RNA viruses Flashcards by Katherine E Nordstrom

Enveloped RNA virus withe segmented genome
Replicates in nucleus, but is put together in cytoplasm
Can only infect humans
does not cause epidemics
spread by airways droplets
mild respiratory disease

Influenza Virus C– Orthomyxoviridae family

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Criteria for Measels Diagnosis

clinical presentation alone can be adequate
seroconversion, or viral RNA test
- 4-fold titer increase between acute adn convalescent phases (~3 weeks apart)
Giant cells can be observed in tissue samples

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enveloped RNA virus with segmented genome
spread primarliy by ticks and mosquitoes
only few reporded cases of human disease
feve, meningitis, encephalitis, hepatitis, low platelets

Thogotovirus – Orthomyxoviridae family

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Why is post-exposure innoculation successful in rabies infection? What other post infection management protocol is important?

Long incubation allows post exposure immunization

antibodies will block disease progression if produced in time

Wash wound soap/water, injuct anti-rabies Ig near wound

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enveloped RNA virus
2nd leading cause of cold
gown better at 33-35, limited to URT
petal shpaed glycoproteins on envelope

Coronavirus

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Diagnositc Criteria RSV

By RT-PCT or immunofluorescence and EIA
Presence of viral antigens in nasal wshings or tissue samples
negative in hemadsorption test

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enveloped RNA virus
ubiquitous, almost all serotype positive by 5
asymptomatic or common cold
serious bronchiolitis adn pneumonia may oaccur
most infections in winter

Huan Metapneumovirus– not very common that people go to the doctor for it

Identified by RT-PCR

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Patient presents with symptom shown in picuture. Where can you take cultures of this virus for further analysis? What is the name of the symptomw when the lesions are only present in the soft palate?

Cocksackie A16 virus

Hand-Foot-Mouth Disease

Virus can be cultred from lesions or feces

Soft palate lesions = Herpangina

Self-limited - requires only symptomatic management

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Where is a culture recoverable for polio? For coxsackie & echovirus? Is a culture realistic for diagnosis for myocarditis?

polio: pharynx & feces, rarely CSF

coxsackie & echovirus: throat, stool, and CSF

rarely in myocarditis- symptoms occur weeks after initial infection

Genome (RT-PCR for viral RNA) and serology studies

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What are possible complications that occur from an influenza infection? Why are patients susceptible to these complications?

bacterial pneumonia, myositis, carditis, encephalitis

since the virus damages the epithelial, ciliated and mucuos secreting cellls, the risk for secondary baterial pneumonia is very high, this is particualy true for immunocompromised individuals

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Naked RNA virus
destruction of motor neurons, results in flaccid paralysis
endemic to Pakistan, Afghanistan, and Nigeria
may cause back pain and muscle spasms
may cause fever, headache, sore throat

Poliovirus – Enterovirus group— Picornaviridae family

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What are the diagnositic criteria for Parainfluenza?

RT-PCR detection viral genome, or seroconversion
hemadsorption or hemadsorption inhibition, synctia
lower respiratiory disease

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Enveloped RNA virus withe segmented genome
Replicates in nucleus, but is put together in cytoplasm
Can infect broad range of host (bird, pig, horses, humans)
annual epidemic
infect URT adn LRT (symptoms due to INF & cytokines)
Damages epithelial ciliated and mucus-secretign cells
fever, malaise, headache, myaglias, nasal discharge, and cough

Influenza Virus A –orthomyxovirus

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what is croup?

Subglottal sweiing that may close the airway– steeple sign in x-ray

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naked RNA virus
Star of David capsomers
usually infects infants and young children
fecal-oral transmission and causes gastroenteritis
watery diarrhea, nausea, vomiting, resolves ~20 hrs

Astrovirus –Calciviridae family

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Enveloped, RNA virus, bullet-shaped
Mainly from dogs to humans
Replicates in muscles–> variable incubation period
virus infects peripheral nerve endings
Travels via axon to spinal cord adn brain
Via afferent neurons to highly innervated tissues (salivary gland)
CNS symptoms- seixures, disorintation, hyperactivity, hydrophobia

Rabies Virus– Rhabdoviridae

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What are the three deadly coronaviruses? What property increases their virulence? What is their common clinical presentation?

