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J Blomberg

Publications and source records attributed to J Blomberg.

At least 37 records · Page 2Linked to original sources
PubMed1999

Isolation of a human endogenous retroviral HERV-H element with an open env reading frame.

About 100 elements of the human endogenous retroviral HERV-H family have full-length env genes potentially coding for Env proteins with sequences highly similar to the immunosuppressive peptide CKS-17 from the MLV transmembrane protein p15E. However, previously sequenced HERV-H env genes have contained stop codons or framehifts. To isolate elements with open env reading frames, we first tried to assess the diversity of HERV-H env genes by comparing PCR-generated env sequences from genomic DNA with published HERV-H sequences. A region at the beginning of env displayed a similarity of 84-98% among 15 different elements. We then used a probe from one of the PCR-generated clones, 98% similar to the consensus sequence in this region, to screen a human genomic lambda library. Three HERV-H elements displaying ca. 98% identity in the env gene were isolated and were shown to have integrated relatively recently, after the divergence of the orangutan and the african great ape lineages. One of these elements, HERV-H19, had a 1752-bp open env reading frame, producing a 77-kDa Env protein in in vitro translation reactions. This is the first demonstration of a coding competent member of the HERV-H family. These findings raise the possibility that HERV-H Env proteins may play a biological role in human cells.

Amino Acid Sequence↗
PubMed1999

Characterization of human MMTV-like (HML) elements similar to a sequence that was highly expressed in a human breast cancer: further definition of the HML-6 group.

Previously, we found a retroviral sequence, HML-6.2BC1, to be expressed at high levels in a multifocal ductal breast cancer from a 41-year-old woman who also developed ovarian carcinoma. The sequence of a human genomic clone (HML-6.28) selected by high-stringency hybridization with HML-6.2BC1 is reported here. It was 99% identical to HML-6.2BC1 and gave the same restriction fragments as total DNA. HML-6.28 is a 4.7-kb provirus with a 5'LTR, truncated in RT. Data from two similar genomic clones and sequences found in GenBank are also reported. Overlaps between them gave a rather complete picture of the HML-6.2BC1-like human endogenous retroviral elements. Work with somatic cell hybrids and FISH localized HML-6.28 to chromosome 6, band p21, close to the MHC region. The causal role of HML-6.28 in breast cancer remains unclear. Nevertheless, the ca. 20 Myr old HML-6 sequences enabled the definition of common and unique features of type A, B, and D (ABD) retroviruses. In Gag, HML-6 has no intervening sequences between matrix and capsid proteins, unlike extant exogenous ABD viruses, possibly an ancestral feature. Alignment of the dUTPase showed it to be present in all ABD viruses, but gave a phylogenetic tree different from trees made from other ABD genes, indicating a distinct phylogeny of dUTPase. A conserved 24-mer sequence in the amino terminus of some ABD envelope genes suggested a conserved function.

Adult↗
PubMed1999

A novel serological technique: polymerase chain reaction enhanced immunoassay. Application to enterovirus IgM diagnosis.

The polymerase chain reaction (PCR) method is a sensitive, specific and rapid technique for virus detection. The principles of a PCR enhanced immunoassay (PIA) are described. The method combines solid phase serological techniques with the PCR, providing a versatile and sensitive method for antibody detection. By linking the antigenicity of virus particles with their content of nucleic acid, the method provides new possibilities for virus serology: for example, antibody specificity can be coupled to viral sequence in patients with chronic infections caused by highly variable viruses such as HIV and HCV. An application of the PIA technique is described for the detection of anti-enterovirus IgM. IgM is captured to anti-human IgM-coated microwell plates. The anti-enterovirus IgM is allowed to bind crude enterovirus antigen. Bound virus is heat denatured and the released RNA is used as a template for reverse transcription PCR (RT-PCR) amplification. Amplicons are detected by hybridisation to an affinity labelled probe in a microwell colorimetric assay. In a pilot study, 18 serum specimens from patients with enterovirus infections were examined. Using a mixture of ten crude enterovirus antigens, the frequency of IgM positivity was 6/18 (33%). Titres between 1/500 and 1/100,000 were recorded. Predominantly type-specific antibodies were detected. The results were compared with a procapsid enterovirus radioimmunoassay (RIA). After further optimisation, the PIA has the potential to be a clinically useful assay for the detection of antiviral antibodies.

Adult↗
PubMed1999

Diversity of human endogenous retrovirus class II-like sequences.

