Transformed fusions

The occasional accidental fusion between somatic cells is probably harmless to an organism, as the resulting cell generally does not divide. But viruses have the ability to create proliferative fused cells, according to Duelli et al. (page 493). The authors wonder whether viruses might thus contribute to carcinogenesis.The authors were studying human fibroblasts expressing the E1A oncogene when they noticed that the cells fused with normal fibroblasts. The fusogenic activity derived from a contaminating retrovirus, Mason-Pfizer monkey virus (MPMV), in the oncogenic cell line. Exosome-like infectious MPMV particles caused fusion between these cells and the normal fibroblasts. It is not known how the virus causes fusion, although the authors show that exosomal tetraspanins are required.

Virus-instigated fusion is not new, but the products of these fusions were oddly proliferative. The...