Semester 2 - Non-enveloped Viruses Flashcards
What are some examples of DNA viruses?
Adenovirus
Papillomaviruses
Paroviruses
What are some features of non-enveloped viruses?
Many are resistant to common disinfectants, desiccation, acidification = highly stable
Commonly associated with GI and respiratory tract infections
What are some examples of RNA viruses?
Picornaviruses (poliovirus, rhinovirus, enterovirus)
Hepevirus
Noroviruses
Reoviruses (rotavirus)
What are some characteristics of Adenoviruses?
Large, dsDNA virus, 57 human serotypes
Highly stable virions - non-enveloped viruses more resistant to desiccation, acid treatment, etc.
Ubiquitous human virus, used as a vector of gene therapy/vaccination approaches
Infection often asymptomatic (depends on serotype)
How are genes expressed in Adenoviruses?
Occurs in the nucleus using host cell machinery
Genes are spliced and modified similarly to host genes
Early genes (E genes) enzymatic/regulatory
Late genes (L genes) structural
What are the symptoms of a respiratory adenovirus infection (1, 2, 5, 6, 14)?
Associated with acute respiratory disease
Croup (upper airway inflammation), hoarseness of the throat
Fever, rhinorrhea, cough, sore throat
Tonsilitis, bronchiolitis, pneumonia in more severe cases
What are the symptoms of an enteric Adenovirus (40, 41) infection?
Associated with gastroenteritis
Food-borne illness, fecal-oral transmission
Diarrhea, fluid and electrolyte loss
What are the signs and symptoms of conjunctivitis/keratoconjunctivitis Adenovirus (3, 4, 7, 8, 19, 37) infection?
Direct inoculation of the eye
Infection of the conjunctiva and/or cornea
Unilateral ‘red-eye’ may spread to both eyes
Highly contagious, also associated with fever and pharyngitis (pharyngoconjunctival fever)
What are the signs and symptoms of a hemorrhagic cystitis Adenovirus (11, 21) infection?
Inflammation of the bladder
Dysuria, painful urination, hematuria
Also associated with nephritis
More common in children/adolescents, and immunocompromised patients
How are the adenoviruses transmitted?
Mucosal (respiratory, fecal-oral)
How are the adenoviruses treated?
Generally self-resolving
Supportive treatment (treat symptoms)
Antivirals for more severe infections
What are some characteristics of Human Papillomaviruses (HPV)?
Large, dsDNA virus, >100 human serotypes
Infection of undifferentiated basal keratinocytes (skin, mucous membrane), replication in terminally differentiated epithelial cells
Utilize host DNA polymerase
Different serotypes are associated with distinct pathologies
What are some main characteristics of Genital warts?
HPV
Includes vulvar, penile, and anal warts, as well as oral papillomas
90% caused by serotypes 6, 11
How is HPV transmitted?
Contact, sexual
What are some characteristics of cancer caused by HPV?
Cervical, anal, oropharyngeal
Subtypes 16, 18, others
HPV drives cell cycle progression to activated cellular DNA polymerase for use by the virus
E6 early protein inhibits p53 tumor suppressor gene
E7 early protein inhibits pRb tumor suppressor gene
What is Gardasil and what serotypes does it work for?
Indicated for girls 9-26 years
Types 16, 18 cause 75% of cervical cancer genes
Types 6, 11 associated with most cases of genital warts
Recombinant subunit vaccine (L1 capsid protein)
What is the treatment for HPV?
Prevention - vaccine
Imiquimod (immune modulator)
Podofilox (inhibits topoisomerase II DNA replication)
Trichloroacetic acid (kills replicating cells)
Cryotherapy
Non-pharmacological interventions are suitable for many superficial warts
What does a PAP smear look for?
Abnormal cells
Not infection alone and not serotype
What are some characteristics of parvovirus?
(+) ssDNA, non-enveloped
Most members infect animals (canine, bovine etc) but NOT zoonotic
Replication occurs in the nucleus and utilizes host cellular functions
Virus particle is highly stable - resistant to dessication, acidification, and heat
How is parvovirus transmitted?
Fecal-oral
What are the symptoms of a parvovirus infection?
Hemorrhagic diarrhea and vomiting
What are the human parvoviruses?
Parvovirus B19
Adeno-associated virus (AAV)
What are the signs and symptoms of a Parvovirus B19 infection?
Generally asymptomatic
Children: erythema infectiosum, low grade fever, followed by rash on face spreading to extremeties (may last several weeks). Typically mild
Adults: rash more severe, typically itches. Arthritic symptoms and joint inflammation common (hands, wrists, knees, ankles)
How is Parvovirus B19 transmitted?
Respiratory droplets
What is the treatment for Parvovirus B19?
Supportive, typically unnecessary
What are some characteristics of Picornaviruses?
Small, (=) ssRNA, non-enveloped viruses (pico = small)
Icosahedral capsid comprised of 4 proteins VP1-4
What are the human pathogens of Picornaviruses?
Rhinovirus
Poliovirus
Coxsackie
Hepatitis A
Where does replication occur for the Picornaviruses?
Replication occurs in the cytoplasm
Direct translation of (+) genome into a single polyprotein, following by proteolytic cleavage by viral protease
What are the signs and symptoms of a Rhinovirus infection?
