Viruses Shuffled Flashcards
Rotavirus
- a family of segmented, dsRNA GI viruses
- triple layer capsid with VP6, VP4, VP7
- major cause of infantile diarrhea
- most common in those 6-24 months old in the cooler months
- 2 day incubation period followed by 7 days osmotic diuresis, vomiting, abdominal pain
- diagnosed via EIA or latex agglutination of stool sample
- vaccine available is only meant to limit severity
- pathogenesis relies on NSP4 enterotoxin and cell lysis- most common is group A G1P[8]
Which family of viruses has an incredibly rapid life cycle and inhibits host translation to favor viral translation?
picornaviruses
How does B19 infection present in adults?
with long lasting joint pains and arthritis
Areas of irregular granularity in white matter are a feature of which disease?
JC virus/PML
Dengue fever virus causes what two diseases?
- hemorrhages fever
- dengue shock syndrome
Negri bodies are a feature of what infection?
rabies virus
How do most arboviruses survive the winter?
in dormant female mosquitos and eggs
What kind of vaccine is the VZV vaccine?
a live, attenuated vaccine
What are the three possible outcomes of a poliovirus infection?
- asymptomatic or mild illness
- non-paralytic poliomyelitis or aseptic meningitis
- paralytic poliomyelitis
When is respiratory syncytial virus most common?
in the winter
Describe the genome of parvoviruses.
- ssDNA with inverted repeats that form hairpins
- these hairpins allow the genome to self-prime
The severity of mono correlates with what?
the age of infection with younger being associated with milder illness
Where is yellow fever endemic?
South America and sub-saharan Africa
How is hantavirus treated?
ribavirin early in the disease course
Describe the genome of HIV-1.
a diploid RNA retrovirus with 3 major genes: env, pol, gag
HSV-1
- a dsDNA virus of the alpha herpesviridae subfamily
- spread primarily via saliva
- infects mucoepithelial cells
- remains latent in trigeminal ganglia or DRG and reactivated by stress, light, immunosuppressants
- typically cause oral lesions but also cause encephalitis, keratoconjunctivitis, herpes whitlow, and herpes gladitorium
What is important to remember about rift valley fever?
- perpetuated by sheep and found primarily in Africa
- peak incidence follows rainfall
- 2-6 day incubation period is followed by 2-5 days of flu-like symptoms
Describe the HepB genome.
- a relaxed circular DNA virus
- C gene encodes HBc and HBe antigens
- P gene encodes polymerase
- S gene encodes S, S1, S2
Flaviviruses cause which group of diseases?
hemorrhagic fevers
Describe the timecourse of ebola hemorrhagic fever.
- 3-21 day incubation period
- 7-14 days until death
How does the adeno-associated virus establish a latent infection?
it integrates its genome into the human chromosome 19 via homologous recombination
How do most dengue fever viral infections conclude?
resolution after the febrile phase
How do we define congenital CMV?
presence of CMV in saliva or urine within 3 weeks of birth
What is the most common cause of gastroenteritis worldwide?
norwalk virus
What is the most common form of Burkitt’s lymphoma in the US?
sporadic
Describe the picornaviridae family genomes.
positive strand RNA viruses that yield a poly protein that must be cleaved
What are the significant complications of B19 disease?
- aplastic crisis
- anemia
- hydros fetalis
Rubella
- a positive strand RNA virus that infects the respiratory tract
- presents with fever, sore throat, lymphadenopathy and a characteristic rash lasting up to five days that is less severe than measles
- causes arthralgia and arthritis in adults
- can be passed during first trimester to cause congenital rubella
- pathology is partially antibody mediated
Describe the presentation of influenza A.
- 3 days of systemic symptoms
- plus dry cough,, pharyngeal pain, and nasal congestion
Neonatal Herpes
- a usually fatal infection by HSV-2 acquired in utero, usually during a primary infection of the mother
- spreads to liver, lungs, and CNS because the immune system isn’t fully developed
- causes brain atrophy
What is a typical incubation period for rabies?
