Virus Flashcards
Name the family of virus associated with (+) ssRNA. Name 2 ssRNA viruses.
picornavirus. Hepatitis A and Rhinovirus
What is the mode of transmission for HepA? Rhinovius? What is the associated disease for each?
Hepatitis A- Oral anal Rhinovirus aka Common Cold- respiratory droplets
Name the family of virus associated with dsDNA. Name 4 dsDNA viruses.
Herpesvirus. cytomegalovirus, HSV-1, HSV-2, Epstein Barr
What disease is caused by cytomegalovirus and how is it transmitted?
Mononucleosis syndrome Respiratory droplets
What disease is caused by HSV-1 and how is it transmitted?
gingivostomatits (child), herpes labialis (adult) Oral (saliva)
What disease is caused by HSV-1 and how is it transmitted?
Genital herpes Genital (sexually transmitted)
What disease is caused by Epstein Barr and how is it transmitted?
Infectious Mono Respiratory Droplets
Name the family of virus associated with (-) ssRNA. Name 3 ssRNA viruses.
Paramyxovirus. Measles, Mumps, Respiratory synctial virus
What disease is caused by Measles and how is it transmitted?
Measles (Rubeola) Respiratory droplets
What disease is caused by Mumps and how is it transmitted?
Rubella (german measles) Respiratory droplets
What disease is caused by Respiratory syncytial virus and how is it transmitted?
Bronchiolitis and pneumonia in infants Oral-anal
What is the genome for Hepatitis C? Family? Transmission? Disease?
SS-RNA Family- Flavivirus Transmission- Blood borne Disease- Hep C
What is the genome for Hepatitis D? Family? Transmission? Disease?
ss-RNA Family- Delta virus Transmission- Blood Borne Disease- Hepatitis D (can only infect cells that were previously infected with Hep B
What is the genome for Hepatitis E? Family? Transmission? Disease?
SS-RNA Family- Herpeviradae Transmission- oral-anal Disease- Hepatitis E
What is the genome for Influenze? Family? Transmission? Disease?
SS-RNA Family- Orthomyxovirus Transmission- respiratory droplets Disease- influenza NOTE: genome is segmented (contributes to antigenicity)
What is the genome for HIV? Family? Transmission? Disease?
SS-RNA Family- retrovirus Transmission- blood borne, genital Disease- AIDs
What is the genome for Hepatitis B? Family? Transmission? Disease?
DS-DNA Family- hepadnavirus Transmission- blood borne Disease- Hep B
What is the genome for Adenovirus? Family? Transmission? Disease?
DS-DNA Family- adenovirus Transmission- respiratory droplets Disease- pharyngitis, pneumonia , conjunctivitis
What are reoviruses? What is the genome of the viral protein?
nonenveloped and have icosahedral capsid composed of an outer and inner protein shell containing segmented, DOUBLE STRANDED RNA
What do reoviruses contain in order to successfully multiply in the human host? Why?
RNA dependent RNA polymerase Required because human cells lack this enzyme and therefore cannot synthesize mRNA from an RNA template.
What are two important reovirus family that cn cause human disease?
Rotavirus aka gastroenteritis virus type B Coltivirus
Rotavirus aka gastroenteritis virus type B causes the most common what? How is it spread?
the most common cause of gastroenteritis in kids (2 under). Spread via fecal oral route. Can survive the acidic conditions in the stomach after which it is adsorbed in the small intestine.
What is the alternative name for Coltivirus? What does this cause?
Colorado tick fever virus. Colorado tick fever
What is a self limiting disease often referred to as the 24 hour or intestinal flu? Does influenza virus cause this?
Viral gastroenteritis No
What are the characteristics of viral gastroenteritis? What is the recovery time?
Vomiting, low grade fever, diarrhea, metabolic consequences of water and electrolyte loss. Recovery time is 12-24 hours.
What are the RNA nonenveloped virus families? (3)
Picornvirus Reovirus Caliciviruses
List all the picornviruses (5)
Poliovirus, coxsackie A & B viruses, Rhinovirus, Hep A virus
What is the only member of the paramyxovirus family that lacks the envelope glycoproteins hemagglutinin and neuraminidase?
