Rift Valley Fever Virus DIVA vaccine

ChAdOx1-GnGc is a DIVA (differentiating infected from vaccinated animals) vaccine composed of a replication-deficient simian adenovirus vector expressing Rift valley fever phlebovirus envelope glycoproteins (amino-terminus and carboxy-terminus glycoproteins). Together, the glycoproteins form virus-like particles, which are expected to elicit a strong immune response to viral challenges in livestock, such as sheep, goats, cattle and dromedary camels. The disease is characterized by high rates of mortality in newborn animals and abortions in those that are pregnant. The modified adenovirus is not expected to replicate within the animal due to the deletion of gene E1, which is responsible for replication.

ChAdOx1 (Chimpanzee Adenovirus Oxford 1) is a replication-deficient vaccine vector derived from Chimpanzee adenovirus Y25 and contains a deletion of the gene responsible for replication, E1.

ChAdOx1

Gene expression
Transcription of the Rift valley fever phlebovirus glycoproteins Gn and Gc are under control of the Human cytomegalovirus major immediate-early promoter and the Bos taurus bovine growth hormone terminator. A human tissue plasminogen activator leader sequence is also included to enhance the expression of the glycoproteins.

Note:
- The Human cytomegalovirus immediate early promoter contains intron A, which enhances expression of the downstream elements by promoting strong transcription.
- The Human cytomegalovirus immediate early promoter contains the following portions: Regulatory sequence (437 bp); Enhancer (481 bp); Promoter (62 bp); Exon A (120 bp); and Intron A (824 bp) (total size 1924 bp).
- The Rift valley fever virus glycoproteins Gn and Gc were isolated from the M segment of the viral genome (base pairs: 411 to 3614)

Please note: Genetic element sizes have not been confirmed