RESUMO
Two studies were performed in pregnant heifers to determine whether inoculation with two bovine viral diarrhoea viruses (BVDV), one BVDV-1 and one BVDV-2, inoculated separately into either nostril, results in fetal infection with both viruses. Dual transplacental infection of the fetus with BVDV-1 and BVDV-2 was observed in one case, but not consistently.
Assuntos
Doença das Mucosas por Vírus da Diarreia Viral Bovina/virologia , Vírus da Diarreia Viral Bovina Tipo 1/patogenicidade , Vírus da Diarreia Viral Bovina Tipo 2/patogenicidade , Doenças Fetais/veterinária , Transmissão Vertical de Doenças Infecciosas/veterinária , Complicações Infecciosas na Gravidez/veterinária , Animais , Doença das Mucosas por Vírus da Diarreia Viral Bovina/transmissão , Bovinos , Vírus da Diarreia Viral Bovina Tipo 1/fisiologia , Vírus da Diarreia Viral Bovina Tipo 2/fisiologia , Feminino , Doenças Fetais/virologia , Feto/virologia , Masculino , Gravidez , Complicações Infecciosas na Gravidez/virologiaRESUMO
Bovine viral diarrhea virus (BVDV) with deletions in the 5'-nontranslated region (5'-NTR) were tested for their suitability as live BVD vaccines. Firstly, the genetic stability of the mutants was established by culturing over 15 passages in bovine cells. Secondly, two deletion mutants and the parent strain CP7-5A were characterised with respect to in vivo replication competence, attenuation and induction of protective immunity against BVDV. Naïve calves (n = 5 per group) were inoculated with mutants d2-31 and d5-57 or CP7-5A and 5 weeks later, a challenge with the BVDV type 1 strain New York was performed. The mutants were found to be genetically and phenotypically stable. Moreover, the results indicate that the mutants were attenuated with regard to effects including pyrexia and drop in leucocyte counts. Infection with the mutants induced moderate to high titers of BVDV neutralizing antibodies and completely prevented viremia after challenge infection with a heterologous BVDV strain. Taken together, the 5'-NTR deletion mutants combine a good safety profile with good efficacy and are therefore well suited as candidate live vaccines.
Assuntos
Regiões 5' não Traduzidas/genética , Regiões 5' não Traduzidas/imunologia , Doença das Mucosas por Vírus da Diarreia Viral Bovina/prevenção & controle , Doença das Mucosas por Vírus da Diarreia Viral Bovina/virologia , Doenças dos Bovinos/prevenção & controle , Doenças dos Bovinos/virologia , Vírus da Diarreia Viral Bovina/genética , Vírus da Diarreia Viral Bovina/imunologia , Vacinas Virais/imunologia , Replicação Viral , Animais , Northern Blotting , Temperatura Corporal/fisiologia , Doença das Mucosas por Vírus da Diarreia Viral Bovina/fisiopatologia , Bovinos , Doenças dos Bovinos/fisiopatologia , Vírus da Diarreia Viral Bovina/crescimento & desenvolvimento , Eritrócitos/virologia , Cinética , Contagem de Leucócitos , Contagem de Linfócitos , Mutação/genética , Testes de Neutralização , Fenótipo , RNA Viral/biossíntese , Vacinas Atenuadas/genética , Vacinas Atenuadas/imunologia , Ensaio de Placa Viral , Vacinas Virais/administração & dosagem , Viremia/sangueRESUMO
This study was designed to answer to two distinct questions. Firstly, is it possible to reproduce clinical signs of acute bovine virus diarrhoea virus (BVDV) type 2 infection including signs of haemorrhagic disease under experimental conditions in cattle at 20 weeks of age? Secondly, what is the extent of the protection afforded by vaccination with an inactivated BVDV type 1 vaccine against BVDV type 2 infection? Calves were vaccinated at 12 and 16 weeks of age with a commercially available inactivated BVDV type 1 vaccine (Bovilis BVD). At 20 weeks they were challenge infected with BVDV type 2 virus together with unvaccinated control calves. The unvaccinated animals developed typical signs of respiratory disease, diarrhoea with erosions and haemorrhages along the whole length gastro-intestinal tract, and depletion of lymphocytes in lymphatic organs. These signs were either absent or markedly less severe in the vaccinated animals. The beneficial effects of vaccination were most striking in the haematological parameters thrombocytopenia and leukopenia. It can be concluded that vaccination with Bovilis BVD affords cross-protection against clinical effects of a challenge-infection with heterologous type 2 BVDV.