RSV (respiratory syncytial virus)
What does RSV commonly cause?
Respiratory tract infection epidemics in the winer ranging from common cold to pneumonia and bronchiolitis. Severe presentations occur in infants and the immunocompromised.
What kind of envelope does the paramyxovirus have?
Covered with spikes which contain either hemaaglutinin or neuraminidase or a fusion protein that causes cell fusion
Is there a vaccine for RSV? Treatment?
No Yes, use aerosolized ribavirin in severe cases
What are antigenic drift?
major changes based on reassortment of genome pieces
What are antigenic shift?
minor changes based on point mutations
What do Parainfluenza viruses cause? Where is this infection limited to?
Croup (acute laryngotracheobronchitis) and pneumonia in children and resembles the common cold in adults. Respiratory tract (upper respiratory tract disease is most common)
What kind of envelope used for Parainfluenza viruses?
Envelope has surface spikes. Consists of hemagglutinin, neuraminidase, and fusion proteins.
How are Parainfluenza viruses transmitted?
These viruses are transmitted by respiratory droplets and direct contact.
Interstitial pulmonary inflammation is most characteristic of?
Viral pneumonia
List the general characteristics of paramyxovirus.(3) What virus do they resemble?
negative sense ssRNA Enveloped Contain and RNA dependent RNA polymerase Resembles orthomyxoviruses except they are usually larger in size and have different surface proteins as well as segmented genomes
What is the hallmark of viral infection? Describe.
Cytopathic effect (CPE)- this change starts with alterations in cell morphology, derangement of cell function and lysis and death of cells.
Can all viruses cause CPE?
NO
Give examples of CPE
necrosis, hypetrophy, giant cell formation, hypoplasia , metaplasia, altered shape, detachment from substrate, lysis, membrane fusion, altered membrane permeability, apoptosis
Name the viruses that belong to the Herpes virus family. (8)
HSV-1, HSV-2, VZV, Epstein Barr, Human Herpesvirus types 6,7,8 and cytomegalovirus
Where do herpes viruses replicate?
nucleus
How do herpesvirus obtain their envelope?
Herpesvirus are the only virus to obtain their virion envelopes by budding from the host nuclear or golgi membrane, not the host plasma membrane.
What is the hallmark of herpesvirus infections?
the ability of the virus to establish latent (or silent) infections that then persist for the life of the individual.
Where do each of these remain latent in the body? HSV1 HSV2 VZV CMV EBV
HSV1 - trigeminal ganglion HSV2- sacral ganglia VZV- dorsal root and cranial nerve ganglia CMV- nuclei of the cells in the endotheliium of the arterial wall and in T lymphocytes EBV- resting memory B lymphocytes
what are the 3 viruses that cause vesicular rash?
HSV 1 & 2, VZV
What herpes virus has oncogenic potential? Name the associated cancers to each virus.
Epstein Barr - Burkitt lymphoma, nasopharyngeal carcinoma Human herpesvirus type 8- Kaposi sarcoma
Name the DNA enveloped viruses
Herpes virus Poxvirus Hepadnavirus
What is prion disease or transmissible spongiform encephalopathies (TSEs)?
a family of rare progressive neurodegenerative disorder that affects both humans and animals. Usually rapidly progressive and always fatal.
what are prions?
the causative agent for TSE. Abnormal pathogenic agents transmissible and are able to induce abnormal folding of specific cellular proteins called prion proteins, predominantly found in the brain
Special characteristics of prions?
resistant to proteases, heat, radiation and formalin treatments
What is a capsid?
A capsid is the protein coat that encases either single stranded/double stranded DNA or RNA (never both)
The combination of nucleic acid and protein capsid is called?
Nucleocapsid.
What do viruses not have?
no cells, not capable of reproducing independently, no nucleus, no organelles, cannot be seen in microscope
What are viroids? Do they cause human diseases?
Consist solely of a single molecule of circular RNA without a protein coat or envelop. No, seen in plants.
