35 - Virology DNA Viruses Flashcards
what produce eruptive skin pustules called pocks or pox that leaves scars
poxviruses
what is the largest and most complex animal virus
poxvirus
what has the largest genome of all human viruses
poxvirus
describe structure of poxvirus
single linear dsDNA molecule of 130-300 kb with
hairpins at either end
where do poxvirus multiply
cytoplasm in factory areas
what does poxvirus have specificity for
cytoplasm of epidermal cells and subcutenaous CT
what are human pox viruses
- orthopoxvirus
- molluscipoxvirus
what is variola virus (smallpoxl monkeybox)
orthopoxvirus
what is molluscum contagioscum virus
molluscipoxvirus
cytopathology of pox
- extremely cytopathic
- inhibit DNA, RNA, and protein synthesis
- replication occurs in cytoplasmic factories
what is first disease eliminataed by vacc
smallpox
how does smallpox exposure occur
inhalation of skin contact
incubation period of smallpox
5-17 day
what other symptoms do smallpox pt have
high fever, headache, malaise, prostruation, rash
infections associated with smallpox
variola major and minor
variola major or minor:
highly virulent, caused toxemia, shock, and intravascular coagulation
major
variola major or minor:
less mirulent
minor
when was smallpox eradicated? when did routine vacc end
1977; 1972
when was the vaccine for small pox reintroduced for who
2002 - military and certain medical personnel
what is this:
Primarily an infection of children
in endemic areas.
Transmitted by direct contact and
fomites.
In U.S., most commonly an STD.
molluscum contagiosum
what does molluscum contagioscum look like
Lesions are 2-5 mm small,
smooth macules in genital area
and thighs.
Pearly papules with a central
depression whose core may be
expressed, producing a white
cheesy material.
symptoms of molluscume contagiosm
AIDS patients suffer an atypical
form which attacks the skin of
the face and forms tumor-like
growths.
treatment of molluscum contagioscum
freezing, electric cautery, chemical agents
how is monkeypox transmit
Transmitted by direct contact with lesions or contaminated surfaces
(bedding/towels).
Commonly intimate contact (sexual).
Also by contact with respiratory secretions.
incubation period of monkeypox
3-17 day
what is considered milder form of small pox (including pock-like rash)
monkeypox
what is this:
Lesions are firm or rubbery, well-circumscribed, deep-seated, and often
develop umbilication (resembles a dot on the top of the lesion).
Often painful until healing phase.
Typically not disseminated; commonly genital, anorectal, oral.
monkeypox
symptoms of monkeypox
Fever, lymphadenopathy (diagnostic from smallpox), malaise, headache, etc… may occur before or after lesion appearance
how is animal poxvirus transmitted
direct contact with lesions (ocupations, wild animals, cow sheep_
what do animal poxvirus look like
single nodular lesion forms at point of contact. lesion resolves after 4-5 weeks without scarring
vaccines against poxvirus
- vaccinia (ACAM2000)
- JYNNEOS
what vaccine:
Live virus used to vaccinate against Smallpox.
Distinct species of Orthopoxvirus.
Administered by variolation (skin pricking)
Vaccinia against POXVIRUS NOT SMALLPOX
clinical features of poxvirus vaccine
Localized pustular lesion at site of inoculation
Swelling of draining lymph nodes
Secondary lesions are atypical
Immunocompromised individuals
Mechanical transfer from primary inoculation site
Large number of Contraindications & Complications:
Progressive vaccinia (immunocompromised individuals)
Eczema vaccinia
Encephalitis (rare)
what vaccine:
Live-attenuated virus delivered by sub-cutaneous injection.
2 dose vaccination, 14-day interval.
Considered protective 14 days after second dose.
Unknown efficacy (immunity comparable to ACAM2000)
JYNNEOS for poxvirus
types of alpha herpesvirus
HSV-1
HSV-2
VZV
types of beta herpesvirus
CMV
HHV-6 (Roseola)
HHV-7
types of gamma herpesvirus
EBV
HHV-8 (Kaposi’s
sarcoma)
what is a common, persistent human virus
herpesvirus
what is this:
All members show latency and cause recurrent infection; viral DNA forms episome.
