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.

About author

Himanshu Paneru’s journey in the world of medical sciences led him to create DOC NOTE MASTER, a platform where education meets expertise. Having earned his Master’s in Medical Microbiology from Netaji Subhash Chandra Bose Subharti Medical College, Dehradun, Uttarakhand, he is dedicated to making medical knowledge more accessible through his writing.