VACCINIA VIRUS

INTRODUCTION

• Vaccinia virus is a member of the Poxviridae family.

• Poxviridae family are largest DNA virus.

• Vaccinia virus not cause any disease to human.

• It play important role in the development of the smallpox vaccine.

• The smallpox vaccine derived from cowpox & vaccinia virus.

MORPHOLOGY

• Shape:

• Brick-shaped

• Size:

• Size of the Vaccinia virus is large compared to other viruses.

• Approx. length 360, width 270, height 250 nm

• Symmetry:

• Complex symmetry

• Enveloped Structure:

• Vaccinia virus is enveloped, meaning it is surrounded by a lipid bilayer membrane.

• The envelope is derived from the host cell membrane during the process of viral assembly.

• Genome:

• Double-stranded DNA genome.

• Surface:

• Outer surface of the virus is covered with viral glycoproteins that play a role in host cell recognition & entry.

ANTIGENIC STRUCTURE

• The antigenic structures are primarily associated with the viral envelope & proteins expressed on the virus surface. Here are key points regarding the antigenic structure:

• 1. Envelope Proteins:

  • The outer envelope of the Vaccinia virus .

  • Envelope proteins are crucial for interactions with host cells during the infection process.

• 2. Glycoproteins:

  • Glycoproteins are proteins with attached carbohydrate chains.

  • Glycoproteins on the surface of the virus play a role in host cell recognition and entry.

• 3. Immunodominant Proteins:

  • Some proteins of the Vaccinia virus are particularly immunodominant (strong immune response.

  • They are often targeted in the development of vaccines.

PATHOGENESIS

• Vaccinia virus is not pathogenic in the same way as the variola virus (which causes smallpox).

• Vaccinia virus is generally less virulent & used as a live attenuated vaccine.

  Ø Mode of transmission:

  • Direct contact

  • Airdrop

  • Contaminated object

  • Skin-to-skin contact

  Ø Route of entry:

  • Skin entry

  • Mucous membrane

  • Respiratory entry

    Ø Incubation period:

  • Infection with Vaccinia virus begin with an incubation period usually lasting between 10 to 14 days.

    Ø Spread:

  • Step1- Primary infection occur at the site of entry, often the skin or mucous membranes.

  • Step2- Then enters into host cell & replicate.

  • Step3- The virus can spread locally from the initial site of infection to neighboring cells, formation of lesion and pock occur.

  • Step4- Now virus enter into bloodstream or the lymphatic system.

  • Step5- The virus in multiple organs causing a more widespread impact on the body.

Sign & symptoms

• The vaccinia virus causes symptoms related to the smallpox vaccination.

• Common symptoms include:

  • Pain, redness, & swelling at the vaccination site.

  • Fever.

  • Body aches.

LABORATORY DIAGNOSIS

• Laboratory diagnosis of vaccinia virus infection involves several methods to identify and confirm the presence of the virus.

• It include:

1. Virus Isolation: vaccinia virus isolation is the Vero cell line, derived from the African green monkey kidney.

2. Molecular methods: PCR can be used to detect and amplify specific regions of the vaccinia virus genome.

3. Immunohistochemistry IHC): HC involves the use of antibodies to detect viral antigens in tissue samples.

4. Serological Tests: ELISA & other serological tests can detect antibodies produced in response to vaccinia virus infection.

5. Electron Microscopy: Electron microscopy can be used to visualize viral particles directly.

6. DNA Sequencing: DNA sequencing determination of the genetic makeup of the virus.

7. Real-time PCR (RT-PCR): Real-time PCR is a quantitative method that allows for the real-time monitoring of the amplification process.