Virology Flashcards
Name the general features of viral structure
Naked (nonenveloped) virus with icosahedral capsid
Enveloped virus with icosahedral capsid
Enveloped virus with helical capsid
Bacteriophage
What are the main components of naked (nonenveloped) virus with icosahedral capsid.
Capsid and nucleic acid
What are the main components of enveloped virus with icosahedral capsid
Surface protein, lipid bilayer, capsid, nucleic acid
Name the main components of enveloped virus with helical capsid
Surface, lipid bilayer, helical capsid with viral RNA
What are the main components of bacteriophage
Capsid, nucleic acid, collar, core, helical sheath, base plate, spikes
What are the viral genetics definitions
Recombination, reassortment, complementation, phenotypic mixing
Exchange of genes between 2 chromosomes by crossing over within regions of significant base sequence homology
Recombination
What is reassortment
When viruses with segmented genomes (eg influenza virus) exchange genetic material. For example the the 2009 H1N1 influenza this was a pandemic emerged via complex viral reassortment of genes from human swine and avian viruses
When 1 of 2 viruses that infect the cell has a mutation that results in a nonfunctional protein, the nonmutated “complements” the mutated one by making a functional proteins that serves both viruses
Complementation
Give examples of complementation
Hepatitis D virus requieres the presence of replicating hepatitis B virus to supply HBsAg, the envelope protein for HDV
Occurs with simultaneous infection of a cell with 2 viruses. For progeny 1, genome of virus A can be partially or completely coated (forming pseudovirion) with the surface proteins of virus B. Type B protein coat determines the tropism (infectivity) of the hybrid virus. Progeny from subsequent infection of a cell by progeny 1 will have a type A coat that is encoded by its type A genetic material
Phenotypic mixing
Regard their genetic material what are the infective and non infective virus
Naked nucleic acids of most dsDNA viruses (except pox viruses and HBV) and + ssRNA viruses are infectious.
Naked nucleic acid of negative strand ssRNA and dsRNA viruses are not infectious.
Why the negative strand ssRNA viruses and dsRNA are not infectious
Because they lack the required polymerase to replicate
How virions of negative strand ssRNA transcribe negative strand to positive
Viruses carry RNA dependent RNA polymerases to transcribe
What are the characteristics of DNA viruses
All have dsDNA genomes like our cells except parvoviruses (ssDNA). All are linear except papilloma negative polyoma negative and hepadnaviruses (circular)
What are the characteristics of RNA viruses
All have ssRNA genomes except Reoviridae (it’s dsRNA). They can be + stranded, negative or segmented
What are the RNA viruses + stranded (mRNA)
Retro, toga, flavi, corona, hepe, calici and picornaviruses.
What are the RNA viruses with negative stranded
Arena, bunya, paramyxo, orthomyxo, filo, and rhabdoviruses.
What are the RNA viruses that are segmented
Bunya, Orthomyxo, Arena and reoviruses
Describe the characteristics of viral envelopes
Enveloped viruses acquire their envelopes from plasma membrane when they exit from cell. Exceptions include herpesviruses which acquire envelopes from nuclear membrane
What are the enveloped DNA viruses have helpful protection
Herpes virus, hepadnavirus, pox virus
All of this kind of viruses (except pox virus) are icosahedral and replicate in the nucleus
DNA viruses
What DNA viruses are envelope
Herpesviruses, poxvirus and hepadnavirus
Describe DNA structure and medical importance of herpes viruses
DS and linear, see herpesviruses entry 🤔
What are the DNA structure and medical importance of poxvirus.
DS and linear (largest DNA virus). Small pox eradicated world wide by use of the live attenuated vaccine. Cowpox (milkmaid blisters). Molluscum contagiosum
Flesh colored Papule with central umbilications keratinocytes contain Molluscum bodies
Molluscum contagiosum
Describe DNA structure and medical importance of hepadnavirus
Partially DS and circular. HBV: Acute or chronic hepatitis. Not a retrovirus but has reverse transcriptase
What is the DNA structure and medical importance of adenovirus
DS and linear. Febrile pharyngitis (sore throat). Acute hemorrhagic cystitis, pneumonia, conjunctivitis (pink eye) Gastroenteritis and myocarditis
What are the DNA viruses without envelope
Adenovirus, papillomavirus, polyomavirus, parvovirus.
