Biomedical subjects

M Eiden

Publications and source records attributed to M Eiden.

10 recordsLinked to original sources

PubMed2006

Atypical BSE in Germany--proof of transmissibility and biochemical characterization.

Intensive active surveillance has uncovered two atypical German BSE cases in older cattle which resemble the two different atypical BSE phenotypes that have recently been described in France (designated H-type) and Italy (designated L-type or BASE). The H-type is characterized by a significantly higher molecular size, but a conventional glycopattern of the proteinase K treated abnormal prion protein (PrP(Sc)), while the L-type PrP(Sc) has only a slightly lower molecular size and a distinctly different glycopattern. In this paper we describe the successful transmission of both German atypical BSE cases to transgenic mice overexpressing bovine PrP(C). Upon challenge with the L-type, these mice developed BSE after a substantially shorter incubation period than any classical BSE transmission using these mice to date. In contrast, the incubation period was distinctly prolonged when these mice were challenged with the H-type. PrP(Sc) accumulated in the brains of these mice were of the same atypical BSE type that had been used for the transmission. These atypical cases suggest the possible existence of sporadic BSE cases in bovines. It is thus feasible that the BSE epidemic in the UK could have also been initiated by an intraspecies transmission from a sporadic BSE case.

Amino Acid Sequence↗

PubMed2006

Synthetic prions.

The prion theory postulates that prions are novel infectious agents that are composed largely, if not entirely, of abnormally folded host-encoded prion proteins. However, the existence of different prion strains is enigma, if these novel infectious agents lack a genetic element, such as a nucleic acid. The best proof for this 'protein-only' concept would be the in vitro generation of prions from synthetic sources. Indeed, a substantial body of evidence has meanwhile been accumulated in favour of this postulate. This mini review recapitulates all relevant studies and experimental data on the generation of synthetic prions.

Animals↗

PubMed2005

Strain typing of German transmissible spongiform encephalopathies field cases in small ruminants by biochemical methods.

Following the implementation of a large scale transmissible spongiform encephalopathies (TSE) surveillance programme of small ruminants, evidence for a natural transmission of bovine spongiform encephalopathy (BSE) to a French goat has been found. During the years 2002-2004, a massive TSE rapid testing programme on >250,000 small ruminants was carried out in Germany. In this national survey, 186 scrapie-affected sheep were found which originated from 78 flocks. The majority of these cases were of the classical TSE type (115 sheep belonging to 14 outbreaks). However, 71 cases coming from 64 flocks were of the novel atypical scrapie type. According to the regulation EU 999/2001, all TSE cases in small ruminants have to be examined by strain typing methods to explore any possibility of the existence of BSE cases in the field sheep population. Here we report on a biochemical typing strategy (termed FLI-test), which includes the determination of molecular masses, antibody binding affinities and glycosylation pattern of the TSE induced abnormal prion protein. Based on this typing approach none of the analysed German classical TSE outbreaks (total number of analysed sheep: 36) displayed biochemical features indicative for a BSE infection. However, in two cases distinct but BSE-unrelated PrP(Sc) types were found, which alludes to the existence of different scrapie strains in the German sheep population.

Animals↗

PubMed2004

Classification of signatures of Bovine Spongiform Encephalopathy in serum using infrared spectroscopy.

Signatures of Bovine Spongiform Encephalopathy (BSE) have been identified in serum by means of "Diagnostic Pattern Recognition (DPR)". For DPR-analysis, mid-infrared spectroscopy of dried films of 641 serum samples was performed using disposable silicon sample carriers and a semi-automated DPR research system operating at room temperature. The combination of four mathematical classification approaches (principal component analysis plus linear discriminant analysis, robust linear discriminant analysis, artificial neural network, support vector machine) allowed for a reliable assignment of spectra to the class "BSE-positive" or "BSE-negative". An independent, blinded validation study was carried out on a second DPR research system at the Veterinary Laboratory Agency, Weybridge, UK. Out of 84 serum samples originating from terminally-ill, BSE-positive cattle, 78 were classified correctly. Similarly, 73 out of 76 BSE-negative samples were correctly identified by DPR such that, numerically, an accuracy of 94.4 % can be calculated. At a confidence level of 0.95 (alpha = 0.05) these results correspond to a sensitivity > 85% and a specificity > 90%. Identical class assignment by all four classifiers occurred in 75% of the cases while ambiguous results were obtained in only 8 of the 160 cases. With an area under the ROC (receiver operating charateristics) curve of 0.991, DPR may potentially supply a valuable surrogate marker for BSE even in cases in which a deliberate bias towards improved sensitivity or specificity is desired. To the best of our knowledge, DPR is the first and--up to now--only method which has demonstrated its capability of detecting BSE-related signatures in serum.

