Infection Pathogenesis

Question 1

acute infection

Answer 1

HAV

self limiting

Question 2

latent infection

Answer 2

varicella zoster

Question 3

chronic infection

Answer 3

HBV
late diseases:
HLTV 1
HIV
HBV
BCV

Question 4

localized

Answer 4

at the specific site
papiloma
flu

Question 5

systemic infection

Answer 5

disseminated usually via blood or lymphatics viremia means virus in the blood
chicken pox
measles

Question 6

inhalation

Answer 6

Particles in upper tract are usually swallowed
Particles in lower tract are swept to back of throat and coughed out
Small particles (<5μM) enter lungs and reach alveolar sacs - no mucus or ciliated cells
macrophages and IgG and IgA are there. MØ engulf particles.

Question 7

examples of inhalation viruses

Answer 7

Common cold viruses:Rhinovirus, Parainfluenza virus
Adenoviruses
Influenza viruses
Mumps
Measles
Chickenpox
Hantavirus
Corona viruses:
SARS (Severe Acute Respiratory Syndrome) (2003)
MERS (Middle East Respiratory Syndrome) (2013)

Question 8

mumps, measles, chickpox

Answer 8

walk into the room- get it

Question 9

airborne

Answer 9

easily spread via small (ca. 5 μM) aerosols that

are naturally produced by breathing.

Question 10

“Droplet”

Answer 10

larger than aerosols but don’t linger in the air efficiently, such as a
sneeze.

Question 11

respiratory viruses with respiratory symptoms

Answer 11

Rhinovirus
influenza A n B
Parainfluenza 
Adenovirus
Coronavirus (SARS), (MERS)

Question 12

respiratory viruses that don’t cause respiratory symptoms but rashes

Answer 12

Mumps
Measles
Varicella zoster
Variola virus
Hantaan v

Question 13

digestive tract

Answer 13

acidic
intestine is alkaline, has mucus and IgA
digestive enzymes - trypsin cleaves proteins at arginine and lysine amino acids
bile detergents
rotaviruses are activated by stomach/intestinal proteases.

Question 14

Examples of enteric viruses

Answer 14

Picornaviruses (Polio, Enteroviruses, Coxsackievirus)
Enteric Adenoviruses
Reoviruses - rotaviruses
Enteric Coronaviruses( only enveloped here)
HAV - Hepatitis A Virus - (causes acute disease)

Question 15

Sexually transmitted viruses

Answer 15

Herpes Simplex Virus Type 2 (HSV-2)
(HSV-1 through oral-genital contact)
HPV - Human Papillomaviruses
HIV - also via blood
HBV - also via blood
HCV - also via blood

Question 16

skin viruses

Answer 16

epidermis=localized infection cuz no blood vessels
dermis= systemic
Examples
Papillomaviruses (localized to basal cells)
Rabies virus - bites through skin - virus replicates in neurons ( animals)
Vector borne (mosquitos):
Yellow fever virus
Dengue virus
Zika

Question 17

eye viruses

Answer 17

HSV
Adenoviruses
CMV

(HSV-1 can infect cornea, resulting in blindness,
spread to sensory ganglia - ocular herpes

Question 18

Conjunctivitis

Answer 18

localized eye infection

Question 19

neurotropic viruses

Answer 19

Herpes Simplex Viruses 1, 2 ( replicate in neurons and other cells as well.)
Varicella zoster virus (VZV)
Poliovirus ( primarily a GI infection but can reach the CNS;
enters and replicates mainly in the alimentary tract
but can enter motor neurons and cause paralysis)
Rabies virus( spreads only via neurons)

Question 20

Varicella zoster virus (VZV)

Answer 20

=herpes zoster virus, chickenpox virus

Question 21

not strictly “neurotropic”

Answer 21

HIV
CMV

Some viruses cross the blood brain barrier via infected macrophages
They don’t infect neurons, but can cause neurologic problems
Cytomegalovirus can enter the brain in immunocompromised people

Question 22

parinatal- transplacental

Answer 22

CMV
Rubella
Zika

Rubella virus - can cause congenital rubella
syndrome - deafness, heart, eye problems

