RNA viruses Flashcards
- 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
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
- 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
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
- enveloped RNA virus
- 2nd leading cause of cold
- gown better at 33-35, limited to URT
- petal shpaed glycoproteins on envelope
Coronavirus
Diagnositc Criteria RSV
- By RT-PCT or immunofluorescence and EIA
- Presence of viral antigens in nasal wshings or tissue samples
- negative in hemadsorption test
- 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
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
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
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
- 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
What are the diagnositic criteria for Parainfluenza?
- RT-PCR detection viral genome, or seroconversion
- hemadsorption or hemadsorption inhibition, synctia
- lower respiratiory disease
- 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
what is croup?
Subglottal sweiing that may close the airway– steeple sign in x-ray
- 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
- 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
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
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
- 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
- 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)
- 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
- 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
- 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
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
- 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?
- Polio
- Coxsachkie A
- Coxsachie B
- Echo
- 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.
- Morbillivirus: measles (H-hemagglutinin)
- Paramyoxvirus: parainfluenza and mumps (H-hemagglutinin, N-neuraminidase, F-fusion, and G protein)
- 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
