Viruses: RNA Positive Sense Viruses Flashcards
List the RNA positive sense viruses
- Poliovirus
- Coxsackievirus A
- Coxsackievirus B
- Rhinovirus
5 Hepatitis A - Norovirus/Norowalk Virus
- Hepatitis C
- Coronavirus
- HIV
- Echovirus
- West Nile Virus
- Yellow Fever Virus
- Dengue Fever
Picornaviridae Virus Family
a family of viruses that includes hepatitis A virus, poliovirus, coxsackievirus A and B, echovirus, and Rhinovirus
picornaviruses (i.e. hepatitis A virus, poliovirus, coxsackievirus A and B, echovirus, Rhinovirus) are
- positive-sense RNA viruses
2. naked viruses
hepatitis A virus, poliovirus, coxsackievirus A and B, and echovirus (picornaviruses) are transmitted
fecal-orally (Rhinovirus is transmitted via respiratory droplets)
the genetic material of positive-sense RNA viruses (such as picornaviruses) is structured like
like mRNA and can be directly translated into viral protein products
the whole genome of picornaviruses (i.e. hepatitis A virus, poliovirus, coxsackievirus A and B, echovirus, Rhinovirus) is translated into
one long polyprotein that is cleaved by host and viral proteases
hepatitis A virus
a positive sense-RNA virus in the Picornaviridae family
the Enterovirus genus (positive-sense RNA viruses in the Picornaviridae family) includes
poliovirus, coxsackievirus A and B, echovirus, and rhinovirus
Rhinovirus
a positive-sense RNA virus in the Picornaviridae family
hepatitis A virus can cause
liver inflammation (hepatitis), gastroenteritis, and hepatosplenomegaly
poliovirus
a positive-sense RNA virus in the Picornaviridae family
coxsackievirus A and B
positive-sense RNA viruses in the Picornaviridae family
echovirus
a positive-sense RNA virus in the Picornaviridae family
enteroviruses are the number one cause of
aseptic meningitis
aseptic meningitis (caused by viruses such as enteroviruses (i.e. poliovirus, coxsackievirus A and B, and echovirus)) presents with
a normal CSF glucose level
aseptic meningitis (caused by viruses such as enteroviruses (i.e. poliovirus, coxsackievirus A and B, and echovirus)) is a
self-limited inflammation of the meninges in which a virus, not bacteria, is the causative agent
aseptic meningitis (caused by viruses such as enteroviruses (i.e. poliovirus, coxsackievirus A and B, and echovirus)) presents with an
elevated CSF protein level
viral meningitis caused by enteroviruses (i.e. poliovirus, coxsackievirus A and B, and echovirus) most commonly affects
children
Rhinovirus infection affects the
upper respiratory tract and is spread via respiratory droplets
poliovirus
- a positive-sense
- RNA virus
- in the Picornaviridae family
- naked virus
- acid-stable
replication of poliovirus occurs in
cells of the gut mucosa (such as Peyer’s patches)
poliovirus affects
motor neurons of the anterior horn of the spinal cord
paralysis seen in poliovirus infection is typically
asymmetric
muscle weakness caused by poliovirus can lead to
respiratory failure
poliovirus can cause
aseptic meningitis
the Salk vaccine
the Salk vaccine is an inactivated (killed) vaccine administered by injection to prevent polio
the attenuated Sabin vaccine is
the attenuated Sabin vaccine is administered orally to elicit production of both IgG and IgA antibodies against poliovirus
coxsackievirus A and B Virus
- a positive-sense
- RNA virus
- in the Picornaviridae family
- naked virus
coxsackievirus A
a positive-sense RNA virus in the Picornaviridae family
coxsackievirus A causes
coxsackievirus A causes hand, foot, and mouth disease, which presents with a red, vesicular rash in the mouth, on the fingers and palms of the hands, and the soles of the feet
coxsackievirus A can cause
aseptic meningitis
coxsackieviruses commonly affect
young children during summer months
coxsackievirus B
a positive-sense RNA virus in the Picornaviridae family
coxsackievirus B can cause
