GROUP IV Positive-sense ssRNA viruses Flashcards by Kyra Catedral

GROUP IV
Positive-sense ssRNA viruses

CCP HTF

1) Coronaviridae (Coronavirus, SARS)
2) Caliciviridae (Norwalk virus)
3) Picornaviridae (Poliovirus, Enterovirus, Echovirus,
Coxsackie, Rhinovirus, HAV)
4) Hepeviridae (HEV)
5) Togaviridae (WEE, EEE, VEE, Chikungunya)
6) Flaviviridae (Yellow fever, HCV, Dengue virus)

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Coronaviridae (2)

Coronavirus
SARS

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Caliciviridae (1)

Norwalk virus

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Picornaviridae (6)

PEERCH

Poliovirus
Enterovirus
Echovirus
Rhinovirus
Coxsackie
HAV

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Hepeviridae (1)

HEV

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Togaviridae (4)

Western equine
encephalitis (WEE)

Eastern equine
encephalitis (EEE)

Venezuelan equine
encephalitis (VEE)

Chikungunya

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Flaviviridae (3)

Yellow fever
HCV
Dengue virus

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CORONA

Genera

(2)– bats as natural hosts

(2)– pigs & birds

Alphacoronavirus & Betacoronavirus

Deltacoronavirus & Gammacoronavirus

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 Linear +ssRNA viruses, ~30 kb
 80-160 nm helical nucleocapsid, enveloped

Coronaviridae

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 Proteins:
Spike (S) protein
Hemagglutinin-
esterase (HE) protein
envelope (E) protein
matrix (M) protein

 Display high frequency recombination

CORONAVIRIDAE

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 Have a great ability to mutate which facilitates their transmission from animals to humans; c

rossing the species barrier to infect
humans; r

esults in outbreaks

Coronaviridae

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Large club- or petal-shaped surface
projections (peplomers or spikes) –
solar

Coronaviridae

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About 15% of adult common colds are caused by the___.

coronaviruses

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Coronaviridae

 Important subtypes:

 SARS-CoV (IH: Palm civet)

 MERS-CoV (IH: Camel)

 SARS-CoV2 (IH: Malayan pangolin)

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 Severe Acute Respiratory Syndrome (SARS), 2002-2004

 8,422 cases in 29 countries, 916 deaths worldwide

SARS-CoV (IH: Palm civet)

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 Middle East Respiratory Syndrome (MERS), 2012

 2,600 cases in 24 countries, over 900 deaths

MERS-CoV (IH: Camel)

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 Coronavirus Disease 2019 (COVID-19), 2019-2020

 775,364,261 cases, 7,046,320 deaths (21 April 2024 WHO Dashboard)

 BatCoV RaTG13 has 96% genome sequence identity with the genome
of SARS-CoV-2; while, pangolin-CoV-2020 & CoViD-19 has 90.24%
similarity

SARS-CoV2 (IH: Malayan pangolin)

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Coronaviridae

All subtypes associated with mild…

upper respiratory & gastrointestinal
infections

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Coronaviridae

Cell tropism
 SARS-CoV 1&2: (2)

 MERS-CoV: (1)

cellular receptors -angiotensin-converting enzyme 2 (ACE2);
transmembrane protease, serine 2
(TMPRSS2)

dipeptidyl peptidase 4 (DPP4)

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Coronaviridae

 Dx: RT-PCR, CRISPR-based
assays

 Specimens:

Nasal or pharyngeal swabs
sputum
bronchoalveolar lavage

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Coronaviridae
COVID-19 Transmission:

 Mainly…

 Via aerosols: Infectious viral particles for a duration of___ hours or even longer

 Direct contact transmission: hand-to-face contact

person-to-person primarily via respiratory droplets (sneezing &
coughing)

3 hours

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Coronaviridae

 Fomite (surface) transmission: Viral particles remain infectious on surfaces for up to a few days depending on the material

 Latex, aluminum, copper: ~__ hours
 Cardboard: ~___ hours
 Countertops, plastic, stainless steel: ~ ____days
 Wood, glass: ~___ days

8 hours

24hours

1-3days

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Similarity to SARS-CoV & MERS-CoV:

fecal-oral route also possible

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COVID-19 Variants of
Concern:

