Virology

Question 1

Viral genetics

Recombination

Answer 1

exchange of genes between 2 chromosomes - significant base homology

Question 2

Viral genetics

Reassortment

Answer 2

viruses with segmented genomes exchange genetic material

e.g. H1N1 influenza reassortment of human, swine, avian

Question 3

Viral genetics

Complementation

Answer 3

nonmutated virus “complements” the mutated one by making a functional protein that serves both viruses
e.g. hepatitis D with HBsAg

Question 4

Viral genetics

Phenotypic mixing

Answer 4

simultaneous infection of cell with 2 viruses

Question 5

Live attenuated vaccines (7)

Answer 5

humoral AND cell-mediated immunity

1. smallpox
2. yellow fever
3. rotavirus
4. chickenpox (VZV)
5. Sabin polio virus
6. MMR
7. Influenza (intranasal)

Question 6

Killed vaccine (4)

Answer 6

1. Rabies
2. Influenza (injected)
3. Salk Polio
4. HAV

Question 7

Subunit vaccine (2)

Answer 7

HBV

HPV

Question 8

Herpes virus (8)

Answer 8

dsDNA + linear

HSV-1 - oral lesions, temporal lobe encephalitis, keratoconjunctivitis

HSV-2 - genital lesions (latent in sacral ganglia)

VZV (HHV-3) - chickenpox, zoster (shingles) (latent in DRG or trigeminal ganglia)

EBV (HHV-4) - mono (LAD of posterior cervical nodes, HSM, +Monospot test), Burkitt lymphoma, Hodgkin lymphoma, nasopharyngeal carcinoma (CD20)

CMV (HHV-5) - IS: AIDS retinitis - “owl eye inclusions”/ mono-like in healthy

HHV-6 - ROSEOLA (exanthem subitum) = high fevers that can cause seizures, followed by diffuse macular rash
HHV-7 - less common cause of roseola

HHV-8 - Kaposi sarcoma (skin, GI, lungs)

Dx:
viral culture
CSF PCR for encephalitis
Tzanck test - of vesicle

Question 9

Hepadnavirus (HBV)

Answer 9

dsDNA + circular

hepatitis

Question 10

Adenovirus

Answer 10

dsDNA + linear

febrile pharyngitis - sore throat
acute hemorrhagic cystitis
pneumonia
conjunctivitis - “pink eye”

Question 11

Parvovirus B19

Answer 11

ssDNA + linear

aplastic crises in sickle cell
“slapped cheeks” rash in children (5th disease, erythema infectiosum)
fetus - hydrops fetalis and death

Question 12

Papillomavirus (HPV)

Answer 12

dsDNA + circular

1, 2, 6, 11 - warts
16, 18 - cervical cancer

Question 13

Polyomavirus

Answer 13

dsDNA + circular

JC virus - PML in HIV
BK virus - transplant pts: kidney

Question 14

Poxvirus

Answer 14

dsDNA + linear

cowpox “milkmaid blisters”
molluscum contagiosum - flesh colored papule with central umbilication

eradication with live attenuated vaccine

Question 15

Picornavirus

“PERCH”

Answer 15

ssRNA + linear

1. poliovirus - polio Salk/Savin vaccines (IPV/OPV)
2. Echovirus - aseptic meningitis
3. Rhinovirus - “common cold” (acid labile destroyed by stomach)
4. Coxsackievirus - aseptic meningitis, HAND, FOOT, MOUTH DISEASE
5. HAV - acute hepatitis

Question 16

Yellow fever virus

Answer 16

Flavivirus
Trans: Aedes mosquitoes

high fever
black vomitus
jaundice
Counsilman bodies on liver bx

Question 17

Rotavirus

Answer 17

segmented dsRNA virus

MC cause of infantile gastroenteritis
vaccinate your kids!

Question 18

Influenza viruses

Answer 18

orthomyxoviruses
- ssRNA with 8 segment genome

hemagglutinin - viral entry
neuraminidase - progeny virion release

risk for bacterial superinfection (S. aureus, S. pneumoniae, H. influenzae)

Killed viral and live attenuated vaccines

Question 19

Genetic SHIFT

antigenic shift

Answer 19

Pandemics

e.g. H1N1

Question 20

Genetic DRIFT

antigenic drift

Answer 20

Epidemics

minor changes based on random mutation

Question 21

Rubella virus

Answer 21

togavirus
e.g. German measles

fever
poastauricular and other LAD
arthralgias
fine rash: STARTS ON FACE AND DOWNWARD

congenital = BLUEBERRY MUFFIN appearance (extramedullary hematopoiesis)

Question 22

Paramyxoviruses (3)

Answer 22

ssRNA - linear
nonsegmented
helical

F (fusion) protein

1. Parainfluenza - croup
   seal like barking cough, inspiratory stridor
   CXR: steeple sign
2. RSV - bronchiolitis in babies

3. Measles - RUBEOLA
A. Prodromal fever with:
*Cough
*Coryza (nose inflammation)
*Conjunctivitis
B. KOPLIK SPOTS
C. maculopapular rash STARTS ON HEAD AND DOWNWARD
D. lymphadenitis...SSPE...encephalitis...pneumonia
Tx: VITAMIN A supplementation

4. Mumps
5. parotitis
6. orchitis (testes)
7. aseptic meningitis
   “Mumps makes your parotid glands and testes as big as POM-poms”

Question 23

Rabies virus

Answer 23

bullet shaped virus
Negri bodies - purkinge cells of cerebellum and hipp neurons

fever, malaise
agitation, photophobia, hydrophobia, hypersalivation
paralysis, coma
death

Tx: would cleaning + killed vaccine + rabies Ig

Question 24

Ebola virus

Answer 24

filovirus
targets endothelial cells, phagocytes and hepatocytes

abrupt flu-like symptoms, F/D/V, myalgia
DIC, diffuse hemorrhage, shock

direct contact with bodily fluids or fomites

Question 25

HIV 3 structural genes

Answer 25

diploid genome (2 RNA) 1. env - formed from cleavage of gp160 - gp120: attachment to host CD4 T cell - gp41: fusion and entry 2. gag - p24: capsid protein 3. pol reverse transcriptase: RNA to dsDNA aspartate protease integrase

Question 26

HIV binds CD4 and...

Answer 26

1. CCR5 on macrophages (early infxn) 2. CXCR4 on T cells (late infxn) homozygous CCR5 mutation = immunity heterozygous CCR5 mutation = slower course

Question 27

HIV tests and diagnosis

Answer 27

1. Rule out? ELISA 2. Confirm? Western blot assay 3. Prognosis? Viral load moderate IC < 400 AIDS < 200 CD4 HIV positive with AIDS-defining condition (PCP)

Question 28

Prion (3)

Answer 28

conversion of normal alpha helical prion protein to beta pleated form resists protease degradation resists autoclaving 1. spongiform encephalopathy 2. dementia 3. ataxia 4. death 1. Creutzfeldt-Jakob disease (CJD) - rapidly progressive dementia 2. Bovine spongiform encephalopathy (BSE) - mad cow disease 3. Kuru - human cannibalism