SARS

MERS

COVID19

They can grow at 37 degrees C, thus systemic disease

severe respiratory distress

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Why are children under the age of two particulary susceptibel to RSV?

materal IgG reacts with RSV in infants– induces immune response, which exacerbates the pathology

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naked RNA virus
prodrom of fever, chills, maialise
acute febrile illness
meningeal irritation, including nuchal rigidity
petechiae or a rash may occur
can also cause pericarditis (chest pain, abnormal EKG)

Coxsackie B Virus and Echovirus – both members of the enterogroup – picornaviridae family

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naked RNA virus
sudden fever & unilateral low throacic, pleuritic chest pain
lasts ~4 days, but may relapse after several asymptomatic days
abnormal EKG, increased troponin T, myocarditis

Coxsackie B Virus- enterovirus group– picornaviridae family

Pleurodynia (Bornholm disease or devil’s grip)

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Naked RNA virus
sensitive to acid, heat, detergents
very infectious ID50=1 (nasal secretions and direct contact)
infected cells release bradykinin & histamine, causes coryza (infalmed mucous membrane)
# 1 cause common cold
most common early autumn and late spring

Rhinovirus – Picornaviridae family

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naked RNA virus
Fecal-oral transmission
enters blood via oropharynx, then to liver parenchyma
acute infection, CMI attacked infected hepatocyes
fever, anorexia, nausea, vomiting, followed by jaundice

Hepatitis A virus

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Naked RNA virus
Shamm cups in surface of the virus in the shape of the start of David
gastroenteritis
fecal-oral transmission
mostly infects older children and aults
watery dirrhea, nausea and vomiting

Calciviridae – nrovirus

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Describe the progression of the measels rash.

itchy rash in 3-5 days after prodrome

begins in front of an below ears and on the side of the neck

starts as irrecular, flat, red ares that soon become raised

In 1-2 days trunk, arm, palms, and soles

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* enveloped RNA virus * kidney-shaped * causes enteric infections (GI) * non0bloody diarrhea with nausea and vomiting in children * mild fever

Torovirus-- coronavirus family

* large, enveloped RNA virus * H glycoproteins present * transmission from inhalation of large droplet aerosols * one of 5 classic childhood exanthems * contagious several days before and several days after rash * replicates in RT, UT, CNS * prodrome: high fever, "CCC & P" cough, coryza, conjunctivitis, and photophobia * koplik spots (mucous membrane lesions)in 2d after prodrome-- mostly buccal mucosa

Measels-- morbillivirus-- paramyoxoviridae

* enveloped RNA virus * severe encephalitis * broad host range (pigs, humans, dogs, horses, cats, bats) * human acquisition from eating contaminated food * human accidental host * flulike symptoms, then seizures & coma

Nipah & Hendra virus-- Paramyxoviridae family

What are the 5 viruses that belong tot he enterovirus group? What is their family?

1. Polio 2. Coxsachkie A 3. Coxsachie B 4. Echo 5. Hep A Picornaviridae family

Name the 3 genera of Paramyxoviridae viruses. Include which glycopriteins are found on the surface of each, and the individual viruses the make up that genera.

1. Morbillivirus: measles (H-hemagglutinin) 2. Paramyoxvirus: parainfluenza and mumps (H-hemagglutinin, N-neuraminidase, F-fusion, and G protein) 3. pneumovirus: respiratory syncytial virus (N-neuraminidase, F-fusion, and G protein)

What are the diagnostic critera of aseptic meningitis? What virus is generally responsible for aseptic meningitis?

no neutorphils, slighly low glucose, slighly high protein Enterovirus

* large, enveloped RNA virus * infection by inhalation large-droplet aerosols * croup in children " * hoarseness, "seal bark" cough, tacypenea, ttachycardia * positive hemaglutination test

Parainfluenza-- paramyxovirus- paramyxoviridae

* endemic in East Africa in bats/wild monkeys * enveloped RNA virus * cytopathogenesis and necrosis of tissue * leads to severe or fatal hemorrhagic fever * fever, muscle & headache, vomiting, diarrhea, swolen glands, edema, bleeding

Ebolavirus and Marburg-- Filoviridae

Rotavirus diagnositic criteria

* wheel-like appearance under EM * detectable in stool by ELISA, latex agglutination, EM * Serology is not used much because titers are so common (vaccine)

Very sich child with temperares exceeding 104 degrees presents with shown rash. What is the viral cause of the symptoms?