Omicron (S. Africa, 2021)
Gamma (Brazil, 2020)
Beta (S. Africa, 2020)
Delta (India, 2020)
Alpha (UK, 2020)

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End to covid 19 pandemic

May 5, 2023

Most common cause of ***adult GASTROENTERITIS***  Outbreaks - nursing homes, hospitals, preschools, cruise ships

Caliciviridae Noroviruses

Caliciviridae Noroviruses High risk: (3)

Elderly & immunocompromised patients Severe in children younger than 5 years of age

 Naked virus: Acid stable (survive in the GIT), resistant to heat (60° C), pH 3, detergent, even chlorine levels of drinking water  Transmission: Fecal-oral route  Incubation period: 12-48 hours

Caliciviridae Noroviruses

Syndrome: Nausea, acute onset vomiting, watery, non-bloody diarrhea (explosive diarrhea), abdominal cramps, myalgia & headache  Symptoms resolve after____ hours, without serious complications  Viral shedding in stools even after___ weeks of recovery  Lab diagnosis: RT-PCR, ELISA

Caliciviridae Noroviruses 48 4

Gk: calyx ***(cup or goblet);*** cup-shaped depressions; +ssRNA, non-segmented, NAKED, icosahedral, 27 nm

Caliciviridae Noroviruses

PiCORna – acronym for “

poliovirus insensitive to ether coxsackievirus orphan virus rhinovirus ribonucleic acid

Gk: calyx ***(cup or goblet);*** cup-shaped depressions; +ssRNA, non-segmented, NAKED, icosahedral, 27 nm

Caliciviridae Noroviruses

Picornaviridae 5 Notable genera:

1. Enterovirus 2. Hepatovirus - Hepatitis A virus 3. Cardiovirus 4. Aphthovirus (foot-and-mouth disease virus)

Enterovirus o(5)

Polioviruses Coxsackieviruses Echoviruses Parechoviruses Rhinoviruses (acid labile, used to be a separate genus)

(foot-and-mouth disease virus)

Aphthovirus

very small unit; 28 to 30 nm naked icosahedral capsid +ssRNA infectious genome-linked protein (VPg)

Pico

Picornaviridae “Enteroviruses”  Agent of POLIOMYELITIS, affects all age groups  usually, asymptomatic infection or mild febrile illness  aseptic meningitis

Poliovirus serotypes 1, 2, & 3

Picornaviridae “Enteroviruses”  Serotype___ causes 85% of paralytic polio  1 in 200 with irreversible paralysis; 5-10% die (breathing muscles are immobilized)

S1 Poliovirus serotypes 1, 2, & 3

Picornaviridae “Enteroviruses”  Tropism: Infect ***epithelial cells of the alimentary tract*** and ***cells of the CNS***  Transmission: Person-to-person, fecal-oral route, contaminated water or foo

Poliovirus serotypes 1, 2, & 3

Picornaviridae “Enteroviruses” Poliovirus serotypes 1, 2, & 3  vaccine associated _____  paralytic polio (sporadic) cases following exposure to oral polio vaccine (live attenuated poliovirus); since 2000, inactivated polio vaccine (IPV) has been used.  ***Only Afghanistan & Pakistan*** has endemic transmission of the wild poliovirus. Failure to stop polio could result in global resurgence of the disease.

Vaccine-associated paralytic poliomyelitis disease (VAPP)

Picornaviridae “Enteroviruses” Acute hemorrhagic conjunctivitis –__________ Other types: aseptic meningitis paralysis encephalitis exanthems colds pneumonitis of infants diarrhea hepatitis

Coxsackie A viruses [Types 1-24] coxsackievirus A24v

Picornaviridae “Enteroviruses” Herpangina: lesions on soft palate & uvula; Types 2-6, 8, 10

Coxsackie A viruses [Types 1-24]

Picornaviridae “Enteroviruses” Hand-foot-and-mouth disease: lesions on hands, feet, mouth, tongue; Types 5, 10, 16

Coxsackie A viruses [Types 1-24]

Picornaviridae “Enteroviruses” Myocardial and pericardial infections – Types 1-5 Other types: aseptic meningitis paralysis encephalitis exanthems hand-foot-mouth disease colds pneumonia hepatitis undifferentiated febrile illness

