Viruses Flashcards
Meaning of SARS
severe acute respiratory syndrome
Cause of swine flu and avian flu
influenza virus
Are there more existing antibiotic or antiviral agents?
more antibiotic
A viral infection which is likely to be eradicated in the future
poliovirus
What viral infection has already been eradicated globally?
smallpox
What are the two things that started the golden era of virology?
observation of virus with electron microscope and development of cell tissue culture
Name that viruses got after people discovered that it cannot be retained by filtration
filterable agents or filterable viruses
Virus discovery came about when the cause of ____ cannot be explained by the presence of bacteria
rabies
Earliest piece of evidence for viruses
hieroglyph of an Egyptian priest with poliomyelitis
Smallest virus which is approximately 28nm in size
poliovirus
Size of mimivirus
750nm
Refers to the protein core or coat of the virus
capsid
Is poliovirus linear or circular in its viral genome?
linear
Is hepatitis B virus linear of circular in its viral genome?
circular
How many segments does influenza have in its viral genome?
8 segments
What is the characteristics of influenza RNA in terms of sense and number of strand?
minus sense ss
How many segments/molecules does poliovirus viral genome have? What is the sense and number of strand/s of its RNA?
one molecule, plus sense ss
What is the sense of a virus whose RNA can be directly translated by the host ribosome?
plus sense
Explain how retroviruses encode their genome
Its RNA undergoes reverse transcription with an enzyme called reverse transcriptase to make a DNA. This DNA will be transcripted into mRNA which is due for translation into proteins.
Why is it important to consider if a genome is infectious or not when choosing a viricidal agents?
If the viricidal get only damages the viral capsid or envelope and not the nucleic acid, there might be an occurrence of multiplicity reactivation
Is poliovirus infectious or not?
infectious
Refers to the complementary reconstruction of an infectious particle by hybridization of gene pool of inactivated virus.
multiplicity reactivation
Functions to protect nucleic acid from detrimental chemical and physical conditions such as disinfection
viral capsid
Refers to subunits of viral capsids
capsomeres
How many architectural styles/conformations can capsomeres result to?
3
Year when advent of virology was observed
1931
Contribution of Max Knoll and Ernst Ruska in virology
invention of the 1st electron microscope
Do viruses have energy or not?
energy-less: they float around until they encounter a host cell
Occurs when virus takes control of the host cell’s synthetic machinery
replication
Purpose of glycoprotein
viral reception, important for infectivity
Enzyme that facilitates transcription of minus sense RNA to plus sense RNA
RNA-dependent RNA polymerase
Nature of viral genome is important for development of antiviral treatment as it helps in ____
identifying drug targets
Another term for viral particle
virion
Capsomeres are a number of subunits of ______ chains arranged into _______
polypeptide, globular proteins
Exhibits geometric conformation composed of triangular phases
icosahedral
Conformation that resembles the shape of a spring
helical symmetries
Complex capsomere structure of mammalian viruses wherein a proteinaceous structure envelopes the viral genome core can be found in p_____ and r______
poxviruses and rhabdoviruses
Complex structure consisting of capsid head, a tail and fibres
bacteriophages (bacterial viruses)
Capsomeres are held together by this type of intermolecular force
non-covalent - allows release of viral genomes upon dissociation
Do capsomere subunits make up more of the genetic information in viral genome or formation or capsid?
more genetic information in viral genome
Capsomere conformations that form hexons and pentons
icosahedral capsid
Number of hexons and pentons that make up an adenovirus
240 hexons and 12 pentons
Number of hexons and pentons that make up a poliovirus
20 hexons and 12 pentons
What capsid shapes does influenza and mumps viruses have?
helical
(T/F) Viral nucleic acid of helical structures are found at the ridges on the inside of each subunit fills the core.
