37 - Rhabdoviruses - Rabies and other enveloped RNA viruses Flashcards
do Rhabdoviruses have (+) sense ssRNA or (-) sense ssRNA genome
(-) sense ssRNA genome
what are the primary reservoirs for rhabdoviruses?
wild mammals
T/F Rhabdoviruses have segmented RNA expression
False, non-segmented
how is Rhabdoviruses spread?
bites, scratches, and inhalation of droplets
T/F Rabies is almost always fatal once clinical signs/symptoms appear
true
where will the rhabdoviruses replicate
local replication at bite site and replication in peripheral nerves
where are the highest levels of rhabdoviruses found?
salivary glands and sensory nerves in oral mucosa
what is the incubation period for rhabdoviruses?
variable (1 day to years; 75% w/n 90 days)
what happens during the prodromal phase of a rhabdovirus infection?
fever, headache, malaise (general systemic viral signs)
what symptoms are present in the furious form of rhabdovirus infection?
encephalitis, hydrophobia, delirium, agitation, seizures
average time for pt to die of rabies
18 days after onset of clinical symptoms
what treatment can reduce risk of rabies infection?
wound cleaning/care
which virus is depicted as relatively large RN viruses with distinctively spaced spikes on their envelopes
Coronaviruses
what are the 3 major types of human coronaviruses
cold
enteric viruses
pandemic coronaviruses (e.g. SARS, MERS, CoVID-19)
what happens with coronavirus during early phase of replication?
genome is translated and polymerase is synthesized, which makes (-) sense copy of RNA
what happens with coronavirus during late phase of replication?
(-) sense RNA is used to replicate new genomes and produce 5-7 nested mRNA’s
up to _______% of adults are seropositive to common respiratory strains with the coronavirus epidemiology
90
what season is coronavirus more prevalent in?
winter and early spring
229E and NL63 are what type of coronavirus?
alpha
OC43, HKU1, SARS-CoV, SARS-CoV-2, and MERS-CoV are what type of coronavirus?
Beta
what cells are the primary infection with coronavirus?
epithelial cellswh
at is the incubation period for coronavirus?
~3 days (range 2-5); slightly longer for SARS (4; 2-10), & MERS (5, 2-14)
SARS virus infects and leads to destruction of the _________ epithelium
alveolar
what are the disease manifestations of Coronaviruses?
respiratory infection with common cold-like symptoms
What is the disease manifestation of SARS/MERS
atypical pneumonia with high fever, chills, rigors, headache, dizziness, malaise, myalgia, cough, or breathing difficulty
what is recommended for prevention of coronaviruses?
good hygiene
what is the mean incubation period for SARS-CoV-2
4-5 days (up to 14)
_________% of identified pt’s experienced fever, cough, or shortness of breath, _______% had muscle aches, and ________% reported headaches with SARS-CoV-2
70, 36, 34
what are example tx’s of COVID-19
itonavir-boosted nirmatrelvir [Paxlovid] (protease inhibitor)
Remdesivir (nucleoside analog)
Molnupiravir (nucleoside analog)
Corticosteroids (Dexamethasone)
immune modulators
monoclononal antibody therapies (EUAs)
T/F Rubella is a ssRNA with a loose envelope
true
how is rubella transmitted?
respiratory secretions
when was rubella eliminated in the U.S.?
1966 (usually < 10 cases/year)
what are the two clinical forms of rubella?
postnatal rubella (age 5-9) (generally mild, lasting only 3 days)
congenital (intrauterine) rubella (infection during the 1st trimester; likely will cause miscarriage or multiple defects)
T/F no specific tx available for highly contagious rubella
True
is Flavivirus (-) sense or (+) sense virus?
(+) sense, ssRNA
is flavivirus enveloped or non-enveloped?
enveloped
flavivirus will enter via ____________ mediated endocytosis
receptor
where will flaviviruses replicate?
in membranous ER structures
how many polyproteins are in flavivirus genome
single polyprotein
what important genes are within the flavivirus genome
NS3 (serine protease)
NS5a (replication complex protein)
NS5b (polymerase)
These are major drug targets!
how is hepatitis C virus primarily acquired?
blood contact (blood transfusions, needle sharing by drug abusers)
what percentage of pt’s will remain infected indefinitely with hep C?
75-85%
__________ can also result from chronic hep c infection
cancer
what were the cons of the initial tx of hep c with pegylated interferon and ribavirin?
horrible side effects for a 50-50 chance of helping
what are the cons of the new tx for hep c that target polymerase complex and protease
incredibly expensive ($63k-$189k)
how are arboviruses spread?
arthropod vectors (e.g. mosquitoes, fleas, ticks, gnats)
a majority of illnesses caused by arboviruses are [mild, moderate, severe] fevers?
mild, some may cause sever encephalitis, and life-threatening hemorrhagic fever
what does acute arbovirus infection result in?
undifferentiated mild fever with rash
what is a common complication of arbovirus infections?
viral encephalitis
T/F typical arbovirus infection resolve with no long-term effects
True (rare complication arise with secondary infection and invasion of a target organ)
where do vectors and viruses tend to be clustered?
tropics and subtropics
____________ life cycles are closely tied to the ecology of the vectors
arbovirus
what can dengue virus, west nile virus, and zika virus be grouped into?
flaviviruses
example of alphavirus
chikungunya virus
what will be caused by a flavivirus carried by Aedes aegypti and Aedes albopictus?
Dengue
what is a complication to dengue?
dengue hemorrhagic fever (DHF) and dengue shock syndrome (DSS)
prevention for dengue?
dengvaxia vaccine (questionable efficacy due to possible risk of hospitalization 2 years after vaccine)
an estimated 70-80% of human ____________ infections are subclinical or asymptomatic
West Nile Virus Disease
why is there no specific tx or vaccine for west nile virus disease?
companies aren’t super interested as it doesn’t cause much disease
what are the complications of zika virus?
assoc. with congenital microcephaly, other congenital neurological defects, and possible assoc with guillain-barre syndrome (most are asymptomatic)
what is the common sign/symptom for chikungunya virus?
fever & joint pain (polyarthralgia)
what are the hallmarks of retroviruses?
reverse transcription
integration into host genome
major drug targets for general retrovirus replication
reverse transcription
integration
maturation (protease)
what mediates reverse transcription?
RNA-dependent DNA polymerase (reverse transcriptase)
T/F Reverse transcriptase is highly accurate
False. it is highly error-prone which allows for rapid evolution of the virus
what are the two major types of error generated by reverse transcriptase?
nucleotide misincorporation
strand transfers
what mediates the integration process of retroviruses?
integrase enzyme
when does HIV-1 maturation occur?
during/after budding
viral ______ cleaves polyproteins for HIV-1 maturation
protease
T/F HIV transmission occurs by direct and specific routes
true
Can HIV survive long outside the body?
No
where is the major site of replication for HIV
lymph nodes in the gut