Clinical complications of latency and recurrent infections become more severe with advancing age, cancer chemotherapy, or other conditions that compromise the immune defenses.
herpesvirus
what is this:
Common and serious opportunists among AIDS patients.
Large enveloped icosahedral dsDNA.
Replicates within nucleus.
herpesvirus
humans are susceptible to whwat HSV
- HSV-1
- HSV-2
what HSV:
usually lesions on the oropharynx, cold sores, fever blisters Typically acquired in early childhood.
HSV-1
epidemiology of HSV
Lifelong infection.
Transmitted by secretions
and close contact.
what HSV:
lesions on the genitalia, possibly oral
Typically acquired in ages 14-29. Can be spread without visible lesions.
HSV-2
how do you get HSV-2
sexual of birth
what is ubiquitous HSV
HSV-1 is ubiquitous. World-wide estimate is 67% of the population has HSV-1. Estimated prevalence in
the Americas is 40-50%.
pathogenesis is similar for what HSV? what is the difference tho
HSV-1 and 2
1 is associated with above the waist
2 is below
how is HSV 1 and 2 transmited
Transmission by direct exposure to secretions containing the virus; active lesions most significant
source; genital herpes can be transmitted in the
absence of lesions.
where does HSV infection initiate
mucoepithelial cells
T/F: In HSV 1 and 2, local viremia and establishment of latent infection in innervating neurons.
TRUE
how does HSV 1 travel
retrograde transport to ganglia
Trigeminal (HSV-1) or Sacral (HSV-2)
what cells are inomportant for maintaining latency in HSV1 and 2
CD8 T-cells and gamma-interferon are
important for maintaining latency.
what can reactivate HSV
various stimuli
what happens when HSV is reactivated
Upon reactivation the virus returns to initial site of infection.
Inapparent.
Vesicular lesions.
Generally are less severe than original infection.
tissue damage results from what in HSV? how do lesions heal
Tissue damage results from both viral and cellular
(immune) induced damage.
Lesions generally heal without scarring.
what herpes, specific type
fever blisters, cold sores; most
common recurrent HSV-1 infection; vesicles
occur on mucocutaneous junction of lips or
adjacent skin; itching and tingling prior to vesicle
formation; lesion crusts over in 2- days and
heals within 14 days.
Can occur throughout the mouth: palate, pharynx,
gingivae, tongue.
herpes labialis - type 1
what herpes, specific type
infection of
oropharynx in young children; fever, sore throat,
swollen lymph nodes.
herpetiv gingivostomatitis, type 1
what herpes, specific type
- ocular herpes
inflammation of eye; gritty feeling in the eye,
conjunctivitis, sharp pain, and sensitivity to light.
Herpetic keratitis, type 1
what herpes and type
herpes genitalia starts with malaise,
anorexia, fever, and bilateral swelling and tenderness in the groin; clusters of sensitive vesicles on the genitalia, perineum, and buttocks; urethritis, painful urination, cervicitis, itching; vesicles ulcerate.
genital herpes type 2
where does latency occur in type 2
sacral ganglia
are recurrent bouts more or less severe in type 2 herpes? triggered by what
LESS - triggered by menstruation, stress, and concurrent bacterial infection
herpes of newborn 1 vs 2
HSV-1 (rare) and HSV-2 (typical)
is neonatal herpes fatal
yes in neonate and fetus
how can newborn get herpes
Infant contaminated by mother before (in
utero) or during birth; or after birth by contact
transmission to infant.
Infection of mouth, skin, eyes, CNS, or
disseminated disease.
if pregnant women are positive for HSV, how are babies delivered
C-section at time of birth
what infection:
HSV-1 or HSV-2 can
Infection of skin through a cut or
abrasion.
Extremely painful and itchy.
Whitlow is common in healthcare
workers treating HSV patients
(dentists!)
Gladiatorum is associated with
wrestling.
herpetic whitlow and gladiatorum
___ rare complication but most common sporadic form of viral encephalitis in the U.S.
HSV-1 encephalitis
how to diagnose herpes simplex
- Vesicles and exudate are typical diagnostic signs.
