At necropsy, several dogs which died showing symptoms of hemorrhagic diarrhea, had significant lesions of the mucosa that were found especially in the duodenum and upper part of the small bowel. Study of ultrathin sections from the diseased mucosa revealed particles resembling parvoviruses in altered nuclei of cells of the intestinal crypts. Electron microscopic examination of intestinal contents by negative staining has shown the presence of many viral particles which have a diameter of 24 nm and whose profile is consistent with an icosahedral shape. These virions float at a density of 1.43 g/cm3 in cesium chloride and agglutinate rhesus monkey and swine red blood cells at 4 degrees C. A possible etiological role is discussed. This virus is compared with the minute virus of canines and the Feline Panleukopenia virus.
Background: The human immunodeficiency virus type 1 (HIV-1) proviral DNA persists in infected cells, even after prolonged successful HAART. In the present study, a relative quantification assay of HIV-1 proviral DNA by LightCycler ® real-time PCR based on SYBR Green I detection was developed in comparison to the number of purified CD4+ cells as estimated by the quantification of the β-globin gene.
As previously reported, a C-type retrovirus, referred to as retrovirus X was isolated from HIV infected cells. In order to further characterize this virus, the proviral DNA was cloned and sequenced. The organization of the genome (8379 bp) appeared to be typical of the mammalian type C retroviruses. The virus was shown to be closely related to the gibbon ape leukaemia virus (GALV) with 87% similarity when the sequence was compared with the published genome of the Seato strain of GALV. At the level of the long terminal repeat where comparison was possible with other strains, the closest relationship was found with the San Francisco strain of GALV and with the simian sarcoma virus. These results suggest that the isolate should be considered as a strain of GALV.
A study by electron microscopy of HUT 78 cells infected with the ARV-2 strain of HIV-1 revealed, in addition to virions having the characteristic morphology of a lentivirus, the presence of numerous C-type particles, suggesting that the analysed specimen might in fact contain two different viruses. In order to further investigate this observation, the cell culture supernatant was filtered and mixed at serial dilutions with uninfected HUT 78 cells. In this way, it was possible to obtain cells producing only virions with C-type morphology and a Mn++ dependent reverse transcriptase activity which in a sucrose gradient was found to peak at a buoyant density of 1.16 g/cm3. The RNA purified from the culture medium was not detected by reference DNA probes for either HIV-1 and -2 or HTLV-I and -II. In an indirect immunofluorescence assay, sera from patients seropositive for these human retroviruses failed to recognize any antigen in the cells producing only the C-type particles. Using the same technique, plasma samples from 100 blood donors also gave negative results. The presence of this retrovirus could be the result of previous laboratory contamination but the possibility that it is indeed a human virus has to be considered.
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