Viruses, Cancer, and Immunology

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Viruses are known for the diseases they cause. They are pathogens of bacteria, plants, and animals. Some viruses are deadly, such as the fast-acting Ebola virus, which can have a mortality rate of more than 85%, and the slow-acting but equally deadly hiunan immimodeficiency virus (HIV), which causes acquired immunodeficiency syndrome (AIDS). Other viruses might be simply annoying, such as rhinovirus, which causes common colds. 

Human Immunodeficiency Virus (HIV) spreads from cell to cell. The viral RNA is packaged in the red cone structure and is surrounded by a membrane, part of which comes from the host cell. This picture shows the virus bursting free of the infected helper T-cell. It will then find another cell to bind to and infect. 

Although many characteristics distinguish viruses, most are organized by 

Most viruses cannot survive for long periods outside cells, so they must quickly gain access to a cell. There are several mechanisms for gaining access, and preventing access to the cell has been a major focus of pharmaceutical 

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Both viral and non-viral approaches to gene therapy have been used in clinical trials to treat illnesses such as cystic fibrosis and several forms of cancer. Viruses have evolved efficient ways of targeting cells, delivering genetic material and expressing it. However, inflammatory and immunological responses induced by viruses may limit their utility for repeated administration. 

Wolfe, L.G., R.D. Smith, J. Hoekstra, B. Mar-czynska, R.K. Smith, R. McDonald, R.L. Northrop, and F. Deinhardt. 1972. Oncogenicity of feline fibrosarcoma viruses in marmoset monkeys pathologic, virologic, and immunologic findings. /. Nat. Cancer Inst. 49 519-539. 

As a final word, there is the pranise in some quarters that AIDS and cancer are somehow connected, both being immunologically deficient diseases. There may be even more to consider. The AIDS virus is considered to mutate, to be ever-changing, so that no treatment can pin it down. This, however, is a characteristic known as pleomorphism, a phenomenon that has been connected with cancer-causing viruses or microbes, and one about which there is much disagreement (Walters, 1993, p. 16 Moss, 1992, pp. 490-492). 

Using an indirect immunoperoxidase technique an antigen, immunologically related to a glycoprotein of mouse mammary tumour virus, has been identified in sections of human breast cancer. Cross-reactivity between the human and murine antigens is due to the polypeptide rather than the oligosaccharide component. ... 

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