Animals↗

PubMed2001

Identification of envelope determinants of feline leukemia virus subgroup B that permit infection and gene transfer to cells expressing human Pit1 or Pit2.

The retroviral vector systems that are in common use for gene therapy are designed to infect cells expressing either of two widely expressed phosphate transporter proteins, Pit1 or Pit2. Subgroup B feline leukemia viruses (FeLV-Bs) use the gibbon ape leukemia virus receptor, Pit1, as a receptor for entry. Our previous studies showed that some chimeric envelope proteins encoding portions of FeLV-B could also enter cells by using a related receptor protein, Pit2, which serves as the amphotropic murine leukemia virus receptor (S. Boomer, M. Eiden, C. C. Burns, and J. Overbaugh, J. Virol. 71:8116--8123, 1997). Here we show that an arginine at position 73 within variable region A (VRA) of the FeLV-B envelope surface unit (SU) is necessary for viral entry into cells via the human Pit2 receptor. However, C-terminal SU sequences have a dominant effect in determining human Pit2 entry, even though this portion of the protein is outside known receptor binding domains. This suggests that a combination of specific VRA sequences and C-terminal sequences may influence interactions between FeLV-B SU and the human Pit2 receptor. Binding studies suggest that the C-terminal sequences may affect a postbinding step in viral entry via the Pit2 receptor, although in all cases, binding of FeLV-B SU to human Pit2 was weak. In contrast, neither the arginine 73 nor specific C-terminal sequences are required for efficient binding or infection with Pit1. Taken together, these data suggest that different residues in SU may interact with these two receptors. The specific FeLV-Bs described here, which can enter cells using either human Pit receptor, may be useful as envelope pseudotypes for viruses used in gene therapy.

Animals↗

PubMed1997

Three distinct envelope domains, variably present in subgroup B feline leukemia virus recombinants, mediate Pit1 and Pit2 receptor recognition.

Subgroup B feline leukemia viruses (FeLV-Bs) evolve from subgroup A FeLV (FeLV-A) by recombining with portions of endogenous FeLV envelope sequences in the cat genome. The replication properties of FeLV-B are distinct from those of FeLV-A; FeLV-B infects many nonfeline cell lines and recognizes the human Pit1 (HuPit1) receptor, whereas FeLV-A infects primarily feline cells, using a distinct but as yet undefined receptor. Here, we demonstrate that some FeLV-Bs can also use human Pit2 (HuPit2) and hamster Pit2 (HaPit2) for entry. By making viruses that contain chimeric surface (SU) envelope proteins from FeLV-A and FeLV-B, and testing their infectivity, we have defined genetic determinants that confer host range and specific receptor recognition. HuPit1 receptor recognition determinants localize to the N-terminal region of the FeLV-B SU, amino acids 83 to 116, encompassing the N-terminal portion of variable region A (VRA). While this 34-amino-acid domain of the FeLV-B VRA is sufficient for infection of some cells (feline, canine, and human), amino acids 146 to 249 of FeLV-B, which include variable region B (VRB), were required for efficient infection in other cell types (hamster, bovine, and rat). Chimeras encoding FeLV-B VRA and VRB also infected cells expressing HaPit2 and HuPit2 receptors more efficiently than chimeras encoding only the VRA of FeLV-B, suggesting that VRB provides a secondary determinant that is both cell and receptor specific. However, viruses containing additional FeLV-B sequences in the C terminus of SU could not recognize HuPit2, implying that there is a determinant beyond VRB that negatively affects HuPit2 interactions. Thus, Pit2 recognition may drive selection for the generation of specific FeLV-B recombinants, offering an explanation for the two major classes of FeLV-B that have been observed in vivo. Furthermore, the finding that some FeLV-Bs can use both Pit1 and Pit2 may explain previous observations that FeLV-B and GALV, which primarily uses Pit1, display nonreciprocal interference on many cell types.

Animals↗

PubMed1986

Serological characterization of human T-cell leukemia (lymphotropic) virus, type I (HTLV-I) small envelope protein.

