EFFECTIVE PRIMING OF NEONATES BORN TO IMMUNE DAMS AGAINST THE IMMUNOGENIC PSEUDORABIES VIRUS GLYCOPROTEIN GD BY REPLICATION-INCOMPETENT ADENOVIRUS-MEDIATED GENE-TRANSFER AT BIRTH

One of the main limitations of the vaccination of neonates from vaccin ated or infected mothers is the interference by inherited maternal ant ibodies, which are known to inhibit the immune response against both l ive and inactivated vaccines, The efficiency of bypassing this inhibit ion by the transfer of an immunogenic glycoprotein gene, the gD gene o f pseudorabies virus (PRV), into neonates was explored, The experiment s were conducted in 1-day-old piglets, which are immunocompetent at bi rth, The same transcription unit (gD of PRV under the control of the a denovirus major late promoter) was delivered intramuscularly at birth either in the form of naked DNA or cloned in the genome of a replicati on-defective adenovirus. A booster injection of a conventional live PR V vaccine strain was given at 10 weeks of age, the replication of whic h was greatly restricted by the residual amounts of colostral antibodi es in control animals, Piglets were challenged at the age of 16 weeks with a virulent PRV strain, The replication-defective adenovirus was a ble to efficiently prime piglets born to immune dams against gD in suc h a way that inoculation with the Bartha strain protected them against a subsequent challenge with the same level of efficacy in piglets bor n to naive or immune dams, In contrast, piglets born to immune dams in to which the gD gene was not transferred, or transferred as naked DNA at birth, were not protected, These results open the way for early imm unization of neonates born to vaccinated or infected mothers.