- PCR of lesions, CSF or blood is preferred method.
- Scrapings from base of lesions showing giant cells.
- Direct fluorescent antibody tests also used.
what meds to tx herpes simplex
- acyclovir
- famciclovir/penciclovir
- valacyclovir
- abreva/docosanol
- topical medications
what med:
Specifically activated by HSV
induced thymidine kinase
enzyme
Inhibits HSV viral polymerase as a
competitor of dGTP, causing DNA chain
termination
acyclovir (nucleoside analog)
what med:
Acyclyic nucleoside analog of
guanosine
Less potent than Acyclovir; but better
uptake & half-life
Famciclovir/Penciclovir
what med:
L-valyl ester of acyclovir
Valacyclovir
what med:
Thought to act by blocking fusion of the
virus with the host cell.
Abreva/Docosanol
chicken pox and shingles are what type of virus
varicella-zoster virus
only natural host of VZV? is it highly contagious
humans; yes!
how is VZV transmitted
Transmitted by contact, aerosolized virus and possibly respiratory dróplets.
- Airborne infection is initiated in respiratory tract.
- ~14 day incubation period.
- Contagious 1-2 days prior to appearance of rash.
pathology of VZV
Chickenpox - characterized by itchy rash, progresses
rapidly from macules to papules to vesicular lesions which
crust.
Children typically exhibit 2-3 days of fever.
what is breakthrough varicella
- VZV infection of vaccinated individuals.
- Typically afebrile illness with < 50 lesions.
T/F: VZV primary infection does NOT give you life long immunity
FALSE! primary infection confers life-long immunity
in VZV, does virus enter neuron and remain laten
yes
what:
Reactivation of the virus results in
shingles with vesicles localized to distinctive
areas, dermatomes.
Commonly in older patients
Zoster
complictions of zoster
- postherpetic neuralgia
- opthalmic involvement
- bacterial superinfectino
- nerve palsies
what zoster complication:
Persistent pain at rash site after resolution.
Risk increases with age.
postherpetic neuralgia
tx for VZV
treat symptoms in uncomplicated
infections; acyclovir, famciclovir, interferon for
systemic disease.
vaccine for VZV
- varicella (zostavax)
- zoster (shingrix)
most infections in ___ are asymptomaticc
cytomegalovirus
is CMV mostly asymp?
yes
what:
Ubiquitous in the population
70 - 90% of adults are infected
Produce giant cells with nuclear
and cytoplasmic inclusions.
cytomegalovirus (CMV)
how is CMV transmitted
Transmitted in saliva, respiratory
mucus, breast milk, urine, semen,
cervical secretions.
Commonly latent in various
tissues.
what groups develop a virulent form of disease in CMV
- fetuses
- newborns
- immunodeficient adults
newborn complicatins of CMV
Newborns may exhibit enlarged liver and spleen, jaundice,
capillary bleeding, microcephaly, and ocular inflammation;
may
be fatal.
Babies who survive develop neurological sequelae, hearing,
visual disturbances and mental retardation
perinatal complications of CMV
Perinatal CMV infection
mostly asymptomatic, but can
cause pneumonitis, or a mononucleosis-like symptoms.
AIDS pt complications of CMV
AIDS patients - CMV mononucleosis, disseminated CMV,
retinitis.
complications of CMV for transplant patients
Transplant patients - pneumonitis, hepatitis, myocarditis,
meningoencephalitis.
what disease:
Etiologic agent of “Mono” or “Kissing
Disease.” “Ultimate B-cell parasite.”
Ubiquitous Worldwide distribution. ~90% of adults have antibodies.
EBV
how is EBV transmitted
spread by body fluids especially saliva
pathogenesis of EBV
Viremia spreads virus throughout the body via lymphatic system and blood.
Latency occurs with infection
of B-cells that differentiate into
B-memory cells.
1 B-cell/milliliter
where does EBV infection intitiate
Infection initiates in epithelial cells in oropharynx or nasopharynx.
B-cells in tonsils.
Virus shedding into saliva.
EBV drive _-cell activation and proliferation with spurious production of ___
B-cell, antibodies
what cells response to proliferation of B cells in EBV? what happens?