What are the DNA structure and medical importance of papilloma virus
DS and circular. Warts, cancer (cervical, anal, penile or oropharyngeal) serotype 1,2,6 11 associated with warts and 16, 18 with cancer
What are the DNA structure and medical importance of polyomavirus
DS and circular. JC virus progressive multi focal leukoencephalopathy in immunocompromised patients. BK virus transplant patients commonly targets kidney
What is the DNA structure and medical importance of parvovirus
SS and linear (smallest DNA virus; parvus=small). B19 virus aplastic crises in sickle cells disease. Slapped cheek rash in children (erythema infectiosum, or fifth disease) infects RBC precursors and endothelial cells causes RBC destruction hydroplane fetails and death in fetus, pure RBC aplasia and rheumatoid arthritis like symptoms in adults
What kind of virus is herpes virus
Enveloped DS and linear viruses. Recent data suggest both HSV1 and HSV2 can affect both genital and extragenital areas.
Route of transmission, clinical significance of herpes simplex virus 1
Respiratory secretions, saliva. Gingivostomatitis, keratoconjintivitis herpes labialis (cold sores) herpetic whitlow in finger, temporal lobe encephalitis, esophagitis, erythema multiforme. Responsible for a growing percentage of herpes genitalis
Where can herpes simplex virus 1 can stay as latent way
In trigéminas ganglia.
What is the most common cause of sporadic encephalitis and how is manifested
Herpes simplex virus 1. Can present as altered mental status, seizures and/or aphasia
Route of transmission and clinical significance of herpes simplex virus 2
Sexual contract, perinatal. Herpes genitalis, neonatal herpes. Viral meningitis is more common with HSV2 than with HSV1.
Where does herpes simplex 2 live in a latent way
In sacral ganglia
Transmission and clinical significance of varicella zoster virus
Respiratory secretions contact with fluid from vesicles. Varicella zoster (chickenpox, shingles, encephalitis pneumonia) Most common complication of shingles is post herpetic neuralgia
Where does varicella zoster virus (HHV3) used to live in a latent way
In dorsal root or trigéminas ganglia; CN V1 branch involvement can cause herpes zoster ophtalmicus
Transmission, clinical significance of epstein Barr virus (HHV-4)
Respiratory secretions, saliva also called kissing disease (common in teens young adults). Mononucleosis is the clinical significance but also associated with lymphoma (eg endemic Burlington lymphoma (especially Asian adults) lymphoproligerative disease in transplant patients)
Describe mononucleosis
Fever hepatosplenomegaly pharyngitis and lymphadenopathy (especially posterior cervical nodes). Avoid contact sports until resolution due to risk of splenic rupture
What cells infect epataron Barr
CD 21
What test is positive in epataron Barr infection describe
Positive monospot test. Heterophobia antibodies detected by agglutination of sheep or horse RBC.
What happens if mononucleosis receive amoxicillin for presumed strep pharyngitis
Can cause maculopapular rash
Transmission and clinical significance of CMV (HHV-5)
Congenital, transfusion, sexual contact, saliva, urine, transplant. Infection in immunocompromised especially pneumonia in transplant patients; esophagitis, AIDS retinitis that cause: hemorrhage cotton wool exudates, vision loss. Congenital CMV
Epstein Barr has a specific characteristic in microscopic view
Infected cells have characteristic owl eye intramuscular inclusions. CMV live latente in mononuclear cells
Transmission and clinical significance of herpes viruses 6 and 7
Saliva, rosella infantum (exanthem subitum) high fevers for several days that can cause seizures, followed by diffuse macular rash (starts on thunk then spreads to extremities) usually seen in children less two years
Transmission and clinical significance of herpes virus 8
Sexual contact. Kaposi sarcoma (neoplasm of endothelial cells) seen in HIV/AIDS and transplant patients. Dark violaceous plaques or nodules representing vascular proliferations. Cas also affect GI tract and lungs
Name the diagnosis technique of HSV identification
PCR of skin lesions is test of choice
CSF PCR for herpes encephalitis
Tzanck test (outdated) a smear of an opened skin vesicles to detect multinucleated giant cells
And cow dry A inclusions
Where are seen multi nucleated giant cells and intranuclear eosinophilic Cowdry A
HSV1, HSV2 and VZV
Receptors of this virus: CMV, EBV, HIV, parvovirus B19, rabies, rhinovirus and Sars cov 2
CMV: integrins (heparan sulfate)
EBV: CD21
HIV: CD4, CXCR4,CCR5
Parvovirus B19: P antigen on RBC
Rabies: Nicotinic AChR
Rhinovirus: ICAM-1
Sars cov 2: ACE2
Name the 16 kind of RNA viruses
Reoviruses, picornaviruses, hepevirus, calicivoruses, flaviviruses, togaviruses, matonaviruses, Retroviruses, coronaviruses, orthomyxoviruses, paramyxoviruses, Rhabdoviruses, filoviruses, arenaviruses, bunyaviruses, deltaviruses
Name the nonenveloped RNA viruses
Reo picorna hepe y calicivoruses
Haga ya the RNA structure capsid symmetry and medical importance of
DS linear, multi segmented , icosahedral double capside and rotavirus important cause of diarrhea in young children may be fatal
Envelope, RNA structure, capsid symmetry of picornaviruses
No envelope, rna SS positive linear, icosahedral
What are the medical virus that are picornaviruses and their diseases
Poliovirus - polio Salk Sabin vaccine IPV/OPV
Echovirus - aseptic meningitis
Rhinovirus- common cold
Cocsackievirus- aseptic meningitis; herpqngina (mouth blisters, fever); hand foot and mouth disease myocarditis pericarditis.
