#vaccine technology

Vaccine

Which plant was engineered to produce edible Hepatitis B vaccine?

Banana was specifically engineered to produce edible Hepatitis B vaccine demonstrating fruit-based oral immunization feasibility. Hepatitis B surface antigen HBsAg 226 amino acid small surface protein self-assembles into 22 nm virus like particles highly immunogenic protective against HBV infection. Early work by Thanavala 1995 expressed HBsAg in transgenic tobacco plants showing assembly. Subsequent collaboration by Arntzen, Mason and colleagues introduced HBsAg gene under fruit specific promoter E8 and constitutive CaMV 35S with endoplasmic reticulum retention signal KDEL into Cavendish bana

Ref: Thanavala et al. PNAS 1995 92:3358 Banana HBsAg; Arntzen 1997 Edible Hepatitis B banana; Lancet.

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Vaccine

DNA vaccines deliver genes in the form of:

DNA vaccines deliver genetic instructions as circular plasmid DNA rather than protein antigen or RNA. Plasmid constructs typically contain bacterial origin pUC, antibiotic resistance for selection during manufacturing, and eukaryotic expression cassette comprising strong promoter cytomegalovirus CMV immediate early with intron A enhancing transcription, codon optimized antigen gene, polyadenylation signal bovine growth hormone BGH or SV40 preventing mRNA degradation. Plasmids produced in Escherichia coli fermentation high copy number, purified supercoiled isoform removing endotoxin via chromat

Ref: Wolff et al. Science 1990 DNA vaccines plasmid; Plotkin DNA vaccines; WHO DNA plasmid.

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Vaccine

AZD1222 (Covishield) vaccine uses which vector?

AZD1222 vaccine known in India as Covishield produced by Serum Institute Pune under license from AstraZeneca Oxford University uses chimpanzee adenovirus vector ChAdOx1. ChAdOx1 derived from chimpanzee adenovirus isolate Y25 taken from chimp stool 1960s, selected because human population seroprevalence low compared to human adenovirus 5 where 40-60 percent adults have neutralizing antibodies compromising vector. Vector engineered by deleting E1 genes essential for replication making it replication deficient incapable of causing disease, requiring E1 complementing cells HEK293 for manufacturing

Ref: Voysey Lancet 2021 397:881 AZD1222 ChAdOx1; Oxford ChAdOx1 history; WHO Covishield.

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Vaccine

Viral vector vaccines deliver antigen genes using:

Viral vector vaccines deliver genes encoding pathogen antigens using harmless viruses engineered to be replication deficient as transportation vehicles. Concept employs vector virus lacking pathogenic genes but retaining ability to infect mammalian cells, deliver DNA into nucleus, transcribe transgene using host polymerase, translate antigen intracellularly mimicking natural infection. Vector backbone commonly human adenovirus serotypes 5 and 26, chimpanzee adenovirus ChAdOx1, canarypox ALVAC, modified vaccinia Ankara MVA, vesicular stomatitis virus VSV, adeno associated virus. Deletion of E1

Ref: Tatsis Ertl Mol Ther 2004 Viral vectors; Draper Heeney Nat Rev Microbiol Vector vaccines.

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