Molecular analysis of the envelope gene and long terminal repeat of Friend mink cell focus-inducing virus: implications for the functions of these sequences

Abstract

We sequenced the envelope (env) gene and 3' long terminal repeat of a Friend mink cell focus-inducing virus (F-MCFV). We also sequenced the gp7O coding regions for two cDNA clones of another F-MCFV. The deduced amino acid sequence of the env gene products of both F-MCFVs were compared to the corresponding sequences of other MCFVs and of ecotropic viruses. The env polypeptides of the different viruses showed long stretches of homology in the carboxy-terminal half of gp7O and in p15env ("constant region"). The amino-terminal half of gp7O was very similar in all MCFVs, but showed extensive variations relative to the ecotropic viruses ("differential region"). This differential region in all MCFVs is of endogeneous origin. We show evidence that this region carries determinants for ecotropic or polytropic host range. No indication could be found that the env gene products determine the histological type of disease caused by particular MCFVs. When the long terminal repeats of F-MCFV and Friend murine leukemia virus were compared with those of other viruses causing either lymphatic leukemia or erythroleukemia, several nucleotides were localized which might determine the histological type of disease caused by these viruses.

Reflections on scrapie and related disorders, with consideration of the possibility of a viral aetiology

“…MCF-like viruses have also been recovered from feline (Neil et aL, 1991) and avian oncogene-murine chimeric systems (Feuer et aL,i993). Other references that provide a useful entry to this field include Adachi et al (1984), Chattopadhyay et aL (1991), Di Fronzo and Holland (1993), Khan et aL (1987), Koch et aL (1984), Levy et al (1985), Makino et al (1990), Oliff et al (1984), Quint et al (1984) and Shields et al (1991).…”

Pathogenicity of a Mutant Friend Spleen Focus‐Forming Virus Encoding an Env‐Like Membrane Glycoprotein (gp55) with Substitution by a Xenotropic Murine Leukemia Virus Env gp70 Sequence

“…The primary structure of gp55 closely resembles that of the replication-competent polytropic (dualtropic) MCF MuLV Env protein (1,5,10,21). There are two major modifications in the primary structure of gp55 as compared to that of the MCF MuLV Env protein.…”

“…Previously, we reported that genetically engineered F-SFFV encoding the mutant gp55 which has an ecotropic F-MuLV (clone K-1) gp70 amino-terminal region instead of the MCF MuLV gp70 sequences was nonpathogenic (19). Since the ecotropic F-MuLV gp70 amino-terminal region has, at most, about 30% sequence identity to the MCF MuLV gp70 amino-terminal region with several gaps introduced (10), differences other than those causing the inability to bind to the MCF MuLV receptor protein in the primary structure of this mutant The indicated number (from 10i to 101) of BS-resistant Ba/F3 or BER28C cells expressing either wild-type (WT) gp55 or XE gp55 was inoculated in 24 wells of a 24-well multiwell plate (0.4 mllwell) using medium without Epo or IL-3. Ten days after inoculating the cells, the number of wells with growing cells was scored by microscopic observation.…”

Molecular cloning of biologically active Rauscher spleen focus-forming virus and the sequences of its env gene and long terminal repeat

“…8) and is very similar to the sequences obtained for other murine retroviruses. It contains the transcriptional regulatory sequences and short terminal repeats that are characteristic of retroviral LTRs, but it lacks the 65to 75-base-pair repeat in the U3 region which occurs in Moloney MuLV, Moloney murine sarcoma virus, and F-MuLV (22). A comparison of the homology between the R-SFFV LTR and related MuLV LTRs is presented in Fig.…”

“…There is greater than 95% homology between R-SFFV and the three viruses presented, F-SFFV, Friend mink cell focus-inducing leukemia virus (F-MCF), and F-MuLV. Because the tissue tropism of murine retroviruses has recently been associated (6,22) with the U3 domain of LTRs, which also are known to contain enhancers of transcription, a search was made for homology to a putative enhancer "core sequence" (23,24) in the U3 domain of the R-SFFV LTR. At the same relative position in the R-SFFV U3 (Fig.…”