RNA VIRUSES Flashcards
Classification of LCM, Lassa fever virus, Lujo virus, Machupo virus, Guanarito virus, Sabia virus, Chapare virus
Arenaviridae (smallest RNA, enveloped, spherical capsid; SS(-) RNA)
Classification of Astrovirus
Astroviridae (Naked, Star-like capsid SS(+))
Classification of Cardiovirus, Poliovirus, Coxsackie A virus, Coxsackie B virus, Parechovirus, Enterovirus, Hepatitis A virus, Rhinovirus
Picornaviridae (naked, icosahedral, Single stranded(+))
Classification of Hepatitis E virus
Hepeviridae (Naked, Icosahedral, SS(+))
Classification of Norovirus, Sapovirus
Caliciviridae (Naked, Icosahedral, SS(+))
Classification of Arbovirus, Yellow fever, Dengue virus, West Nile, Zika virus, Japanese B encephalitis, St. Louis encephalitis, Hepatitis C virus
Flaviviridae (Enveloped, Icosahedral, SS(+))
Classification of Rubella virus, Alpha virus
Togaviridae (Enveloped, Icosahedral, SS(+))
Classification of Rotavirus, Colorado tick fever
Reoviridae (Naked, Icosahedral, Rota/wheel-shaped, DS)
Classification of Influenza viruses
Orthomyxoviridae (Enveloped, Spherical, SS(-))
Classification of Hantavirus, Rin nombre virus
Hantaviridae (Enveloped, Spherical, SS(-))
Classification of HIV 1 & 2, HTLV 1 & 2
Retroviridae (Enveloped, Icosahedral, SS(+))
Classification of SARS-CoV, MERS-CoV, SARS-CoV-2
Coronaviridae (Enveloped, Helical, Crown-shaped, SS(+))
Classification of Rabies virus
Rhabdoviridae (Enveloped, Helical, Bullet-shaped, SS(-))
Classification of Marburg virus, Ebola virus
Filovirus (Enveloped, Complex, SS(-))
Classification of Mumps, Measles, Parainfluenza, RSV, Metapneumovirus
Paramyxoviridae (Largest RNA, Enveloped, Spherical, SS(-))
All RNA viruses are single-stranded except
Reoviridae
Which viruses replicate in the cytoplasm?
All RNA viruses except Retroviridae and Orthomyxoviridae
Smallest RNA virus
Arenaviridae (7-10nm)
Smallest Picornaviridae size
~30nm
LCM
LCM virus
Lassa fever
Lassa fever virus
Lujo hemorrhagic fever
Lujo virus
Bolivian hemorrhagic fever
Machupo virus
Venezuelan hemorrhagic fever
Guanarito virus
Brazilian hemorrhagic fever
Sabia virus
Chapare hemorrhagic fever
Chapare virus
Myocarditis, encephalitis, Type 1 DM
Cardiovirus
Poliomyelitis, Acute flaccid myelitis
Poliovirus
Herpangina
Coxsackie A virus
Pleurodynia
Coxsackie B virus
Diarrhea, aseptic meningitis
Parechovirus
Aseptic meningitis, pneumonia
Enterovirus
Infectious/Short incubation Hepatitis
Hepatitis A virus
Common colds
Rhinovirus
Hepatitis E
Hepatitis E virus
RNA virus that causes gastroenteritis
Norovirus, Astrovirus, Sapovirus, Rotavirus
Encephalitis
Arbovirus
Yellow fever
Yellow fever virus
Dengue fever
Dengue virus
Zika fever
Zika virus
Encephalitis
Japanese B encephalitis
Encephalitis
St. Louis encephalitis
Non-A, Non-B Hepatitis
Hepatitis C virus
German measles/Atypical scarlet fever
Rubella virus
Fever, arthralgia, encephalitis (Chikungunya, O’nyong nyong virus; Eastern, Western, Venezuelan equine encephalitis)
Alpha virus
Tick fever
Colorado tick fever
Flu
Influenza viruses
Hemorrhagic fever with renal syndrome
Hantavirus (rodents)
Respiratory infections
Sin nombre virus
AIDS
HIV 1 & 2
Adult T cell leukemia/Lymphoma
HTLV 1 & 2
Respiratory infections
SARS-CoV
Respiratory infections
MERS-CoV
Respiratory infections
SARS-CoV-2
Seizure, Hallucinations, Paralysis
Rabies virus
Hemorrhagic fever
Ebola virus,Marburg virus
Parotitis (Orchitis, Oophoritis)
Mumps
Fever, Skin rashes, Pneumonia
Measles
Croup, Pneumonia