2-12 weeks but ranging from 4 days to 1 year
Describe the presentation of roseola infantum.
- 6m to 3y old
- abrupt onset high fever lasting three days (possibly with febrile seizures)
- rapid cessation of fever and onset of mild, pink, morbiliform exanthema lasting 1-2 days
What are negri bodies filled with?
coiled ribonucleoprotein
When does coronavirus incidence peak?
summer/fall
Which virus is a common cause of GI problems on cruise ships?
norwalk virus
What is the most common cause of sporadic encephalitis?
herpes infection
What role do ebola virus proteins play in the pathogenesis of ebola hemorrhagic fever?
- GP forms virus like particles and causes cell death and endothelial activation
- sGP has anti-inflammatory properties (particularly against TNFa)
- VP24 and VP35 are type I interferon antagonists
When are rubella outbreaks common in the US?
in college
Where does HTLV-1 have a particularly high prevalence?
Japan
How does ebola reach humans from bats?
via ecological “spillover dynamics”
How do coronaviruses compare to rhinoviruses?
- have a longer incubation period and shorter symptomatic period
- coronavirus peaks in winter/early spring while rhinovirus peaks in summer/fall
Enterovirus
- a species of the picorna family that includes coxsackie A and B, poliovirus, and echovirus
- enter via GI or respiratory tract and then enter lymphatics
- viral replication responsible for pathology
- rarely cause GI disease
- usually cause asymptomatic or mild flu-like illness
- can cause meningitis, orchitis, myocarditis, paralysis, ARD, or febrile exanthems
Which types of hantaviruses are less fatal?
the ones other than sin nombre which cause renal pathology rather than the pulmonary syndrome
What are VP40 and VP24 in the context of filoviruses?
they are matrix proteins
Describe the presentation of norwalk virus including incubation period.
- 2-4 day incubation period
- nausea, vomiting, anorexia, diarrhea, headache
What are the two leading causes of mental handicap at birth?
1) Down’s syndrome
2) congenital CMV infection
Cryptococal Meningioencephalitis
- a cryptococcus neoformans infection common in those with a CD4 count below 100 cells/uL
- presents with subacute fever, malaise, headache, stiff neck, and photophobia
- diagnose with CSF analysis and culture
Parainfluenza Virus
a paramyxovirus with immune-mediated pathology that includes croup, bronchiolitis, and pneumonia in stem cell and organ transplant patients
What are Downey cells?
abnormally activated lymphocytes associated with EBV infection and transformation of B cells
Name the two important phleboviruses.
- rift valley fever
- sandfly fever
Mycobacterial Disease
- a reactivation of M.tb or M. avium complex in HIV patients
- M.tb associated with pneumonia
- MAC associated with disseminated disease in HIV patients
Which group of dsDNA viruses replicate in the cytoplasm?
poxviruses
What is the mortality associated with arena viruses?
15-30 percent
Describe an acute genital herpes infection.
- incubation period of 5 days
- tender lymph nodes, fever, dysuria, itching
- followed by lesions
- resolves 3-4 weeks later with recurrences being shorter
Describe the presentation of infectious mono.
- cervical lymphadenopathy
- splenomegaly
- exudative pharyngitis
- hepatomegaly
- presence of heterophil antibodies and downey cells
Poliovirus targets which CNS cells.
autonomic and motor neurons of the anterior horn, pons, and medulla
What are three pulmonary and three non-pulmonary complications of influenza A?
- pulmonary: pneumonia, croup, exacerbation of COPD
- non-pulmonary: myositis, toxic shock syndrome, Guillan-Barre syndrome
Describe the Filoviruses.
- long and skinny but pleomorphic in shape
- polyploidy, negative strand RNA with 1-20 copies per virion
Describe African aggressive Kaposi sarcoma.