Question 23

parinatal-at the time of birth

Answer 23

HBV
HCV
HSV2
HIV
Papiloma

So give the mother antivirals prior to birth for
HBV, HCV, HSV-2, HIV

Question 24

paranatal- milk

Answer 24

HIV

CMV

Question 25

Transplants and Transfusions

Answer 25

``` HIV HBV HCV CMV Epstein-Barr Virus EBV West Nile Virus ``` Rabies - only one documented occurrence

Question 26

Blood for transfusions is tested for:

Answer 26

``` HIV-1, HIV-2 HBV HCV HTLV-1, HTLV-2 West Nile Virus ```

Question 27

TORCH, TORCH Syndrome

Answer 27

``` T – Toxoplasmosis / Toxoplasma gondii O – Other infections R – Rubella C – Cytomegalovirus H – Herpes simplex virus 2 / neonatal herpes simplex ``` ``` Other infections includes: • Syphilis • Coxsackievirus • VZV • Chlamydia • HIV • HTLV • parvovirus B19 • enteroviruses ```

Question 28

TORCH symptoms

Answer 28

``` affect newborns fever; difficulties feeding; small areas of bleeding under the skin, causing the appearance of small reddish or purplish spots; enlargement of the liver and spleen (hepatosplenomegaly); yellowish discoloration of the skin, whites of the eyes, and mucous membranes (jaundice); hearing impairment; abnormalities of the eyes; and/or other symptoms and findings. ```

Question 29

Typical Progression of Viral Replication

Answer 29

barriers to infection Innate immune response Adaptive immune response

Question 30

barriers to infection

Answer 30

entry to the body Initial replication at or near site of infection if virus spreads, this causes primary viremia (4-6 days) (lymph nodes)

Question 31

Innate immune response

Answer 31

1. Replication in target tissue( liver, spleen), inducing signs of disease and secondary viremia(day 14) 2. Spread to other tissues and production of virus that can escape the host

Question 32

Adaptive immune response

Answer 32

Resolution, or establishment of persistent infection/chronic disease

Question 33

virulence

Answer 33

The relative degree to which an organism causes disease

Question 34

genes influencing these and and become target for drugs

Answer 34

- virus replication efficiency:how fast, how many new virions are generated - virus effects on cells: death or interference in normal functions - immune responses - viral spread: how efficiently does the virus infect cells and new hosts

Question 35

Viruses cause disease by

Answer 35

-Cytopathic effects on infected tissues • Inducing Immune responses that cause symptoms. • Indirect effects that may be less understood (HIV causes generalized immune activation) Often, symptoms caused by viral infections are not an “intentional” or direct consequence of infection but rather are often a secondary outcome of the immune response. However, some disease symptoms can assist virus spread, such as excessive mucous generation, external sores, sneezing, coughing, some behavioral changes.

Question 36

Pathogenesis influenced by the infected individual:

Answer 36

* Age * Nutrition * Immune health * Prior immunity * Other underlying pathologies * Genetics - e.g. MHC alleles

Question 37

Viral Cytopathogenesis: | Toxic viral components

Answer 37

adenovirus fibers, some HIV proteins. Production of large amounts of viral proteins can disrupt functions of organelles even if the proteins are not “intentionally” toxic.

Question 38

Viral Cytopathogenesis: | Inhibition of cellular macromolecular synthesis

Answer 38

- many viruses do this. Herpes simplex viruses inhibit cellular DNA and mRNA synthesis, degrade cell RNA. Poliovirus inhibits cellular protein synthesis.

Question 39

Viral Cytopathogenesis: | Syncytia

Answer 39

- Herpes simplex, varicella zoster virus. HIV? This is the fusion of cells caused by the virus spikes being expressed on the surface of infected cells coming into contact with the virus receptors on uninfected cells and causing fusion between the cells (instead of fusion between virus and cell).

Question 40

Viral Cytopathogenesis: | Bystander killing

Answer 40

HIV envelope glycoprotein binds to CD4 on uninfected cells and induces them to undergo apoptosis.

Question 41

Viral Cytopathogenesis: | Triggering cell suicide

Answer 41

- cell’s have sensors to detect invading nucleic acid of viral genomes - dsRNA, cytoplasmic DNA, and then kill themselves via apoptosis or other programmed cell death mechanism.