Parainfluenza
Croup, Bronchiolitis
RSV
Bronchiolitis, Bronchitis, Pneumonia
Metapneumovirus
Arenaviridae Old World viruses
Lymphocytic choriomeningitis virus (LCMV - BSL3), Lassa fever virus (BSL4 - shock, respiratory distress, hemorrhage, death), Lujo virus (hemorrhagic fever)
Arenaviridae New World viruses
Chapare, Guanarito, Junin, Machupo, Sabia, Whitewater Arroyo viruses (hemorrhagic fevers)
Astroviridae characteristics
Star-like surface structure, Gastroenteritis (Pediatric, military troops, nursing homes, immunocompromised)
Best lab test for detection of Astroviridae
Electron microscopy
Human caliciviruses (HuCVs), formerly norwalk-like and safford-like virus
Caliciviridae
Outbreaks occur in semi-closed environments (e.g., cruise ships, nursing homes, schools); The most common cause of acute gastroenteritis worldwide, affecting all age groups
Norovirus
Causes gastroenteritis in infants and toddlers, similar to astrovirus.
Sapovirus
Crown-like surface projections. Winter outbreaks, with 55% of common colds caused by rhinovirus and coronavirus.
Coronaviridae
SARS-CoV originates from bats → civet cat → human.
Beta coronavirus (SARS-CoV)
MERS-CoV originates from bats → camel → human.
Beta coronavirus (MERS-CoV)
Originated from bats → armadillo (?) → human. Mode of transmission: contaminated respiratory secretions and aerosols. Receptor: ACE-2 paired with TRMPSS2. Incubation period: 2-14 days. Initial symptoms include headache, fever, body ache, shortness of breath, and loss of taste/smell.
SARS-CoV-2 (n-CoV-2019)
SARS-CoV-2 variant that is more transmissible in hospitals and more severe than original strain
Alpha variant
SARS-CoV-2 variant that is more transmissible and causes more hospitalization than the original strain
Beta variant
SARS-CoV-2 variant that causes the most severe respiratory symptoms and hospitalizations
Delta variant
SARS-CoV-2 variant with mutations in the spike protein, more transmissible than the Delta variant but less severe
Omicron variant
Specimen types for SARS-CoV-2 testing
NPS/OPS, Sputum, Saliva, Nasal swab, Bronchial washing, NPS aspirate
Biochemical markers for SARS-CoV-2 testing
Inflammation: CRP, IL-6, IFN-Y, high LDH, AST, D-dimer
RT-PCR for SARS-CoV-2: Multiplex Real-time RT-PCR; Ct value is interpreted and reported a:
SARS-CoV-2 virus detected or not detected)
Culture media for SARS-CoV-2
Vero-CCL81 or Vero-E6 cell line; CPE: Rapid cell rounding, refractivity, and detachment
Initially used treatments for SARS-CoV-2
Chloroquine, Hydroxychloroquine (Terminated due to life-threatening toxicities)
Inhibits viral RNA synthesis
Remdesivir
Human monoclonal antibody to Interleukin-6 SARS-CoV-2 treatment
Tocilizumab
For SARS-CoV-2 from donors with no COVID-19 symptoms and negative for RT-PCR for at least 14 days
Convalescent plasma
FDA-approved COVID-19 drugs
Casirivimab + Imdevimab, Molnupiravir, Nirmatrelvir + Ritonavir (Paxlovid)
Prevention of SARS-COV-2 variant
Immunization
Pfizer-BioNTech and Moderna method of immunity
Modified nucleoside
AstraZeneca, Janssen, Sputnik V method of immunity
Recombinant
CoronaVac, Covaxin, Sinopharm method of immunity
Inactivated
Covovax method of immunity
Protein nanoparticle
Filoviridae characteristics
Filamentous, pleomorphic, long rod-like
Filoviridae viruses
Marburg, Ebolavirus (Zaire, Sudan, Bundibugyo, Reston, Tai Forest)
Ebolavirus exceptions and mortality
Reston (nonhuman primates only), >80% mortality
Ebolavirus transmission