myopericarditis leading to dilated cardiomyopathy
coxsackievirus B causes
Bornholm disease (also known as the devil’s grip or epidemic pleurodynia), which is characterized by severe, unilateral pleuritic pain in the lower chest
Rhinovirus
- a positive-sense
- RNA virus
- in the Picornaviridae family
- naked virus
- acid labile
Rhinovirus is transmitted via
- respiratory droplets
2. contact with people or fomites
hand washing reduces the risk of contracting or spreading Rhinovirus by transmission via
fomites (inanimate objects such as toys, door handles, and faucets)
Rhinovirus binds
Rhinovirus binds the ICAM-1 (intercellular adhesion molecule 1) protein of host cells for cellular entry
Rhinovirus replicates more efficiently in temperatures around
33ºC
Rhinovirus causes
upper respiratory tract infections
there are roughly _____ different serotypes of Rhinovirus
there are roughly 100 different serotypes of Rhinovirus
hepatitis A virus
- a positive-sense
- RNA virus
- in the Picornaviridae family
- naked virus
- acid stable
hepatitis A virus causes
liver inflammation (hepatitis), gastroenteritis, and hepatosplenomegaly
hepatitis A virus is transmitted
fecal-orally
water contaminated with hepatitis A virus can be purified by
chlorination, bleach, UV irradiation, or boiling
contaminated water is a common source of
hepatitis A virus in developing countries
contaminated shellfish are a common source of
hepatitis A virus in developed countries
hepatitis A virus infection is commonly seen in
travelers in areas where HAV is endemic
hepatitis A virus infection can cause
nausea, vomiting, and abdominal pain
hepatitis A virus infection often presents with
jaundice
anicteric hepatitis
anicteric hepatitis (hepatitis without jaundice) is more likely to be seen young children and infants infected with hepatitis A virus
smokers with hepatitis A often develop
an aversion to smoking
the duration of hepatitis A symptoms typically last around a
month
hepatitis A is often a
self-limiting infection
hepatitis A has no
carrier or chronic state
the hepatitis A vaccine is an
inactivated (killed) vaccine
Norovirus/Norwalk virus
- positive sense
- RNA virus
- Caliciviridae family
- naked virus
the whole genome of Norovirus/Norwalk virus is translated into
one long polyprotein that is cleaved by host and viral proteases
Norovirus/Norwalk virus outbreaks commonly occur in
- places where people are in close quarters (i.e. cruise ships)
- day care centers and schools
Norovirus/Norwalk virus infection is associated with
consumption of contaminated shellfish
Norovirus/Norwalk virus can cause
explosive watery diarrhea
flaviviruses (i.e. hepatitis C virus, West Nile virus, Yellow fever virus, Dengue virus) are
- RNA viruses
- Positive sense viruses
- enveloped
flaviviruses
- hepatitis C virus
- West Nile virus
- Yellow fever virus
- Dengue virus
the genomes of flaviviruses (i.e. hepatitis C virus, West Nile virus, Yellow fever virus, Dengue virus) contain
a single RNA segment
Dengue virus
- RNA viruses
- Positive sense viruses
- enveloped
- flaviviridae
the _____ is the vector of Dengue virus
aedes mosquito
type 2 dengue fever is alternatively called
breakbone fever
classic dengue fever can progress to
classic dengue fever can progress to dengue hemorrhagic fever in severe cases, leading to thrombocytopenia and spontaneous bleeding
dengue fever can lead to
acute renal failure
Yellow fever virus
- RNA viruses
- Positive sense viruses
- enveloped
- flaviviridae
the ______ is the vector of Yellow fever virus
Aedes mosquito
yellow fever often presents with
jaundice
yellow fever can present with
muscle pain, especially severe backache
yellow fever is a
yellow fever is a hemorrhagic fever and can cause spontaneous bleeding in the gastrointestinal tract and mucous membranes (including the nose, mouth, and eyes)
Yellow Fever Vaccine