Measels (Rubeola) -Morbillivirus - paramyxoviridae

Mumps complications and presentation in adults

* orchitis in adults (painful inflammation testes) * Meningitis (1-10%) and encephalitis (\<.1%) * Rare permanenet brain damage (deafness, paralysis)

Diagnostic criteria rhinovirus

* Symptoms indistinguishabl from other viruses causing URT * begins with sneezing, followed by rhinorrhea (discharge thin, nasal mucosal fluid) and cough * peaks 3-4 days, may persis 7-10 * diagnosis based on clinicla picture, no lab diagnosis needed -- would find naked RNA virus

* fecal-oral transmission * naked RNA virus * conecn in resource-poor setting * acute infection in immunocompetent -- possible chronicity among I/C patients * general malaise, URQ abdominal pain, anorexia, nausea and fever * followed by jaundice-- yellow skin, dark urine, and pale stools

Hepatitis E -- HepEviridae

* large, enveloped RNA virus * spread by inhalation large-droplets aerosols * usually 5-10 yrs * infects epithelium RUT, then spreads by ciremia * Swelling of parotid gland, adn other glands * most common in late winter adn early spring * high temperature

Mumps--paramyzovirus-- paramyxoviridae

What are the diagnostic criteria for influenza virus?

* typical symptoms during an epidemice- suficient for diagnosis * Hemadsorption or hemagglutination inhibition may be specific

What is the most common cause of epidemic viral gastroenteritis in the US? What is the cause of the watery diarrhea typical of this disease? What are the diagnositc criteria?

Calciviridae (Norovirus) virus damages small intestine- poor reabsorption fo fluid Diagnosis: EM adn detection of giral genome in RT-PCR

What are the possible complications of measels infection?

* Risk of secondary bacterial infection (pneumonia or otitis media) -- 60% measels death are from pneumonia * Encephalitis- 0.5% * 7-10 days after onsent characteristic measels * immune rxn causes demyelination of neurons * more common in older children and adults * Subacute sclerosing panencephalitis (SSPE) * due to persistence of defective measles virus in breain * can't produce M protein needed for release of new virions * affects multiple brain loci (panencephalitis) * may affect personality, behavior, cognition, and memory * myoclonic jerks, blindness, induce coma and death

Rabies diagnosis criteria

clinical picture- brain, corneal tisue show presence of Negri bodies Unique cytoplasmic inclusion body (agregates of viral nucleocapsids) Rabies antigen by immunofluorescence and viral RNA by RT-PCR

Diagnosis Mumps

* Rt-PCR, * syncytia * (+) hemagglutination

* naked RNA virus * fever, sore throat, anorexia, vomitin and vesicular lesions * lesions aroudn soft palate & uvula * may lesions may be present on hands and feet also * usually in children under 10

cocksackie A Virus -- entericvirus group -- picornaviridae family

* enveloped RNA virus * transmitted in aerosols * most frequent cause fatal acute RT infections worldwide * no hemagglutinin * Invations RT epithelium * Infects children younger than 2 * bronchiolitis (mucus plugs, hyperinflation lungs) * pneumonia

Respiratory Sunctial Virus (RSV)- pneumovirus-- paramyxoviridae

* naked RNA double layered capsid, segmented genome * diarrhea in children * Viral ISVP infect and replicate in GI columna epithelial cells (shortening and blunding microvilli) * disruption enterocyte tight junctions * fatal in malnourished or dehydrated infants

Rotavirus- Reoviridae

Describe the difference between genetic shift and genetic drift. Which occur in Influenza A and B?

Genetic shift is when a cell is infected by 2 viral strains simultaneously, usually human and animal strains. This results in a hybrid virus. This only occurs in Influenza type A Genetic drift is annual recombination that occurs for better fitness in both Influenza A and Influenza B.

