrum of reactivity than those induced by commercial vaccines. This vaccine may represent a future alternative for the control of BVDV infection in Brazil.
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