Herpesviridae Viruses & influenza

Question 1

Herpesvirus family

Answer 1

Epstein-Barr Virus (EBV)
Cytomegalovirus (CMV)
varicella Zoster Virus

Question 2

Innate defense to viruses

Answer 2

Viral DNA is detected by toll-like receptors
infected cells stimulate interferons (IFN) & inflammatory cytokines
CD8+ kill virally infected cells

Question 3

Virus Escaping Immune Defenses

Answer 3

1. frequent genetic mutations - poor fidelity polymerase
2. recombine their genome with other related viruses
3. evade interferons & phagocytic cells etc
4. latent virus / provirus

Question 4

Laboratory testing for viral infections

Answer 4

viral antigens
serology
molecular tests

Question 5

Epstein Barr Virus

Answer 5

large, dsDNA, w/ capsid & envelop
capable of establishing a latent infection
Infectious Mononucleosis!
lymphoproliferative disease

Question 6

EBV infection

Answer 6

mainly infects B lymphocytes
infected EBV cells cause release of large amounts of cytokines
~95% of world’s population exposed to virus

Question 7

EBV transmission

Answer 7

most are exposed to virus before 5 years old (asymptomatic)
second wave occurs during late adolescence
via saliva

Question 8

Infectious Mononucleosis

Answer 8

^^ WBC -flipped diff
+ for heterophile antibodies
Mono-spot test - collodial gold immunoassay w/ cow RBC extracts

Question 9

Cytomegalovirus General Characteristics

Answer 9

member of the herpes family
most people are asymptomatic
50-80% of adults are infected
spread via saliva, urine etc

Question 10

CMV risk in babies

Answer 10

pregnant mothers become infected (most common virus transmitted to the fetus)
80% born with congenital CMV are asymptomatic
10% are symptomatic
10% are asympomatic at birth but develop issues later

Question 11

CMV symptoms

Answer 11

most are asymptomatic
will only re-emerge if immune system is shot
characteristic dot rash

Question 12

CMV in transplants

Answer 12

CMV infects most cell types

could cause an infection / death in a transplant patient

Question 13

Preventing CMV transmission via transplants

Answer 13

1. use CMV seronegative blood
2. use leukoreduced RBCs ( has resulted in transmission of CMV through blood products in transplant recipients to around 0.1%)

Question 14

CMV testing

Answer 14

IgM antibodies to CMV - current or recurrent infection
IgG antibodies to CMV- past infection
PCR amplification of CMV DNA

Question 15

Varicella - Zoster Virus General Characteristics

Answer 15

causes 2 diseases:
varicella - Chickenpox
Herpes zoster - Shingles
highly contagious - aerosols

Question 16

Vericella Primary Infection Characteristics

Answer 16

Chickenpox - mild & self-limiting
blistering rash w/ lesions
mostly on head & trunk

Question 17

Varicella Secondary Infection Characteristics

Answer 17

Shingles- illness caused by reactivation
most often in individuals over 50
painful blisters

Question 18

Varicella Zoster Vaccine

Answer 18

2005 vaccine that combines varicella vaccine w/ measles, mumps, & rubella

Question 19

Influenza Viral Structure

Answer 19

surface contains:
Hemagglutinin (H) - binds to surface sialic acid
Neuraminidase (N)- cleaves sialic acid for virus exit from the cell
ssRNA in 8 segments

Question 20

Influenza Grouping

Answer 20

3 groups: based on internal nucleoprotein
Influenza A: most widespread ‘pandemics’
Influenza B: less widespread
Influenza C: mild, not widespread

Question 21

Influenza Subtypes

Answer 21

3 types of hemagglutinin bind to human cells : H1, H2, H3

2 different neuraminidase N1 & N2

Question 22

Influenza A Characteristics

Answer 22

human pandemics
massive antigenic variation
highly contagious - aerosol
antigenic drift & antigenic shift makes people susceptible to re-infection
~90% of deaths occur over age 65

Question 23

Influenza A diagnosis & Testing

Answer 23

rapid influenza tests - colloidal gold immunoassays (nasal swab)
reverse-transcriptase PCR is the gold standard

Question 24

Antigenic Drift

Answer 24

minor DNA changes (point mutations)

missense mutation leads to evasion of antibodies

Question 25

Antigenic shift

Answer 25

reassortment in doubly infected cell in which a viron is packed with a segment of RNA from a different virus creating a new virus
only influenza A can infect animal cells for this to occur