T-cell response to proliferation of B and limit outgrowth.
“Civil war” between B- & T-cells.
Lymphocytosis- 10-80% of WBC
count.
Symptoms result from immune
system “fight”.
EBV complications
how to diagnose EBV
- Differential blood count shows lymphocytosis, neutropenia, and large atypical lymphocytes; cervical lymphadenopathy.
- Serological assays to detect antibodies and antigen. Immunoassays / PCR
treatment of EBV
Treatment directed at relief of
symptoms of fever and sore
throat.
Acyclovir can block EBV
replication, but does not affect
clinical symptoms of AIM.
Disseminated disease
may be
treated with IV gamma globulin,
interferon, acyclovir, and
monoclonal antibodies.
what this:
Originally known as human B-
lymphotropic virus.
1 of 5 classic exanthems.
Transmitted by close contact with
saliva and other secretions; very
common.
HHV 6 and 7
what:
Causes roseola, an acute febrile
disease in babies 2-12 months;
begins with fever, followed by a
faint maculopapular rash; usually
self-limited (1-2 days).
High seroprevalence.
HHV 6 and 7
symptoms of HHV 6 and 7
Adults may
get mono-like
symptoms, lymphadenopathy and
hepatitis.
what:
present in Kaposi sarcoma, primary effusion lymphoma and multicentric Castleman disease Endemic in Africa. Assoc. w/ AIDS patients in US.
HHV-8
how does HHV-8 spread
Spread primarily as a sexually transmitted disease, direct contact with infected secretions, including saliva.
primary target of HHV-8
B-cell primary target, also
endothelial cells, monocytes,
epithelial cells, and sensory
nerve cells.
where is latency in HHV-8? incubation period
blood lymphocytes and lymphoid tissue
incubation period unknown
what type of virus is hep B
hepadnavirus
what is an inflammatory disease of liver cells that may result from several viruses.
Hepatitis
what interferes with liver’s excretion of bile pigments, bilirubin accumulates in blood and tissues causing jaundice, a yellow tinge in skin and eyes.
hepatitis
3 principal viruses in hep
Hepatitis B, hepatitis A (RNA virus), hepatitis C (RNA virus)
why has incidence of hep plummeted
Incidence has plummeted in US due to
surveillance, and vaccines for A & B.
structure of HBV
- Small, enveloped DNA virus; 42 nm.
- Genome is circular and partially dsDNA3200 bases.
what does HBV encode
Encodes a reverse
transcriptase and replicates
through an RNA
intermediate.
During late step of infection.
T/F: in HBV, defective particles of HBsAg outnumber infectious virions. May be spherical or filamentous.
TRUE
how does HBV replicate
transmission of hep B
pathogenesis of hep B
latency of HBV
diagnosis of Hep B
Typically picked up by clinical symptoms/elevated liver enzymes.
Serological tests to detect viral antibodies or antigen.
treatment of acute and chronic hep b
- Post-exposure prophylaxis with anti-HB immunoglobulin for persons exposed, or possibly exposed, including neonates born to infectedmothers
- Acute Infection= Supportive therapy.
- Chronic Infection (Interferon alpha, pegylated interferon and Nucleoside analogs)
nucleoside analogs for tx of chronic hep b
- tenofovir (HIV reverse transcriptase inhibitors)
- entecavir (deoxyguanosine analog)
prevention against hep B
what is this:
Only B19 and bocavirus are
parvoviruses known to cause human
disease.
B19= Fifth disease-#5 childhood
exanthem (rash)
Boca = mild respiratory infection
parvovirus
what is smallest human DNA virus
parvovirus
structure of parvovirus
Linear ssDNA molecule.
(+) and (-) strands can be packaged into
virions.
where does parvovirus replicated and how do they exit
Replicate only in mitotically active
cells.
Erythroid lineage
Requires S phase for complementary
strand synthesis.
Exit by lysis
describe fifth disease
what is worst complicatin of fith disease
hydrop fetalis
what is infection of seronegative mother and virus can infect fetus and kill erythrocyte precursors resulting in anemia and congestive heart failure
hydropfetalis
