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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

CD4+ T-lymphocytopenia without HIV infection: increased prevalence among patients with primary Sjögren's syndrome

OBJECTIVE

Primary Sjögren's syndrome (1 degree SS) is an autoimmune disease, usually accompanied by manifest immune hyperactivity. In some cases the disease converts to malignant neoplasia. On the other hand, there are clinical similarities to HIV infection. Since the rare phenomenon of persistent depletion of CD4+ T-lymphocytes in peripheral blood without HIV infection was recently defined as idiopathic CD4+ T-lymphocytopenia (ICL), we have used the ICL criteria to investigate the prevalence of this phenomenon among 1 degree SS patients.

METHODS

During the period 1988-94, 115 caucasian patients (10 males), mean age 57.8 (range 19-82) years, with 1 degree SS were prospectively studied. Lymphocyte subsets were investigated by means of monoclonal antibodies and flow cytometry. For the detection of HIV and HTLV antibodies, we used an enzyme immunoassay (for HIV-1 and HIV-2), Western blot techniques (HIV-1, HIV-2, HTLV-I and HTLV-II), and the polymerase chain reaction procedure (HIV-1, HTLV-I and HTLV-II). HIV antigens were tested for with the HIV-1 p-24 Ag test.

RESULTS

Six patients with 1 degree SS fulfilled the criteria for ICL. While the clinical condition of 5 of those six patients remained stable, one patient developed malignant lymphoma three years after her disease was classified as a case of ICL. The prevalence of ICL among our 115 patients with 1 degree SS was 5.2%, which is significantly higher than the rates reported for any other patient or population group. We have estimated the relative risk of ICL in 1 degree SS patients to vary from 3.4 to 6,000 (P values of 0.0001-0.025).

CONCLUSION

We suggest that subjects with ICL should be carefully examined for 1 degree SS and, if its presence is confirmed, that they should be followed with regard to the possible complications of this disease, including the development of malignant lymphoma.

Continuity and discontinuity in the anti-V3 IgG response of human immunodeficiency virus type 1-infected persons in a cross-sectional and longitudinal study using synthetic peptides

The principal neutralization domain (PND) of the V3 region of human immunodeficiency virus type 1 (HIV-1) gp120 is central to HIV pathogenesis. The IgG antibody response to PND was followed in 15 HIV-1-infected persons from southern Sweden over 2-5 years using 32 synthetic V3 peptides. Five peptides had amino acid sequences derived from isolates from each of 5 patients. Sera obtained simultaneously with isolate almost always reacted strongly with these cognate peptides; however, reactivity was undetectable in 1 patient's serum and short lived in the sera of another, indicating inducible holes in the antibody repertoire, which would facilitate dissemination of the corresponding virus strains. Reactivity to other V3 peptides correlated with sequence similarity to the cognate peptide. Strong, stable reactivity to peptides with sequences similar to a south Swedish V3-consensus was accompanied by transient activity to less similar ones. The latter may reflect viral variation, B lymphocyte clonal depletion, or both. Certain IgG responses appeared to preclude others, suggesting clonal dominance.

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.

Hospital-based study of sexually transmitted diseases at Murewa rural district hospital, Zimbabwe 1991-1992

BACKGROUND AND OBJECTIVES

In Zimbabwe, sexually transmitted diseases are highly prevalent and represent a significant amount of the workload for physicians.

GOAL OF THIS STUDY

To estimate the prevalence of sexually transmitted diseases and human immunodeficiency virus as well as symptoms related to sexually transmitted diseases.

STUDY DESIGN

This was a cross-sectional study of 500 volunteers (285 women and 215 men) attending an sexually transmitted disease clinic in the Murewa District, 100 km northeast of the capital, Harare. Information on background characteristics and symptoms were obtained with a standardized questionnaire, and samples were collected and immediately transported to the laboratory for examination.

RESULTS

The majority of the patients were 20-29 years old. Half of the men and 12% of the women had never been married, and 7.9% of the men and 12% of the women were divorced. Genital ulcers and dysuria were the most prevalent symptoms in men (64% and 62%, respectively). In women, the most prevalent symptoms were lower vaginal discharge and lower abdominal pain (91% and 79%, respectively). Almost 50% of the men and women were positive for human immunodeficiency virus-1 antibodies. The prevalence of Treponema pallidum and Neisseria gonorrhoeae was 15% and 18%, respectively, in men and 19% and 10%, respectively, in women. Chlamydia trachomatis showed the lowest prevalence (8%) in both sexes. No relationship was found between human immunodeficiency virus and other sexually transmitted diseases.