a live attenuated vaccine can be administered to prevent yellow fever (especially important for those traveling to Africa and South America)
West Nile virus
- RNA viruses
- Positive sense viruses
- enveloped
- flaviviridae
______ are the reservoir for West Nile virus
birds
_____ are the vectors of West Nile virus
Culex spp. mosquitoes
West Nile virus infection can have manifestations, including
- encephalitis
- viral meningitis
- flaccid paralysis
- seizures
- coma
hepatitis C virus
- RNA viruses
- Positive sense viruses
- enveloped
- flaviviridae
hepatitis C virus can cause
liver inflammation and damage (hepatitis), which can result in jaundice
hepatitis C virus can be transmitted via
- exposure to infected blood (i.e. sharing needles or blood transfusions)
- sharing needles or needlestick injuries
the envelope proteins of the hepatitis C virus exhibit
antigenic variation
the virion-encoded RNA polymerase of hepatitis C virus
the virion-encoded RNA polymerase of hepatitis C virus lacks proofreading exonuclease activity in the 3’-5’ direction, making it prone to frequent mutations → antigenic variation
hepatitis C virus can cause
liver inflammation and damage (hepatitis), which can result in jaundice
60-80% of patients infected with hepatitis C virus develop
chronic infection
hepatitis C virus can cause
- cirrhosis
2. hepatocellular carcinoma (usually after development of cirrhosis)
ALT in hepatitis C
ALT will be elevated during the acute stage of hepatitis C virus infection and fall after 6 months
hepatitis C virus infection is associated with
hepatitis C virus infection is associated with mixed cryoglobulinemia (development of predominantly IgM immunoglobulins that precipitate at colder temperatures)
Treatment of Hepatitis C
ribavirin is used in combination therapy with interferon alpha to treat hepatitis C virus infection
protease inhibitors block replication of hepatitis C virus by
protease inhibitors block replication of hepatitis C virus by preventing cleavage of proteins vital for producing infectious forms of the virus
togaviruses
- Eastern Equine Encephalitis
- Western Equine Encephalitis
3 Venezuelan Equine Encephalitis - Rubella virus
togaviruses (i.e. Eastern/Western/Venezuelan equine encephalitis virus, Rubella virus) are
- RNA Viruses
2. Positive sense
Togaviruses in the Alphavirus genus (i.e. Eastern/Western/Venezuelan equine encephalitis virus) are
arboviruses (viruses that are arthropod-borne)
Arboviruses
viruses that are arthropod borne
Alphavirus Genus
- Eastern Equine Encephalitis
- Western Equine Encephalitis
3 Venezuelan Equine Encephalitis
_______ are common vectors of togaviruses (i.e. Eastern/Western/Venezuelan equine encephalitis virus, Rubella virus)
mosquitoes
Western equine encephalitis virus (WEEV), Eastern equine encephalitis virus (EEEV), and Venezuelan equine encephalitis virus (VEEV) cause
encephalitis
Rubella
rubella (or the German measles) is a childhood exanthem caused by Rubella virus
Rubella virus, Western equine encephalitis virus (WEEV), Eastern equine encephalitis virus (EEEV), and Venezuelan equine encephalitis virus (VEEV) are
enveloped
Rubella virus
- positive sense
- RNA virus
- Togaviridae family
rubella can present with
tender postauricular and occipital lymphadenopathy
rubella typically presents with a
distinctive maculopapular rash that begins on the face and spreads inferiorly
Rubella virus is transmitted via
respiratory droplets
Rubella virus can be transmitted
vertically
Rubella viruses are a _____ infection
TORCHeS
The classic triad of symptoms seen in congenital rubella
- patent ductus arteriosus
- congenital cataracts
- sensorineural deafness
congenital rubella may present with
- blueberry muffin rash
2. jaundice
rubella in adults may present with
arthritis or arthralgias of the knees, wrists, and fingers
