Rabbit kidney vacuolating virus: extraction of infectious DNA

Novel human polyomaviruses--re-emergence of a well known virus family as possible human carcinogens

Polyomaviruses belong to a family of DNA tumor viruses that frequently cause cancer upon inoculation into heterologous hosts. The rhesus monkey virus SV40 and mouse polyomavirus have been studied in particular detail. Two members of the polyomavirus family, BK and JC viruses, were identified as human pathogens more than 30 years ago. Both are oncogenic when inoculated into newborn rodents. Their possible role in human cancers has been intensively investigated; conclusive results are, however, still missing. During the past year 3 new members of the polyomavirus family have been identified in humans, KI, WU, and MC-Polyomavirus. Whereas the first 2 were only found in respiratory fluids of children with respiratory infections and in healthy individuals, the third virus was found to be specifically linked to Merkel tumors, a rare human cancer of neuroendocrine origin. The positive Merkel cells contain viral DNA in an integrated and clonal form, suggesting an involvement of this virus in the etiology of those tumors. This article will summarize the results of recent polyomavirus isolations from humans and animals and also address the potential role of members of this virus family in other human malignancies. It also makes reference to observations of polyomavirus-like particles in other conditions, particularly in hair-follicle cell-related proliferations.

Transfection mediated by Mycoplasmatales viral DNA

DNA isolated from Mycoplasmatales viruses MVL51 and MVGs51 was infectious when mixed with Acholeplasma laidlawii BN1-Na1(R) cells. Infectivity was destroyed by deoxyribonuclease but not by ribonuclease, Pronase, or specific antiserum to the virus. Host mycoplasma cells were only competent for transfection during late-log growth phase. The rates of the establishment of DNase insensitivity of viral DNA transfectants were similar to those of bacteriophage systems. The dose-response curve for transfection suggested that an average of six molecules of DNA must interact with a cell in order to produce one infectious center. Mycoplasmatales virus DNA exhibited a low efficiency of infection; one infectious center required 4 x 10(5) virus equivalents of DNA.