Virology Letur 7

Front 1

what is a localized infection?

Back 1

virus replication and spread is restricted to body surface through which it entered the host

Front 2

what systems are acute localized infections often found in?

Back 2

respiratory tract and alimentary tract

Front 3

what are examples of viruses that cause acute, localized infection of the intestinal tract?

Back 3

rotavirus, coronavirus

Front 4

what are examples of viruses that cause acute, localized infection of the respiratory tract?

Back 4

influenza virus, rhinovirus

Front 5

what is enteritis?

Back 5

an acute localized viral infection of the intestinal tract infection

Front 6

what are some examples of enteric virus infections?

Back 6

rotavirus, coronavirus, calicivirus, astrovirus, adenovirus, parvovirus

Front 7

what occurs in a normal intestine epithelia?

Back 7

normal absorption >>>> Normal Secretion = NET ABSORPTION

Front 8

where do most enteric viruses replicate?

Back 8

mature villous epithelium

Front 9

where does parvovirus replicate?

Back 9

in crypt cells

Front 10

what type of infection is parvovirus?

Back 10

a systemic infection with clinical signs principally due to intestinal damage

Front 11

the loss of mature villous epithelium results in?

Back 11

loss of absorptive cells (causing malabsorption), loss of brush border disaccharidases/peptidases (causing maldigestion), undigested and unabsorbed food particles in lumen of gut osmotically traps water in lumen, crypt epithlium proliferates and migrates out of crypt at an accelerated rate in attempting to replace absorptive/digestive cells that are destroyed (these are undifferentiated secretory cells that contribute to diarrhea by hypersecretion)

Front 12

the loss of crypt cells results in?

Back 12

damaged crypts fail to replace mature villous epithelial cells as they are shed, loss of absorptive cells, loss of cells having brush border disaccharidases, osmotic effects, slugging regeneration (loss of progenitor cells that, in fatal cases, does not ever regenerate, a condition known as mucosal collapse)

Front 13

what types of influenza are there?

Back 13

human, equine, swine, avian

Front 14

how does influenza infect?

Back 14

virus in aerosolized droplets makes contact with epithelium, virus must make attachment to prevent elimination by MCE

Front 15

how does influenza virus spread?

Back 15

via cell-to-cell + cilia movement + air movement >>> spread to all levels of respiratory tract

Front 16

what does influenza result in?

Back 16

destruction of respiratory epithelium & MCE: dead cells and inflammatory fluids spill into respiratory lumen

Front 17

what does MCE stand for?

Back 17

mucociliary escalator

Front 18

influenza causes severe disease when?

Back 18

virus-induced damage of alveoli, obstruction of airways, over-exuberant inflammatory response (cytokine storm) and secondary bacterial infection (bronchopneumonia)

Front 19

how does a secondary bacterial infection occur with influenza?

Back 19

virus induced destruction of MCE, exposure of colonization sites, cell debris and inflammatory products provied substrate for bacterial growth (protein, iron)

Front 20

what is shipping fever in cattle?

Back 20

virus-induced damage of respiratory epithelium (by herpesvirus, paramyxovirus, adenovirus) which leads to secondary bacterial infection (pasteurella multocida, mannheimia hemolyticum) leading to bronchopneumonia

Front 21

what is infectious canine tracheobronchitis known as?

Back 21

kennel cough

Front 22

what occurs in infectious canine tracheobronchitis infections?

Back 22

virus-induced damage of respiratory epithelium (canine distember, canine adenovirus, canine herpesvirus, paramyxovirus) and a secondary infection (mycoplasma spp, bordetella bronchisepticum) resulting in a persistent coubh and bronchopneumonia

Front 23

what is infectious laryngotracheitis?

Back 23

a herpesvirus infection of chickens

Front 24

what occurs in infectious latrygotracheitis infections?

Back 24

epithelial damage leads to obstruction

Front 25

what is a systemic infection?

Back 25

when virus replication and cell damage occur at sites distant to the site of virus entry

Front 26

what are examples of viruses that cause systemic infection?

Back 26

smallpox, polioencephalomyelitis, west nile infection, yellow fever, canine parvovirus

Front 27

how do viral infections become systemic?

Back 27

as a result of lymphatic/blood spread

Front 28

what are the sequential steps of systemic infections resulting from lymphatic/blood spread?

Back 28

entry & replication at site of entry, drainage to regional LNs, replication in regional LN, primary viremia (low titer) with spread to other organs, secondary viremia (high titer) with spread to other organs, clinical signs

Front 29

what infection is studied as a model of smallpox?

Back 29

mouse pox

Front 30

what are mouse pox infections?

Back 30

systemic viral spread via viremia

Front 31

how do mouse pox infections occur?

Back 31

replication in foot pad, drainage to regional LN, primary viremia (spread to spleen, liver for replication), secondary viremia (spread to spleen, liver, skin for replication), onset of clinical signs

Front 32

what are smallpox infections?

Back 32

systemic viral with viremic spread

Front 33

how do smallpox infections occur?

Back 33

entry/replication in respiratory tract, drainage to regional LN, replication in LN, primary viremia (replication in liver and spleen), secondary viremia (replication in liver, spleen, skin), onset of clinical signs

Front 34

what are canine parvovirus infections?

Back 34

unknown if systemic, experimental reproduction via oral exposure but not gastric lavage

Front 35

how do canine parvovirus infections occur?

Back 35

entry/replication in pharynx, drainage to regional LN, replication in LN, primary viremia (replication in bone, marrow, thymus, spleen), secondary viremia (replication in intestinal crypt, epithelium), onset of clinical signs

Front 36

what happens with vaccines for enteric coronavirus and rotavirus?

Back 36

usually ineffective

Front 37

what happens with vaccines for anine parvovirus 2 infections?

Back 37

highly effective

Front 38

what occurs with viruses that become systemic as a result of spread in nerves?

Back 38

entry/replication at site of entry (muscle cells), cell-to-cell spread in muscle then attachment/penetration of nerve endings, retrograde (centrepetal) spread in axoplasm of nerves to CNS, replication in CNS, onset of clinical signs

Front 39

what is an inapparent infection?

Back 39

an infection without clinical signs

Front 40

how do inapparent infections occur?

Back 40

result of infection by attenuated or avirulent strains of viruses, or a highly effective immune response to the infecting virus

Front 41

why are inapparent infections important?

Back 41

epidemiologicly, they represent unrecognized sources for virus dissemination