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)