Primary herpetic gingivostomatits occurs in children under what ages?
10 & under
what symptoms do you see in acute herpetic gingivostomatitis? what is the most serious problem associated?
acute symptoms: fever, irritability, cervical lymphadenopathy, fiery red gingival tissues, painful ulcers in mouth serious: dehydration due to child not wanting to eat or drink because of pain
Adult recurrence of HSV-1 is also known as? Where does it remain latent? What happens when it reactivates? What is the most common site of recurrence?
also known as Herpes Labialis or cold sore Trigeminal ganglion Reactivation causes localized paresthesia in the lip before the appearance of cold sore. Most common site: vermillion border of the lip
What are some complications with HSV-1 infection?
eye acute encephalitis skin infections- herpetic whitlow and erythema multiforme
How can you diagnose HSV infection?
Tzank prepartions. Look for tzank cells.
What is temperate phage?
bacteriophage capable of replication by alternate method in which the phage genome is incorporated in to the bacterial chromosome, it persists through many cell divisions of the bacterium without destroying the host.
virulent phage
differs from temperate phage because it lyses and kills host bacterial cells
What kind of phage contains temperate bacteriophage?
lysogenic bacterium
What is lysogenic conversion?
the alteration of a bacterium to a virulent strain by the transfer of a DNA temperate bacteriophage.
What is a integrated viral DNA?
prophage
what phage infects e.coli?
prophage
what are plasmids?
extrachromosomal, double stranded, circular DNA molecules that are capable of replication independently of the bacterial chromosome
what is transduction?
transfer of DNA from a donor cell to a recipient cell with the DNA packaged within a bacteriophage Transduction is the process by which foreign DNA is introduced into a cell by a virus or viral vector
what is transformation?
gene transfer resulting from the uptake by a recipient cell of a naked DNA from a donor cell Viral transformation is the change in growth, phenotype, or indefinite reproduction of cells caused by the introduction of inheritable material.
what is conjugation?
exchange of genetic material from one bacterial cell (donor) to another (recipient) by the close association of the two cells and the passage of the bacterial chromosome or plasmid through the F pilus.
What are some characteristics of retrovirus? How are they distinguished from other RNA viruses?
single stranded, postiive sense RNA molecules contain RNA dependent DNA polymerase (reverse transcriptase) They have a unique ability to replicate through a DNA intermediate using an enzyme reverse transcriptase
How does reverse transcriptase work?
uses the viral RNA as a template to create viral DNA which is then incorporated into the host DNA to form a provirus. this provides the template for viral RNA synthesis by host derived mechanisms.
What are two main types of human lymphotrophic retroviruses?
Lentivirus Oncovirus
What are the two types of Lentivirus?
HIV-1 and HIV-2; both causes AIDS
What are two types of oncovirus?
HTLV-1; adult T cell leukemia HTLV-2; causes myelopathy
For RNA virus, where does transcription occur? What are the exceptions?
Occurs in cytoplasm except for retrovirus and influenza viruses
For RNA virus, what does transcription involve? Exceptions?
RNA dependent RNA polymerase; exception are retroviruses because they use reverse transcriptase (RNA dependent DNA polymerase)
For DNA viruses, transcription occurs where? Involves what enzyme?
Nucleus; host cell DNA dependent RNA polymerase
Name the associated virus to the site of latency 1. trigeminal ganglia 2. sacral ganglia 3. Resting memory B lymphocytes 4. T lymphocytes 5. dorsal root and cranial nerve ganglia
- HSV-1 2. HSV-2 3. EBV 4. Cytomegalovirus 5. VZV
What is the primary disease for EBV? Secondary diseases (4)
Primary- infectious mono Secondary: Burkitt’s lymphoma, B-cell lymphoma, Hairy leukoplakia, nasopharyngeal carcinoma
What is the primary disease for VZV? Secondary disease?
Primary- chicken pox Secondary- shingles
What is the primary disease for HSV-1? Secondary diseases (3)?
Primary- gingivostomatitis Secondary- cold sore, keratitis, encephalitis
What are the family of RNA viruses that have no envelope?
picornavirus, reovirus, calcivirus, hepeviridae
What are the family of DNA viruses that have no envelope?
