The bovine leukemia virus vaccine is safe and efficiently protects natural infection

GERONIMO GUTIERREZ; SOWUL M; SUAREZ ACHILLA; PERSEN MARCOS; CARIGNANO HUGO; CALVINHO LUIS; ABDALA, ALEJANDRO; ALVAREZ IRENE; DE BROGNIEZ ALIX; WILLEMS LUC; TRONO KARINA

Tokio

Conferencia; 18th Conference on Human Retrovirology: HTLV and RGutierrez Geronimoelated Viruses; 2017

Gutierrez Geronimo, Sowul Mariana, Suarez Archilla GA., Persen Marcos, Carignano Hugo, Calvinho Luis, Abdala Alejandro, Alvarez Irene, Alix de Brogniez. Willems Luc., Trono KarinaThe bovine leukemia virus vaccine is safe and efficiently protects natural infectionWe recently designed a novel strategy to vaccinate against bovine leukemia virus using a live-attenuated BLV provirus. We previously showed that the vaccine strain replicates at reduced levels in cows and elicits a strong anti-BLV immune response. We demonstrated that vaccinated animals but not uninfected controls resist challenge by the natural wild type BLV virus. The vaccine strain does not spread to uninfected sentinels when maintained during 5 years in the same herd supporting its biosafety. Passive immunity, but not viral infection, is transmitted to the newborn calves via the maternal colostrum.We now show that milk produced by vaccinated cows is not infectious when inoculated to host-susceptible sheep. Furthermore, the vaccine strain is undetectable by PCR in newborn calves. None of the calvesbecame infected by the attenuated vaccine during three cycles of delivery and milking. Compositional analysis indicates that milk from vaccinated, naturally infected and control cows is substantially similar. Moreover, 10ml of blood from vaccinated cattle is not sufficient to transmit the vaccine strain to naive calves, revealing a very low risk of propagation even through iatrogenic procedures. These results support the safety of the vaccine strain at the herd level. After obtaining approval of the authorities (SENASA), a large trial in a dairy facility is currently ongoing in standard productive conditions. Results of this trial will be presented.