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Mouse mammary tumor virus (MMTV) has previously been shown to encode a functional homolog of the human immunodeficiency virus-1 (HIV-1) nuclear export protein Rev, termed Rem. Here, we show that deletion of the rem gene from a MMTV molecular clone interfered with the nucleo-cytoplasmic transport of genomic length viral mRNA and resulted in a loss of viral(More)
BACKGROUND The role of mouse mammary tumor virus (MMTV) as a causative agent in human breast carcinogenesis has recently been the subject of renewed interest. The proposed model is based on the detection of MMTV sequences in human breast cancer but not in healthy breast tissue. One of the main drawbacks to this model, however, was that until now human cells(More)
Mouse mammary tumor virus (MMTV) has long been speculated to be involved in human breast cancer and more recently in human primary biliary cirrhosis. Despite complete proviral sequences markedly homologous to MMTV being identified in human breast cancer tissue, no convincing evidence has been presented to date that MMTV can infect human cells. Using both(More)
The major envelope glycoprotein genes (ORF5) of seven Czech isolates of porcine reproductive and respiratory syndrome virus (PRRSV) were amplified and their nucleotide sequences were determined. ORF5 displayed nucleotide and amino acid identities of 87.5-100% and 87. 6-100%, respectively, among the isolates. In a phylogenetic tree, all European isolates(More)
Based on integration site preferences, retroviruses can be placed into three groups. Viruses that comprise the first group, murine leukemia virus and foamy virus, integrate preferentially near transcription start sites. The second group, notably human immunodeficiency virus and simian immunodeficiency virus, preferentially targets transcription units. Avian(More)
Astroviral infection has been described as one of the causes of porcine diarrhoeal disease. Here we describe the detection of astrovirus-like particles by electron microscopy in a diarrhoeal specimen. Furthermore, a cytopathic virus was isolated and propagated in an established porcine kidney cell line, PK-15. Reverse transcription and PCR performed with(More)
We have identified a novel, multiple spliced, subgenomic mRNA species in MMTV producing cells of different origin containing an open reading frame encoding a 39-kDa Rev-like protein, Rem (regulator of expression of MMTV). An EGFP-Rem fusion protein is shown to be predominantly in the nucleolus. Further leptomycin B inhibits the nuclear export of nonspliced(More)
Mouse mammary tumour virus (MMTV) is a betaretrovirus that infects rodent cells and uses mouse tranferrin receptor 1 (TfR1) for cell entry. Several MMTV strains have been shown to productively infect, in addition to murine cells, various heterologous cell lines including those of human origin, albeit less efficiently than murine cells. Furthermore, there(More)
Porcine reproductive and respiratory syndrome virus is a virus with a relatively high level of sequence variation, especially between the European and the American-type strains. This high degree of sequence variations will influence the accuracy of results obtained by molecular diagnostic methods, especially if mutations are located in the primer or probe(More)
Mouse mammary tumor virus (MMTV) is a complex, milk-born betaretrovirus, which preferentially infects dendritic cells (DC) in the gastrointestinal tract and then spreads to T and B lymphocytes and finally to the mammary gland. It is not clear how the prototypic betaretrovirus infects mucosal DCs and naïve lymphocytes as these cells are considered to be(More)