What are the diagnostic critera for toroviruses?

electron microscope and immuno-based methods

Patient presents with the symptoms shown in the image. The virus is a naked RNA virus and it was acquired through the fecal/oral route. What virus is responsible for the disease and what are the diagnositc criterai?

Hepatitis A virus _Diagnosis_: symptoms, fecal/oral serology, increased ALT/AST/AP & bilirubin

* Enveloped RNA virus withe segmented genome * Replicates in nucleus, but is put together in cytoplasm * Can only infect humans * annual epidemic * infect URT adn LRT (symptoms due to INF & cytokines) * Damages epithelial ciliated and mucus-secretign cells * fever, malaise, headache, myaglias, nasal discharge, and cough

Influena Virus B-- orthomyxoviridae

Which group of people are of paricular concern for HepE infection? What is the diagnositc criteria for HepE?

pregnant women in their 3rd trimester (25% mortality) Diagnosis: symptoms, fecal oral, serology, increased ALT/AST/AP & bilirubin

Name the virus responsible for this clinical presentation. What additional criteria are important for diagnosis?

Poliovirus-- Enteric group-- Picornaviridae family Diagnosis: culture, serology, and immuno-based methods

* naked RNA, segmented virus * Transmitted from the bite of the tick Dermacentor andersoni * 3-6 day incubation, followed by "saddleback fever" (fever, no fever, fever) * Flu symptoms - headache, myalgia, arthralgia, fatigue * Leukopenia involving both neutrophils & lympocytes

Colorado Tick Fever --Coltivirus (Reoviridae)

Diagnosis of Colorado Tick Fever (Coltivirus)

viral antigens on RBC using serolgy

* enveloped RNA virus * usually aympromatic * more of a problem to livestock than to humans * can cause crippling arthritis

Chikungunya--Alphavirus--Arbovirus

* enveloped RNA viruscommon in SE Asia, Central &South America * mild in children (low fever, fatigue, runny nose, cough) * severe back and joint aches in adults * symptoms 2-3 days (occasionally fatal) * bleeding from nose, mouth, GI during 2nd infection * transmitted by Aedes mosquito

Dengue--Flavivirus (arbovirus)

Why is the second infectin of Dengue more severs?

* non-neutralizing antibody * memory T cells become activated * initiates release cytokines & inflammation * results in weakening and rupture of the vasculature

Dengue diagnosis

symptoms who live or have been to vrus area RT-PCT

* enveloped RNA virus * mosquito-borne, mostly in Africa & South America * sudden, high fever, myalgia, headache, jaundice, black vomit * 3-6 incubation-- mortality 50%

Yellow Fever-- Flavivirus (arbovirus)

* enveloped RNA virus * mosquito borne, restricted to North America * South, Central, and Western States * flu-like illness and encephalitis (10% mortality)

St. Louis encephalitis --Flavivirus--(arthovirus)

Diagnosis St. Louis Encephalitis

immuno-based, RT-PCR

* enveloped RNA virus * tick-borne-- transmitted quickly (5-10 minutes) * aseptic meningitis or encephalitis * fever, headache, vomitin, weakness, confusion, seizures

Powassan Virus -- Flavivirus-- (arbovirus)

Diagnosis Powassan virus

serology of blood and CSF or RT-PCR

* enveloped RNA virus * spread by Aedes mosquitos * causes microcephaly and other brain defects in the fetus * causes mild fever, rash joint/muscle pain, headache in adults

Zika Fever Virus -- Flavivirus (arthovirus)

An infant is born with the condition depicted in the image. What is the name of this condition? What is the likely viral cause? How is this virus diagnosed?

microcephaly Zika Fever Virus Diagnozed via blood and urine tests

* RNA enveloped virus * transmitted by mosquitos (birds are resevoir) * fever-- can cause miningoencephalitis

West Nile Virus-- Flavivirus

How is West Nile Virus Diagnosed?

