UNLABELLED Intron-containing mRNAs are subject to restricted nuclear export in higher eukaryotes. Retroviral replication requires the nucleocytoplasmic transport of both spliced and unspliced RNA transcripts, and RNA export mechanisms of gammaretroviruses are poorly characterized. Here, we report the involvement of the nuclear export receptor NXF1/TAP in the nuclear export of gammaretroviral RN...

The Graffi murine leukemia virus (MuLV) was isolated in 1954 by Arnold Graffi, who characterized it as a myeloid leukemia-inducing retrovirus. He and his team, however, soon observed the intriguing phenomenon of hematological diversification, which corresponded to a decrease of myeloid leukemias and an increase of other types of leukemias. Recently, we derived two different molecular clones cor...

Contaminations of cell cultures with microbiological organisms are well documented and can be managed in cell culture laboratories applying reliable detection, elimination and prevention strategies. However, the presence of viral contaminations in cell cultures is still a matter of debate and cannot be determined with general detection methods. In the present study we screened 577 human cell li...

Murine leukemia viruses (MuLVs) are the prototypical gammaretroviruses, and they have been extensively studied with regard to how they cause disease. Leukemogenesis by two MuLVs is reviewed here: the endogenous Akv MuLV of AKR mice, and exogenous Moloney MuLV. Important features of MuLV leukemogenesis include the in vivo generation of envelope recombinants (MCFs) through recombination with endo...

Repeated percutaneous applications of 7,12-dimethylbenz(a)anthracene on weaning DBA/2 and ST/a mice induced 100% leukemias with short latency periods. Endogenous C-type viruses were activated during the treatment as evidenced by (a) increased expression of the murine leukemia virus major core protein, p30, in blood and spleens and (b) increased frequency of detection of ecotropic virus by cocul...

We have developed a system to induce oncornavirus-specific secondary cytotoxic response in vitro. When Moloney strain of murine sarcoma virus-immune spleen cells were cultivated with purified infectious Moloney murine leukemia virus (M-MuLV) or with supernates of tissue culture cells containing infectious virus, a virus-specific secondary cytotoxic response directed against type-specific determ...

Major virion low-molecular-weight polypeptides were isolated from the Moloney strain of murine leukemia virus (type C) by agarose chromatography in 6M guanidine hydrochloride and were shown to have molecular weights of 15,000 (p15), 12,000 (p12), and 10,000 (p10) by their elution volumes and by their relative mobilities in sodium dodecyl sulfate-polyacrylamide gels. Each polypeptide could be io...

The effect of caffeine on the expression of murine endogenous virus in mouse cells induced by radiation and chemicals was studied. Postirradiation treatment of K-BALB cells with caffeine enhanced cell killing as well as the induction of xenotropic virus after ultraviolet light irradiation. The degree of enhancement for the virus induction was comparable to that for cell killing. On the other ha...