Class II human endogenous retroviruses (HERVs), often referred to as mouse mammary tumour virus (MMTV)-like or HERV-K elements, have similarities to several animal infectious retroviruses. Single clones from each of nine class II HERV groups (NMWV 1 to NMWV 9), isolated from a human breast cancer cell genomic library, were sequenced over a 244 bp stretch of the conserved reverse transcriptase region. These sequences were aligned to related exogenous and endogenous retroviruses and a phylogenetic tree was constructed. Sequences with more than 80% identity were considered as members of one group and we report here that the class II HERV family consists of at least ten groups. Three of the sequenced clones, from groups NMWV 3, 7 and 9, could not be related to any other previously identified elements and constituted their own groups. NMWV 8 had no similarity to any retroviral sequences in the sequenced region and is so far considered to be non-retroviral.

Amino Acid Sequence↗
PubMed1999

Comparative studies on neutralisation of primary HIV-1 isolates by human sera and rabbit anti-V3 peptide sera.

IgG binding to V3 peptides and serum neutralising responses were studied in four HIV-1 infected individuals with progressive disease over a period of 31-70 months. The 18-20 mer peptides comprised residues 299-317 (numbering of HIV1 MN) in the N-terminal half of the V3 loop of the envelope glycoprotein gp120 and were derived from the sequences of autologous, as well as heterologous isolates. All four individuals studied lacked anti-V3 IgG binding to at least one autologous V3 sequence. V3 peptides to which autologous sera lacked binding IgG were all immunogenic in rabbits and induced antisera that were broadly cross-reactive by EIA and broadly cross-neutralising to primary HIV-1 isolates. This indicates that the peptides are immunogenic per se and that the respective human hosts have selective defects in recognising the corresponding V3 sequences. Despite the absence of antibody binding to autologous V3 peptides, the human sera had neutralising antibodies to autologous (three out of four cases), as well as heterologous isolates (all cases). Moreover, in vitro exposure of the patients' isolates to autologous neutralising serum or the homologous rabbit antiserum selected for variants with amino acid substitutions close to the crown of the V3 loop or in regions outside the sequence corresponding to peptides used for immunisation. The amino acid exchanges affected V3 positions known to be antigenic and which are also prone to change successively in infected persons. It is likely that neutralising antibodies recognise both linear and conformational epitopes in the V3 loop. Apparently, there are several, but restricted, numbers of ways for this structure to change its conformation and thereby give rise to neutralisation resistant viruses.

Acquired Immunodeficiency Syndrome↗
PubMed1998

Screening for human T cell leukaemia/lymphoma virus among blood donors in Sweden: cost effectiveness analysis.

OBJECTIVE: To analyse the cost effectiveness of a national programme to screen blood donors for infection with the human T cell leukaemia/lymphoma virus. DESIGN: Three models for calculating the costs and benefits of screening were developed. The first model analysed the cost of continuously testing all donations; the second analysed the cost of initially testing new blood donors and then retesting them after five years; the third analysed the cost of testing donors only at the time of their first donation. Patients who had received blood components from donors confirmed to be infected with the virus were offered testing. SETTING: Sweden. MAIN OUTCOME MEASURES: Prevalence of infection with the virus among blood donors, the risk of transmission of the virus, screening costs, and the outcome of infection. RESULTS: 648 497 donations were tested for the virus; 1625 samples tested positive by enzyme linked immunosorbent assay. 6 were confirmed positive by western blotting. The prevalence of infection with the virus was 2/100 000 donors. 35 patients who had received blood infected with the virus were tested; 3 were positive. The cost of testing every donation was calculated to be $3.02m (1.88m pounds); this is 18 times higher than the cost of testing new donors only, and only 1 additional positive donor would be discovered in 7 years. Regardless of the model used, screening was estimated to prevent only 1 death every 200 years at a minimum cost of $36m (22.5m pounds). CONCLUSION: Based on these estimates the Swedish National Board of Health and Welfare decided that only new blood donors would be screened for infection with the virus.

Adult↗
PubMed1998

Coamplification and dispersion of adjacent human endogenous retroviral HERV-H and HERV-E elements; presence of spliced hybrid transcripts in normal leukocytes.

In an RT-PCR study of HERV-H spliced subgenomic transcripts, we found transcripts with HERV-H leader and protease-encoding sequences spliced to HERV-E integrase-encoding sequences in lymphocytes from healthy blood donors. In other cell types, including two T-cell leukemia cell lines, these transcripts were absent. The PCR fragments of the hybrid transcripts contained two open reading frames (ORFs). One was a hybrid HERV-H protease/HERV-E integrase ORF and the other was the HERV-E envelope surface glycoprotein ORF. Alternative splice products were also identified. The genomic DNA origin of the hybrid transcripts was shown to be a HERV-H element with a large 3'-end deletion, adjacent to a HERV-E element lacking the 5'-LTR. This hybrid structure was shown to be amplified and dispersed to six different human chromosomes. Thus, a relatively large part of full-length HERV-E elements (15-20%) is potentially under the transcriptional control of HERV-H LTRs. The HERV-H/HERV-E junction was present in multiple copies also in the chimpanzee and gorilla, but not in the orangutan or old world monkeys.