False, core is hollow
What is the result of the close association between viral nucleic acid and capsid proteins in a helical structure?
nucleic acid is damaged in the disaggregation of capsid after physical or chemical treatments
The viral envelope is a lipidic envelope which came from the _____
host cell
When is the viral envelope added to the virion?
during replication or excision of viral progeny from host cells
Where does the herpes simplex virus gets its envelope from?
host cell nuclear membrane
Where does the influenza virus gets its envelope from?
host cell cytoplasmic membrane
Part of the viral envelope that plays an important serological role
viral proteins
Do proteins on the viral envelope come from the host cell or encoded by viral genome
encoded by viral genome
Are viruses with viral envelopes more or less susceptible to chemical and physical conditions outside the host cell?
more susceptible
Do viruses with viral envelopes persist longer or shorter on organic soil, organic solvents and detergents?
longer
Lipids in viruses are generally _____
phospholipids
Virus-encoded structures responsible for viral infectivity as they recognize the host cell receptor site for viral specificity.
glycoproteins
Glycoproteins in bacteriophages may take the shape of _____
tail fibres
Systemic viral infection that causes vesicular rashes on face, arms and legs
smallpox
Causative agent of smallpox
variola (poxvirus)
Poxvirus from cowpox virus which is used to immunize against smallpox
vaccinia (poxvirus)
Size and structure of adenovirus
icosahedral particles, 80nm in diameter
Causes upper respiratory tract infection which might produce latent infections on tonsils and adenoids
adenovirus
Produced by adenovirus when injected on hamsters, rats or mice
tumours
Structure of herpesviruses
150nm, enveloped icosahedral symmetry
Type of herpesvirus which causes infection on oral membrane in children, >80% are infected by adolescence; after primary infection, individual retains virus DNA on trigeminal nerve ganglion and has 50% of developing into cold sores
herpes simplex virus 1 (HSV1)
Area targeted by HSV2
genital area (causes recurrent genital herpes)
Herpesvirus which causes chickenpox in children
Varicella zoster virus (VZV)
Remains dormant in any dorsal root of the CNS; release of immune control among elderly may cause reactivation which is manifested by shingles
Varicella zoster virus (VZV)
Group where VZV belongs to
Herpesvirus
Structure and size of cytomegalovirus (CMV)
150nm, enveloped icosahedral symmetry
Acquired in childhood as a subclinical infection, 50% of adults carry the virus in dormantstate in the white blood cells
cytomegalovirus
On cytomegalovirus: severe diseases (e.g. pneumonia, hepatitis, encephalitis) may be acquired when patient is ______; primary infection during pregnancy may cause serious _______ abnormalities in fetus
immunocompromised, congenital
Structure of Epstein-Barr virus (EBV)
150nm, enveloped icosahedral symmetry
How does infection occur for Epstein-Barr virus?
salivary exchange
This virus causes an infection that is asymptomatic in children but persists in latent form in lymphocytes (WBC). Infection is delayed until adolescence which is manifested as glandular fever.
Epstein-Barr virus
In tropical Africa, severe infection of EBV in early life predisposes children to develop ______ (Burkitt’s lymphoma)
malignant facial tumours
Size and structure of hepatitis B virus
42nm diameter of spherical enveloped particle enclosing a 27nm inner icosahedral capsid
In Southeast Asia and Africa, most children are infected thru prenatal infection while Westerners usually acquire this through blood or sexual means
hepatitis B virus
Strong evidence shows that HBV can progress to this type of cancer
liver cancer
Papilloma viruses are under this group
papovaviruses
Multiply on epithelial cells and mucous membrane which causes warts. Evidence associates some types of this virus to cervical carcinoma.
papilloma virus
(DNA/RNA virus) papilloma virus
DNA virus
(DNA/RNA virus) hepatitis B virus
DNA virus
(DNA/RNA virus) epstein-bar virus
DNA virus
(DNA/RNA virus) herpes simplex virus
DNA virus
(DNA/RNA virus) varicella zoster virus
DNA virus
(DNA/RNA virus) cytomegalovirus
DNA virus
(DNA/RNA virus) vaccinia
DNA virus
(DNA/RNA virus) poxviruses
DNA virus
(DNA/RNA virus) variola
DNA virus
(DNA/RNA virus) adenovirus
DNA virus
Structure and size of papilloma virus
50nm in diameter, naked icosahedral
Kissing virus
Epstein-Barr virus