Contact with infected primate
Filoviridae tests
RT-PCR, Cell culture (BSL4)
Yellow fever virus reservoirs
Monkeys (jungle), Humans (urban)
Yellow fever vector
Aedes aegypti
Yellow fever symptoms
Jaundice, black vomit, melena, ecchymoses
Dengue fever symptoms
Fever, Breakbone fever, Hemorrhagic fever
Dengue virus vectors
Aedes aegypti, Aedes albopictus
Dengue virus incubation
4-7 days
Dengue virus tests
CBC, NS1 ELISA, Dengue Duo, PRNT (RITM confirms serotypes)
West Nile virus reservoir and vector
Birds (reservoir), Mosquito (vector)
West Nile transmission
Blood, tissue, breast milk
West Nile symptoms
Fever, encephalitis, meningitis
Zika virus associations
Neuropathy, Guillain-Barre, microencephaly
Zika virus transmission
Mother-fetus, sexual, blood transfusion, organ transplant
Zika virus tests
<7 days: NAAT; >7 days: IgM ELISA
Hepatitis C virus
Hepatitis, subclinical
Hantaviridae previous classification
Bunyaviridae
Hantaviridae transmission
Rodent-borne, aerosols from excreta (vacuuming, sweeping, shaking rugs)
Sin nombre virus host and disease
Deer mouse (Peromyscus maniculatus), Hantavirus pulmonary syndrome
Bayou virus carrier
Rice rat
Black Creek Canal virus carrier
Cotton rat
New York-1 virus carrier
White-footed mouse
Orthomyxoviridae genome
Segmented genome
Proteins distinguishing Influenza A, B, C
Matrix (M), Nucleoprotein (NP)
Proteins for Influenza A subdivision
Hemagglutinin (HA), Neuraminidase (NA)
Influenza A infections
Humans, Birds, Seals, Cats, Horses, Swine
Influenza B and C infections
Humans only
Influenza A continuous antigenic changes subtype H1N1
Spanish flu/Swine flu
Influenza A subtype H2N2
Asian flu
Influenza A subtype H3N2
Hongkong flu
Influenza A subtype H5N1
Avian/Bird’s flu
Influenza A subtype H7N9
Avian flu (poultries) in China
Influenza B severity
Common, mild
Influenza C severity
Less common, mild form
Coinfection with Influenza A
MRSA secondary infection
Specimens for Influenza testing
Nasopharyngeal swab, washes, or aspirate
Tests for Influenza
Immunoassay, NAAT, Cell culture (PMK, MDCK cell lines)
Gold standard for respiratory virus identification
RT-PCR
Test for antigenic characterization of Influenza viruses
Hemagglutination-Inhibition test
Most common viral respiratory agent in children
RSV
Upper respiratory agent in children
Parainfluenza
Paramyxoviridae genome
Non-segmented (not prone to antigenic changes)
Cause of croup in children
Parainfluenza virus
Parainfluenza 1 most common disease
Croup
Parainfluenza 3 in children
Severe disease and fatalities
Parainfluenza 4 unique feature
Does not cause croup
Tests for Paramyxoviridae viruses
NAAT, cell culture confirmed by IFA or DFA
Mumps virus hallmark symptoms
High fever, fatigue, inflamed parotid gland
Complications of mumps virus
Meningoencephalitis, orchitis, oophoritis, polyarthritis, pancreatitis
Specimens for mumps testing
Oral fluid, CSF, saliva, throat swab, urine
Measles hallmark feature
Koplik spots
Measles rash progression
Forehead > behind ears > trunk > arms > legs
Complications of measles
Congenital malformations, encephalomyelitis, SSPE
Prevention for measles and mumps
MMR vaccine
Picornaviridae size
One of the smallest relevant to humans
Enteroviruses diseases
Aseptic meningitis, poliomyelitis, encephalitis, myocarditis, pericarditis
Specimens for enterovirus testing
Stool, rectal swabs, NPS/OPS, CSF, serum, conjunctival swabs, tears
Enteroviruses transmission
Respiratory, fecal-oral
Poliovirus complications
