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The mechanism by which H. pylori causes cancer may involve chronic inflammation, or the direct action of some of its virulence factors, for example, CagA has been implicated in carcinogenesis. [ 44 ] As reviewed by Chang and Parsonnet , [ 45 ] chronic H. pylori infection in the human stomach is characterized by chronic inflammation. [ 45 ]
A viral infection does not always cause disease. A viral infection simply involves viral replication in the host, but disease is the damage caused by viral multiplication. [5] An individual who has a viral infection but does not display disease symptoms is known as a carrier. [17] Mechanisms by which viruses cause damage and disease to host cells
Indirect viral oncogenicity involves chronic nonspecific inflammation occurring over decades of infection, as is the case for HCV-induced liver cancer. These two mechanisms differ in their biology and epidemiology: direct tumor viruses must have at least one virus copy in every tumor cell expressing at least one protein or RNA that is causing ...
Viral Oncogenesis through transformation can occur via 2 mechanisms: [1] The tumor virus can introduce and express a "transforming" gene either through the integration of DNA or RNA into the host genome. The tumor virus can alter expression on preexisting genes of the host. One or both of these mechanisms can occur in the same host cell.
Alternatively, the viral vector can be coated with a polymer such as polyethylene glycol, shielding it from antibodies, but this also prevents viral coat proteins adhering to host cells. [47] Another way to help oncolytic viruses reach cancer growths after intravenous injection, is to hide them inside macrophages (a type of white blood cell).
At this point, the viral genome is transported to the nucleus by unknown mechanisms and establishes itself at a copy number of 10-200 viral genomes per cell. A sophisticated transcriptional cascade then occurs as the host keratinocyte begins to divide and become increasingly differentiated in the upper layers of the epithelium.
The mechanism by which H. pylori causes cancer may involve chronic inflammation, or the direct action of some of its virulence factors, for example, CagA has been implicated in carcinogenesis. [7] Another bacteria that is in this genus is Helicobacter hepaticus, which causes hepatitis and liver cancer in mice. [8]
In pathology, pathogenesis is the process by which a disease or disorder develops. It can include factors which contribute not only to the onset of the disease or disorder, but also to its progression and maintenance. [1] The word comes from Ancient Greek πάθος (pathos) 'suffering, disease' and γένεσις (genesis) 'creation'.