Vol II Ch. 1: Infection of a susceptible host

Question 1

What was the name of the bad air originally thought to cause disease?

Answer 1

miasma

Question 2

What is Koch’s postulate?

Answer 2

1. The organism must be regularily associated with the disease
2. The organism must be isolated from the infected host and grown in culture
3. The disease must be reproduced when the pure culture is introduced to a healthy host
4. The organism must be reisolated from this infected host

Question 3

Study Slide 3

Answer 3

about the circle of infection

Question 4

What are the bottlenecks of the infection process?

Answer 4

1. tissue architecture
2. immune system
3. cell machinery

Question 5

What are the three requirements for infection?

Answer 5

1. sufficient virion qty enters host cell
2. Cells at site of entry must express receptors required for entry (susceptible) and contain intracellular components required for virion reproduction (permissive)
3. Local host antiviral systems must be absent or initially ineffective

Question 6

In principle, only one virion is necessary for infection, but in reality many are needed due to …

Answer 6

1. host defenses (physical and immune), the complexity of the infection process,

Question 7

Steps for dissemination and pathogenesis of mouse pox:
Invasion through skin of footpad, multiplication in ___ ____ ___, systemic infection through _____ which is known as _____, spleen and liver multiplication and tissue necrosis, secondary _____, Skin: focal infection and multiplication; followed by symptoms of the disease

Answer 7

localized lymph node; bloodstream; viremia; viremia;

Question 8

What are the routes of entry? Which is the most common

Answer 8

skin (scratches or injuries), rectum, urogenital tract, respiratory tract*, GI tract, conjunctiva, endothelia due to arthropods

Question 9

How does mucus dispose of foreign particles in upper respiratory tract?

Answer 9

They are trapped in mucus, carried to back of throat and swallowed

Question 10

How does mucus dispose of foreign particles in lower resp. tract?

Answer 10

mucus moved by ciliary action to the throat

Question 11

How is debris in alveoli disposed of?

Answer 11

Alveolar macrophages

Question 12

The stomache has ___ pH and the intestine has ___ pH. epithelium are lined with ____. Luminal surfaces have defenses such as _____ and _____.

Answer 12

low; high; mucus; antibodies; phagocytes

Question 13

Apical surfaces of intestinal epithelial cells densely packed with ____

Answer 13

microvilli

Question 14

Membranous epithelial cells ingest and deliver _____ to lymphoid tissue via ______. This is a common route of entry for ____ ____. What virus replicates in M cells?

Answer 14

antigen; transcytosis; enteric virus; rhodavirus

Question 15

virus can enter urogenital tract during ____ _____. What are its defenses? what forms local lesions here? what is the urogenital tract for HIV? Normal sexual activity can create minute tears in vaginal epithelium, which can allow viral entry

Answer 15

sexual activity; low pH, mucus antibodies; human papillomavirus; the site of infection

Question 16

Skin is an effective barrier due to dead _____ cells. Entry through this route is generally due to ____ or _____. Hypodermic needles and arthropods cause which virus infections? What can rashes be an indication of?

Answer 16

keratinized; puncture or abrasion; hepatitis, HIV; bunyavirus or flavivirus; virions leaving blood vessels

Question 17

for epithelial infection and release: release of virus through apical surface generally doesn’t lead to _____. Release of virus through ____ ____ does.

Answer 17

viremia; basal membrane

Question 18

Virions that escape local defenses may enter the bloodstream to produce a ________

Answer 18

hematogenous spread

Question 19

Virus can also be released into interstitial fluid, where it is taken up by the ____ _____ ____. Here they encounter _____ ____ of the immune system. This is how viral pathogenesis resulting from infection of immune cells is initiated. Ex: HIV and measles virus

Answer 19

lymphatic vascular system; migratory cells

Question 20

What are the two types of viremia? What is the difference between them? What is primary viremia? how is viral concentration compared to disseminated infection

Answer 20

Active and passive; active is produced by release of replicated particles into the blood; passive is produced by particles entering the blood without replicating at the site of entry; primary viremia results from release of virus at primary site of infection. Conc. is low compared to viremia due to disseminated infection (secondary viremia)

Question 21

What are the three methods of dissemination from blood to tissue

Answer 21

1. Replication in endothelia 2. transcytosis 3. trafficking lymphocyte or monocyte

Question 22

Many virus can spread by infecting local nerve endings. _____ ____ can be the definitive characteristic of their pathogenesis such as rabies virus. Mumps, HIV, and measles replicate in brain but spread by hematogenous route. Viral replication usually occurs in ___ _____ ____ first

Answer 22

neuronal spread; non-neuronal cells

Question 23

kynesin motors spread virus in ____ direction. Dynein motors spread virus in ___ direction

Answer 23

anterograde; retrograde

Question 24

For ________ virus, the virion must be transported to the ___ ___ for replication to occur via cellular machinery. After replication, virion may be released from ___ ____ ,travel down the axon, or infect ____ cells

Answer 24

neurotropic; cell body; cell body; glial

Question 25

Organ invasion: Liver, spleen, bone marrow contain _____ lined with ______ known as ____ ____. They function to filter the blood and remove foreign particles. They often serve as a ____ ___ _____

Answer 25

sinusoids; macrophages; kupffer cells; portal of entry

Question 26

Transcytosis of virus across kupffer cells or endo thelia or infection and replication in them can lead to infection of hepatocytes, termed

Answer 26

hepatitis