Alternative Splicing↗
PubMed1998

Two domains of the Borna disease virus p40 protein are required for interaction with the p23 protein.

Borna disease virus (BDV) has five major open reading frames, which encode the proteins p40, p23, gp18, p57 and p190. By analogy with other negative-strand RNA viruses, p40 is a putative nucleoprotein and p23 is a putative phosphoprotein. These proteins are known to form complexes with each other and with the polymerase protein in other viruses. In this paper, it is shown that BDV p40 and p23 can form complexes with each other in infected cells. Furthermore, the amino acids of p40 that are necessary for formation of this complex have been mapped.

Amino Acid Sequence↗
PubMed1997

Prevalence and risk factors for HTLV-II infection in 913 injecting drug users in Stockholm, 1994.

The prevalence and risk factors for acquisition of human T-cell lymphotropic virus type I and II (HTLV-I and II) were investigated in a prospective study of 913 injecting drug users (IDUs) in Stockholm in 1994. Epidemiologic data were recorded, and blood samples were tested for antibodies against HTLV-I and HTLV-II; human immunodeficiency virus (HIV) types 1 and 2; and hepatitis A (HAV), B (HBV), C (HCV), and D (HDV). Positive serologic results for HTLV were confirmed by Western blot (WB) and polymerase chain reaction (PCR). Of the 905 participants with conclusive HTLV-II status, 29 (3.2%) were HTLV-II positive, and all but three were of Nordic descent. None was HTLV-I infected. One person was infected as early as 1981, before HIV had reached the IDU population in Sweden. The prevalence of HTLV-II infection was 12% among HIV-1-seropositive and 1.8% among HIV-1-seronegative participants. The overall seroprevalences were 14% for HIV-1, 0% for HIV-2, 41% for HAV, 75% for HBV, 92% for HCV, and 8% for HDV. Although amphetamine has been the main injecting drug in Sweden for several decades, heroin abuse combined with a debut of injecting drugs before 1975 was identified as the most important risk factor associated with HTLV-II infection. HAV and HIV seropositivity were also independent risk factors.

Adult↗
PubMed1997

Transcription of human endogenous retroviral sequences related to mouse mammary tumor virus in human breast and placenta: similar pattern in most malignant and nonmalignant breast tissues.

The human genome contains a large variety of sequences related to the mouse mammary tumor virus (MMTV). We have investigated the range of expression of human endogenous retroviral sequences (HERVs) related to MMTV (human MMTV-like; HML) as RNA in 60 breast cancers, 8 nonmalignant breast tissues, and 9 placentas. This was monitored using HML group-specific oligonucleotide probes in hybridizations toward PCR amplificates of HML pol sequences and internal control. The degree of expression of five HML groups varied between individuals and between tissues. On average, all HML groups were less expressed in breast tissues than in placenta. The hybridization signals of some HML RNAs were strongly correlated, indicating a nonstochastic mechanism and a concerted regulation of their expression. The PCR product from one breast cancer (BC 6), which gave an exceptionally high expression with probe hml-6, with a 20 times stronger signal than the rest of the cancers, was cloned and sequenced. The HML-6 transcript sequences were homogeneous in BC 6. The most predominant clone derived from the cancer was used as a probe in Southern hybridizations. The same restriction fragments were detected in human breast tissues, PBMCs (peripheral blood mononuclear cells), and breast cancer cell lines, except for one of the breast cancers and one of the nonmalignant breast tissues, which gave different banding patterns. A comparison of HML expression in normal and malignant breast tissue from the same individual would have been more precise than our comparison of samples from different persons. Bearing this limitation in mind, with a single exception, human MMTV-like sequences were not more actively expressed in malignant than in nonmalignant breast tissues. Nevertheless, an interesting diversity in their expression, especially between individuals, was found.

Adult↗
PubMed1997

Spliced human endogenous retroviral HERV-H env transcripts in T-cell leukaemia cell lines and normal leukocytes: alternative splicing pattern of HERV-H transcripts.