the measles, mumps, and rubella (MMR) vaccine is
the measles, mumps, and rubella (MMR) vaccine is a live attenuated vaccine administered to prevent rubella (as well as measles and mumps)
______ is a contraindication for the MMR vaccine
pregnancy
the live attenuated MMR vaccine should only be administered to HIV-positive patients who have a
CD4+ count >200
the whole genome of togaviruses (i.e. Eastern/Western/Venezuelan equine encephalitis virus, Rubella virus) is translated into
one long polyprotein that is cleaved by host and viral proteases
Coronaviridae
- positive sense
- RNA Virus family
- enveloped
the capsules of coronaviruses are
helical
coronaviruses can cause the
common cold
coronaviruses can cause
upper respiratory infections that can lead to SARS or MERS (and even acute respiratory failure)
Human immunodeficiency virus (HIV)
- positive sense
- RNA virus
- Retroviridae family
- enveloped
if left untreated, HIV infection can lead to
acquired immunodeficiency syndrome (AIDS)
HIV is a
diploid virus; each HIV virion is composed of two copies of positive-sense RNA
the gag gene of HIV
encodes the p24 protein (thousands of p24 protein products comprise the conical capsid of HIV)
the env gene of HIV
- the env gene of HIV encodes the gp41 and gp120 envelope proteins
- the env gene encodes HIV envelope proteins, including the transmembrane protein gp41
- the env gene encodes HIV envelope proteins, including the surface protein gp120
the pol gene of HIV
the pol gene of HIV encodes a reverse transcriptase (an RNA-dependent DNA polymerase), which converts RNA to DNA
HIV initially infects
macrophages
HIV infects
CD4+ helper T-cells
acute HIV infection
acute HIV infection (or HIV prodrome) frequently presents with flu or mono-like symptoms such as cervical lymphadenopathy and pharyngitis
acute HIV infection (or HIV prodrome) frequently presents with
fever
CD4+ helper T-cells (which are targeted by HIV) are
CD4+ helper T-cells (which are targeted by HIV) are white blood cells (lymphocytes)
HIV undergoes
HIV undergoes a clinical latent period (or incubation period) that can last up to 10 years
a ______ is the diagnostic marker of AIDS
a CD4+ count <200 is the diagnostic marker of AIDS
patients with HIV are at a higher risk of
patients with HIV are at a higher risk of some cancers, such as diffuse large B-cell lymphoma
HIV gains entry into host cells via
- the CCR5 receptor in early stages of infection
2. the CXCR4 receptor in later stages of infection
ELISA and HIV
detects the presence of anti-HIV antibodies (ELISAs are used to screen for HIV)
______ are used to screen for HIV
ELISAs
_______ is done to confirm HIV infection in patients who tested positive on an ELISA screening test
a western blot (which detects the p24 antigen) is done to confirm HIV infection in patients who tested positive on an ELISA screening test
nucleotide/nucleoside reverse transcriptase inhibitors (NRTIs) are
non-functional nucleotide analogs that prevent the elongation of DNA molecules synthesized by HIV’s reverse transcriptase (NRTIs are incorporated into the DNA chain)
_______ should be used for pregnant HIV patients to reduce the risk of transmitting HIV to the fetus
Zovudine
non-nucleoside/nucleoside reverse transcriptase inhibitors (NNRTIs) block
non-nucleoside/nucleoside reverse transcriptase inhibitors (NNRTIs) block the reverse transcriptase enzyme of HIV so that the reverse transcription of RNA to DNA cannot occur (NNRTIs are not incorporated into the DNA chain)
NRTIs and NNRTIs are
reverse transcriptase inhibitors
protease inhibitors block replication of HIV by
protease inhibitors block replication of HIV by binding proteases and preventing cleavage of proteins that are vital for producing infectious forms of the virus
______ blocks the CCR5 host cell membrane protein, preventing HIV from fusing with the host cell
maraviroc