Papovaviridae (Human Papilloma virus), parvoviridae, adenoviridae,
What are adenovirus characteristics? (5)
naked (non-enveloped) medium sized virus composed of icosahedral nucleocapsid double stranded linear DNA genome Have glycoproteinaceous projection (spikes) - composed of hemagglutinin proteins
What is the general virus structure? (5)
virion capsid nucleocapsid envelope matrix protein
what is a virion?
infectious, complete virus particle : RNA or DNA and proteins
what is a capsid?
composed of repeating subunits called protomers protects viral genome from extracellular nucleases impart structural symmetry to virion (icosahedral, helical) essential for infectivity of virus provokes host immune response
Naked viruses have no envelope so how does it accommodate to attaching to host cells?
the capsid serves as attachment protein that binds to host cell receptors.
Reoviridae has how many capsid layers? Typically how many layers do most viruses have?
2;1
What is a nucleocapsid?
capsid and nucleic acid
Envelope
a viral membrane, lipid bilayer carrying proteins
What is the matrix protein in virus?
welds the capsid or nucleocapsid to the envelope
Polio virus causes what? What are the primary symptoms of the disease?
Causes poliomyelitis. Initial symptoms are headache, vomitting, constipation and sore throat. Paralysis may follow and is asymmetric and flaccid.
what is flaccid paralysis?
gives rise to limp and floppy muscles that lack firmness due to lack of activity in mm. voluntary control is lost and reduces ability to contract
what is spastic paralysis?
gives rise to muscle stiffness, spasms are spontaneous and uncontrolled
What are the two vaccines for polio? What are the differences between the two? How is it administered?
salk vaccine- inactivated virus given IV sabine vaccine- live, attenuated virus admin orally
Which is the largest and most complex DNA virus family?
Poxvirus
what are the three viruses of medical importance of the Poxvirus family?
smallpox (variola virus) vaccina virus molluscum contagiosum virus
Size of poxvirus?
300nm x 200nm
Where do poxvirus multiply? what are poxvirus associated with?
cytoplasm of host cells (the only DNA virus that replicates here); skin rashes
what is small pox?
acute, highly infectious, often fatal disease that is characterized by high fever, prostration, and vesicular, pustular rash
Poxvirus uses what enzyme? explain why.
DNA dependent RNA polymerase because the virus replicates in the cytoplasm and do not have access to RNA polymerase which is located in the nucleus
Coxsackie group A virus causes what?
- herpangia appear on throat, palate, tongue 2. hand foot mouth disease appear on the buccal mucosa and gingiva
Coxsackie group B virus causes what?
fever and chest pain with headache, fatigue, and aching muscles lasting 4-5 days
Picornavirus characteristics? (3)
non-enveloped, ss stranded positive send RNA with icosahedral capsid
What are three major genes in HIV genome (similar to retrovirus)
env gene- codes for 2 envelope proteins (GP 120, GP 41) pol gene- codes for 3 enzymes gag gene- codes for core proteins
HIV infects and kills what cells? what is the result?
Kills helper CD4 T cells resulting the depression of both humoral and cell mediated immunity
what cell does HIV infect first?
macrophages
Retroviruses have what kind of polarity? Has the same base sequence as?
Positive sense. Same base sequence as mRNA
If a RNA virus has a positive polarity what does this imply? What does it imply for negative polarity?
Since the first step in a viral gene is mRNA synthesis, the positive sense RNA viruses can use their RNA genome directly as mRNA. For those with negative polarity, they must transcribe their own mRNA by using the negative strand as a template and because the cell does not have an RNA polymerase capable of using RNA as a template, the virus carries its own RNA dependent RNA polymerase.
Vaccinia vaccine is for?
VZV; small pox
When a child is diagnosed with chicken pox what is contraindicated for administration?