Coxsackie B viruses: (B for body) [Types 1-6]

Picornaviridae “Enteroviruses” Pleurodynia (epidemic myalgia) - ***Bornholm disease, devil’s grip;*** sudden onset of fever, excruciating pleuritic chest pain; Types 1-5

Coxsackie B viruses: (B for body) [Types 1-6]

Picornaviridae “Enteroviruses” Infect human enteric tract Can be recovered by inoculation in tissue cultures Associated with: aseptic meningitis paralysis encephalitis exanthems pleurodynia myocarditis pericarditis colds diarrhea hepatitis generalized disease of infants (Type 11)

Echoviruses (enteric cytopathogenic human orphan viruses) Types 1-33

 Aseptic meningitis, paralysis, encephalitis (Type 71, one of the main causes of CNS disease around the world), herpangina,  HFM disease (Type 71, outbreak in China, 2008, 4500 cases, 22 deaths in infants and children),  acute hemorrhagic conjunctivitis (Type 70), colds, pneumonia (Type 68), pneumonitis

Enterovirus Types 68-116

Picornaviridae “Enteroviruses”  Aseptic meningitis, paralysis, encephalitis (Type 71, one of the main causes of CNS disease around the world), herpangina,  HFM disease (Type 71, outbreak in China, 2008, 4500 cases, 22 deaths in infants and children),  acute hemorrhagic conjunctivitis (Type 70), colds, pneumonia (Type 68), pneumonitis

Enterovirus Types 68-116

Picornaviridae “Enteroviruses” acute hemorrhagic conjunctivitis (Type 70), colds, pneumonia (Type 68), pneumonitis

Enterovirus Types 68-116

Picornaviridae “Enteroviruses”  The common cold viruses of >150 types  Cause upper respiration tract infections and the common cold syndrome

RHINOVIRUSES

Picornaviridae “Enteroviruses”  Tropism: Major group use intercellular adhesion molecule-1 (ICAM-1) as receptor; the minor group binds members of the low-density lipoprotein receptor (LDLR) famil

RHINOVIRUSES

Picornaviridae “Enteroviruses”  IP: 2-4 days, acute illness – 7 days, nonproductive cough – 2-3 weeks;  1-2 attacks per year characterized by sneezing, nasal obstruction, nasal discharge, sore throat, headache, mild cough, malaise, chilly sensation, little or no fever

RHINOVIRUSES

Picornaviridae “Enteroviruses”  Replicate in the respiratory/gastrointestinal tract; associated with aseptic meningitis, paralysis, myocarditis, pericarditis, colds, pneumonia, diarrhea

Parechovirus Types 1-19

Picornaviridae  Human infections with: -Vilyuisk human encephalomyelitis virus (VHEV) -Saffold virus (SAF-V)

Cardiovirus

Picornaviridae  Infections: Gastroenteritis, influenza-like symptoms, non-polio-associated acute flaccid paralysis  Transmission: zoonosis and fomites  Described in North America, Europe, South Asia

Cardiovirus

Picornaviridae  foot-and-mouth disease in cattle, sheep, pigs, goats; may be transmitted to humans by contact or ingestion

Aphthovirus

Picornaviridae  Causes an infectious disease of the liver, many have few or no symptoms, especially in the young, some are asymptomatic but may spread the virus to others

Hepatovirus A (HAV) – Hepatitis A

Picornaviridae  agent of infectious hepatitis  Sources: feces, contaminated food or water supplies, shellfish contaminated with sewage (fecal-oral and rarely blood routes)  IP: 2-4 weeks; 8 weeks: symptoms nausea, diarrhea, jaundice, fever, abdominal pain, appetite loss, dark urine

Hepatovirus: Hepatitis A virus (HAV) (formerly Enterovirus 72)

Picornaviridae  10-15% experience recurrence of symptoms during the 6 months after initial infection (relapse)  Acute liver failure rarely occurs  More common in the elderly  Chronic infection does not occur.