Poliomyelitis, acute flaccid myelitis (AFM)
Poliovirus prevention
SALK (inactivated) or SABIN (live-attenuated) vaccines
Foot and mouth disease cause
Apthovirus (present in bovines or cattle)
Parecho virus former name
Echo virus (Enteric Cytopathic Human Orphan)
Parecho virus diseases
Mild gastrointestinal and respiratory illness, meningitis, neonatal sepsis in children
Rhinovirus characteristic
Acid sensitive
Rhinovirus disease
Common colds (self-limiting)
Specimen for Rhinovirus
Nasal secretions
Acidification of sample distinguishes Rhinovirus from
Acid-stable enterovirus
Viral gastroenteritis in children causative agents
Norovirus, Sapovirus, Astrovirus, Rotavirus
Viral gastroenteritis in adults causative agent
Norovirus
Reoviridae characteristics
Respiratory enteric orphan viruses
Rotavirus structure
Outer shell, inner shell, core (wheel-like appearance)
Rotavirus major disease
Severe infantile gastroenteritis (6 months to 3 years old)
Suspected airborne Rotavirus outbreaks
Nursing home, hospital, day care centers
Tests for Rotavirus
ELISA, Latex agglutination, RT-PCR
Most significant cause of lower respiratory tract infection in children <5 years old
Respiratory Syncytial Virus (RSV)
Hallmark of RSV
F (fusion) protein mediating host cell fusion into syncytial cells
RSV associated disease
Bronchiolitis
Human Metapneumovirus (HMPV) diseases
Bronchiolitis, pneumonia in infants, lower respiratory infection in older adults
Ranking of HMPV in pediatric hospitalization for LRTIs
2nd or 3rd most common
Tests for HMPV
NAAT (gold standard), cell culture, rapid antigen test kits
TAX gene association in HTLV-1
Causes T-cell leukemia/lymphoma and myelopathy/tropical spastic paresis
Difference between HIV-1 and HIV-2
HIV-1: more aggressive, causes HIV pandemic; HIV-2: mostly in Africa
Targets of HIV
CD4+ (CXCR4) T lymphocytes, CCR5+ Monocytes/Macrophages
Leading causes of HIV infection (highest to lowest)
MSM > Heterosexual contact > IV drug use > Vertical transmission
Common coinfections with HIV
MAC, Pneumocystis pneumonia, Candida, Cryptococcus, Kaposi-sarcoma, etc.
Normal CD4 to CD8 ratio
2:1 or 1.5:1
CD4 to CD8 ratio in AIDS
< 0.9
Stage 1 AIDS criteria
CD4 ≥29%, ≥500 cells/µL, No AIDS-defining condition
Stage 2 AIDS criteria
CD4 14-28%, 200-499 cells/µL, No AIDS-defining condition
Stage 3 AIDS criteria
CD4 <14%, Observation of AIDS-defining condition with lab confirmation
Function of gp160 in HIV
Precursor of envelope glycoprotein
Function of gp120 in HIV
Outer envelope glycoprotein
Function of gp41 in HIV
Transmembrane envelope glycoprotein
Group-specific antigen (Gag gene) p24
Nucleocapsid core protein
Polymerase (Pol gene) p51
Reverse transcriptase
Polymerase (Pol gene) p32
Integrase
HIV Envelope (Env gene)
gp160, gp120, gp41
HIV Group-specific antigen (Gag gene)
p24
HIV Polymerase (Pol gene)
p51, p32
Rhabdoviridae Rabies virus shape under microscope
BULLET-shaped
Rhabdoviridae Rabies virus reservoir
Dogs, cats, fox, coyotes, wolves, raccoons, bats, skunk
Rhabdoviridae Rabies virus transmission
Saliva (animal bite)
Rhabdoviridae Rabies virus rabies symptoms
tingling pain at exposure site, Furious type: Aggression, Dumb type: Lethargy and paralysis
Gold standard for Rabies diagnosis
Direct Immunofluorescent Antibody (DFA) technique
CDC method for Rabies diagnosis
RT-PCR for human antemortem and animal postmortem (not routinely used)
Rabies histological feature
Seller’s stain for NEGRI bodies in CNS biopsy