Construction and Characterization of a Novel Recombinant Attenuated and Replication-Deficient Candidate Human Adenovirus Type 3 Vaccine:'Adenovirus Vaccine Within an Adenovirus Vector'

摘要

Human adenoviruses(HAd Vs)are highly contagious and result in large number of acute respiratory disease(ARD)cases with severe morbidity and mortality.Human adenovirus type 3(HAd V-3)is the most common type that causes ARD outbreaks in Asia,Europe,and the Americas.However,there is currently no vaccine approved for its general use.The hexon protein contains the main neutralizing epitopes,provoking strong and lasting immunogenicity.In this study,a novel recombinant and attenuated adenovirus vaccine candidate against HAd V-3 was constructed based on a commercially-available replication-defective HAd V-5 gene therapy and vaccine vector.The entire HAd V-3 hexon gene was integrated into the E1 region of the vector by homologous recombination using a bacterial system.The resultant recombinants expressing the HAd V-3 hexon protein were rescued in AD293 cells,identified and characterized by RT-PCR,Western blots,indirect immunofluorescence,and electron microscopy.This potential vaccine candidate had a similar replicative efficacy as the wild-type HAd V-3 strain.However,and importantly,the vaccine strain had been rendered replication-defective and was incapable of replication in A549 cells after more than twentygeneration passages in AD293 cells.This represents a significant safety feature.The mice immunized both intranasally and intramuscularly by this vaccine candidate raised significant neutralizing antibodies against HAd V-3.Therefore,this recombinant,attenuated,and safe adenovirus vaccine is a promising HAd V-3 vaccine candidate.The strategy of using a clinically approved and replication-defective HAd V-5 vector provides a novel approach to develop universal adenovirus vaccine candidates against all the other types of adenoviruses causing ARDs and perhaps other adenovirus-associated diseases.