History of human DNA tumor viruses and cancer
What causes cancerous transformation of cells?
Malignant transformation is the process by which cells acquire the properties of cancer. This may occur as a primary process in normal tissue, or secondarily as malignant degeneration of a previously existing benign tumor.
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Why can viruses be Cytocidal?
Infections of permissive cells are usually productive because infectious progeny virus is produced. Most productive infections are called cytocidal (cytolytic) because they kill the host cell. Infections of nonpermissive cells yield no infectious progeny virus and are called abortive.
Is the most feared property of malignant Tumours?
The most feared property of malignant tumors is this characteristic called metastasis. Therefore, metastasis demonstrates the characteristics of cancer.
What are the stages of malignant transformation of cells?
Carcinogenesis can be divided conceptually into four steps: tumor initiation, tumor promotion, malignant conversion, and tumor progression (Figure 17-1). The distinction between initiation and promotion was recognized through studies involving both viruses and chemical carcinogens.
How do viruses get infected in cells?
A virus attaches to a specific receptor site on the host cell membrane through attachment proteins in the capsid or via glycoproteins embedded in the viral envelope. The specificity of this interaction determines the host—and the cells within the host—that can be infected by a particular virus.
Latent infection is characterized by the lack of demonstrable infectious virus between episodes of recurrent disease. Chronic infection is characterized by the continued presence of infectious virus following the primary infection and may include chronic or recurrent disease.