DNA immunization with plasmids encoding fusion and nucleocapsid proteins of bovine respiratory syncytial virus induces a strong cell-mediated immunity and protects calves against challenge.
Boxus, Mathieu ; ; et al
in Journal of Virology (2007), 81(13), 6879-89
Respiratory syncytial viruses (RSV) are one of the most important respiratory pathogens of humans and cattle, and there is currently no safe and effective vaccine prophylaxis. In this study, we designed ... [more ▼]
Respiratory syncytial viruses (RSV) are one of the most important respiratory pathogens of humans and cattle, and there is currently no safe and effective vaccine prophylaxis. In this study, we designed two codon-optimized plasmids encoding the bovine RSV fusion (F) and nucleocapsid (N) proteins and assessed their immunogenicity in young calves. Two administrations of both plasmids elicited low antibody levels but primed a strong cell-mediated immunity characterized by lymphoproliferative response and gamma interferon production in vitro and in vivo. Interestingly, this strong cellular response drastically reduced viral replication, clinical signs, and pulmonary lesions after a highly virulent challenge. Moreover, calves that were further vaccinated with a killed-virus vaccine developed high levels of neutralizing antibody and were fully protected following challenge. These results indicate that DNA vaccination could be a promising alternative to the classical vaccines against RSV in cattle and could therefore open perspectives for vaccinating young infants. [less ▲]Detailed reference viewed: 4 (1 ULg)
Bovine enterotoxaemia in Belgium. III. Comparison of different protocols of immunisation against the alpha toxin of Clostridium perfringens
; ; et al
in Annales de Médecine Vétérinaire (2004), 148(3), 147-152
Previous surveys demonstrated the association between the bovine enterotoxaemia syndrome and proliferation of Clostridium perfringens toxintype A. The purpose of this study was to establish rules for ... [more ▼]
Previous surveys demonstrated the association between the bovine enterotoxaemia syndrome and proliferation of Clostridium perfringens toxintype A. The purpose of this study was to establish rules for vaccination of calves against the a toxin. Bovines were Belgian Blue (BBB) or BBB x Charolais originating from 6 farms with no history of clostridial vaccination. One hundred and thirty-three calves were injected with Tasvax (R) and 70 with Miloxan (R) at one and two months of age, while 94 calves received no vaccine. To study sero-conversion in calves born from vaccinated dams, 67 cows were vaccinated with Tasvax at 7 and 8 months pregnancy. Twenty-nine calves born from these cows were vaccinated at one and two months of age with the same vaccine while 38 calves were not vaccinated. The results of these 67 calves were also compared to the results obtained from the calves born from non-vaccinated cows and vaccinated with Tasvax. Anti-alpha toxin antibodies were measured using an indirect ELISA assay. Anti-alpha toxin antibodies are naturally present in the serums of non vaccinated animals and are transferred to the newborn calf by the colostrum. The two vaccinal injections cause sero-conversions in proportion of the total amount of immunogen received. The best protocol for calf vaccination is a first injection at one month of age, followed by a booster injection four weeks later. Boosters every six months are necessary to maintain a high level of antibody. In case of early problems (< 2 months of age) of enterotoxaemia in a farm, high antibody titres are obtained only following the vaccination of the pregnant cow and colostral transfer. Unfortunately this protocol is not compatible with vaccination of the calf itself. [less ▲]Detailed reference viewed: 128 (0 ULg)
A role for the Clostridium perfringens beta 2 toxin in bovine enterotoxaemia?
; Daube, Georges ; Jauniaux, Thierry et al
in Veterinary Microbiology (2002), 86(3), 191-202
Non-enterotoxigenic type A Clostridium perfringens are associated with bovine enterotoxaemia, but the alpha toxin is not regarded as responsible for the production of typical lesions of necrotic and ... [more ▼]
Non-enterotoxigenic type A Clostridium perfringens are associated with bovine enterotoxaemia, but the alpha toxin is not regarded as responsible for the production of typical lesions of necrotic and haemorrhagic enteritis. The purpose of this study was to investigate the putative role of the more recently described beta2 toxin. Seven hundred and fourteen non-enterotoxigenic type A C. perfringens isolated from 133 calves with lesions of enterotoxaemia and high clostridial cell counts (study population) and 386 isolated from a control population of 87 calves were tested by a colony hybridisation assay for the beta2 toxin. Two hundred and eighteen (31%) C perfringens isolated from 83 calves (62%) of the study population and 113 (29%) C. perfringens isolated from 51 calves (59%) of the control population tested positive with the beta2 probe. Pure and mixed cultures of four C perfringens (one alpha+beta2+, one alpha+enterotoxin-1 and two alpha+) were tested in the ligated loop assay in one calf. Macroscopic haemorrhages of the intestinal wall, necrosis and haemorrhages of the intestinal content, and microscopic lesions of necrosis and polymorphonuclear and mononuclear cell infiltration of the intestinal villi were more pronounced in loops inoculated with the a and beta2-toxigenic C. perfringens isolate. These results suggest in vivo synergistic role of the alpha and beta2 toxins in the production of necrotic and haemorrhagic lesions of the small intestine in cases of bovine enterotoxaemia. However, isolation of beta2-toxigenic C. perfringens does not confirm the clinical diagnosis of bovine enterotoxaemia and a clostridial cell counts must still be performed. (C) 2002 Elsevier Science B.V. All rights reserved. [less ▲]Detailed reference viewed: 122 (25 ULg)