Term
| What are the general mechanisms through which viruses cause cancer? |
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Definition
1) DNA damage
2) Chronic inflammatory response “lapsing” into cancer
3) immunosuppression |
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Term
| Do oncoviruses include RNA or DNA viruses? |
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Definition
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Term
What are these:
Poxviridae
Herpetoviridae
Adenoviridae
Hepadnaviridae
Papovaviridae |
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Definition
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Term
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Definition
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Term
| How does a proto-oncogene become an oncogene? |
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Definition
1) Mutation of proto-oncogene that results in over production of protein
Eg.
a) Gene amplification (50-100 copies)
b) Chromosomal rearrangement that changes the regulatory sequence
2) Mutation of proto-oncogene that results in production of a defective, hyperactive protein (mutation is often a point-mutation or translocation) |
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Term
| Characteristics of poxvirus (eg. Myxomatosis, Molluscum) |
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Definition
Very complex viruses consisting of a single, large molecule of double-stranded DNA
Transmission is typically via insect vectors or direct contact
Viral replication occurs in the cytoplasm, resulting in the formation of unique viral particles
Eosinophilic intracytoplasmic inclusion bodies
Typical infection produces cutaneous or mucosal lesions characterized by extensive epithelial cell hypertrophy, hyperplasia, and necrosis
Variably oncogenic – lesions may be extremely proliferative and tumor-like but not true neoplasms
Tumors generally undergo spontaneous regression weeks or months after their induction |
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Term
| Characteristics of polyoma virus: |
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Definition
Genome is a single, circular molecule of double-stranded DNA
Multiplication occurs in the nucleus and the viral genome is integrated into the host cell genome
Not all species are oncogenic |
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Term
| Characteristics of papillomaviruses: |
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Definition
Generally speaking, papillomaviruses are extremely species-specific
Transmitted by direct contact, facilitated by cutaneous abrasions
Not all papillomas are caused by viral infection
Lesions are usually benign and regress spontaneously, but can undergo malignant transformation
Malignancies occur following integration of viral genome into host |
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Term
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Definition
| Persistant, sarcoma-like fibroproliferative cutaneous lesion |
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Term
| WHat is Marek’s disease of chickens? |
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Definition
| Oncogenic herpesvirus (Avian Herpesvirus-2) |
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Term
| What is Malignant catarrhal fever? |
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Definition
| Ovine Herpesvirus-2 (oncogenic virus) |
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Term
| Characteristics of Hepadnaviruses: |
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Definition
Double-stranded DNA viruses
Infects humans and chimpanzees, though woodchucks and ducks are important animal models
Viral DNA becomes integrated into host DNA in multiple copies; viral replicative cycle is quite complicated
Virus does not encode for oncogenes or transforming proteins
Commonly associated with hepatocellular carcinoma (Most studied virus is Human Hepatitis B Virus) |
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