Human polyoma virus

Molecular alterations underlying the development and progression of Merkel cell carcinomas are poorly understood. Recently, Feng and coworkers reported the identification of a fifth human polyoma virus that was designated Merkel cell polyomavirus on the basis of its detection in Merkel cell carcinomas. A subsequent study by Kassem and colleagues analyzed 39 Merkel cell carcinomas and found the presence of Merkel cell polyomavirus DNA in 77% of cases. This study was limited in that the use of formalin-fixed paraffin tissues... 

DNA viruses, such as adenoviruses and papovaviruses (e.g. polyoma and SV40), induce cellular transformation in rodents. Other viruses have been implicated in human cancers. Epstein-Barr virus, for example, has been implicated with nasopharyngeal carcinoma, (3-cell lymphomas and Hodgkin s lymphoma. Human papilloma virus is linked to most cervical cancers. 

DNA viruses that can trigger tumors are found in the classes of the polyomaviruses, the adenoviruses and the papUloma viruses. The polyoma viruses with the SV40 virus as a well studied representative, adenoma virus and human papUloma virus (HPV) are associated with formation of tumors in humans and have genes coding for proteins with the properties of oncoproteins. The oncoproteins of aU three viruses interfere with the pRb function by Ufting its inhibition of transcription factor E2F. It is assumed that the tumor-promoting activity of the proteins is due, in particular, to this property. 

Virus-receptor interactions have also been shown to be affected by these ManN derivatives [154,155]. Treatment of human B-lymphoma BJA-B cells or African green monkey kidney epithelium cells with either ManProp, ManBut, or ManPent resulted in structural modification of about 50% of total cell surface sialic acids. Polyoma viruses, which use sialic acids as ligands for binding prior to infection, show either reduced or enhanced ability to infect cells carrying these modified sialic... 

Abbreviations HSV = herpes simplex virus HeLa = human carcinoma of the cervix PyBHK = polyoma-virus transformed B(aby) H(amster) K(idney) cells SV = simian virus 3T3 = mouse fibroblasts and + = ampholyte forms complexes. 

Papillomaviridae Human papilloma (wart)virus polyoma virus SV 40 dsDNA, circular DMA Icosa 55... 

Compare the lengths of the DNA molecules in polyoma virus, the bacterium E. coli, and the average human chromosome. 

Hybrids between human and mouse cell have also been used in mapping the polio receptor site (52). Hamster-mouse hybrids, and human-mouse hybrids are susceptible to polyoma virus (53) as long as the parental mouse chromosomes (permissive cell line) were... 

Papillomarirus (wart viruses, genital condylomas, and DNA tumor viruses). Polyomavirus (human polyoma-like viruses, SV-40). 

Following the early observation of Klenk and Yamakawa and their associates, the presence of sialic acid residues at the surface of numerous cells was established, either by action of neuraminidase followed by determination of the cell electrophoretic mobility or by determination of the sialic acid released. For example, sialic acid residues were detected at the surface of EMich ascites tumor cells (Wallach and Eylar, 1961 Cook et aL, 1962), hamster kidney fibroblasts transformed by polyoma virus (Forrester et aL, 1964), squamous epithelial cells (Berwick and Coman, 1962), solid and ascites sarcoma cells (Cook et aL, 1963 Wallach and de Perez Esandi, 1964), normal and malignant rat liver cells (Kalant et aL, 1964), cells from human bronchial carcinoma, cells from rat myeloma, HeLa cells, and L-strain mouse fibroblasts (Fuhrmann etaL, 1962). 

Viruses produce CPEs on cells and are the agents for many diseases in humans and other animals. In addition, many viruses (e.g. oncoma viruses, herpes type II, adenovirus and polyoma and SV40) are believed to be agents responsible for tumour formation in animals. Moreover, due to their ability to pass through bacteriological filters it is difficult to exclude viruses from uninfected cell cultures if the viruses are present in suspension in the air of the culture room. For these reasons it is recommended practice to take special precautions when using viruses. 

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