HAV acute viral hepatitis
Hepe virus envelope, RNA, capsid Simmetry
No envelop, RNA SS + linear capsid icosahedral,
Name hepevirus
HEV
Calciviruses envelope RNA capsid simmetry and medical importance
No envelope, SS + linear, icosahedral, norovirus- viral gastroenteritis
Flaviviruses envelop, RNA, capsid simmetry
Yes, SS+ linear icosahedral
Name flaviviruses and their disease
HCV, yellow fever, dengue, West Nile virus- miningoencephalitis, acute asymmetric flaccid paralysis
Zika virus
Togaviruses envelope RNA structure capsid simmetry
Yea, SS+ linear, icosahedral.
Toga crew - name the togaviruses
Chikingunya virus (co-infection with dengue virus can occur) Rubella, eastern and western equine encephalitis
Matona virus envelope RNA structure, capsid simmetry, medical importance
Envelope yes, SS+ linear icosahedral cause rubella
Retroviruses envelope RNA structure, capsid simmetry
Yes envelope, SS + linear, icosahedral (HTLV) and conical (HIV)
Clinical importance of retroviruses
Have reserve transcriptase, HTLV T cell leukemia, HIV AIDS
Coronaviruses envelope, RNA structure, capsid simmetry and clinical importance
Envelope yes, SS linear +, helical. Common cold Sars, covid-19, MERS
Orthomyxoviruses enveloped, RNA structure, capsid symmetry, clinical importance
Envelope yes, SS- linear multi segmented, helical, influenza virus
Paramyxoviruses envelope, RNA structure, capsid symmetry, medical importance.
Yes envelope, SS negative linear, helical, parainfluenzae croup, RSV bronchiolitis in babies, Measles, Mumps.
Rhabdoviruses enveloped, RNA structure, capsid simmetry
Yes envelope, SS negative linear, helical, rabies
Filoviruses envelope, RNA structure, capsid simmetry, medical importance,
Yes envelope, SS negative linear, helical, cause Ebola/ Marburg hemorrhagic fever often fatal
Arenaviruses, envelope RNA structure, capside simmetry and clinical importance
Yes, SS + and negative circular multisegmented, helical. LCMV lymphocytic choriomeningitis virus, Lasda fever encephalitis- spread by rodents
Bunyaviruses enveloped, RNA structure, capsid simmetry and clinical importance
Yes, SS negative circular multisegmented, helical, California enchephalitis, sandfly Rift valley fevers, Crimean Congo hemorrhagic fever, hantavirus, hemorrhagic fever, pneumonia
Delta virus envelope, RNA structure, capsid simmetry, medical importance
Yes envelope, SS negative circular, uncertain, HDV
What picornaviruses are enteroviruses and can cause aseptic viral meningitis
Poliovirus, echovirus and coxsackievirus
Peculiarities of rhinovirus
Is a picornavirus that doesn’t infect GI (is not a enterovirus) because tus acid labile destroyed by stomach acid. Is cause of common cold more than 100 serologic types
Is the most important global cause of infantile gastroenteritis. Major cause of acute diarrhea in the United States during winter specially in day care centers kindergartens
Rotaviruses
What does rotavirus cause in Villous
Villous destruction with atrophy leads to decrease absorption of Na and loss K
CDC Recomemdations and exceptions of rotavirus vaccine
To all infants except those with a history of intussuception (rare adverse am effect of rotavirus vaccination) or SCID (severe combined immunodeficiencies)
Describe de influenza viruses infection and diss ease infections
Influenza viruses are orthomyxoviruses that contain hemagglutinin (binds sialic acid and promotes viral entry) and neuraminidase (promotes progeny virion release) antigens
What it’s a imminent risk of influenza virus infection
Bacterial superinfection (most commonly S aureus, S pneumoniae and H influenzae.