Hepatovirus: Hepatitis A virus (HAV) (formerly Enterovirus 72)

Picornaviridae HAV-specific IgM antibodies & IgG; increase liver enzymes, ALT Prevention: Vaccination (LIVE OR ATTENUATED vaccines), good hygiene, sanitation

Hepatovirus: Hepatitis A virus (HAV)

 Acute viral hepatitis, genotypes 1-4  Acute, asymptomatic, or self-limiting

Hepatitis E (HEV), genus Orthohepevirus

Hepatitis E (HEV), genus Orthohepevirus Type___ infection of pregnant women exacerbate into fulminant hepatitis resulting in a high rate of case fatality

Type 1 HEV

Hepatitis E (HEV), genus Orthohepevirus Type___ chronic infection in immunocompromised patients with rapid progression

Type 3 chronic infection

Hepatitis E (HEV), genus Orthohepevirus Transmission: ***fecal-oral, drinking feces- contaminated water*** ***consumption of contaminated water and meat*** from infected animals

(HEV1 & HEV2); (HEV3 & HEV4)

 “____” – cloak; inactivated by acid pH, heat, lipid solvents, detergents, bleach, phenol, 70% alcohol & formaldehyde  All viruses are serologically or antigenically related; E1 & E2 (viral glycoproteins, spikes) elicit neutralizing antibodies from the host. most possess hemagglutinating ability

Togaviridae

 – Arthropod Borne viruses (mosquitoes)

ARBOviruses

 Chikungunya, Eastern, Western, and Venezuelan equine encephalitis viruses, Mayaro, O’Nyong-nyong, Ross River, Semilki Forest, and Sindbis viruses  Persistent infections in mosquitoes and transmitted between vertebrates  Worldwide in distribution

Alphavirus

- Rubella virus (not an arbovirus)

Rubivirus

Enveloped, spherical, 60 to 70 nm +ssRNA, 11.7 kbp, 3 (rarely three) surface glycoproteins, icosahedral nucleocapsid, released by budding through the plasma membrane.

Cell tropism: very-low density lipoprotein receptor (VLDLR) –heart, skeletal muscles, adipose tissue, brain (apolipoprotein E receptors, APOER2, neuronal migration)

Togaviridae - Alphaviruses

Disease: 1. fever, malaise, headache, and/or symptoms of encephalitis (e.g., eastern, western, or Venezuelan equine encephalitis viruses 2. fever, rash, and arthralgia (e.g., chikungunya, Ross River, Mayaro, lines such as Vero, where they produce a CPE, or using and Sindbis viruses)

Togaviridae - Alphaviruses

Lab dx: Viral isolation from the brain, blood, CSF or throat washing using suckling mice or a variety of vertebrate cell lines such as Vero, where they produce a CPE, or using and Sindbis viruses) mosquito cell lines, where no CPE is seen or specific rise in IgG antibody, or the presence of IgM antibody

Togaviridae - Alphaviruses

Togaviridae - Rubivirus  Virus:

Rubella (‘little red’) virus / German measles virus

 Disease: Rubella, German measles, or three-day measles  An acute febrile illness with rash & lymphadenopathy, affects children and young adults; mildest of the viral exanthems  Infection during early pregnancy may result in serious abnormalities of the fetus, including congenital malformations and mental retardation (congenital rubella syndrome)

Togaviridae - Rubivirus

Transmission: person-to-person via aerosolized particles from respiratory secretions, transplacental (TORCH)

Togaviridae - Rubivirus

 Low-grade fever, malaise, rash starts on face then to trunk and extremities; transient arthralgia & arthritis in adults; self-limiting; recovery with lasting immunity

Togaviridae - Rubivirus Postnatal rubella

 Infection during first trimester of pregnancy – about 85% cases results in abnormalities  May result in fetal death and spontaneous abortion

Togaviridae - Congenital Rubella Syndrome

 Classic triad of congenital rubella:  Cataracts, cardiac abnormalities, deafness

Congenital Rubella Syndrome

 Most common developmental manifestation – moderate to profound mental retardation.  Rare complication – progressive rubella panencephalitis (2nd decade of life in children with congenital rubella

Congenital Rubella Syndrome

- one of the five classic childhood exanthems (chickenpox, fifth disease, measles or rubeola, roseola)

Rubella

GROUP IV Positive-sense ssRNA viruses Flashcards

(80 cards)