… Prt. 2 Flashcards
(30 cards)
Unique properties:
Small (45 nm), nonenveloped icosahedral
capsid (resistant to inactivation)
Circular dsDNA (5kbp), replicates & assembled in the nucleus
Three structural proteins, cellular histones condense DNA in virion
Polyomaviridae
Virus persists in hosts; asymptomatic shedding
likely; stimulate cell DNA synthesis, viral oncoproteins (T, t antigens) interact with cellular tumor suppressor proteins;
o an important model tumor viruses;
o can cause neurologic and renal disease,
o may cause human cancer
Polyomaviridae
Polyomaviridae
o associated with Merkel cell skin carcinomas, skin tumors of
neuroendocrine origin
o Merkel cell virus
o associated with nephropathy in transplant recipients; latent - kidneys
o BK virus
o causative agent of progressive multifocal leukoencephalopathy (a CNS (demyelinating) complication in immunosuppressed individuals, ex.
AIDS, multiple sclerosis);
latent – kidneys, B cells, monocyte-lineage
o JC virus
o Large family divided into 16 genera; five contain members that infect
humans: Alpha-, Beta-, Gamma-, Mupa-, and Nupapillomavirus
PAPILLOMAVIRIDAE – HUMAN PAPILLOMAVIRUS (HPV)
Slightly larger than polyomaviruses – 55 nm in diameter, icosahedral,
2 structural proteins
Larger genome – 8 kbp, circular dsDNA, cellular histones condense DNA virion
PAPILLOMAVIRIDAE
o Most common viral infection of the reproductive tract, 660 million people worldwide
o Accepted as the cause of anogenital cancers, 99% cervical cancer, 80% anal cancers;
PAPILLOMAVIRIDAE
(most commonly detected in cervical carcinomas)
HPV-16 or HPV-18
Transmission by close contact (sexually transmitted) then infect epithelial cells of skin or mucous membranes; persist in basal cell layers
Cause different kinds of warts, condylomas, papillomas, several cancers
PAPILLOMAVIRIDAE
Human Papilloma Viruses (HPV)
Koilocytes (enlarged keratinocytes)- type of dysplastic squamous cell found in potentially precancerous cervical lesions
Human Papilloma Viruses (HPV)
Isolated in 1953 from human adenoid cell culture
Wide range of illnesses, from mild respiratory infections in young children (“common cold”)
to life-threatening multi-organ disease in immunosuppressed individuals
ADENOVIRIDAE – Human Adenoviruses (HAdV)
o Spread by aerosol, close contact, or fecal-oral means to
establish pharyngeal infection; fingers spread virus to eyes
o Infects mucoepithelial cells in the RT, GIT, urinary tract,
conjunctiva or cornea causing cell damage
o Persists in lymphoid tissues, Group C adenoviruses (tonsils,
adenoids, Peyer patches)
ADENOVIRIDAE – Human Adenoviruses (HAdV)
Respiratory Diseases
febrile, undifferentiated upper respiratory infection (I, YC)
pharyngoconjunctival fever (C, A)
acute respiratory disease, HAdV Group C: 1-7 (I, YC, MR)
pertussis-like syndrome (I, YC)
pneumonia, HAdV 3,4,7, 21 (I, YC, MR, ICP)
ADENOVIRIDAE – Human Adenoviruses (HAdV)
Other Diseases
gastroenteritis, HAdV 40, 41, 42 (I, YC, ICP)
acute hemorrhagic cystitis (C, ICP)
**epidemic keratoconjunctivitis, ** HAdV 8, 19, 37 (A)
systemic infections (i.e., hepatitis) (C, ICP)
ADENOVIRIDAE – Human Adenoviruses (HAdV)
smallest of DNA viruses
- 18 to 26 nm
Naked icosahedral capsid, cubic symmetry, 32 capsomeres
Single-stranded linear DNA genome, plus and minus
strands, 5kb in size
PARVOVIRIDAE – Human parvoviruses
PARVOVIRIDAE – Human parvoviruses
Two causing human infections:
Human parvovirus B19 (Erythroparvovirus genus)
Human bocavirus (Bocaparvovirus genus)
PARVOVIRIDAE – Human parvoviruses
replicates only in actively dividing cells (immature erythroid cells) in the bone marrow; lytic infection → viremia (can cross the placenta)
Cellular receptor = blood group P antigen (expressed on mature
erythrocytes, erythroid progenitors, megakaryocytes, endothelial
cells, placenta, and fetal liver, & heart - thus the narrow tissue
tropism & difficulty to culture)
Spreads via oral secretions; causes several adverse consequences, including aplastic crisis, fifth disease, and fetal death
Human parvovirus B19
PARVOVIRIDAE – Human parvoviruses
Syndromes:
erythema infectiosum or fifth disease or slapped cheek syndrome
a mild febrile exanthematous disease
transient aplastic crisis in patients with chronic hemolytic anemia
(sickle cell anemia, thalassemias, acquired hemolytic anemias)
Human parvovirus B19 (Erythroparvovirus genus)
PARVOVIRIDAE – Human parvoviruses
Name derived from 2 known hosts: bovine and canine
Fourth most common virus in respiratory samples behind rhinoviruses, respiratory syncytial virus, and adenoviruses.
Human bocavirus
o Major member of the hepadnaviruses;
Genus:
Orthohepadnavirus
Hepatitis B Virus (HBV)
o Establish chronic infections, esp. in those infected as infants; a major factor in the eventual development of liver disease and hepatocellular carcinoma
o Cause acute and chronic hepatitis, often progressing to permanent carrier states
hepatitis B
According to the 2017 Global Burden of Disease Study, cirrhosis and liver cancer due to_______ accounted for approximately 709400 deaths
annually
hepatitis B
