Pox Viruses - The Morphology & Cultivation of Vaccinia & Variola Virus

POX VIRUSES – THE ERADICATED CULPRIT OF SMALLPOX (VACCINIA & VARIOLA VIRUSES)

INTRODUCTION TO POX VIRUSES

Pox viruses are the largest and the most complex of all viruses, belongs to the family poxviridae and causes a number of diseases, are large enough to be seen under the light microscope.

MORPHOLOGY OF POX VIRUSES

Poxviruses are brick-shaped.

Genetic Material – dsDNA

Poxviruses have complex symmetry.

Largest animal viruses of size – 300*200*100 nm.

Enveloped viruses.

POX VIRUSES - VACCINIA VIRUS - VARIOLA VIRUS - SMALLPOX
POX VIRUSES

Poxviridae consists of 3 genera as –

  1. Orthopoxvirus –
    • Variola & Vaccinia ( in human)
    • Cowpox (in cows)
    • Monkeypox (in monkey)
  2. Parapoxvirus – milker’s node & orf (in cow & Sheep)
  3. Yatapoxvirus – Tanapox & Yabapox (in monkeys)

CULTIVATION OF POX VIRUSES

Poxviruses grow in Chorioallantoic membrane (CAM) of chick embryo and in tissue culture; Variola & Vaccinia produce pocks on the CAM in 48-72 hours.

Tissue cultures of monkey kidney, HeLa & chick embryo cell can be used to grow these viruses.

VARIOLA & VACCINIA VIRUS

⇒ Variola virus causes smallpox

  • Has narrow host range i.e. humans & monkeys only.
  • The virus causing classical smallpox was called Variola major that causing alastrim called Variola minor, are antigenically identical but differs in certain biological characteristics.
  • Smallpox has been eradicated and routine vaccination is now stopped.
  • On May 8, 1980, WHO announced the global eradication of smallpox.

Origin of Vaccinia virus is unknown.

  • In past, was used for smallpox vaccination.
  • ‘Artificial virus’ that doesn’t occur in nature and may have evolved from smallpox or cowpox virus.
  • Causes localized skin infection.
  • Employed as a vector for the development of recombinant vaccines.
  • Vaccinia & Variola viruses are similar in their properties.

SAHIL BATRA

Hi, I'm the Founder and Developer of Paramedics World, a blog truly devoted to Paramedics. I am a Medical Lab Tech, a Web Developer and Bibliophiliac. My greatest hobby is to teach and motivate other peoples to do whatever they wanna do in life.

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