Micro - Virology (Specifics of RNA Viruses)

Question 1

What viruses are included in the Picornavirus group?

Answer 1

(1) Poliovirus (2) Echovirus (3) Rhinovirus (4) Coxsackievirus (5) HAV; Think: “PERCH on a “peak” (pico)”

Question 2

How are functional viral proteins made by Picornaviruses?

Answer 2

RNA is translated into 1 large polypeptide that is cleaved by proteases into functional viral proteins

Question 3

What is the main condition than can be caused by Picornavirus? What 2 Picornaviruses do NOT cause this?

Answer 3

Can cause aseptic (viral) meningitis; Except Rhinovirus and HAV

Question 4

What is the major way by which Picornaviruses are spread, and what kind of viruses can they be called on that basis? Which Picornavirus is the exception to this spread/name?

Answer 4

All are enteroviruses (fecal-oral spread), except Rhinovirus

Question 5

What is Picornavirus’ size like, and what kind of genome does it have?

Answer 5

Small; RNA: Think: “picoRNAvirus = small RNA virus”

Question 6

To what group of viruses does Rhinovirus belong? Does it have an envelope? What is its genome?

Answer 6

A Picornavirus. Nonenveloped RNA virus.

Question 7

What condition/disease does Rhinovirus cause?

Answer 7

Cause of common cold; Think: “Rhino has(/causes) a runny nose”

Question 8

Approximately how many serologic types are there of Rhinovirus?

Answer 8

> 100 serologic types

Question 9

What is an important limitation of Rhinovirus? What implication/consequence does this have?

Answer 9

Acid labile - destroyed by stomach acid; therefore, does not infect GI tract (unlike other picornaviruses)

Question 10

To what group of viruses does Yellow fever virus belong?

Answer 10

A flavivirus (also an arbovirus)

Question 11

How is Yellow fever virus transmitted? What is its reservoir?

Answer 11

Transmitted by Aedes mosquitoes (i.e., it is an arbovirus); Virus has a monkey or human reservoir.

Question 12

What are the symptoms associated with Yellow fever virus?

Answer 12

High fever, black vomitus, and jaundice; Think: “Flavi = yellow, jaundice… also, Yellow fever virus gives two of the symptoms”

Question 13

What is most significant to remember about Rotavirus?

Answer 13

The most important global cause of infantile gastroenteritis

Question 14

To what virus group does Rotavirus belong? What are ways to describe its genome?

Answer 14

Reovirus; Segmented dsRNA virus

Question 15

Of what is Rotavirus a major cause, and especially in what settings?

Answer 15

Major cause of acute diarrhea in the US during winter, especially in day-care center, kindergartens

Question 16

What is the mechanism/effect of Rotavirus infection?

Answer 16

Villous destruction with atrophy leads to decreased absorption of Na+ and loss of K+

Question 17

What is the CDC recommendation with regard to Rotavirus?

Answer 17

CDC recommends routine vaccination of all infants

Question 18

Again, what condition does Rotavirus cause?

Answer 18

Acute diarrhea; Think: “ROTAvirus = Right Out The Anus”

Question 19

To what virus group do Influenza viruses belong?

Answer 19

Orthomyxoviruses

Question 20

Describe the genome of Influenza viruses. More specifically… Are they enveloped? Are they single or double stranded RNA or DNA? Is their genome segmented?

Answer 20

Enveloped, negative single-stranded RNA viruses with 8-segment genome

Question 21

What kinds of antigens do Influenza viruses contain, and what are the roles played by those antigens?

Answer 21

(1) Hemagglutinin - promotes viral entry (2) Neuraminidase - promotes progeny viron release

Question 22

For what do Influenza infections put patients at risk?

Answer 22

Patients at risk for fatal bacterial superinfection

Question 23

What kind of changes are associated with Influenza viruses?

Answer 23

Rapid genetic changes

Question 24

What is important to know about the most frequently used mode of Influenza protection/vaccination? More specifically, what kind is it and when/how is it made?

Answer 24

Killed viral vaccine is most frequently used; Reformulated vaccine (“the flu shot”) containing the viral strains most likely to appear during the flu season

Question 25

What kind of mutant is contained in the alternative Influenza vaccine? Where in the body does it replicate? How is it administered?

Answer 25

Live, attenuated vaccine (temperature-sensitive mutant), that replicates in the nose but not in the lung, administered intranasally

Question 26

What do genetic shift/antigenic shifts versus Genetic drift cause?

Answer 26

(1) Genetic shift/Antigenic shifts - Cause pandemics (2) Genetic drift - Cause epidemics

Question 27

What is the mechanism behind Genetic shift/Antigenic shifts? What is an example of this?

Answer 27

Reassortment of viral genome; segments undergo high frequency recombination, such as when human flu A virus recombines with swine flu A virus

Question 28

What is the mechanism behind Genetic drift?

Answer 28

Minor (antigenic drift) changes based on random mutation

Question 29

What is the difference between Genetic shift and Genetic drift?