What is the influenza viruses treatments and it’s mechanism
Supportive +/- neuraminidase inhibitor (eg oseltamivir and sanamivir)
How is the influenza viruses vaccine
Reformulated vaccine (the flu shot) contains viral strains most likely to appear during the flu season due to the virus rapid genetic change
What are the kinds of vaccines for influenza viruses
Reformulated already described, killed viral vaccine is most frequently used. Live attenuated vaccine contains temperature sensitive mutant that replica Rea un the nose but not un the lung administered intranasally
What is genetic antigenic shift
Infection of 1 cell by 2 different segmented viruses (eg swine influenza and human influenza viruses) RNA segmented reassortment dramatically different virus ( genetic shift) major global outbreaks (pandemic)
What is genetic antigenic drift
Random mutation in hemagglutinin (HA) or neuraminidase (NA) genes conducts minor changes in HA or NA protein (drift) occur frequently conducts to local seasonal outbreaks (epidemics)
What are the two genetics antigenic a changes that happen in influenza viruses infection
Genetic antigenic shift and drift
What is the other name of rubella
Herman 3 day measles.
Describe rubella
Fever postauricular and other lymphadenopathy arthralgias and fine maculopapular rash that starts on face and spreads centrifugally to involve thunk and extremities. Cause mild disease in children but serious congenital disease
What are the congenital rubella findings
Include classic triad of sensorineural deafness, cataracts, and patent ductus arteriosus. Blue berrry muffin appearance may be seen due to dermal extra medullary hematopoises
What are the children’s disease of paramyxoviruses
Parainfluenzae (croup) mumps, measles, RSV and human metapneumovirus. All subtypes can cause respiratory tract infection (bronchiolitis pneumonia) in infants. All contain surface F (fusion) protein which causes respiratory epithelial cells to fuse and form multinucleated cells
What is the inmmunoteraphy of RSV paramyxoviruses and what does it do
Palivizumab that is a monoclonal antibody against F protein prevents pneumonia caused by RSV infection in premature infants
Also called croup
Acute laryngotracheobronchitis.
What is the kind of viruses that cause croup (acute laringotracheobronchitis) and how does it work
Parainfluenza viruses. Virus membrane contains hemagglutinin (binds sialic acid and promotes viral entry) and neuraminidase (promotes progeny virion release) antigens.
Name some characteristic of acute laryngotracheobronchitis
Seal like barking cough and and inspiratory stridor. Narrowing of upper trachea and sub glottis leads to characteristics steeple sign on x ray
Usual presentation involves prodromal fever with cough coryza and conjuctivitis then eventually koplik spots followed 1-2 days later by maculopapular rash that starts at the head neck and spreads downward.
Measles rubeola virus
What are koplik spots
Bright red spots with blue white center on buccal mucosa
What is warthin finkeldey giant cells
They are multinucleated giant cells having appearance akin to grape like clusters or mulberry. These are large cells enclosing multiple round regular sized nuclei incounspicuous nucleoli
Name other clinical finding of measles (rubeola) that has a own name
Lymphadenitis with warthin finkeldey giant cells (fused lymphocytes) in a background of paracortical hyperplasia
Name the three possible sequelae
Subacute sclerosis from panencephalitis SSPE personality changes dementia autonomic dysfunction death (accura years later)
Encephalitis (1:1000): symptoms appear within few days of rash
Giant cell pneumonia (rare except in immunosuppressed)
Name the 4 C of measles
Cough
Coryza
Conjuctivitis
C oplik spots
What reduce morbidity and mortality from measles particularly in malnourished children
Vitamin A supplementation
What is the most common cause of measles associated death in children
Pneumonia
Symptoms of mumps virus
Parotitis, orchitis, aseptic meningitis and pancreatitis. Can cause sterility (especially after puberty)
What is the virus type of chikungunya symptoms and diagnosis
Alpha virus/ toga virus
High fever maculopapular rash headache lymphadenopathy and inflammatory poly arthritis arthralgias are more commonly reported (vs dengue) joint swelling is highly specific for chikungunya. Thrombocytopenia leukopenia and hemorrhagic manifestation are less common
Diagnosis: RT-PCR and serology
How is the treatment an prevention of chikungunya
Supportive, steroids or DMARDs for chronic arthritis. Prevention minimize mosquito exposure no vaccine currently available
What is the virus type, symptoms and diagnosis of dengue virus
Flavivirus
Dengue fever: fever, rash, headache, myalgias, arthralgias, retro orbital pain, neutropenia.
