Micro - Virology (Specifics of RNA Viruses) Flashcards
Pg. 159-162 Sections include: Picornavirus Rhinovirus Yellow fever virus Rotavirus Influenza virus Rubella virus Paramyxoviruses Measles virus Mumps virus Rabies virus
What viruses are included in the Picornavirus group?
(1) Poliovirus (2) Echovirus (3) Rhinovirus (4) Coxsackievirus (5) HAV; Think: “PERCH on a “peak” (pico)”
How are functional viral proteins made by Picornaviruses?
RNA is translated into 1 large polypeptide that is cleaved by proteases into functional viral proteins
What is the main condition than can be caused by Picornavirus? What 2 Picornaviruses do NOT cause this?
Can cause aseptic (viral) meningitis; Except Rhinovirus and HAV
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?
All are enteroviruses (fecal-oral spread), except Rhinovirus
What is Picornavirus’ size like, and what kind of genome does it have?
Small; RNA: Think: “picoRNAvirus = small RNA virus”
To what group of viruses does Rhinovirus belong? Does it have an envelope? What is its genome?
A Picornavirus. Nonenveloped RNA virus.
What condition/disease does Rhinovirus cause?
Cause of common cold; Think: “Rhino has(/causes) a runny nose”
Approximately how many serologic types are there of Rhinovirus?
> 100 serologic types
What is an important limitation of Rhinovirus? What implication/consequence does this have?
Acid labile - destroyed by stomach acid; therefore, does not infect GI tract (unlike other picornaviruses)
To what group of viruses does Yellow fever virus belong?
A flavivirus (also an arbovirus)
How is Yellow fever virus transmitted? What is its reservoir?
Transmitted by Aedes mosquitoes (i.e., it is an arbovirus); Virus has a monkey or human reservoir.
What are the symptoms associated with Yellow fever virus?
High fever, black vomitus, and jaundice; Think: “Flavi = yellow, jaundice… also, Yellow fever virus gives two of the symptoms”
What is most significant to remember about Rotavirus?
The most important global cause of infantile gastroenteritis
To what virus group does Rotavirus belong? What are ways to describe its genome?
Reovirus; Segmented dsRNA virus
Of what is Rotavirus a major cause, and especially in what settings?
Major cause of acute diarrhea in the US during winter, especially in day-care center, kindergartens
What is the mechanism/effect of Rotavirus infection?
Villous destruction with atrophy leads to decreased absorption of Na+ and loss of K+
What is the CDC recommendation with regard to Rotavirus?
CDC recommends routine vaccination of all infants
Again, what condition does Rotavirus cause?
Acute diarrhea; Think: “ROTAvirus = Right Out The Anus”
To what virus group do Influenza viruses belong?
Orthomyxoviruses
Describe the genome of Influenza viruses. More specifically… Are they enveloped? Are they single or double stranded RNA or DNA? Is their genome segmented?
Enveloped, negative single-stranded RNA viruses with 8-segment genome
What kinds of antigens do Influenza viruses contain, and what are the roles played by those antigens?
(1) Hemagglutinin - promotes viral entry (2) Neuraminidase - promotes progeny viron release
For what do Influenza infections put patients at risk?
Patients at risk for fatal bacterial superinfection
What kind of changes are associated with Influenza viruses?
Rapid genetic changes
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?
Killed viral vaccine is most frequently used; Reformulated vaccine (“the flu shot”) containing the viral strains most likely to appear during the flu season
What kind of mutant is contained in the alternative Influenza vaccine? Where in the body does it replicate? How is it administered?
Live, attenuated vaccine (temperature-sensitive mutant), that replicates in the nose but not in the lung, administered intranasally
What do genetic shift/antigenic shifts versus Genetic drift cause?
(1) Genetic shift/Antigenic shifts - Cause pandemics (2) Genetic drift - Cause epidemics
What is the mechanism behind Genetic shift/Antigenic shifts? What is an example of this?
Reassortment of viral genome; segments undergo high frequency recombination, such as when human flu A virus recombines with swine flu A virus
What is the mechanism behind Genetic drift?
Minor (antigenic drift) changes based on random mutation
What is the difference between Genetic shift and Genetic drift?
(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”
To what group of viruses does Rubella virus belong?
A togavirus
What condition/disease does Rubella virus cause? What is an old name for this condition/disease?
Causes Rubella, once known as German (3-day) measles
What symptoms are associated with Rubella?
Fever, postauricular adenopathy, lymphadenopathy, arthralgias, fine truncal rash that starts at head and moves down
What is the range of severity for Rubella, and in what contexts?
Causes mild disease in children but serious congenital disease (a ToRCHeS infection)
In what patient population do Paramyxoviruses cause disease?
Paramyxoviruses cause disease in children
What conditions/disease do viruses in the Paramyxoviruses group cause?
(1) Parainfluenza (croup: seal-like barking cough) (2) Mumps (3) Measles (4) RSV, which causes respiratory tract infection (bronchiolitis, pneumonia) in infants
What kind of virus is RSV? What condition/disease does it cause, and in what patient population(s)?
Paramyxoviruses; Causes respiratory tract infection (bronchiolitis, pneumonia) in infants
What protein do all Paramyxoviruses contain, and what role does this protein play?
All contain surface F (fusion) protein, which causes respiratory epithelial cells to fuse and form multinucleated cells
What is Palivizumab, and what role does it play?
Monoclonal antibody against F protein, prevents pneumonia caused by RSV infection in premature infants
What is the name of the monoclonal antibody against F protein, and what role does it play?
Palivizumab; Prevents pneumonia caused by RSV infection in premature infants
What kind of virus causes Measles?
Measles virus = a Paramyxovirus that causes measles
What are the characteristic clinical findings of Measles?
(1) Koplik spots (red spots with blue-white center on buccal mucosa) and (2) Descending maculopapular rash are characteristic
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?
(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)
What Measles finding presents last, and how is it characterized?
Rash presents last and spreads from head to toe, includes hands and feet (vs. truncal rash in rubella)
How does the rash seen in Measles differ from the rash seen in Rubella?
Includes hands and feet (vs. truncal rash in rubella)
What condition should you be careful not to confuse with Measles? What virus causes this condition?
Do not confuse with Roseola (caused by HHV-6)
What are the “3 C’s of measles”?
(1) Cough (2) Coryza (3) Conjuctivitis; Think: “Koplik spots as 4th ‘C’”
What kind of virus is the Mumps virus?
A paramyxovirus
What are the 4 major symptoms/signs/conditions associated with Mumps virus?
(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”
What kind of morphology does Rabies virus have?
Bullet-shaped virus
What histological finding is characteristic of Rabies virus infection? Where is this commonly found?
Negri bodies are characteristic cytoplasmic inclusions in neurons infected by rabies virus; Commonly found in Purkinje cells of cerebellum
What is important to know about the time course of Rabies virus infection?
Rabies has long incubation period (weeks to months) before symptom onset
What is the postexposure treatment for Rabies?
Postexposure treatment is wound cleansing and vaccination with or without rabies immune globulin
Where does the Rabies virus travel to in the body, and how?
Travels to the CNS by migrating in a retrograde fashion up nerve axons
What is the progression of disease following Rabies infection?
Progression of disease: fever, malaise –> agitation, photophobia, hydrophobia –> paralysis, coma –> death
What are the sources of Rabies in the US? Which are more common?
More commonly from bat, raccoon, and skunk bites than from dog bites in the US
