483

baseline23 has provided evidence that low dietary magnesium is predictive of IHD. 7-day weighed dietary records were kept by 665 men.4 Prevalent heart disease was identified by the London School of Hygiene and Tropical Medicine questionnaire and by electrocardiography, with standard criteria,5 and men were divided into those with symptomatic heart disease (previous myocardial infarction and/or current angina; 97 men) and those with no relevant symptoms (568 men). Incident heart disease events were identified during the following 5 years. These consisted of deaths certified as due to IHD (ICD 410-414) and non-fatal myocardial infarctions that fulfilled World Health Organisation criteria .6 Mean daily intakes of magnesium were: Quantitative HIV-1 and HHV-6 PCR assays on maternal and fetal PBMC DNA. DNA submitted to PCR was serially five-fold diluted from 100 ng (lane to 0-03 ng (lane 6) for maternal PBMCs and from 5 Jlg (lane 7) to 1 6 pg (lane 12) for fetal PBMCs HIV-1 amplification was done with the primers P3/P46 and HHV-6 PCR with the primers 022/023, the sequences of which are located m the major capstde protein gene (022: 5’-GCG TGA ATC AAA CCT CGC TCG-3’; 023. 5’GCC TTA CTC GGA ATC TAC TGC-3’)." Amplified products were analysed on agarose gel, transferred on nylon membranes, and hybridised with ’P-labelled

No of men

/Vo symptomatic IHD //D at af baseline /)aNe//ne No incident event An IHD event af baseline &ae//ne Sy/npfo/TMf/c //-/0 at No incident event An IHD event

Nosymptomatic Symptomatic IHD

1)

oligomer probes. Our results show that HHV-6 can be transmitted in utero in association with maternal viraemia. The absence of maternal HHV-6 IgM antibodies indicates that transmission can occur even when the mother has previous immunity to the virus, but this remains to be confirmed. Intrauterine transmission strengthens even more the relation of HHV-6 to human cytomegalovirus which is also supported by the comparison of genomic organisation8 and antiviral susceptibility.9

JEAN-THIERRY AUBIN Bactériologie-Virologie, CERVI, Hôpital Pitié-Salpétrière, 75651 Paris, France

LAURENT POIREL HENRI AGUT JEAN-MARIE HURAUX

Centre d’Hémobiologie Périnatale, Hôpital Saint-Antoine, Paris

CHRISTIANE BIGNOZZI YVES BROSSARD

Laboratoire d’Embryoilogie Pathologique, et de Cytogénétique, Hôpital Saint-Antoine, Paris

NICOLE MULLIEZ JOELLE ROUME

Service de

FABRICE LECURU ROLAND TAURELLE

Laboratoire de

Gynécologie-Obstétrique, Hôpital Boucicaut, Paris

K, Okuno T, Shiraki K, et al. Identification of human herpesvirus-6 as causal agent for exanthem subitum. Lancet 1988; i: 1065-67. 2 Prusksananonda P, Breese Hall C, Insel RA, et al. Primary human herpesvirus 6 infection in young children. N Engl J Med 1992; 32: 1445-50. 3. Ueda K, Kusuhara K, Hirose M, et al. Exanthem subitum and antibody to human herpesvirus-6. J Infect Dis 1989; 159: 750-52. 4 Aubin JT, Collandre H, Candotti D, et al. Several groups among human herpesvirus 6 can be distinguished by southern blotting and polymerase chain reaction. J Clin Microbiol 1991; 29: 367-72 5. Ou CY, Kwok S, Mitchell SW, et al DNA amplification for direct detection of HIV-1 in DNA of peripheral blood mononuclear cells. Science 1988, 239: 295-97. 6 Laure F, Courgnaud V, Rouzioux C, et al. Detection of HIV-1 DNA in infants and children by means of polymerase chain reaction. Lancet 1988; ii: 538-40. 7 Robert C, Agut H, Aubin JT, et al. Detection of antibodies to human herpesvirus 6 using immunofluorescence assay. Res Virol 1990; 141: 545-55. 8 Lawrence GL, Chee M, Craxton MA, Compels UA, Honess RW, Barrell BG. Human herpesvirus 6 is closely related to human cytomegalovirus. J Virol 1990; 64: 287-99. 9. Agut H, Aubin JT, Huraux JM. Homogeneous susceptibility of distinct human herpesvirus 6 to antivirals in vitro. J Infect Dis 1991; 163: 1382-83. 1 Yamanishi