Aspirin because it can increase the incidence of Reye Syndrome (encephalitis and liver impairment)
What is adenosine arainoside?
suppress the synthesis of VZV and HSV tends to diminish new lesion formation and duration of fever prevents the spread of the virus through viscera
Influenza A is responsible for what?
pandemics and epidemics
What is an epidemic?
occurs more frequently than normal within a population
what is a pandemic?
has a worldwide distribution
what is an endemic?
occurs at minimal levels within a population
What is the disorder with the following symptoms? painful swelling of the parotid
mumps
What is the disorder with the following symptoms? skin rash with Koplik spots
Measles
What is the disorder with the following symptoms? Flu like symptoms and lymphdenopathy followed by a rash on the entire body.
Rubella
What is the disorder with the following symptoms? Inflammation of the pharynx
Pharyngitis
What is the disorder with the following symptoms? High fever (101-102F) that begins suddenly, muscle body aches, chills, tiredness, and sudden onset
Influenza
Order the steps in the replicative cycle of viruses. A. release by budding through host plasma membrane or plasma membrane rupture? B. Replication and viral protein production C. Attachment through a receptor D. Assembly of new virus particles E. Entry via receptor mediated endocytosis or membrane fusion. F. Uncoating triggered by pH changes in endosomes
- C 2. E 3. F 4. B 5. D 6. A
What is the eclipse phase? How long does it last? Is the virus detected at this time?
Lasts 10-12 hours, corresponds to the period during which the input virus becomes uncoated. No infectious virus detected at this time.
What is synthetic phase? When does this typically start?
Corresponds to the time during which new virus particles are assembled.Starts around 12 hours post infection.
what is Latent Period?
During this period no extracellular virus can be detected. After a certain time period, extracellular is detected. Ultimately, production will reach a max plateau level
What does segmented genome mean?
Viruses with segmented RNA genomes can produce at least one protein per segment, sometimes more. Another way to get around the limitation that eukaryotic mRNAs can only encode one protein.
What are the viruses that cross the placenta?
Toxoplasmosis, other (syphilis, varicella, mumps, parvovirus, HIV), rubella, cytomegalovirus, and herpes simplex.
What is the pneumonic for viruses that can cross placenta?
TORCH
What are the viruses that cause respiratory diseases in children? (5)
RSV, parainfluenza virus, rhinovirus, adenovirus
Most common pediatric viral diseases with a rash? (5)
Measles, Rubella, Roseola (HHV6), VZV, Erythema infectiosum
Common viral causes of pharyngitis? (4)
Coxsackie virus A, adenoviruses, orthomyxoviruses (influenza viruses), EBV
Common causes of viral gastroenteritis?
rotavirus (most common cause in children) norovirus and sapovirus adenoviruses and astrovirus (common in adults)
most common cause of mental retardation in the U.S.?
Mental retardation
Causes of common cold
rhinovirus coronavirus coxsackie adenovirus
Common causes of aseptic meningitis?
coxsackie echvirus mumps virus
What are the 5 classic childhood exanthems?
rubella, measles, roseola, fifth disease and chickepox
What is the earliest most prominent and characteristic symptom of rubella?
Lymphadenopathy of the post auricular, occipital, posterior cervical lymph nodes.
What is rubella typically depicted as?
Maculopapular rash that disappears first on the face and neck and quickly spreads to the trunk and upper extremities and then to the legs. Rash lasts 3-5 days.
What is the classic triad of congenital rubella syndrome?
cataracts, heart defects, and deafness
What are interferons?
Gylcoproteins that originate from infected host cells to protect other non-infected host cells.
How are interferons antiviral? What does IFN alpha treat? Toxicity?
Interferons do not directly affect viruses but instead nonspecifically prevent their replication within host cells.
Blocks various stages of viral RNA/DNA synthesis
IFN-alpha treats chronic Hep B and C
Toxicity: neutropenia
Describe the Lytic cycle & lysogenic cycle
Lytic: the process by which phages replicate within the host cell, producing hundreds of new progeny phage, the host cell is ultimately destroyed
Lysogenic: the process by which some phages incorporate theu DNA in host cell chromosome. The integrated DNA is called prophage. Replication only occurs when the host DNA is damaged, excising the viral DNA. The host cell is not damaged.