- seen in East and Central Africa
- nodular, infiltrative, lympho-adenopathy
- rapidly fatal and without treatment
What are the three outcomes associated with an EBV infection?
- active infection
- latent infection
- stimulation and immortalization of B cells to cause cancer
Describe the presentation and time course of sandfly fever.
- not seen in the US
- a 2-6 day incubation period is followed by rapid onset, high fever and malaise for 2-4 days
Hepatitis C
- a positive strand RNA virus of flavi family
- types Ia, Ib, 2, and 3 most common in the US
- transmitted percutaneously and permucosally
- replicates, assembles at membranous web, can spread through basolateral membrane
- 6-7 week incubation period but acute infection goes unnoticed
- high incidence of chronic infection
- alcohol, >40, HIV, HBV, male all increase morbidity
When does rhinovirus incidence peak?
winter/early spring
How is rhinovirus spread?
via aerosol and fomites
Hepatitis B
- a relaxed circular DNA virus of the hepadna family
- genome can integrate into host genome
- transmitted perinatally, parenterally, and sexually
- 60-90d incubation period
- chronic complications more common in those <5 y.o.
- complications: HCC, PAN, glomerulonephritis, cirrhosis
- pathology is immune mediated
What is zostavax?
a zoster vaccine given to those over the age of 60
Which proteins are important for the infectivity of the influenza viruses?
- hemaglutinin
- neuraminidase
- M2
Which papillomavirus genes are oncogenic?
E6 and E7 inhibit p53 and Rb
JC virus enters the host via the ___ but persists in what two places?
- enters via respiratory tract
- persists in B cells and the kidney
Papillomaviruses belong to what family?
papovaviridae
HTLV-1 is known to cause what diseases?
- asymptomatic infection in 95% of cases
- infection in early life results in adult T cell leukemia/lymphoma
- tropical spastic paraparesis
- HTLV-1 associated myelopathy
Describe the transmission cycle of dengue fever virus.
human-vector-human
The leading cause of the common cold is what?
rhinovirus
Describe polyomaviridae virions.
- dsDNA genome complexed with histones
- genome has a control region separating bidirectional early and late genes
- transcription controlled by Large T antigen
Describe the presentation of Lassa fever.
- 3-5 day incubation period with insidious onset
- ulcerative pharyngeal lesions
- possible pneumonia, myocarditis, shock
- hemorrhagic fever
- sensorineural deficits during convalescence
How do most influenza viruses spread?
large droplets, aerosol, or fomites
The first ever retrovirus identified was what?
Human T-cell Leukemia Virus 1
Describe the spread of VZV in humans.
- transmitted via droplets to the respiratory tract
- carried by lymphatics to the blood
- then onto the skin and mucous membranes
What is west nile neurologic disease?
- meningitis
- encephalitis
- polio-like flaccid paralysis
Infectious mono is associated with what infections?
EBV and CMV
Describe the rotavirus vaccine.
produced by human/bovine reassortment and meant only to prevent severe disease, not all disease
Describe the presentation of a cold sore.
- pain, tingling, and itching followed by the appearance of erythema and edema
- papule and vesicles form within 24 hours
- ulcerates and heals 7-10 days later
What is the most classic feature of rabies disease?
“hydrophobia” - don’t want to drink or eat
To which family do the rhinoviruses belong?
picornaviridae
What is Hantaan pulmonary syndrome?
a form of Hantaan disease in which the endothelial damage is concentrated in the lungs, causing shock and cardia complications
Measles belong to which family of viruses?
paramyxoviridae
What is the most important type of immunity for rabies virus?
humoral immunity focused on anti-G protein antibodies
Describe the herpesviridae life cycle.
- enter via fusion event
- transcription of genome via host RNA pol II in nucleus
- capsid assembles in the nucleus
- capsid leaves via a double envelopment proccess
- acquires an envelop from the golgi
- leaves the cell via lysis
The most common fungal infection in HIV patients is what?
candidiasis
What diseases does HSV-2 cause?