The majority of human endogenous retroviral HERV-H elements in the human genome have large deletions in pol and lack most of env, 5-10% are more or less complete with a potentially immunosuppressive transmembrane protein-encoding env region. Spliced HERV-H env transcripts were detected in T-cell leukaemia cell lines and lymphocytes from healthy blood donors by using RT-PCR. The transcripts all contained a splice donor in the leader region downstream from the primer-binding site and a previously unreported splice acceptor in the integrase-encoding region of pol, absent in the HERV-H deletion elements. In singly spliced transcripts the leader and integrase regions were joined directly whereas in multiply spliced transcripts they were joined with an alternative exon from the protease-encoding region located between the two regions. env transcripts from three different HERV-H elements were identified: one element similar to a HERV-H consensus sequence was primarily amplified from the T-cell leukaemia cell lines and two other more defective elements were amplified from normal lymphocytes. One of these elements was shown to be a reintegrated spliced transcript where the protease and integrase regions were joined, removing most of pol but leaving gag intact. Other spliced transcripts, joining the protease region and the 3'-LTR, were also amplified. The fact that HERV-H elements with an intact env splice acceptor also use the splice sites in the protease-encoding region suggests that this unusual multiple splice pattern could have a biological function in the intact HERV-H.

Alternative Splicing↗
PubMed1997

Structure and genomic organization of a novel human endogenous retrovirus family: HERV-K (HML-6).

Prototypic elements of a novel human endogenous retrovirus (HERV) family were identified and cloned from a human genomic library by the use of a pol fragment, HML-6, related to type A and type B retroviruses and class II HERVs. Out of 39 polhybridizing clones, five contained structures of full-length retroviral proviruses, with regions showing similarity to gag, pol and env, flanked by long terminal repeats (LTRs). Restriction mapping and partial sequence analysis of each full-length clone revealed few conserved restriction sites among HML-6 genomes, and about 20% sequence divergence over the reverse transcriptase region sequenced, suggesting that HML-6 constitutes a heterogeneous, but distinct family of elements belonging to the HERV-K superfamily. Sequence analysis of two clones, HML-6p and HML-6.17, revealed a lysine (K) tRNA UUU primer-binding site, and 40-68% nucleotide sequence similarity to LTR, gag, pro, pol and env regions of type B retroviruses and class II HERVs. HERV-K (HML-6) elements are present at about 30-40 copies per haploid genome. The HML-6 LTRs contain putative progesterone-responsive elements, which may be involved in the regulation of HML-6 expression. Furthermore, there are about 50 additional solitary HML-6 LTRs per haploid genome. Such LTRs were integrated within the pol region of two clones belonging to the same HML-6 family, indicating that some site preference may be involved in HERV integration.

Amino Acid Sequence↗
PubMed1996

Differential expression of human endogenous retroviral sequences similar to mouse mammary tumor virus in normal peripheral blood mononuclear cells.

Mouse mammary tumor virus (MMTV) is a retrovirus that causes breast cancer in certain strains of mice. In a previous study we identified, by sequencing clones from human lymphocytes, six groups with similarities to MMTV. Using a primer pair derived from pol sequences conserved within types A, B, and D retroviruses and probes from the six human MMTV-like (HML-1 to HML-6) groups in an internally controlled hybridization assay we investigated the normal variation of expression in PBMCs. Variations occurred within all groups but was most significant within group HML-1, where hybridization signals differed by more than 500-fold between individuals. Groups HML-2 and HML-3 showed consistently stronger hybridization signals than groups HML-1 and HML-5, while group HML-6 resulted in weak signals for all individuals. Stringent hybridization of the amplified cDNA to 20 individual HML clones also demonstrated a marked heterogeneity of expression. Hybridization signals from some groups and sequences were found to be correlated, either in a positive or negative fashion. RNA isolated from PBMCs collected from two donors at four different time points (in the morning and in the afternoon on the same day, repeated 1 week later) was also analyzed using the six hml probes. A small variation in hybridization signals was seen in samples collected on the same day, but a larger difference was observed in samples taken 1 week later. The correlations and the differences in the expression of HMLs between individuals implicate a complex transcriptional regulation system of these sequences.

Adult↗
PubMed1996

Selective antibody reactivity with peptides from human endogenous retroviruses and nonviral poly(amino acids) in patients with systemic lupus erythematosus.