Answer 29

(1) Genetic shift = Causes pandemics. Reassortment of viral genome; Segments undergo high-frequency recombination (2) Genetic drift = Causes epidemic. Minor (antigenic drift) changes based on random mutation; Think: "Sudden Shift is more deadly than graDual Drift"

Question 30

To what group of viruses does Rubella virus belong?

Answer 30

A togavirus

Question 31

What condition/disease does Rubella virus cause? What is an old name for this condition/disease?

Answer 31

Causes Rubella, once known as German (3-day) measles

Question 32

What symptoms are associated with Rubella?

Answer 32

Fever, postauricular adenopathy, lymphadenopathy, arthralgias, fine truncal rash that starts at head and moves down

Question 33

What is the range of severity for Rubella, and in what contexts?

Answer 33

Causes mild disease in children but serious congenital disease (a ToRCHeS infection)

Question 34

In what patient population do Paramyxoviruses cause disease?

Answer 34

Paramyxoviruses cause disease in children

Question 35

What conditions/disease do viruses in the Paramyxoviruses group cause?

Answer 35

(1) Parainfluenza (croup: seal-like barking cough) (2) Mumps (3) Measles (4) RSV, which causes respiratory tract infection (bronchiolitis, pneumonia) in infants

Question 36

What kind of virus is RSV? What condition/disease does it cause, and in what patient population(s)?

Answer 36

Paramyxoviruses; Causes respiratory tract infection (bronchiolitis, pneumonia) in infants

Question 37

What protein do all Paramyxoviruses contain, and what role does this protein play?

Answer 37

All contain surface F (fusion) protein, which causes respiratory epithelial cells to fuse and form multinucleated cells

Question 38

What is Palivizumab, and what role does it play?

Answer 38

Monoclonal antibody against F protein, prevents pneumonia caused by RSV infection in premature infants

Question 39

What is the name of the monoclonal antibody against F protein, and what role does it play?

Answer 39

Palivizumab; Prevents pneumonia caused by RSV infection in premature infants

Question 40

What kind of virus causes Measles?

Answer 40

Measles virus = a Paramyxovirus that causes measles

Question 41

What are the characteristic clinical findings of Measles?

Answer 41

(1) Koplik spots (red spots with blue-white center on buccal mucosa) and (2) Descending maculopapular rash are characteristic

Question 42

Again, what are the 2 characteristic clinical findings of Measles? What are 3 other possible sequelae of Measles and the associated contexts in which they occur?

Answer 42

(1) Koplik spots (red spots with blue-white center on buccal mucosa) and (2) Descending maculopapular rash are characteristic; (1) SSPE (subacute sclerosing panencephalitis, occurring years later) (2) Encephalitis (1:2000) (3) Giant cell pneumonia (rarely, in immunosuppressed)

Question 43

What Measles finding presents last, and how is it characterized?

Answer 43

Rash presents last and spreads from head to toe, includes hands and feet (vs. truncal rash in rubella)

Question 44

How does the rash seen in Measles differ from the rash seen in Rubella?

Answer 44

Includes hands and feet (vs. truncal rash in rubella)

Question 45

What condition should you be careful not to confuse with Measles? What virus causes this condition?

Answer 45

Do not confuse with Roseola (caused by HHV-6)

Question 46

What are the "3 C's of measles"?

Answer 46

(1) Cough (2) Coryza (3) Conjuctivitis; Think: "Koplik spots as 4th 'C'"

Question 47

What kind of virus is the Mumps virus?

Answer 47

A paramyxovirus

Question 48

What are the 4 major symptoms/signs/conditions associated with Mumps virus?

Answer 48

(1) Parotitis (swollen neck and parotid glands) (2) Orchitis (inflammation of testes) (3) aseptic Meningitis. (4) Can cause sterility (especially after puberty); Think: "Mumps makes your parotid glands and testes as big as POM-poms"

Question 49

What kind of morphology does Rabies virus have?

Answer 49

Bullet-shaped virus

Question 50

What histological finding is characteristic of Rabies virus infection? Where is this commonly found?

Answer 50

Negri bodies are characteristic cytoplasmic inclusions in neurons infected by rabies virus; Commonly found in Purkinje cells of cerebellum

Question 51

What is important to know about the time course of Rabies virus infection?

Answer 51

Rabies has long incubation period (weeks to months) before symptom onset

Question 52

What is the postexposure treatment for Rabies?

Answer 52

Postexposure treatment is wound cleansing and vaccination with or without rabies immune globulin

Question 53

Where does the Rabies virus travel to in the body, and how?

Answer 53

Travels to the CNS by migrating in a retrograde fashion up nerve axons

Question 54

What is the progression of disease following Rabies infection?

Answer 54

Progression of disease: fever, malaise --> agitation, photophobia, hydrophobia --> paralysis, coma --> death

Question 55

What are the sources of Rabies in the US? Which are more common?

Answer 55

More commonly from bat, raccoon, and skunk bites than from dog bites in the US