Dietary magnesium and prediction

of heart

disease SIR,-The LIMIT-2 trial (June 27, p 1553) makes a most important contribution to a confused topic-ie, the relevance of magnesium to ischaemic heart disease (IHD). This new evidence establishes the value of magnesium in the treatment of myocardial mfarction. But what is its role in prevention before infarction? Magnesium has long been of interest in relation to IHD. One observation consistent with an aetiological role is reduced amounts in the myocardium of subjects whose deaths had been certified as due to heart disease, even when death had been "sudden". The Caerphilly Heart Disease study of men aged 45-59 years at

540 28 87 10

Mean intake

(SD) (mg Mgjday) 310 310 (105) 274 (81) 283 283 (91) (91)

248 (86)

The mean daily intake of magnesium was about 12 % lower in men who later had an IHD event, both in those with IHD at baseline and those without. Overall, the intake was lower by 38-9 mg (95% confidence interval [CI] 5 3-72mg) in those who had an event, and adjustment for the presence or absence of baseline symptoms reduces this difference to 35-6 mg daily (95% CI 2-0-691).

MRC

Epidemiology Unit (South Wales), Llandough Hospital, Penarth, South Glamorgan CF6 1XX, UK

P. C. ELWOOD A. M. FEHILY P. M. SWEETNAM J. W. G. YARNELL

1. Elwood

2.

3.

4. 5.

6.

PC, Sweetnam PM, Beasley WH, Jones D, France R. Magnesium and calcium in the myocardium: cause of death and area differences. Lancet 1980; ii: 720-22. Caerphilly and Speedwell Collaborative Group Caerphilly and Speedwell collaborative heart disease studies. J Epidemiol Community Health 1984; 38: 259-62. The Caerphilly Collaborative Heart Disease Studies. Project description and manual of operations. Cardiff: MRC Epidemiology Unit, 1985. Fehily AM, Yarnell JWG, Butland BK. Diet and ischaemic heart disease in the Caerphilly study. Human Nutr Appl Nutr 1987; 41A: 319-26. Bainton D, Baker IA, Sweetnam PM, Yarnell JWG, Elwood PC. Prevalence of ischaemic heart disease: the Caerphilly and Speedwell Surveys. Br Heart J 1988; 59: 201-06. Yarnell JWG, Baker IA, Sweetnam PM, et al. Fibrinogen, viscosity, and white blood cell count are major risk factors for ischemic heart disease: the Caerphilly and Speedwell Collaborative Heart Disease Studies. Circulation 1991; 83: 836-14.

Striking identity between HIV-1 envelope glycoprotein gp120 and its CD4 receptor SIR,--Oligopeptides, such as the pentapeptides homoregulatory peptide and epidermal pentapeptide,l are involved in many biological processes.1-s Some have been mapped in the HIV-1 envelope.4,5 On the basis of the homology that they share with immunoregulatory molecules such as interleukin-2 receptorbinding domain or a-interferon-p I 5E, they are likely to have a role in the immune dysregulation observed in AIDS.4,5 We have designed software (Automat) to find systematically all peptidic homologies between proteins in a bank and a given protein.5 Scanning the HIV-1 envelope sequences revealed a pentapeptide identity (SLWDQ) with the CD4 molecule at positions 110-114 in the HIV-1envelope and 60-64 in CD4. Exploration of the MIPS data bank revealed the pentapeptide sequence in only one other protein, the aminotransferase A64988. The sequence is perfectly conserved among all HIV-1strains (but is lacking in HIV-2 and simian immunodeficiency virus) and in human and chimpanzee CD4. The SLWDQ pentapeptide is located in the N-terminal part of the gpl20 external membrane protein of HIV-1. This segment lies on an accessible loop of the first domain of CD4,6 and is the epitope for the OKT4a monoclonal antibody.’ Moreover this region has an important function in the CD4 molecule since OKT4a monoclonal antibodies (specifically directed towards this region) can block T4 cell immune activation,8 and a W-to-C mutation suppresses the binding of HIV-1.’ In agreement with the above mentioned biological characteristics, the