RT-PCR for viral RNA

* RNA enveloped virus * spread via blood & sexual fluids * can cause chronic cirrhosis or liver cancer * rarely causes acute jaundice

Hepatitis C --Flavivirus

Diagnostic Criteria for Hepatitis C

* symptoms, blood/sex serology, increased ALT/AST/AP & bilirubin

* enveloped RNA virus * might regulate AIDS progression & non-Hodgkin lymphoma

GB virus C -- flavivirus diagnosis by RT-PCR for viral RNA

* RNA enveloped virus * one of 5 childhood exanthems * transmitted via repiratory droplets * in 14-21 days, runny nose, cough, painless red spots on roof of mouth * spots merge into blush over back of throat * rash on face and neck that lasts about 3 days * adults complain of joint pain * can cause miscarriage, stillbirth, or sever birth defects

Rubella --Rubivirus

What is the classic triad for congenital rubella syndrome? When is the fetus most susceptible to rubella?

* cardiac abnormalities, cataracts, deafness * sometimes a blueberry muffin rash * most susceptible during first 16 weeks of pregnancy

Diagnostic criteria for Rubella?

* Based on typical clinical symptoms * definite diagnosis necessary durign pregnancy * measuign levels of antibodies in the blood, or searcing for RNA genome

* enveloped RNA virus * spread by inhalation of infected rodent urine aerosois * petechial hemorrhagic lesions and bleeding of gums * cardiopulmonary symdrome * later interstitial pulmonary edema, respiratory failure

Sin Nombre virus -- hantavirus-- Bunyaviridae

* enveloped RNA virus * transmitted through exposure to fresh mouse urine, droppings, saliva or nest * febrile illness with flulike myalgia * (~10%) meningeal illness 10 days after initial illness

Lymphocytic Choriomeningitis-- Arenaviridae

Diagnosis Lymphocytic Choriomeningitis

Recent travel to endemic areas, serology, RT-PCR

* enveloped RNA virus * endemic to West Africa * most asymptomatic or mild, * can cause moderate to severe hemorrhagic fever * 1-3 week incubation, fever, headache, muscle and join pain * pharyngitis, vomiting, diarrhea, increast ALT/AST and hematocrit

Lassa Fever-- Arenaviridae

Diagnosis of Lassa Fever

* Recent travel to endemic areas, serology and RT-PCR

* RNA enveloped virus * transmitted in blood, semen, and vaginal secretions * transmitted transplacentally to fetus, mother's milk to babies * great majority in sub-Saharan Africa and Asia * destruction of lymphocytes-- immune supression * susceptible to opportunistic infection * fever, rashes, swollen lymph nodes possible within a few weeks

HIV-- retroviridae

Explain the HIV Pathogenesis

* Infection begins with binding of viral gp120/gp41 with the CD4 * co-receptor CCR5 is involved * CCR5 deficient people are resistant to HIV * HIV genome in chromosome * provirus transcriped to a lengthy RNA, prrocessed to several mRNA * Retrovirus but out or spread celltocell through synctia * synctia are fragile an enhave cytolytic activity of virus

What are common opporunistic infections often experienced by AIDS patients? What is the criteria to switch from HIV+ to AIDS?

* cancers * CNS effects- memory loss, ataxia, cognition, dementia * Opportunisitc infections: Kaposi's sarcome (HHV-8), lymphomas, p.jiroveci, MAC, CMV * CD4 T cell is \<200 micro liters & viral load is \> 75k/ml

HIV Diagnosis

* By ELISA, but no antibodies in first 1-2 months * p24 antigen appears much sooner * new generation ELISAs target HIV-1, HIV-2, and p24 antigen * RT-PCR can detect (and quantify) viral genome sooner

HIV Treatment

* Antiretroviral therapy (ART) for halting progress to AIDS * regardless of CD4+ count * viral RT fusion proteins, and integrase are drug targets

* enveloped RNA virus * Immortalize or transform host cells * transmission via milk & blood * may cause adult leukemia * ~30 yr latency * tat sequences in cancers

Human T-cell lympotropic virus -- retroviridae

Human T-cell Lymphotropic Virus

Screening by ELISA and confirmation by Western

* circular RNA virus that requires HepB capsid * causes cell death of hepatocytes * common in Africa and South America * intensifies Hep B infection

Hep D or Delta Virus

Hep D diagnosis

serology for antibodies and delta antigen