DNA VIRUSES (NAKED DNA VIRUSES) Flashcards
All DNA viruses have double stranded DNA EXCEPT
Parvovirus
All DNA viruses have linear DNA EXCEPT
Papilloma, Polyoma, and Hepadna
All DNA viruses are icosahedral EXCEPT
Poxvirus
All DNA viruses replicate in the nucleus EXCEPT
Poxvirus
What does the Latin term “parvus” mean?
Small
Among which type of animals is Parvoviridae widely distributed?
Warm-blooded animals.
Which is the single human pathogen among the Parvoviridae?
Parvovirus B-19.
A nonenveloped, icosahedral, single-stranded DNA virus that may appear spherical on electron microscopy.
Parvovirus
What are the major sites of viral replication for Parvovirus
Adult bone marrow and fetal liver cells.
What is another name for Fifth disease caused by Parvovirus B-19?
Erythema infectiosum.
What are the symptoms of Fifth disease?
Bright red cheek rash (slapped cheeks) with fever, coryza, and sore throat.
What can Parvovirus B-19 cause in patients with underlying hemoglobinopathies?
Aplastic crisis, which is transient but severe in conditions like sickle cell anemia, thalassemia, or spherocytosis.
What are the effects of fetal infection with Parvovirus B-19 during the first and second trimesters?
First trimester: fetal death;
Second trimester: hydrops fetalis.
What are the two phases of biphasic illness caused by Parvovirus B-19?
The first phase includes:
marked fever, malaise, myalgia, and chills,
The second phase includes:
rash and arthralgia.
When do IgM and IgG antibodies appear after Parvovirus B-19 infection?
IgM antibodies appear within 7 days, followed by IgG at approximately 14 days.
How is Parvovirus B-19 diagnosed in the laboratory?
By parvovirus-specific IgM or virus-specific IgG antibody testing with paired acute and convalescent sera or by detection of viral DNA using PCR.
Can Parvovirus B-19 be cultivated in typical clinical virology laboratory cells?
No, it cannot be cultivated in the typical cells available in clinical virology laboratories.
Medium-sized (70-90 nm), icosahedral, nonenveloped, double-stranded, linear DNA viruses.
Adenovirus
What are the most common clinical manifestations associated with adenovirus infection?
Respiratory and gastrointestinal diseases.
How is adenovirus most commonly transmitted (MOT)?
Through aerosolized droplets or as airborne particles.
How is respiratory disease caused by adenovirus usually acquired?
respiratory secretions, stool, or fomites.
very stable and can remain viable for weeks at variable temperatures on surfaces and in liquid solutions.
Adenovirus
What is the incubation period for respiratory disease caused by adenovirus?
2-14 days.
What are some common respiratory conditions caused by adenovirus?
Colds, tonsillitis, pharyngitis, pharyngoconjunctival fever, croup and Epidemics in military recruits
How can adenovirus be detected in the laboratory?
From respiratory secretions or stool in cell culture using various epithelial cell lines.
What confirmatory follow-up tests are used for adenovirus detection?
Indirect fluorescent antibody (IFA) technique or enzyme immunoassay (EIA).
What characteristic cytopathic effect (CPE) does adenovirus produce?
A grapelike cluster cytopathic effect known as Cowdry Type B intranuclear inclusions.
Small, nonenveloped, circular, double-stranded DNA viruses.
Papillomavirus
In which species can Papovaviridae cause infections?
Humans, dogs, cattle, monkeys, and many other species.
What are Human Papillomaviruses (HPV) known to cause?
Human warts.
What is the tissue tropism of HPV?
Either cutaneous or mucosal tissue.
What cells do HPV infect and what do they induce?
HPV infects squamous cells and induces the formation of cytoplasmic vacuoles (koilocytes).
What are the functions of the E6 and E7 genes in HPV?
E6 inhibits p53
E7 inhibits Rb,
leading to the inactivation of tumor suppressor genes.
Which HPV types are associated with plantar warts?
HPV-1.
Which HPV types are associated with common warts of the hands?
HPV-2 and HPV-4.
Which HPV types are associated with genital warts (condyloma accuminata)?
HPV-6, HPV-11, and others.
How many types of HPV cause virtually all cases of cervical cancer, and which types cause more than 60% of cases?
-Fifteen to twenty types of HPV cause virtually all cases of cervical cancer
-with types 16 and 18 causing more than 60% of cases.
Which HPV type is associated with a subset of cancers of the oropharynx and penile cancer in males?
HPV-16.
Which HPV type is associated with adenocarcinoma?
HPV-18.
What is the most prevalent sexually transmitted viral disease in the United States?
HPV infection.
How is HPV infection detected?
-Using histopathologic (cutaneous biopsy) or cytologic (cells) examination
-DNA probe assays for identification of specific genotypes in infected epithelial cells.
What are the vaccines available for HPV prevention?
Cervarix, Gardasil, and Gardasil-9.
