By competition radioimmune assays with antisera against AKR murine leukemia virus (MuLV) gp 71 or antisera against xenotropic virus, and iodinated AKR MuLV gp71 or BALB(X) gp71, antigens serologically indistinguishable from the viral antigens can be detected in tissues of normal mice in the absence of overt virus expression. An antigen serologically indistinguishable from AKR MuLV gp71 can be r...

Two leukemogenic viral populations were derived from a radiation leukemia virus of the C57BL mouse. One (FB), in which only B-tropic virus could be detected, was obtained in vivo by serial passage of cell-free extract in newborn rats. The second (3C), a complex containing at least B-tropic and xenotropic viruses, was produced in vitro by a permanent cell line (13-3C) established from the spleen...

The ribonuclease H (RNase H) domain of retroviral reverse transcriptase (RT) plays a critical role in the life cycle by degrading the RNA strands of DNA/RNA hybrids. In addition, RNase H activity is required to precisely remove the RNA primers from nascent (-) and (+) strand DNA. We report here three crystal structures of the RNase H domain of xenotropic murine leukemia virus-related virus (XMR...

We previously delineated a highly conserved immunosuppressive (IS) domain within murine and primate retroviral envelope proteins (Envs). The envelope-mediated immunosuppression was manifested by the ability of the proteins, when expressed by allogeneic tumor cells normally rejected by engrafted mice, to allow these cells to escape, at least transiently, immune rejection. Using this approach, we...

Xenotropic murine leukemia virus-related virus (XMRV) was recently discovered in human prostate cancers and is the first gammaretrovirus known to infect humans. While gammaretroviruses have well-characterized oncogenic effects in animals, they have not been shown to cause human cancers. We provide experimental evidence that XMRV is indeed a gammaretrovirus with protein composition and particle ...

The kinetic properties of two classical inhibitors of aspartic proteases (PRs), pepstatin A and acetyl-pepstatin, were compared in their interactions with HIV-1 and xenotropic murine leukemia virus related virus (XMRV) PRs. Both compounds are substantially weaker inhibitors of XMRV PR than of HIV-1 PR. Previous kinetic and structural studies characterized HIV-1 PR-acetyl-pepstatin and XMRV PR-p...

Nonproducer cells transformed by Kirsten sarcoma virus (KiSV) or Abelson murine leukemia virus (A-MuLV) were infected with N- or NB-tropic helper viruses to rescue the defective transforming virus. The titer of the transforming viruses was determined on NIH/3T3 fibroblast-like cells and cell-free filtrates of virus stock were inoculated into newborn Fv-1nn mice. Friend, Moloney, and Rauscher gr...