Microbiology Test 2

Front 1

Characteristics of Viruses:

Back 1

Obligate intracellular parasites
reproduction in living cells only
no independent metabolism
Small size

Front 2

What pattern of replication do viruses use?

Back 2

Assembly line fashion with a ONE STEP GROWTH CURVE

Front 3

Structure of virus includes?

Back 3

nucleic acids, proteins and lipid containing envelope

Front 4

Capsid vs capsomeres

Back 4

capsomeres are small protein subunits that are composed of several proteins in groups to form the capsid.
capsid is protein covering the core of nucleic acids and (sometimes) enzymes

Front 5

Two basic patterns of nucleic acid genome structure

Back 5

1. extended nucleic acid form: RNA/DNA not wound tightly
2. condensed nucleic acid form: DNA/RNA packed very tightly

Front 6

What is the envelope of a virion (a complete virus particle)

Back 6

combination of host membrane with some virus proteins. the host membrane is studded with viral proteins. The spikes are virus proteins that are embedded in it, they usually have enzymatic activities.

Front 7

True or False. Viruses can have both RNA and DNA.

Back 7

viruses will have DNA or RNA but typically NOT contain substantial amounts of both.

Front 8

Difference between (-) and (+) stranded RNA viruses?

Back 8

(+) stranded can serve as MRNA directly and be directly translated.
(-) stranded has to be transcribed by a VIRUS ENCODED RNA dependent RNA polymerase to get a strand of + polarity to act as mRNA.

Front 9

Viruses are classified based on?

Back 9

Physical features
and
Biological properties

Front 10

What are the stages of animal cell virus replication?

Back 10

1. attachment
2. latent period
3. burst or release of progeny virions.

Front 11

During the synthesis process of viruses you build the virus from the inside out. what does that mean?

Back 11

early genes - genome synthesis
late genes - virion maturation and capsid

Front 12

DNA viruses replication and maturation occurs in the ?
RNA virus replication and maturation occurs in ?

Back 12

Nucleus.

Cytoplasm.

Front 13

Viruses infect cells that ____ dividng and producing DNA.

Back 13

NOT ACTIVELY.

b/c dna replcation is a tightly controlled process.

Front 14

DNA viruses can disrupt host cell cycle and nude the host into sometihing like lke _____

Back 14

S phase to replicate.

Front 15

T/F
some dna viruses can supply their own host cell independent DNA replication fxns.

Back 15

TRUE

Front 16

Since the host has no enzymes capable of performin ghte needed RNA copying tak what happens

Back 16

the molecules are either transported ino the host in the virion itself or synthesized from the virus genome.

Front 17

What is the hallmart of retroviruses?

Back 17

reverse transcription and integration.
RNA --> DNA --> RNA

Front 18

Specific virus infections are strong risk factors for cancer development...what are they?

Back 18

HPV - cervical and oral cancer
Hep B/C - liver cancer
EBV - lymphoma

Front 19

If a virus genome remains associated with the host but its genes are largely unexpressed these viruses are called

Back 19

prophage in bacteria
provirus in eukaryotes

these are temperatue while those that can only kill are called virulent/lytic

Front 20

T/F lysogeny is a replicative strategy for the virus.

Back 20

TURE. the viral genome is replicated each timt he host genome replicates.

Front 21

What happens when a prophage realizes that the bacteria has DNA damage and is in danger?

Back 21

Switches to lytic cycle quickly to escape from the dying host.
there are certain antibiotics that can provoke DNA damage and are strong prophage inducing agents so patients get a severe intoxication reaction when treated with this drug.

Front 22

lysogenic conversion?

Back 22

bacteriophage changes the phenotype of the host cell (example the host cells gets toxin genes and new surface structures). you may with a very dangerous pathogen because of this conversion.

Front 23

Two basical survival strategies of viruses in animal cells?

Back 23

1. lytic infection - host cells die
2. persistent infection - long term residence, resmbles bacterial lysogeny.

Front 24

In persistent infection the host is hostile but the viruses are able to escape immune functions. HOW?

Back 24

1. avoidance-residing in nonpermissive cells or cells that are in immunologically priviledged sites
2. interfering with MHC expression
3.interrupt cytokine synthesis
4.inhibit apoptosis
5.evade antibody/complement killing

Front 25

Three types of persistant infection:

Back 25

1. Latent
2. Chronic
3. Transforming

Front 26

Latent infection means?

Back 26

intermittent acute episodes of virus production between which there may be an absence of virus particles and very limited viral macromolecular synthesis (herpes)

Front 27

Chronic infection means?

Back 27

quasi-nonlytic production of virus, presence of virus even when clinical disease absent (hep B)

Front 28

Transforming infection means?

Back 28

cells immortalized and properties altered to those of cancer cells (HPV)

Front 29

What is called when viruses disseminate through the blood?

Back 29

Viremia

Front 30

Examples of cytopathic effects on cell or tissue? these are changes the virus does to cell

Back 30

1. inclusion body formation: some are diagnostic for a viral infection. ther are sites of viral replcation or product accumulation like Negri bodies for rabies virus.
2. syncytia formation: multinuclaeated giant cells , these enable viruses to evade immune clearance for a long time (ex herpes, measles)
3. nuclear alterations - ring structures

Front 31

difference between hemadsorbtion and hemagulltination

Back 31

hemadsorbtion: RBCs stick to surface of infected cells that express the viral hemaglutin
hemagglutination: RBCs are crosslinked by virion hemagglutinin protein and form a network

Front 32

three steps in diagnosis of viral infection:

Back 32

1. direct examination of clinical samples.
2. viral culture
3. patient serology: looking for an antibody titer increase of 4X or more in the assay

Front 33

How to control viral infections?

