RNA Viruses Flashcards
How are the enteric Picornaviruses (Polio, Coxsackie, Echovirus, Enterovirus) spread?
Respiratory route, fecal/oral
What symptoms are associated with rotavirus infection?
Gastroenteritis - watery diarrhea (common in infants)
What symptoms are associated with hepatovirus A infection?
Hep A infection is generally asymptomatic and self-resolving. Other hepatoviruses may cause jaundice, liver enzyme changes, fever, fatigue, etc.
Poliovirus causes viremia and may cross the blood-brain barrier. What cells are targeted by the virus?
Axons of peripheral nerves
Parainfluenza virus is a Paramyxovirus. How is the virus spread, what is the clinical presentation, and who is most at risk?
Transmission via aerosols
Leading cause of croup
6 months - 6 years old at risk
How is norovirus spread?
Fecal/oral
All RNA viruses replicate in the cytoplasm of the host cell with the exception of which viruses?
Orthomyxovirus & Retroviruses
What are the characteristics of Togaviruses?
Enveloped, icosahedral, +ssRNA
What is the target for the rotavirus vaccine?
Outer shell proteins - VP7 & VP4
What is the most important Calicivirus?
Norovirus
How is hepatovirus A spread?
Fecal/oral, IV drug use, contaminated food (less common)
Describe the clinical appearance of dengue fever.
Fever, chills, malaise, headache, retro-orbital pain, myalgia, arthralgia, nausea, vomiting, rash
Dengue hemorrhagic fever - Thrombocytopenia. Hypovolemic shock, Multiple organ failure, Severe hemorrhage, Encephalopathy
Hepatitis C is protected from the human response. Why is this?
Assembly & release of HCV is intertwined with the maturation & release
of very low density lipoprotein (VLDL) particles. This results in viral antigens that are coated with self-antigens.
What ssRNA viruses are able to act as mRNA to directly translate proteins using host machinery?
+ssRNA
What are the characteristics of Paramyxoviruses?
Enveloped, helical, -ss RNA virus , ubiquitous
What are the characteristics of Coronaviruses?
Enveloped, helical +ssRNA viruses, largest RNA virus, transmission via respiratory route
What are the characteristics of Filoviruses?
(-) ssRNA; enveloped, helical nucleocapsid, filamentous particles
What are the characteristics of Bunyaviruses?
Trisegmented -ss RNA, helical, enveloped
What diseases are caused by Coxsackie B?
Pericarditis, myocarditis
Describe the clinical progression of yellow fever.
3 Stages - Infection, remission, & intoxication
Infection - non-specific symptoms, viremia
Remission - clinical improvement
Inxotication - severe infection, fever, hemorrhage, liver and kidney failure, shock
What are the characteristics of Hepevirus?
Naked, icosahedral virus; +ssRNA; spread fecal/oral
How is Rubella prevented?
Live, attenuated vaccine (MMR or MMRV)
How are rhinoviruses transmitted?
Respiratory route
How is Rubella spread?
Respiratory route
What are the characteristics of Arenavirus (Lassa fever virus)?
ssRNA (2 segments); enveloped, helical capsid
L (large) strand: (-) sense RNA; encodes polymerase
S (small) strand: ambisense RNA; structural proteins
What cells are targeted by Flaviviruses?
Monocytes/macrophages, dendritic cells, endothelial cells
What is the clinical progression of rabies?
Initial flu-like symptoms; hydrophobia (foaming at mouth); CNS symptoms; death
What is the urban cycle of arboviruses?
Human - mosquito - human
What genera make up Togaviruses?
Alphavirus genus & Rubivirus genus
What is the difference between antigenic drift and antigenic shift in influenza?
Antigenic drift involves point mutations in HA and NA proteins that are likely to cause epidemics.
Antigenic shift is a major antigenic change due to reassortment that is likely to cause a pandemic.
What symptoms are associated with Marburg and Ebola?
Non-specific febrile illness; GI symptoms; bleeding abnormalities; post-Ebola syndrome
What symptoms are associated with Coltivirus infection?
Fever (improves then worsens), chills, headache, lethargy, myalgia, rash
Respiratory syncytial virus
is a Paramyxovirus. How is the virus spread, what is the clinical presentation, and who is most at risk?
Transmission via contact with secretions
Leading cause of pneumonia and bronchiolitis in children
Infants, elderly most at risk
How is rotavirus spread?
Fecal-oral
What disease is associated with Hepevirus infection?
Hepatitis E
What is the sylvatic cycle of arboviruses?
Primate - mosquito - human
How is yellow fever treated and prevented?
Treatment of symptoms only. Live, attenuated vaccine
How is hepatovirus prevented?
Vaccine with inactivated virus
What is the clinical presentation of Lassa fever virus?
Hemorrhagic fever - fever, malaise, weakness, headache, hemorrhage, shock, deafness
What is the target of Coltivirus?
Erthryocyte precursors - remains in mature RBCs
What is the relevant Rubivirus?