OBJECTIVE: To investigate antibody responses to a broad panel of peptides derived from human endogenous retroviruses (HERVs) among unselected patients with systemic lupus erythematosus (SLE). METHODS: In sera obtained from 69 patients with SLE and healthy blood donors, immunoassay was used to measure levels of antibody against synthetic peptides derived from HERVs, exogenous retroviruses, and nonviral poly(amino acids). RESULTS: Measurement by immunoassay revealed increased frequencies of antiretroviral antibodies against 2 peptides derived from the env gene of the type C-like class, which includes ERV-9 and HERV-H, and against 2 peptides from the gag region of human T lymphotropic virus type I-related endogenous sequence 1, in patients with SLE. Antibodies to 2 nonviral peptides, polyhistidine and polyproline, were also overrepresented in patient sera. In 1 patient, longitudinal data obtained over a period of 12 years indicated that the concentrations of certain antiretroviral antibodies varied according to disease activity. CONCLUSION: Reactivity to certain type C HERV-derived antigens was found among patients with SLE. This reactivity could be explained by increased exposure to cross-reactive epitopes from essentially complete type C HERVs.

Amino Acid Sequence↗
PubMed1996

Stillbirths and intrauterine infection, histologic chorioamnionitis and microbiological findings.

OBJECTIVE: To analyze whether placental inflammation is associated with stillbirth in Zimbabwe. METHOD: Placentas from 66 stillbirths (> 22 weeks' gestation; patients with congenital malformations, diabetes or preeclampsia were excluded) and 66 term live births were studied for the presence and severity of chorioamnionitis. The morphological results were compared with earlier presented microbiological findings in the same material. RESULTS: Chorioamnionitis was present in 79% of stillbirths and 30% of live births (O.R. 8.5, 95% C.I. 4.0-18). Nine percent of stillbirths but no live births presented vasculitis of the chorionic plate, which verified an inflammatory response from the infant (O.R. 14, 95% C.I. 2.8-72). The same types of microorganisms were isolated from stillbirths and liveborns, but Escherichia coli and group B streptococci were more frequent among stillbirths. CONCLUSIONS: Morphological chorioamnionitis occurred 2.6 times more often in women with stillbirths than in women with live births. In 9% of stillbirths the infant showed an inflammatory response. Thus the infant was alive when the infection occurred and it is therefore reasonable to assume that infection was the cause of death.

Cause of Death↗
PubMed1995

The humanized severe combined immunodeficient mouse as a model for primary human humoral response against HIV1 peptides.

Adequate animal models for the study of human immunodeficiency virus (HIV) infection are important for the analysis of specific cellular and humoral immune responses. Humanized severe combined immunodeficiency (SCID) mice can be constructed either by injecting human peripheral blood lymphocytes (hu-PBL-SCID) or by transplanting human fetal tissues--liver, thymus and bone fragments--(SCID-hu) into these mice. Such animals can produce human immunoglobulins and SCID-hu mice exhibit circulating T and B lymphocytes of human origin. These humanized mice were injected with immunogenic HIV peptides and the specific humoral response was studied. A human antibody response was obtained after de novo contact with HIV1 peptides p583 and p642, from gp41. In SCID-hu mice, a primary, then a secondary response were demonstrated to occur with 225 mg/l of human immunoglobulin (Ig)M and 300-1860 mg/l human IgG. When tested in ELISA, these human antibodies recognized specifically both the immunization peptides and the HIV1 antigens. The antibody response was obviously of a primary nature since the human cells derived from naive fetal cells. When SCID mice received intraperitoneal injections of human peripheral blood lymphocytes pre-incubated in vitro with peptide p583 for 1 week, and when the resulting hu-PBL-SCID mice were injected with the same peptide, only IgM anti-HIV antibodies were produced (372-424 mg/l) and the switch to IgG antibodies did not occur. This model may provide a means to produce human monoclonal antibodies to HIV and to check candidate HIV vaccines.

Amino Acid Sequence↗
PubMed1995

Intrauterine death and infections during pregnancy.

OBJECTIVE: To elucidate whether microbial infections are involved in the etiology of intrauterine death. METHODS: One hundred four cases of stillbirth of unknown etiology and 96 age- and parity-matched referents with live births were analyzed with respect to microbial infection by cultures from the placenta, endocervix and internal organs of the fetuses, external sites of the babies and fetuses, and by serology for bacteria, viruses and Toxoplasma gondii. RESULTS: In 17 cases in whom no other infectious agent was diagnosed, Escherichia coli was isolated from the placenta and one or more internal fetal organs. Tests for Treponema pallidum and Toxoplasma gondii were more frequently positive in cases than in referents (O.R. 8.3 and 3.9, respectively). There was no increased risk for intrauterine death in women with human immunodeficiency virus, cytomegalovirus, herpes simplex virus or rubella virus. CONCLUSIONS: Our findings indicate that infections remain an important cause of intrauterine death in Zimbabwe.

Case-Control Studies↗