Back 33

best way is avoidance!!! if you cant..
1. quarantine
2. vaccination (artificial acquired active immunity)
3. passive immunization
4. antiviral agents (usually toxic to host as well)

Front 34

Slow virus infections ...what are they?

Back 34

slowly progressive CNS infections not caused by viruses but due to PRIONS.

Front 35

what are prions?

Back 35

infectious proteins
very long incubation periods. always lethal. very difficult to inactivate
mad cow disease, scrapie, and CJD

Front 36

what is the zoonotic pool?

Back 36

animal viruses that invade humans

Front 37

What are the clinical manifestations of ARD?

Back 37

-nasal discharge/obstruction
-sneezing, cough, malaise, sore throat with 2-4 days incubation
BENIGN, TRANSITORY, SELF-LIMITED.
-fever not typical

Front 38

Characteristics of Rhinovirueses:

Back 38

RNA virus
single stranded, + sense
nonenveloped
many antigenic types known so can get the cold many times though adults less susceptible bc have build immunity
human forms use ICAM 1 as receptor which is located in deep clefts (might be why you recover from one but doesn't mean the other even though same receptor). production of ICAM stimulated by interferon
grows in 33 C (usually in our nasal turbinates)

Front 39

epidemiology of rhinovirus

Back 39

hyperendemic in winter months
greatest incidence in children and young adults
hands and direct contact spread

Front 40

there are some control measures out there for rhinovirus...what are they and their problems?

Back 40

get severe adverse effects from a drug while the disease doesnt kill the drug might.
1. picovir: prevents proper virion uncoating (problem is MANY viruses cause the common cold not just rhinovirus)
2. 3C protease inhibitors: prevents maturation
3. BIRR4: interfered with cell infection

Front 41

characteristics of adenoviruses:

Back 41

double stranded DNA
non enveloped
types 4 and 7 most common in US
lytic, persistent, and latent infections known.
see DENSE includiosn in cell nucleus

Front 42

Epidemiology and diseases of adenovirus?

Back 42

primary targets children and young adults. CAN HAVE LATENCY.
1. adult pharyngitis: most FREQUENT cause of pharyngitis in adults.
2. Pharyngoconjuctival fever: 1 sided conjuctivitis (one sided)
3. pertussis like syndrome (see in military, college dorms)

Front 43

why is adenovirus detection difficult?

Back 43

adenoviruses may establish permanent infections, making it difficult to be sure virus detection is necessarily correlated to the patient disease at the time of the test.

Front 44

characteristics of coronavirus

Back 44

single stranded RNA
+ sense strand
enveloped
thought to be the SECOND MOST COMMON CAUSE OF COMMON COLD AFTER RHINOVIRUSES.
spread by aerosols an droplets
two major antigenic types known

Front 45

SARS??

Back 45

severe acute respiratory syndrome with a high case fatality rate.
due to a newly emerged coronavirus that we hope to be extinct.
spread through respiratory and fecal matter.
thought to be of animal origin.
we have a very limited ability to recognize (use PCR or AB detection but very low sensitivity and specificity)

Front 46

Croup...what is it?

Back 46

fever, hoarsness, and barking cough in hildren 6-18 months of age
it is a complication of an upper resp tract infection, you get a constriction of the trachea below the vocal cords.
PIV type 1 > PIV type 2 >>RSV

Front 47

Characteristics of parainfluenza viruses.

Back 47

paramyxovirus
nonsegmented, - sense ss RNA
enveloped
4 types known - since so few variations once you get infected you should have a lifelong immunity to it (in reality your immunity decreases)
see syncytia (multinucleated giant cells)

Front 48

how is PIV spread?

Back 48

respiratory droplets
see increase in fall-winter
prevalent in children

Front 49

Sx of PIV?

Back 49

cough, rhinitis, sore throat, SOB, SIGNAL ILLNESS IS CROUP
may also see otitis media, and parotitis as complications

Front 50

how to treat PIV?

Back 50

nasal washings, throat swabs because the virions are stable and may be maintained for several days.
supportive treatments

Front 51

Respiratory Syncytial Virus characteristics

Back 51

paramyxoviirus
cause of fatal acute resp tract infection in infants
creates syncytia in tissue culture
- ssRNA
-enveloped
attached with G protein, fuses with F
two subtypes

Front 52

clinical manifestations of RSV

Back 52

cold to severe pneumonia
older children and adults get upper resp tract infection
infants get bronchiolitis/pneumonia/croup

Front 53

what factors influence RSV exposure and disease development?

Back 53

born in april - sept
has older bro/sis
daycare
lives in crowded condition
not breastfed

Front 54

how to diagnose RSV:

Back 54

time/year
viral antigen detection
serology

Front 55

how to prevent RSV?

Back 55

supportive care, ribavirin in severe cases, passive immunization, prevention - keep children and visitors with resp tracts away!!!