Sore throat, nasal congestion, runny nose, sneezing, cough
Muscle ache, muscle weakness, fatigue
Seasonal epidemiological pattern of infection
How is the Rhinovirus transmitted?
Respiratory droplets
What is the treatment for Rhinovirus?
Supportive
What are some characteristics of the Rhinovirus?
Non-enveloped virus - resistant to desiccation, relatively stable
>100 serotypes - multiple rhinovirus infections in one individual
What are some characteristics of the Polio virus?
Causes poliomyelitis
Occurs primarily in children <5 years
Worldwide vaccination has left only a few endemic areas of disease (Afghanistan, Pakistan, Nigeria)
What are the signs and symptoms of a polio virus infection?
Mild/asymptomatic disease in 95% of individuals
Abortive poliomyelitis 5%: self resolving in about 10 days, URT, GI and flu like symptoms
Non-paralytic aseptic meningitis 1-2%: self-resolving in 10 days, stiffness in the neck, back, legs, muscle spasms
How is the polio virus transmitted?
Fecal-oral
What are the three types of CNS invasion of polio virus?
Spinal (most common): anterior horn cells of spinal column, asymmetrical paralysis)
Bulbar: bulbar region of brainstem (vagus, accessory, glossopharyngeal) affects swallowing, breathing, lung/heart function, neck movement
Bulbospinal/respiratory polio: cervical vertebrae, phrenic nerve (diaphragm) requires ventilator
What is post-polio syndrome?
Chronic, slow to develop, not associated with shedding/infection
Muscle weakness and extreme fatigue
Pathophysiology unknown - neurological involvement
What are the signs and symptoms of a Coxsackievirus infection?
Causes acute febrile illness in symptomatic patients
Fever, nausea, vomiting, fatigue, muscle weakness
Associated with aseptic meningitis in children, infectious myocarditis and pericarditis in susceptible individuals
What are the symptoms of a Coxsackie A infection?
Hand, foot and mouth disease
Fever, malaise, rash, and ulcerating lesions on the hands and feet
Herpangina - blisters or ulcers in mouth and throat
Conjunctivitis
What are the symptoms of a Coxsackie B infection?
Fever, abdominal pain, chest pain, headache
What is the treatment for a Coxsackievirus infection?
Supportive
Symptoms last 1-2 weeks and resolve spontaneously, shedding may occur for weeks following resolution of symptoms
What are some characteristics of Hepatitis A?
(+) ssRNA, noneveloped picornavirus
Polyprotein synthesis followed by proteolytic cleavage
1.4 million cases/year globally
What are the clinical features of Hepatitis A?
Range from mild to severe
Sudden onset fever, malaise, anorexia, abdominal discomfort
10% patients have recurrent illness for 6-9 months following infection
How is Hepatitis A transmitted?
Contaminated food/water
Associated with travellers
What is the treatment for Hepatitis A?
Supportive
Vaccine preventable (inactivated) Combo A/B
Heat food/water to >84 C for more than 1 min or chlorinate
What are some characteristics of Hepatitis E?
Enteric
Hepevirus (+) ssRNA, non-enveloped
How is Hepatitis E transmitted?
Fecal-oral (contaminated water, pork/deer meat) Blood products (rare)
What are the signs and symptoms of a Hepatitis E infection?
Fever, fatigue, nausea, anorexia Abdominal pain, joint pain Jaundice, dark-coloured urine Generally self-limiting Pregnant women - mortality rate high during 3rd trimester Risk of fulminant hepatitis
What is the treatment for Hepatitis E?
Treatment supportive
No vaccine currently approved in North America
What is the function of Alanine transaminase?
ALT converts alanine to pyruvate following lactic acid production in muscles
What does elevated ALT indicate?
Liver pathology
What is cirrhosis?
Fibrosis, scarring, generation of nodules in the liver
Ascites - fluid retention in the abdominal cavity
Jaundice, increased bruising/bleeding
Leads to HCC (Hepatocellular carcinoma)
What are some characteristics of the Norovirus?
Calicivirus family (+) ssRNA nonenveloped 5 genogroups, multiple genotypes
How does the Norovirus replicate?
By polyprotein synthesis followed by cleavage
What are the clinical features of a Norovirus infection?
Severe acute diarrhea and vomiting
What is the treatment for Norovirus?
Supportive (rehydration, electrolyte replacement)
Self resolving 24-72 hours
How is the Norovirus transmitted?
Fecal-oral (highly contagious
What are some characteristics of the Rotavirus?
Reovirus family dsRNA, nonenveloped 11 segmented genome 5 serotypes (A-E) Most common cause of severe diarrhea in young children (90% serotype A)
How does the Rotavirus replicate?
In the cytoplasm using viral replication/transcriptional machinery, host translational machinery
What is NSP4 virulence factor?
Enterotoxin of the Rotavirus
Causes calcium secretion followed by fluid accumulation in the GI tract
What are the signs and symptoms of a rotavirus infection?
Fever, vomiting
Diarrhea, abdominal pain lasting 3-8 days
How is the rotavirus transmitted?
Fecal-oral
Virus is highly stable, can survive for several hours on inanimate objects
How is a Rotavirus infection treated?
Supportive (oral rehydration, IV rehydration in severe cases)
Vaccine available - oral live attenuated virus
Low risk intussusception (Bowel obstruction due to intestinal prolapse) following vaccine administration
