Selection of mouse neuroblastoma cell-specific polyoma virus mutants with stage differentiative advantages of replication.

Abstract

Two mouse neuroblastoma cell lines were analyzed for their permissivity for polyoma virus growth. One (N18) is fully permissive for polyoma replication, the other (41A3) shows limited permissivity and the viral genome persists, without noticeable cell death. Virus persistence does not seem to alter the cells' ability to differentiate in vitro and leads to selection of viral mutants altered in the untranscribed regulatory region of the genome. The mutant types obtained appear to be related to the degree of host cell differentiation. Nucleotide sequence analysis of the restriction fragment covering the regulatory region shows that duplications are present in all mutants, while deletions in the non-duplicated segment are only present in mutants selected from less differentiated cells. These alterations involve both domains of the regulatory region that are considered to be essential for DNA replication and for enhancer activity. Mixed infections with polyoma wild type show that the selected mutants have cis-advantage in replication in neuroblastoma cells and not in 3T6 cells. Mutants carrying the deletion in the non-duplicated segment of the enhancer show a selective advantage in replication over the undeleted one in mixed infection. This advantage is much stronger in neuroblastoma cells in suspension (less-differentiated stage) than in monolayer cells (more-differentiated stage). An interpretation of the overall structure of the regulatory enhancer region, based on the observed differences between the mutants selected at different stages of differentiation in neuroblastoma and previously described mutants selected in undifferentiated cells, is discussed.

Role of sialic acid-containing molecules and the α4β1 integrin receptor in the early steps of polyomavirus infection

“…They rely both on post-cell entry events (regulated by the enhancer and promoter elements of the viral genome) and on the ability of MPyV to recognize branched or straight SA chains and the tightness of the VP1-SA interaction (Amati, 1985;Maione et al, 1985;Caruso et al, 1990;Freund et al, 1991a, b). We showed previously that a4b1 integrin enhances cellular permissivity to MPyV at a post-attachment level (Caruso et al, 2003) and, in this study, we present evidence that this molecule is also used as a SA-containing cell attachment receptor.…”

Medullary thyroid carcinomas in transgenic mice expressing a Polyoma carboxyl-terminal truncated middle-T and wild type small-T antigens

“…To overcome the in vivo low expression level of wild type Py early regulatory sequences (Krippl et al, 1988), we cloned the transgene under the control of the enhancer derived from a Py mutant virus (NB11/1) which displays a wide host cell range (Maione et al, 1985;De Simone and Amati, 1987). Indeed this 0.4 kb Py regulatory fragment has recently been demonstrated to be capable of driving the expression of a reporter gene in a variety of cells of dierent tissue derivation and dierentiation stages (Fimia et al, 1995).…”

A Detailed Analysis Of Duplications Appearing During Early, High Multiplicity Infections With Polyoma Virus

“…Certain rearrangements within this region alter the host range of Py (Vasseur et al, 1982;Melin et al, 1985;Maione et al, 1985;De Simone & Amati, 1987). By dissecting the control region and by mutational analysis, the minimum length of genome sequence required for efficient replication of Py and SV40 has been defined.…”