? Passive transfer of neutralizing antibodies against Bovine Respiratory Syncytial Virus after vaccination of pregnant cows with inactivated bRSV

ALEJANDRA FERELLA; CARLOS MARGINEDA; DIEGO DANIEL GONZALEZ; TOLEDO G; GUSTAVO ZIELINSKI; ANDREA PECORA; DUS SANTOS MARIA JOSE; MARINA MOZGOVOJ

Congreso; XXVIII World Buiatrics Congress; 2014

Bovine respiratory syncytial virus (bRSV) has been established as an important viral component in the bovine respiratory disease complex (BRD) and it is a major cause of severe lower respiratory tract infections causing bronchiolitis and pneumonia in young calves, mainly from 0 to 3 months of age. Animal decreased production and treatment costs cause economic losses to the industry and there is a great need for effective prophylactic measures to control infections. Maternal antibodies are transferred from cows to newborn calves by ingestion of colostrum and the duration of this passively acquired immunity is dependent on the amount of antibodies ingested and absorbed. Although colostral antibodies did not effectively prevent the disease, both the incidence and severity of disease are inversely related to the level of specific maternal antibodies. The aim of this work was to evaluate the passive transfer and duration of maternal bRSV specific antibodies from vaccinated pregnant cattle to the calves. A group of five pregnant cows was inoculated by the intramuscular route with 2 doses of a vaccine containing 105DICT50/ml of BEI inactivated bRSV, at 60 and 30 days before calving. As a control group, five animals were mock inoculated. Cows´ serum samples were obtained at times 60, 30 before calving and at 0, 30, 60, 120 and 180 days postpartum. Sera from calves were obtained at 0, 30, 60, 90, 120, 150 and 180 days after birth, in accordance with protocols approved by an ethical committee of animal welfare. The kinetic of serum specific antibodies from inoculated animals and newborn calves was analyzed by a serum neutralization assay. Only the vaccinated cows serocoverted 60 days post booster and antibody titers remained high 180 days post booster. Five out of six newborn calves showed an effective passive transfer of specific bRSV maternal antibodies, although neutralizing antibody titers were lower than expected. In concordance with control cows, their respective calves showed basal levels of neutralizing antibodies. In this work, it was possible to induced specific bRSV neutralizing antibodies that were passively acquired by newborn calves. However, as colostral antibody levels were not as high as expected and the duration of passive antibody response was short, pose the need of developing new generation vaccines able to prevent infection and disease.