- usually genital lesions
- also encephalitis, pharyngitis, herpes whitlow, and neonatal herpes
Describe the pathogenesis of rotavirus.
produces NSP4, an enterotoxin, and causes lysis of epithelial cells
How does HIV-1 enter target cells?
gp41 and gp120 interact with host CD4 TCR and CCR5 or CXCR4 co-receptors
Eczema Herpeticum
a herpes infection of children with pre-existing atopic dermatitis and burn patients which spreads cutaneous
What is the most significant cause of infantile diarrhea?
the rotavirus family
Why should patients with a B19 infection not be given IVIG?
because part of the pathology is mediated by B19-antibody complexes
What organism causes cryptococcal meningoencephalitis?
cryptococcus neoformans
Describe post-transplant CMV infection.
- presents 1-3 months post-transplant
- with fever, pneumonitis, GI complaints, hepatitis, and poor graft function
BK virus affects which renal cells?
epithelial cells of the tubules and collecting ducts
What accounts for the biphasic nature of B19-related illnesses?
- the first phase is related to viremia
- the second to B19-antibody complexes
Slapped cheek rash is characteristic of what infection?
B19 parvovirus
Describe congenital varicella?
a varicella infection acquired in utero that causes scaring of skin, limb hypoplasia, and CNS defects
List the most common organisms associated with aseptic meningitis.
enteroviruses, primarily coxsackie A and B
BK virus is linked to which cancers?
- beta-islet adenomas of the pancreas
- brain tumors
What is the significance of late and early genes in papillomaviruses?
- early genes are sufficient for cancerous transformation
- late genes expressed in a productive infection
HSV-1 causes what diseases?
- primarily herpes labials (cold sore)
- also encephalitis, keratoconjunctivitis, herpes whitlow, and herpes gladitorum
Why does post-exposure vaccination to rabies work?
because of the long incubation period of the virus
What happens to the positive and negative strands of parvovirus DNA?
they are packaged into separate virions
Which hepatitis virus assembles at the membranous web and can spread directly through the basolateral membrane of the host cell?
hepatitis C
Adeno-associated virus requires co-infection with one of which two viruses?
- adeovirus
- herpesvirus
Describe the presentation of rotavirus infection.
- 2 day incubation period
- 7 days of osmotic diuresis with vomiting, fever, headache, and abdominal pain
What is SARS?
- a coronavirus disease typically acquired during travel that presents with fever, headache, myalgia and progresses to a LRT period 3-7 days later with a dry, unproductive cough
- hasn’t been seen since 2004
BK viruses causes what disease?
polyomavirus associated nephropathy
List the important bunyavirus genera.
- hantaviruses
- phleboviruses
- arenaviruses
Respiratory syncytial virus is the most common cause of what diseases in infants?
- bronchiolitis
- LRTI
- pneumonia
How does papillomavirus present in immunocompromised patients?
they are often covered with large warts
How is ebola hemorrhagic fever treated?
- ribavirin early
- supportive care including blood and clotting factor replacement
- monoclonal antibodies against the virus envelop glycoprotein
How does yellow fever present?
- chills, fever, headache, GI upset
- Paget’s sign (bradycardia) after 3-4 days
- jaundice, hemorrhagic signs
How is cryptococcal meningoencephalitis diagnosed?
CSF analysis and culture
Herpes Keratoconjunctivitis
a monocular conjunctival infection by HSV-1 that my cause corneal damage and blindness with recurrent infection
How does candidiasis present?
white plaques with a “stuck on” appearance found on the tongue, palate, esophagus, or vagina of immunocompromised patients
Why is rabies vaccination unique?
it is one of few that allows for post-exposure vaccination to prevent disease onset
How does congenital rubella present?
- with a classic triad of cataracts, heart defects, and sensorineural deafness
- often have premature delivery and is fatal