Rubella virus
What virus is responsible for the flu? What family does this virus belong to?
Influenza, Orthomyxoviruses
How can rabies be diagnosed?
IF staining, virus isolation, Negri bodies, serology, PCR
What are the relevant Filoviruses?
Marburg & Ebola viruses
What virus is the most frequent cause of the common cold?
Rhinovirus
What is an ambisense virus?
-ssRNA virus that contains a segmented sequence whose complementary strand acts as a template for mRNA
What are the characteristics of Reoviruses?
Segmented, dsRNA, naked, icosahedral
How does the SARS-CoV-2 vaccine provide immunity to the virus?
The vaccine induces an antibody response to the S (Spike) protein that is necessary for attachment and entry into the host cell
What is the clinical progression of Mumps?
Incubation; swollen parotid gland; systemic infection rare
What diseases are associated with poliovirus?
Nonparalytic poliomyelitis (fever, fatigue, stiffness, nausea, etc.) & Paralytic poliomyelitis (muscle weakness, loss of reflexes, etc.)
What is different about influenza replication compared to that of other –ss RNA viruses?
Transcription & replication take place in the nucleus
How is poliovirus prevented?
Inactivated polio vaccine. Previously a live, attenuated vaccine was used to produce herd immunity but this causes polio outbreaks in some areas
What is the clinical presentation of Hantavirus? How is the virus spread?
Non-specific viral symptoms followed by cardiopulmonary symptoms (cough, edema, shock); spread through aerosols with contaminated rodent saliva, feces, or urine
How is rotavirus diagnosed, treated, and prevented?
Diagnosed - antigen in stool, PCR
Treatment - manage dehydration & electrolytes
Prevention - live virus vaccine
How is rabies treated and prevented?
Prevented with live, attenuated vaccine for domestic animals; treatment with Rabies immune globulin (RIG)
What are the major reoviruses?
Rotavirus, coltivirus
What are the characteristics of Orthomyxoviruses?
Helical, enveloped virus; segmented -ss RNA
What is the clinical appearance of Zika virus?
Fever, rash, conjunctivitis, headache, myalgia, Guillain-Barré syndrome (rare)
Congenitally - Microcephaly, intracranial calcifications, hearing & visual defects, limb deformities, club
feet
What diseases are associated with norovirus infection?
Gastroenteritis
What cells are targeted by Lassa fever virus?
Dendritic cells, monocytes, &
macrophages
What are the characteristics of Rhabdoviruses (rabies)?
-ss RNA; helical, enveloped; bullet shaped; animal hosts; highest fatality of infectious viral disease
What disease is associated with Coxsackie A16?
Hand-foot-mouth disease
How is SARS-CoV-2 prevented?
Three vaccines - mRNA vaccine, recombinant vaccine, viral vector vaccine. All target the S protein
What is the clinical presentation of West Nile virus, St Louis encephalitis virus, and Powassan encephalitis N. America
virus?
Typically asymptomatic, may cause mild flu-like symptoms. In rare cases can cause encephalitis
All RNA viruses are enveloped with the exception of which viruses?
Picornaviridae, Caliciviviridae (norovirus),
Hepeviridae (hepatitis E virus), Reoviridae (rotavirus)
How does SARS-CoV-2 enter cells?
Spike protein binds to angiotensin converting enzyme 2 (ACE2)
Hemagglutinin (HA) & Neuraminidase (NA) proteins determine the antigenicity of influenza. What is the function of each protein?
HA - Attaches to sialic acid for viral entry
NA - Cleave sialic residues to promote viral spread
What Enteroviruses are associated with CNS diseases?
Polio, Coxsackie B1, Enterovirus 71, Enterovirus D68
What is the relevant Bunyavirus?
Hantavirus
How is Hepatitis C spread?
IV drug use, contaminated blood, sexual tramission
What is the most common complication of Lassa fever virus infection?
Deafness
What is the clinical progression of Measles?
Incubation period; cough, coryza, conjunctivitis & photophobia; Koplik’s spots (blueish-white spots); morbiliform rash
How is Ebola transmitted?
Person to person
transmission through
contact with contaminated
body fluids
What is the function of NSP4 in rotavirus?
Acts as an enterotoxin
What are the characteristics of Picornaviruses?
+ssRNA, naked, ichosahedral
What are the characteristics of Flaviviruses?
Enveloped, icosahedral, +ssRNA , most are arboviruses
Are RNA viruses are single-stranded with the exception of what viruses?
Rotavirus
What are the characteristics of Caliciviruses?
Naked, icosahedral, +ssRNA virus
What are the major Picornaviruses?
Poliovirus, Coxsackie virus, Echovirus, Enterovirus, Hepatitis A, Parechovirus, Rhinovirus
How is influenza prevented?
Vaccine that protects against the most prevalent circulating strands
What is the clinical appearance of Rubella?
Rash (begins on face and trunk and spreads outwards), fever, lymphadenopathy
Congenital - Cataracts, mental retardation, cardiac
abnormalities, deafness