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LECTURE 18:. Virus vaccines. Viro100: Virology 3 Credit hours NUST Centre of Virology & Immunology. Waqas Nasir Chaudhry. Live recombinant virus vaccines.

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Virus vaccines

LECTURE 18:

Virus vaccines

Viro100:

Virology

3 Credit hours

NUST Centre of Virology & Immunology

WaqasNasirChaudhry


Live recombinant virus vaccines

Live recombinant virusvaccines

  • A recombinant vaccinia virus engineered to contain the gene for the rabies virus G protein has been used to vaccinate wild mammals against rabies


Virus vaccines

Live recombinant virus vaccines


Virus like particles

Virus like particles

  • Virus-like particles are structures assembled from virus proteins

  • The particles resemble virions, but they are devoid of any nucleic acid

  • Therefore be deemed safer than vaccines containing attenuated or inactivated virions

  • Hepatitis B virus (HBV) vaccine is produced in recombinant yeast cells that have the gene for the HBsAginserted into the genome


Virus vaccines

  • The cells are grown in bulk and then broken to release the virus protein.

  • After purification the HBsAg molecules receive a chemical treatment that causes them to aggregate into spherical structures similar to the non-infectious of HBV

  • The major capsid protein of papillomaviruses can self assemble into virus-like particles that bear the epitopes required for generating neutralizing antibodies


Synthetic peptide vaccines

Synthetic peptide vaccines

  • Each protein antigen has one or more epitopes

  • These short amino acid sequences can be synthesized in a machine and it was suggested that the resulting peptides might be used as vaccines

  • Compared with traditional vaccines it would be easier to ensure the absence of contaminants such as viruses and proteins


Virus vaccines

  • A lot of work has been done to try to develop peptide vaccines against foot and mouth disease virus

  • In this virus there is an important epitope within the virion protein VP1

  • Synthetic peptides of this sequence induced reasonable levels of neutralizing and protective antibodies in laboratory animals

  • but when vaccine trials were done in farm animals the results were disappointing


Dna vaccines

DNA vaccines

  • The most revolutionary approach to vaccination is the introduction into the vaccinee of DNA encoding an antigen, with the aim of inducing cells of the vaccineeto synthesize the antigen

  • One advantage of this approach is that there is a steady supply of new antigen to stimulate the immune system

  • Because the antigen (a virus protein in this case) is produced within the cells of the vaccinee, it is likely to stimulate efficient T-cell-mediated responses


Virus vaccines

Production of a DNA vaccine. The virus protein gene is inserted into a plasmid, which is then cloned in bacteria. The plasmid is extracted from the bacterial cells, purified and incorporated into a vaccine


Storage and transport of vaccines

Storage and transport of vaccines

  • Once a vaccine has been manufactured there is a need to preserve its efficacy until it is used

  • For live vaccines this means preserving virus infectivity

  • For vaccines containing inactivated virions, subunits and virus-like particles it means preserving immunogenicity

  • Most vaccines are stored and transported at low temperatures this minimizes losses of infectivity and immunogenicity

  • Substances that reduce the rate of infectivity loss are included in some vaccines, an example being magnesium chloride in live polio vaccines


Virus vaccines

Low temperature storage of virus vaccines


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