DNA Viruses Flashcards
What are the 3 types of viral infections at the cellular level?
Lytic
Nonlytic
Oncogenic
What characterizes lytic viral infections?
Virus accumulates inside cell —> ↑ osmotic pressure —> cell bursting
What characterizes nonlytic viral infections?
Persistent, slow release of virus from cell via exocytosis or membrane budding
Latent infection via virus regulating its gene expression to conserve its genome
What characterizes oncogenic viral infections?
DNA and retroviruses that establish a persistent infection by stimulating uncontrolled cell growth
What is the name for the process in which oncogenic viruses stimulate uncontrolled cell growth by establishing a persistent infection?
Transformation or immortalization
How can oncogenic viruses stimulate uncontrolled cell growth? (4)
Activating growth factors
Removing braking mechanisms that limit cell growth
Preventing apoptosis
Encoding oncogenes (retroviruses)
What are the S&S of primary hepatitis B infection?
Jaundice
Light-coloured stool
Fever
Fatigue for weeks/months
Loss of appetite, nausea, vomiting
What are the S&S of secondary hepatitis B infection?
Positive test for 6 months
Persistent elevated liver enzymes (ALT/AST)
Liver fibrosis
Liver Cirrhosis
Hepatocellular carcinoma
What is the prevention for Hep B?
Vaccine available, but no use once infected
Transmitted via blood and sexual contact
What type of anti-viral is used for the treatment of Hep B?
Nucleoside analogue reverse transcriptase inhibitors
How are HHV transmitted?
Usually via active lesion, but HHV-2 can be shed while asymptomatic
Close bodily contact at mucous membranes
What causes the lesions associated with HHV?
Inflammation and cell death at site of infection
What causes cold sores?
HHV-1
Transmitted via casual contact
What causes genital herpes?
HHV-2
Transmitted via sexual activity
This class of antiviral helps manage several viruses including HHV, VZV, and CMV
Nucleoside analogue inhibitors
How do nucleoside analogue inhibitors work?
False nucleotides that interfere with viral replication
Addition of false nucleotide —> chain termination —> virus unable to make new copies of itself
In retroviruses (ex. HIV) inhibits reverse transcriptase from converting viral RNA into DNA
VZV is highly infectious and seen most commonly in children. What is the severity of this virus like in adults vs children?
More severe in adults than in children
How long after infection do skin lesion appear for VZV?
2-3 wks
How is VZV transmitted?
Resp tract or eyes
What is herpes zoster/shingles?
Reactivation of VZV, typically in adulthood when the immune system is vulnerable
Shingles is a reactivation of VZV. How does its presentation differ from VZV?
VZV is non-localized and tends to be diffuse
Shingles presents as a rash localized over a dermatome (area of skin supplied by a single spinal nerve)
Shingles is a reactivation of VZV; the initial infection moves up a spinal nerves and lies dormant in dorsal root ganglia
Reactivation —> virus moving down dermatome
How is EBV transmitted?
Saliva
What types of cells are affected by EBV and how are they affected?
EBV invases B lymphocytes, becomes latent in them and immortalizes them by suppressing apoptosis
Can cause B cell lymphoma in rare cases
What group of people are susceptible to extreme disease r/t EBV?
Those with T cell deficiencies
This is bc infected B cells aren’t removed by cytotoxic T cells —> virus proliferation
What virus causes “mono”?
EBV
How is CMV transmitted?
Sexual contact
In utero exposure
Vaginal birth
Blood transfusions
Organ transplants
What are the complications associated with CMV?
Birth defects that can result in death
IC pts can develop pneumonia, blindness, or CMV mononucleosis (similar to infectious mononucleosis)
How is CMV diagnosed?
- Detection of abnormally enlarged cell
- CMV viral load
How is CMV treated?
Ganiciclovir or valganciclovir
Fomiversen for CMV eye infections
What virus causes “slapped cheek disease”?
Parvovirus
What is the prevention for parvovirus?
No treatment, no vaccine :(
What are important consideration for parvovirus risk to pregnant individuals?
Spontaneous abortion
Congenital anomalies
Hydrops fetalis (fetal anemia, fetal viral myocarditis, impaired hepatic function)
B19-Specific IgG and IgM can be given to this population
What is the treatment for HPV?
No viral tx
Med for symptoms: podophylin, imiquimod, podofilox
Intervention for symptoms: freezing, electrical burn, laser, direct interferon injection, removal
What is the main concern with HPV infection?
Cancer
This is one of the causative agents of the common cold and is spread via resp droplets
Adenovirus
Infection of the conjunctiva with this virus can cause pinkeye
Adenovirus
