Infectious Disease -- Viral Illness I

Question 1

Example of a species specific virus

Answer 1

HIV

Question 2

Example of a non-specific virus

Answer 2

Rabies

Question 3

Are most viruses species specific or non-specific

Answer 3

Specific

Question 4

How are cells killed in viral illness?

Answer 4

Virus replication at host cell expense

Immune response to infected cell

Question 5

Steps in virus infection and replication

Answer 5

Attachment to Host Cell
Host Cell Penetration
Viral Uncoating
Replication
Re-assembly of virons

Question 6

Examples of Viral Trophism – HIV, EBV, Rabies, Rhino

Answer 6

HIV – CD4
EBV – Complement CD21 receptor
Rabies – Acetylcholine Receptor
Rhinoviruses – ICAM-1

Question 7

Some viruses require special enzymes/promoter elements in host cells. Give an example

Answer 7

JC virus can only infect oligodendrocytes because they have the enzymes that JC needs

Question 8

Ways that Viruses cause host cell death

Answer 8

• Inhibition of host RNA, DNA, or protein synthesis
• Viral proteins damage membrane integrity/promote fusion
• Replication and lyse host cells
• Anti-viral host responses with recognition of viral antigens on infected host cell
• Secondary Infection - suppressed host immune resp.

Question 9

Are viral infections pyogenic?

Answer 9

No

Question 10

Hallmarks of viral spread

Answer 10

Infection of mucosal cells or parenchymal cells at entry
Dissemination via viremia (in most cases)
Lymphocytic inflammation +/- necrosis
Morphologic alterations of infected cells

Question 11

Common viral morphological alterations of infected cells

Answer 11

Vacuolization, Inclusion Bodies, Multinucleated Cells

Question 12

Whats the point of antibody response to a virus?

Answer 12

Neutralizing - prevent viremia, prevent re-infection
Opsonization
Complement-mediated cell / viral uncoating

Question 13

Effects of antibody presence on primary infection?

Answer 13

Pretty much none

Question 14

Antiviral neutralizations

Answer 14

Prevent attachment/Cell Entry

Interfere with Viral Uncoating

Question 15

Negative role of antibodies in some disease states (ex. Hep B, C, HIV)

Answer 15

Immune Complex Reactions

Arthralgias, Glomerulonephritis

Question 16

NK cells are especially effective killers of cells with…

Answer 16

Low MHC1 expression

Question 17

Three major antiviral cytokines

Answer 17

gamma-interferons
interferon alpha
interferon beta

Question 18

Effect of gamma interferons

Answer 18

Inhibition of RNA translation which effects viral translation more than host fxn

Question 19

Effect of interferons alpha and beta

Answer 19

Activation of antiviral responses

Question 20

Pattern for local viral illness

Rhinitis, Influenza, Gastroenteritis

Answer 20

Short Incubation Time

Lesion at entry site (local cytopathic injury, inflammation)

Question 21

Pattern for distant illnesses

Answer 21

Longer incubation times (weeks) – Viremia+nerve passage

Lesions tend to involve immune mediated damage

Question 22

What does the viral incubation period reflect?

Answer 22

Distribution of the Virus

Development of host immune response

Question 23

Four ways that a virus might get distributed through the body

Answer 23

Proliferation at entry site
Viremia dissemination though the blod 
Lymphoid Dissemination (HIV, EBV)
Nerve transmission (herpes, rabies)

Question 24

Characteristic cytopathic features of viral illness

Answer 24

Inclusion Bodies
Lysis (Skin vesicles)
Cytoplasmic Features
Cell Alterations

Question 25

Two viral specific examples of cytoplasmic features given

Answer 25

Hep -- Ground Glass Cytoplasm | HPV -- Koilocytosis

Question 26

Two viral specific examples of cell alterations given

Answer 26

Warthin-Finkeldey -- Measles giant cells | Hep -- Councilman Bodies

Question 27

Characteristic Inclusion body seen in CMV

Answer 27

Distinct intranuclear and ill-defined cytoplasmic inclusions

Question 28

Characteristic Inclusion body seen in Herpes, varicella

Answer 28

Cowdry Type A intranuclear Inclusion bodies

Question 29

Characteristic Inclusion body seen in Rabies

Answer 29

Negri bodies, Cytoplasmic Inclusion Bodies

Question 30

Characteristic Inclusion body seen in HPV

Answer 30

Koilocytes

Question 31

Characteristic Inclusion body seen in Hepatitis

Answer 31

Councilman Bodies

Question 32

Characteristic Inclusion body seen in Measles

Answer 32

Warthin-Finkeldey giant cells with intracytoplasmic and intranuclear inclusion bodies

Question 33

Characteristic Inclusion body seen in adenovirus

Answer 33

Smudge cells | Cowdry type A intranuclear inclusion bodies.

Question 34

Cellular infiltrates seen in tissues responses in viral infection

Answer 34

Mononuclear infiltrates Often Perivascular Remains Interstitial Secondary Bacterial Infection

Question 35

Immune responses in tissue reactions/cell injury

Answer 35

Rashes, Vesicles Hepatitis -- Hepatocellular Necrosis Cytokines -- local inflamm, increased secretions Decreased Fxn -- Loss of Intestinal Absorp. (diarrhea)