The four classes of endogenous murine leukemia virus: structural relationships and potential for recombination

Abstract

The process by which leukemogenic viruses are generated during the lifetime of certain strains of mice is poorly understood. We have therefore set out to define all the murine leukemia virus-related endogenous proviruses of HRS/J mice. We have cloned 34 different proviral fragments and their flanking cellular sequences. These have been characterized by restriction enzyme analysis, by fingerprinting in vitro-synthesized RNA, and by DNA sequencing. We conclude that all the proviruses can be assigned into one of four different classes: the previously characterized ecotropic, xenotropic, and polytropic viruses, as well as a new class we have termed modified polytropic viruses. The xenotropic, polytropic, and modified polytropic classes are closely related to one another, but as a group they differ considerably from the ecotropic class. Sequence analyses show that both polytropic and modified polytropic sequences can contribute env sequences to recombinant viruses.

Disrupting MLV integrase:BET protein interaction biases integration into quiescent chromatin and delays but does not eliminate tumor activation in a MYC/Runx2 mouse model

“…Inbred strains of mice harbor endogenous type C MLVs, which fall into three general classes depending on their receptor usage, and thus their host and tissue specificities. These classes include the ecotropic viruses, limited to rodents (mCAT1 receptor), xenotropic viruses (excluded from infection of inbred mice [22]; Xpr1 phosphate exporter receptor), and polytropic/mixed polytropic viruses [24], infecting mouse and nonrodent species [22,23] using Xpr1 as their receptor [25]. Although many endogenous ecotropic and some xenotropic viruses can form infectious particles, the endogenous polytropic MLVs (P-MLVs) do not produce replication competent viruses [22].…”

Cross-linking of T-cell receptors on double-positive thymocytes induces a cytokine-mediated stromal activation process linked to cell death.

“…The homology was 99% in the first 350 bp, then declined to 60% over the last 170 bp. RV-2 (E2) is more than 95% homologous to the LTR of a modified polytropic murine retrovirus, pMX33 (Stoye and Coffin, 1987).…”

Insertional hypermutation in mineral oil‐induced plasmacytomas

“…This region varies according to virus type, but the flanking amino acid sequences are invariant, so that two (to account for the codon variation) common PCR primer pairs cover the complete spectrum of MLV types. Apart from the expected ecotropic sequence, we found that the PRRs of the proviruses derived from these three cell lines were identical to that of polytropic MLV [26] (Fig. 1B; in P3-X63, there was also a variant, denoted X63-B, with two amino acid replacements).…”