CONCLUSION

Women who enter a sexually transmitted disease clinic with vaginal discharge or lower abdominal pain should be tested for several sexually transmitted diseases and human immunodeficiency virus. Men with dysuria or urethral discharge who enter such clinics should at least be tested for Neisseria gonorrhoeae.

Primary in vitro immunization with multimeric synthetic peptides of HIV-1 envelope glycoproteins: generation of neutralizing human monoclonal antibodies

Peripheral blood lymphocytes from healthy HIV-1 seronegative donors were immunized in vitro with the following synthetic peptides: (i) an octameric poly-L-lysine conjugated peptide of the HIV-1MN V3 loop and (ii) a resin bound synthetic peptide aa642-665 of HIV-1 gp41. Lymphoblastoid cell lines (LCL) were obtained by immortalization with Epstein-Barr virus (EBV). We produced four LCL secreting human monoclonal antibodies (HuMoAbs) of the IgM isotype: three were directed against the V3 domain (FC10, FC81 and CF41) and one against aa642-665 (CA45C). Two of these HuMoAbs (FC81 and CA45C) reacted to viral surface antigen on HIV-1-infected cells. All the HuMoAbs inhibited 40-53% of cell fusion induced by HIV-1-infected H9 cells at 5 micrograms/ml. They also neutralized, at lower concentrations, cell-free infection with HIV-1MN, HIV-1IIIB and four primary clinical HIV-1 isolates. No enhancing activity of the HuMoAbs in the presence of complement was observed. The results presented here show the feasibility of generating neutralizing human monoclonal antibodies against HIV-1 by primary in vitro immunization with selected synthetic peptides of HIV-1 envelope glycoproteins. This approach has provided tools for further studies of synergistic neutralization assays, and generated potential immunoglobulin candidates for passive immunotherapy.

HTLV-I and -II in intravenous drug users from Sweden and Denmark

693 IVDU (intravenous drug user) sera from Copenhagen, Malmö and Stockholm were tested, 247 retro- and 446 prospectively, for antibodies to human T-lymphotropic virus (HTLV), types I and II, by means of a commercial whole-virus EIA and/or an HTLV-I/-II peptide-based EIA. Positive EIA reactions were checked and typed by electrophoretic immunoblotting, a differential peptide-based EIA and nucleic acid amplification/hybridization with HTLV-I and -II specific primers and probes. 3 (0.7%) of the prospectively tested IVDUs from Malmö, none of 100 from Stockholm and none of 45 from Copenhagen were HTLV-seropositive. The 3 Malmö IVDU cases were a female immigrant from South America, her male native Swedish spouse (both HTLV-I), and a male immigrant Italian heroinist (HTLV-II). We conclude that HTLV was uncommon among intravenous drug users, a sentinel population, in Sweden and Denmark during 1986 and 1989. However, the occurrence of 3 HTLV-positive cases in Malmö 1993 indicates that the situation can change rapidly.

HTLV-II among injecting drug users in Stockholm

134 injecting drug users (IDUs) treated at the Department of Infectious Diseases of Roslagstull Hospital, Stockholm, were tested for antibodies to human T-lymphotropic virus, types I and II, by means of 2 HTLV-I/-II peptide-based enzyme immunoassays (EIAs), followed by a whole-virus EIA. Positive EIA reactions were checked and typed by electrophoretic immunoblotting with native HTLV-I and recombinant HTLV-I and -II proteins. 10 IDUs were diagnosed as HTLV-II seropositive. All 10 were of Scandinavian descent. Thus, like HIV-1, HTLV-II infection has entered the injecting drug user population in Stockholm.

Increased antiretroviral antibody reactivity in sera from a defined population of patients with systemic lupus erythematosus. Correlation with autoantibodies and clinical manifestations

OBJECTIVE

The implied role of retroviruses in the pathogenesis of murine systemic lupus erythematosus (SLE) led us to study antiretroviral antibodies in a population-based SLE cohort.

METHODS

Immunoassays using whole virus and synthetic peptides were performed on sera from 72 patients with SLE and 88 control subjects.

RESULTS

Reactions with whole baboon endogenous virus occurred more frequently in patients with SLE, and correlated with the presence of anti-RNP and anti-Sm. Some retroviral env and gag peptides, several of which were similar to U1 small nuclear RNP, reacted more strongly in patients with SLE, and their presence was correlated with discoid rash, hematologic disorder, and other symptoms.

CONCLUSION

These results provide circumstantial evidence for involvement of retroviruses in the pathogenesis of human SLE; further studies should be carried out using other techniques for measurement of retroviral expression.

