SV40 virus

Figure 16.23 Overview of the structure of the SV40 virus particle, showing the packing of pentamers. The subunits of pentamers on fivefold positions are shown in white those of pentamers in six-coordinated positions are shown in colors. The six colors indicate six quite different environments for the subunit. (Courtesy of S. Harrison.)...

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. 

The study of viruses revealed that their genomes are very small. SV40 virus of monkey has 5,243 base pairs in which there are five genes. Now, it is possible to study the gene structure with this small genome. However, still 5000-odd base pairs can be a great challenge... 

Rockwell GA, Sato GH, McClure DB (1980), The growth requirements of SV40 virus transformed Balb/c-3T3 cells in serum-free monolayer culture, J. Cell. Physiol. 103 323-331. 

Table 2.7. Frequency of restriction endonuclease sites in SV40 virus DNA (5243 base pairs)...

Like a ladder. Circular DNA from SV40 virus was isolated and subjected to gel electrophoresis. The results are shown in lane A (the control) of the adjoining gel patterns. 

COST fibroblast morphology recombinant SV40 viruses ... 

The use of polycationic moieties in drug delivery has been a subject of considerable interest for the past several decades. One of the earliest demonstrations of the potential value of polycations in chug delivery was a study by Tan in 1977, which demonstrated increased uptake of the SV40 virus when infections were carried out in the presence of polycations.1 Other early efforts involved direct cationization of proteins to enhance cellular uptake.2,3 Simultaneously, extensive investigations of the ability of a variety of polycationic vehicles to enhance the uptake of DNA were made.4 These vehicles include cationic liposomes,5 6 poly-L-lysine,7 polyethe-leneimine,8 amino-dendrimers,9 and a variety of other natural and synthetic polycations. Only in recent years, however, has the surprisingly diverse potential of polycation-based delivery systems been realized. This revelation has come primarily from the discovery and utilization of nonclassical transport-based pathways. 

Direct transformation of human B lymphocytes with Epstein Barr virus seems to hold great promise since a high percentage of the cells may be transformed. This method met also with some success for rabbit cells, using SV40 virus, but less with murine cells (Zurawski et al., 1978 Steinitz et al., 1980 Reading, 1982). 

A core domain of 100-300 amino acids includes the binding site for the corresponding DNA element and binding sites for viral oncoproteins such as the large T antigen (TAg) of SV40 virus. 

The oncoprotein of the SV40 virus, Tag (see Section 14.6), binds to the p53 protein and can inactivate the p53 function in a similar way to that assumed for inactivation of the pRb protein. 

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