Viral Diseases exam 4

Pathogen: Varicella

Varicella - Chickenpox

cause: Itchiness

• Herpesvirus Varicella-Zoter

• DNA virus

• Transmitted via respiratory route

• Caused Pus-filled Vesicles

• Vesicles on skin (itchy)

  Symptoms

• Latent in neurons of CNS

• Reactivation leads to shingles

• Varicella causes disease by:

  1. Infecting respiratory mucosa.

  2. Disseminating through blood to skin and internal organs.

  3. Causing a systemic immune response and characteristic rash.

Shingles

Result of latent chickenpox

• reactivation leads to shingles - Postherpetic Neuralgia

• Due to stress - low immunity

• Herpes Zoster

• “Varicella - Zoster” - pathogen

• Symptoms: Rash wide spread right side

• emotional stress

Human Immunodeficiency Virus (HIV)

• Retro Virus/ RNA

• Enveloped

• gp120 binds to CD4 receptors on Thelper cells, & macrophages & Dendritic

  Symptoms:

• Rare fungal infections

• Rare cancers

• low white blood cells and T cells count

• weight loss fever

Hiv attach to host cell

Spread by dendritic cells and carried
to the lymphoid organs; contacts
activated T cells
• gp120 spike combines with CD4+
receptor
– CD4 receptor molecules are
carried on T helper cells,
macrophages, and dendritic cells
• Virus fuses and enters into the cell

Pathogenicity of HIV

leading to immune damage*

• HIV DNA will integrate into CD4 host cell Chromosome

• Tend to target memory T Helper cells for integration

• into a Provirus ( Integrate DNA)

into 2 Types of infections

Activation : new virus buds off from the host cell

Latent: DNA integrates into the host chromosomes as a provirus

Virus undergoes rapid antigenic changes and a high rate of
mutation (due to not having
proofreading ability)

3 Stages of HIV infection

Stages of HIV infection
• Phase 1: asymptomatic ( No signs)
• Phase 2: CD4+ T cells decline steadily; only a few infected cells more persistent infection
release the virus; a few serious disease symptoms ( fever, and oral leukoplakia)
• Phase 3: AIDS develops; the CD4+ is count below 200 cells/μl;
risk for many opportunistic infections and rare cancers

Common Cold

• over 200 different viruses types

• Most common : Coronaviruses & Rhinoviruses

• Symptoms: Sneezing, nasal secretion, congestion
  if infections spreads to lower
  respiratory system.
  

• Transmitted: Viruses in mucus
  • Virus can also spread through airborne droplets from coughing
  and sneezing.

• Touching contaminated things

Influenzavirus

Causing agent for the Flu

• 3 Types A & B & C

• A Type is most common and relevant

Influenza virus contains 8 RNA segments and an envelope

Virus has two spikes important for its virulence
- Hemagglutinin (HA)
- Neuraminidase (NA)

Hemagglutinin (HA)

• HA → attaches to host cells

• binds to host epithelial cells in the
  respiratory tract

Neuraminidase (NA)

• NA → During exit prevents curious from sticking together

• helps with budding.
  - Enzyme that breaks down respiratory mucus

Symptoms of the Flu

Chills, fever, headache, muscle
aches, and more

– Formation of new virulent
strains possible

Can infect avian, swine (animals) and human host

Swine - ( mixing vessels) to create new stains

Influenza Flu

Antigenic drift (swerving to a lane) - minor change
– Minor changes in HA and NA

( mutations)
– Allow the virus to elude some host immunity

• Antigenic shifts ( Big change)
– Changes great enough to evade most immunity
– Lead to pandemics
– Reassortment of segments from 2 different viruses

• Antigenic drift (natural or vaccine-induced) fades over time.

• Antigenic shift poses a global health risk because it can introduce a completely new virus strain, causing widespread illness and death.

Reye Syndrome

Children develop when taking aspirin when infected with the flu

can lead to swelling of the liver, brain and damage organs