Characterization of novel reverse transcriptase encoding human endogenous retroviral sequences similar to type A and type B retroviruses: differential transcription in normal human tissues

The polymerase chain reaction was used to amplify genomic DNA and reverse-transcribed RNA from human lymphocytes, using primers derived from conserved regions within the retroviral reverse transcriptase. Sequencing of 33 cloned amplification products revealed that a variety of sequences with similarity to mouse mammary tumor virus, mouse intracisternal A particle, and human endogenous retrovirus K10 were detected with this primer pair. The sequences were divided into six subgroups, with a nucleotide sequence dissimilarity of about 25% between the subgroups. Members within five of the subgroups were most closely related to human endogenous retrovirus K10 and mouse mammary tumor virus, whereas sequences of the sixth subgroup also showed similarity to mouse intracisternal A particle. Ten of the sequences had open reading frames with preference for silent mutations at conserved sites. Southern blot analysis showed that some HML (human endogenous MMTV-like) subgroups (HML-4 and HML-5) were present in a few copies (about 5), whereas others (HML-1 to HML-3 and HML-6) were present in at least 10 to 20 copies per genome. Northern (RNA) blot analysis revealed that several of the subgroups are differentially expressed in human normal tissues. A complex pattern of transcripts from about 12 to 1.4 kb was found in several of the tissues tested. However, the most abundant expression was detected in lung (all subgroups), skeletal muscle (HML-4 and HML-5), placenta (HML-2 and HML-5), and kidney (HML-2, HML-3 and HML-5). Expression of reverse transcriptase sequences in human tissues may have biological consequences. The described sequences are similar to elements which cause carcinoma and are immunoregulatory in mice. It remains to be seen whether human sequences also have such functions.

A survey of synthetic HIV-1 peptides with natural and chimeric sequences for differential reactivity with Zimbabwean, Tanzanian and Swedish HIV-1-positive sera

OBJECTIVE

To determine whether the known sequence differences between African and non-African HIV-1 strains are reflected in the serological response.

DESIGN AND METHODS

We investigated the antibody reactivity of 34 Swedish, 30 Tanzanian and 42 Zimbabwean HIV-1-positive sera to 67 synthetic peptides with sequences from North American and African HIV-1 isolates, mostly derived from regions of gag and env known to be antigenic. Not all sera were tested against all peptides.

RESULTS

Differences in frequency of reactivity were noted with peptides covering the entire third variable domain (V3), which is a primary neutralization determinant, and the carboxyl terminus of gp120, in two regions of gp41, and the carboxyl terminus of p24. In env Tanzanian sera reacted preferentially with a V3 peptide from the strain JY1 (Zaire). Gradual substitutions in the central motif in V3 of ELI from GLGQ to GPGR, typical of many non-African strains, led to a gradual increase in reactivity of many Swedish sera, but did not affect Tanzanian and Zimbabwean sera, suggesting that the major epitopes recognized by these African sera are outside GPGR. V3 peptides from the MN and Z3 strains reacted with most sera, but missed 30% of those of Tanzanian origin. In the carboxyl terminus of gp120 both sets of African sera reacted preferentially with peptides from strains JY1 and MAL. Swedish sera reacted strongest with analogues from strains Z321 and HXB2. In gp41, Swedish sera showed a weak preference for reactivity with HXB2-derived peptides in the immunodominant region (amino acids 590-620), and further towards the carboxyl terminus (amino acids 620-665).

CONCLUSION

The differences in serological reactivity were as great between Zimbabwe and Tanzania as between the two African sets and the Swedish. The geographical differences in the pattern of reactivity with HIV peptides probably depend on both host and viral variation and may be developed into a seroepidemiological tool, useful for optimization of future HIV vaccines.

Three-dimensional structure and antigenicity of transmembrane-protein peptides of the human immunodeficiency virus type 1. Effects of a neutralization-escape substitution

A point mutation (Ala-589 to Thr) in the transmembrane protein of the human immunodeficiency virus type 1 (HIV-1) has been shown to decrease the sensitivity of the virus to the neutralizing effect of human HIV-1 specific antibodies [(1990) J. Virol. 64, 3240-3248]. Here 17-residue peptides with the parental and mutant sequences were compared: the parental peptide bound antibodies of sera from HIV-1 infected persons more frequently and with higher affinity than the mutant peptide. However, according to circular dichroism (CD), NMR spectroscopy and molecular modelling the peptides have indistinguishable backbone conformations under a variety of experimental conditions. These techniques showed for both peptides that no ordered helix was present in water solution. However, for both peptides in alcohol-water solutions approximately 60% alpha-helix could be induced. The three-dimensional structures of these peptides provide a basis for understanding how this mutation in the transmembrane protein may affect the interaction with both the outer envelope glycoprotein and with antibodies.