Murine monoclonal antibodies were developed against the protein products produced by murine C127 cells which had been transfected with a recombinant plasmid clone containing the human T-cell leukemia (lymphotropic) virus type I (HTLV-I) proviral DNA coding regions for part of env, px, and the 3' LTR. Four antibodies with different binding patterns were obtained. One of these antibodies, F1.6, reacted against HTLV-I infected cells but not against noninfected cell lines. This antibody also reacted with sucrose-gradient purified HTLV-I and -II particles with preferential binding against the HTLV-I preparation. The F1.6 antibody bound to two proteins of approximately 21 and 43 kDa in gradient purified HTLV-I preparations, as determined by sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) and Western blots, and to a 43-kDa protein in cell lysates of HTLV-I infected cell lines; the F1.6 antibody did not bind significantly to any HTLV-II proteins in western blots. The three other antibodies F1.1, F1.2, and F1.5, recognized the same size proteins, 21 and 43 kDa in the gradient purified viral preparations of HTLV-I and in the case of the F1.2 antibody, the same size proteins in purified virus preparation of HTLV-II and -III. The F1.2 and F1.5 antibodies bound not only to purified HTLV particles but also to a variety of cellular proteins in HTLV-I infected and noninfected cells suggesting that they recognized epitopes which were shared between HTLV proteins and normal cells. The identity of the 21-kDa viral protein is most likely that of the small envelope glycoprotein. The identity of the larger protein is undetermined.

Antibodies, Monoclonal↗

PubMed1986

Gibbon ape leukaemia virus RNA in leukaemic T-lymphoid cell lines: expression of a novel RNA transcript.

Fibroblast cell lines infected in vitro with different strains of gibbon ape leukaemia virus or the related woolly monkey virus (SSAV) synthesized two RNA species of approximately 8.4 kb and 2.9 kb. The former, a complete RNA, represents the gag-pol mRNA, while the latter is a spliced transcript lacking gag and pol, and represents the env mRNA. In contrast, RNA from one T-lymphoid cell line derived from a gibbon ape T-lymphocytic leukaemia (UCD-144) expressed a viral mRNA in addition to gag-pol and env mRNA. This RNA is 6.4 kb and lacks at least 3.0 kb of sequences derived from the internal region of the viral genome, including most or all of the pol gene. These data, as well as data from Southern blots of UCD-144 DNA, suggest that the 6.4 kb mRNA could represent a transcript from a defective recombinant provirus and may contain cell-derived sequences.

Animals↗

PubMed1985

Type 1 human T-cell leukemia virus small envelope protein expressed in mouse cells by using a bovine papilloma virus-derived shuttle vector.

In an attempt to express the small (transmembrane) envelope protein p21e of type 1 human T-cell leukemia (lymphotrophic) virus (HTLV-1) exclusive of other viral gene products, we have constructed a recombinant plasmid clone (pMBE-1) in a bovine papillomavirus-derived mammalian expression vector. Mouse C127 cells transfected with the pMBE-1 plasmid expressed the introduced HTLV-1 viral gene(s) as demonstrated by Northern blot and indirect immunofluorescence with natural human antisera. The transfected mouse cells were injected into BALB/c mice, and a monoclonal antibody was recovered which specifically recognizes a 21-kilodalton protein present in HTLV-1 virions, indicating that the pMBE-1 plasmid encodes the small envelope protein.

Animals↗

PubMed1984

DNA methylation and expression of HLA-DR alpha.

B-cell lines established from two individuals with T-cell acute lymphocytic leukemia (T-ALL) express HLA-DR antigens, whereas the isogenic T-cells do not. The lack of expression correlates with a lack of detectable HLA-DR mRNA. All of the DR alpha DNA sequences detected by a cloned DR alpha cDNA probe are contained in a BglII fragment which varies slightly in size (4.0 to 4.8 kilobases) from one individual to another. In DNA from the T-cells not expressing DR alpha mRNA, all of the potential HpaII sites within the BglII fragment appeared to be methylated. In contrast, at least some of these sites were not methylated in DNA from the B-cells expressing high levels of DR alpha mRNA. Treatment of these T-cells with 5-azacytidine resulted in the induction of DR surface antigen expression, the appearance of DR alpha mRNA, and the partial demethylation of the DR alpha DNA sequences. T-cell lines established from human T-cell leukemia-lymphoma virus associated T-cell neoplasias, in contrast to the T-cell acute lymphocytic leukemia cell lines, expressed both DR antigens and DR alpha mRNA; the HpaII sites within the BglII fragment of DR alpha DNA of these human T-cell leukemia-lymphoma virus-positive T-cell lines were in all cases at least partially unmethylated. Uncultured peripheral blood T-cells from human T-cell leukemia-lymphoma virus-infected individuals expressed DR antigens at a low level, and the DR alpha locus was partially unmethylated. After 48 h in culture, DR antigen expression was substantially increased, but no significant changes were observed in methylation of the DR alpha locus or in the amount of DR mRNA which was present. This suggests that expression of DR antigens also can be modulated post-transcriptionally.

Adult↗