RNA Viruses Flashcards by Jacob Horvath

How are the enteric Picornaviruses (Polio, Coxsackie, Echovirus, Enterovirus) spread?

Respiratory route, fecal/oral

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What symptoms are associated with rotavirus infection?

Gastroenteritis - watery diarrhea (common in infants)

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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.

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Poliovirus causes viremia and may cross the blood-brain barrier. What cells are targeted by the virus?

Axons of peripheral nerves

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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

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How is norovirus spread?

Fecal/oral

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All RNA viruses replicate in the cytoplasm of the host cell with the exception of which viruses?

Orthomyxovirus & Retroviruses

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What are the characteristics of Togaviruses?

Enveloped, icosahedral, +ssRNA

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What is the target for the rotavirus vaccine?

Outer shell proteins - VP7 & VP4

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What is the most important Calicivirus?

Norovirus

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How is hepatovirus A spread?

Fecal/oral, IV drug use, contaminated food (less common)

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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

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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.

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What ssRNA viruses are able to act as mRNA to directly translate proteins using host machinery?

+ssRNA

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What are the characteristics of Paramyxoviruses?

Enveloped, helical, -ss RNA virus , ubiquitous

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What are the characteristics of Coronaviruses?

Enveloped, helical +ssRNA viruses, largest RNA virus, transmission via respiratory route

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What are the characteristics of Filoviruses?

(-) ssRNA; enveloped, helical nucleocapsid, filamentous particles

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What are the characteristics of Bunyaviruses?

Trisegmented -ss RNA, helical, enveloped

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What diseases are caused by Coxsackie B?

Pericarditis, myocarditis

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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

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What are the characteristics of Hepevirus?

Naked, icosahedral virus; +ssRNA; spread fecal/oral

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How is Rubella prevented?

Live, attenuated vaccine (MMR or MMRV)

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How are rhinoviruses transmitted?

Respiratory route

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How is Rubella spread?

Respiratory route

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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