Positive Sense (+)RNA Viruses

Question 1

What viruses are in the Picornaviridae family and classification?

Answer 1

(+) ssRNA Virus, naked

• Hep A
• Enteroviruses (Polio, Coxsackie, Echo)
• Rhino

Question 2

Where would you most commonly get Hep A from in developed countries?

Answer 2

Uncooked Shellfish – contaminates water

• Patients traveling to endemic areas
• Virus is Acid-Stable

Question 3

What are the clinical signs of Hep A infection?

Answer 3

Jaundice (no jaundice in children)
Tobacco Aversion
1 month duration

Question 4

Where does Polio virus replicate in the GI tract? (Enterovirus)

Answer 4

Peyer’s Patches (2-3 weeks before symptoms)

Question 5

What are complications of Polio infection?

Answer 5

– Attacks the anterior horn in the spinal column, can lead to Resp insufficiency (due to no motor) and aseptic meningitis

Question 6

What are the pros and cons of polio viruses?

Answer 6

Live Virus (Sabin) -- IgA + IgG, but can cause the disease in compromised people and infants. 
Killed Virus (Salk) -- IgG only, not as effective and long lasting.

Question 7

What are the major clinical syndromes of Coxsackie A virus?

Answer 7

Hand, Foot, Mouth Disease – red vessicular lesions everywhere including palsm and feet. Summer time.

Question 8

If a patient is diagnosed with dilated cardiomyopathy, what might have been an infectious agent to cause it?

Answer 8

Coxsackie B Virus

–Can also cause Pleurodynia (Devil’s Grip) very intense sharp pain in the lower chest making it difficult to breath

Question 9

What is the source of the common cold?

Answer 9

Rhinovirus – (+)RNA, naked

– from fomites, attaches to ICAM-1 on resp epithelium, grows best at lower temps, thus Upper Resp infections

Question 10

What are characteristics of Togavirus family?

Answer 10

(+) ssRNA, enveloped – polypeptide precursor, rep in cytoplasm

• • Arbovirus
• • Rubella

Question 11

What can cause encephalitis from a arthropod vector?

Answer 11

Arbovirus - from mosquitos

• Eastern/Western US
• Venezualan

Question 12

What is the classic triade of congenital Rubella?

Answer 12

• Congenital Cataracts
• Deafness
• Patient Ductus Arteriosus
  + Blue berry rash, microcephaly

Question 13

What are the features of childhood rubella?

Answer 13

• postauricular and occipital LAD (Key)
• Macular Rash, starts on face and moves outward
• Resp infection

Question 14

What are the buzz words associated with adult rubella?

Answer 14

Immigrant from another country with LAD, fever, and arthalgias/arthritis

Question 15

How to prevent Rubella (TORCH infection)?

Answer 15

Live Attenuated Vaccine before becoming pregnant, developed countries everyone is usually covered, thus the reason to be suspicious of immigrants

Question 16

What kind of virus are you likely to find on cruiseships, buffets, and daycares – causing explosive diarrhea?

Answer 16

Norwalk / Calicivirus – (+)RNA, naked, produces long polypeptide in cytoplasm that needs to be cleaved.
– Norovirus = most common type

Question 17

What do Dengue Fever, Yellow Fever, Hep C, and West Nile Virus all have in common?

Answer 17

(+) ssRNA, enveloped

– All apart of the Flavivirus Group

Question 18

What causative agent is spread by Aedes Egypti mosquito and causes severe bone pain, thrombocytopenia, and hemorrhagic fever? (Usually around the equator)

Answer 18

Dengue Fever — affects bone marrow

• can lead to renal failure and shock
• usually only happens on the 2nd time being infected by a different strain than the first time.

Question 19

What vector borne illness causes blood diarrhea, hematemesis with jaundice, typically from African region?

Answer 19

Yellow Fever – aedes mosquito, vaccine useful if travel to those regions
– Councilmen Bodies on Liver biopsy

Question 20

How is Hep C classified as a virus?

Answer 20

(+)RNA, enveloped virus – antigenic variable envelope

Question 21

What are the most common means of transmission of Hep C?

Answer 21

• blood exposure
• sharing needles
• sexual
• blood transfusion (pre-1990)
• placenta

Question 22

Why does Hep C have a variable antigenic enveloped capsule?

Answer 22

RNA Polymerase, has no exonuclease 3->5 activity (unable to correct errors) leading to more errors and constantly changing antigens.

Question 23

What are the clinical syndrome of Hep C infection?

Answer 23

Most will go become chronically infected

• jaundice/hepatitis
• fibrosis of the liver
• hepatocellular carcinoma

Question 24

What is a unique attribute of diagnosing Hep C, what test can you perform?

Answer 24

Hep C cryoglobulins (antibodies) if lowered to a cool temperature percipitate (IgM)

Question 25

What causative agent causes SARS/MERS and what can that lead to/

Answer 25

Coronavirus – (+)ssRNA, enveloped, helical virus

• • acute bronchitis that can lead to respiratory distress syndrome
• • highly infectious via resp drop

Question 26

How is HIV different from other RNA viruses?

Answer 26

HIV – (+)RNA virus with envelope. HIV uses it’s reverse transcriptase to convert the RNA into DNA, then infiltrate into the nucleus of the cell (CD4+ cells)

Question 27

What are the three important genes in HIV?

Answer 27

• gap –> p24 capsid protein
• env gene –> gp41 + gp120 transmembrane proteins
• pol gene –> reverse transcriptase

Question 28

What are the initial prodome of HIV, what can it be confused with?

Answer 28

flu-like syndrome, LAD, pharyngitis, fever for several weeks.
– commonly confused with infectious mononucleosis

Question 29

What are the receptors on CD4 cells that the virus binds to and are important for treatment?

Answer 29

CCR5 – early stages

CXCR4 – late stages

Question 30

What are the cancer risks associated with HIV especially?

Answer 30

Diffuse Large Cell Lymphoma

Question 31

What are the best therapy for HIV?

Answer 31

HARRT Therapy
– Nucleotide Reverse Transcriptase Inhibitor
– Non-nucleotide reverse trans inhibitor
– Protease Inhibitor
Maraviroc – CCR5 receptor blocker

Question 32

How do you test for HIV?

Answer 32

ELISA – antibody testing, then confirm with Western Blot