Dengue hemorrhagic feber: dengue fever+ bleeding and plasma leakage due tu severe thrombocytopenia and RBC perturbations. Most common if infected with a different serotype after initial infection due to antibody dependent after enhancement of disease. May procúrese to dengue school syndrome, plasma leakage conducts to circulatory collapse
Diagnosis RT-PCR serology
Treatment and prevention of dengue virus
Supportive. Intravascular volumen repleto on or blood transfusion if severe shock.
Prevention: live recombinant vaccine available derived from the yellow fever virus backbone with insertion of genes for the envelope and ore membrane of dengue virus
What kind of viruses are yellow fever virus
Flavivirus (also arbovirus) transmitted by Aedes mosquito bites.
What are the reservoir and symptoms of yellow fever virus and vaccine
Monkey and human.
High fever, black vomitus, jaundice, hemorrhage, backache. May see councilman bodies. Live attenuated vaccine recommended for travelers to endemic countries
What are councilman bodies
Eosinophilic apoptosis globules on liver biopsy
Virus symptoms and diagnosis in Zika
Flavivirus most commonly transmitted by aedes mosquito bites.
Cause conjunctivitis low grade Pyrexia and itchy rash in 20% of cases. Outbreaks more common in tropical and subtropical climates. May be complicated by guillain barre syndrome. Diagnose with RT-PCR or serology. Sexual and vertical transmission occurs
How is the miscarriage or congenital Zika syndrome
Brain imaging shows ventriculomegaly, subcritical calcifications. Clinical features in the affected newborn include. Microcephaly, ocular anomalies, motor abnormalities (spasticity, seizures)
What are the CNS findings in rabies virus. And how is the shape of this virus
Bullet shaped virus. Negri bodies (cytoplasmic inclusions) commonly found in purkinje cells of cerebellum and in hippocampal neurons.
How is the incubation period and post exposure prophylaxis
Long period weeks to month.
In wound cleaning plus immunization with killer vaccine and rabies immunoglobulin. This is a example of passive active immunity
How does rabies virus move in CNS
Travels to the CNS by migrating in a retrograde fashion (via dynein motors) up nerve axons after binding to ACh receptors
How is the progression of rabies disease
Fever malaise agitation photophobia hydrophobia hypersalivation paralysis coma death
How occurs infection
Are more commonly from bat, rancoon, and skunk bites than from dog bites in the United States; aerosol transmission (eg, bat caves) also possible
What kind of virus is Ebola virus and how occur its infection
A filoviruses. Following an incubation period of up to 21 days present with abrupt onset of flulike symptoms, diarrhea vomiting high fever myalgia. Can progress to DIC diffuse hemorrhage shock. Diagnosed with RT-PCR within 48 h of symptoms onset. High mortality rate
How is the transmission of Ebola virus and treatment
Transmission requires direct contact with bodily fluid fomites (including dead bodies) infected bats or primates (apes monkeys); high incidence of health care associated infection. Supportive care no definitive treatment. Vaccination of contacts, strict isolation of infected individuals and barrier practices for health care workers
Are key to preventing transmission
What is the meaning of SARD-CoV2
Severe acute respiratory syndrome coronavirus 2
What is the kind of the virus of sars cov 2
Positive ssRNA
There are two variants of symptoms of sars cov 2 common and more specific describes
Common: fever myalgia headache nasal congestion sneezing, cough, sore throat, GO symptoms )nausea diarrhea )
More specific: anosmia (loss of smell) dysgeusia (altered taste)
What is the most frequent serious manifestation and complication of sars cov 2
Pneumonia is the most frequent serious manifestation but complications can include acute respiratory distress syndrome, hypercoagulability (thromboembolic complications including DVT, PE, stroke) myocardial injury neurologic sequelae shock organ failure death
Risk factor for severe illness of sars cov 2
Pre existing medical comorbisities (obesity hypertension)
How is diagnose sars cov 2
Nucleic acid amplification test (most commonly RT-PCR) test detecting viral antigen are rapid and more accesible but typically less sensitive NAATs
How is the entrance and pathophysiology in sars cov 2
Host cell entry occurs by attachment of viral spike protein to ACE2 receptor on cell membranes. Anti spike protein antibodies confer immunity. Vaccination (primary series and booster) induces humoral and cellular immunity which decreases risk of contracting or transmitting the virus and confers high rates of protection against severe disease and death.
Name some therapies against sars cov 2
Virus specific options include antivirals (remdesubir, nirmatrelvir-ritonavir, molnupiravir) and antibody based therapies. Therapies directed against the inflammatory response include dexamethasone and immunomodulators (baricitinib, IL-6 pathway inhibitors)
