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Adenovirus antibodies reduce vector vaccine efficacy

  • Category
    Science & Technology
  • Published
    23rd Mar, 2021

Studies have shown that using the same adenovirus subtypes for repeated vaccination might result in reduced efficacy.

Context

Studies have shown that using the same adenovirus subtypes for repeated vaccination might result in reduced efficacy.

What is an Adenovirus antibody?

  • Adenoviruses(family Adenoviridae) are medium-sized (90–100 nm)viruses.
  • They are-enveloped (without an outer lipid bilayer) viruses.
  • They are icosahedral nucleocapsid containing a double-stranded DNA genome.
  • Adenoviruses: These are a group of common viruses that infect the lining of the eyes, airways, and lungs, intestines, urinary tract, and nervous system.
    • They're common causes of fever, coughs, sore throats, diarrhea, and pink eye.
    • The immune system generated against the adenovirus infection causes the antibodies formation.

How these antibodies illicit response action against vector-based vaccine?

  • Pre-existing antibodies cause the relatively low efficacy of the adenovirus-based vaccine in some people.
    • It affects the development of antibodies against the new target.
    • Pre-existing antibodies against adenoviruses will stop the adenovirus particles from getting into cells and making the SARS-CoV-2 spike protein they carry the code for.

Adenovirus as Vector

  • Adenoviruses are excellent vectors for delivering genes or vaccine antigens. Adenovirus-based vectors offer several advantages over other viral vectors such as:
    • a broad range of tissue tropism
    • well-characterized genome
    • ease of genetic manipulation including acceptance of large transgene DNA insertions
    • inherent adjuvant properties
    • ability to induce robust transgene-specific T cell and antibody responses
    • non-replicative nature in host
    • ease of production at large scale

Vector-based Vaccines

  • Viral vectors are tools commonly used to deliver genetic material into cells.
    • This process can be performed inside a living organism (in vivo) or in cell culture (in vitro). 
    • As a medium of transport: Viruses have evolved specialized molecular mechanisms to efficiently transport their genomes inside the cells they infect. 
    • Functioning: They are then inserted into the genome of a non-pathogenic organism, where they are expressed on the organism's surface and can elicit an immune response.
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