484

PEPTIDE INHIBITION OF T-CELL ACTIVATION*

The differences observed in the two studies may be attributable to Lafeuillade’s use of collection strains of mycoplasma, many of which have been stored for years and/or transplanted many times and whose metabolic activities may thus have been altered. Fresh strains of M hominis and U urealyticum do not seem susceptible to AZT in vitro.

agar.2

Department of Microbiology and Infectious Disease Unit, Massachusetts General Hospital, Boston, Massachusetts 02114, USA *PPD and SEB sensltlsed macrophages were co-cultured with autologous HLA-DR T-cells with or without HIV-1 peptides at optimum concentration of 300 J1g/ml Three experiments done in quadrlpllcate with each peptide gave similar results tResults of typical experiment T-cell proliferation measured by thymidine incorporation is reported m cpm Peptides 1 and 2 are experimental peptides, 3 and 4 control peptides

SLWDQ peptide was identified as a "critical site" of CD4 by our software (Critics) designed to unravel functional sites of proteins.5 We next studied the capacity of this HIV-1 peptide to interfere with T4 cell immune activation. Purified HLA-DR-negative T cells from normal human blood were stimulated with autologous macrophages presenting purified protein derivative (PPD) or staphylococcal enterotoxin B (SEB) antigens, in the presence of various HIV-1 derived peptides. Only the two peptides containing SLWDQ strongly inhibited T-cell proliferation (> 50%) (table). These data suggest that the SLWDQ sequence contributes to the impairment of the immune responsiveness observed in AIDS, by mimicking or by inhibiting a CD4 function involved in T4 cell activation. We thank A. Achour, A. Bumy, and I. Callebaut for their Cellular Physiology Laboratory, Université P et M Curie, 75252 Paris, France, Institut Pasteur, Paris; Université P6/P7, CNRS URA09, Paris, and Université Libre de Bruxelles,

negative AIDS.

B. BIZZINI D. ZAGURY

WR, Elgjo K, Laerum OD Peptide growth factors and their receptors.

796-98.

4.

SH, Lorenzetti BB, Bristow AF,

et

al

Interleukin-1 beta

as

a

potent

hyperalgesic agent antagonised by a tripeptide analogue. Nature 1988; 34: 698-700. Reiher WE, Blalock JE, Brunck TK. Sequence homology between acquired immunodeficiency syndrome virus envelope protein and interleukin-2. Proc Natl Acad Sci USA 1986; 83: 9188-92.

5.

Zagury JF, Cantalloube H, Bernard J, et al. Critical sites: a semantic approach to protein sequences: application to the HIV-1 envelope molecule. Biomed Pharmacother (in press). 6. Ryu SE, Kwong PD, Truneh A, et al. Crystal structure of an HIV-binding recombinant fragment of human CD4. Nature 1990; 348: 419-26. 7. Brodsky MH, Warton M, Myers RM, et al. Analysis of the site in CD4 that binds to the HIV envelope glycoprotein. J Immunol 1990; 144: 3078-86. 8. Lamarre D, Capon DJ, Karp DR, et al. Class II MHC molecules and the HIV gp120 envelope protein interact with functionally distinct regions of the CD4 molecule. BMBO J 1989; 8: 3271-77.

Lack of activity of zidovudine against Ureaplasma urealyticum and Mycoplasma hominis and colleagues (Jan 11,

SIR,-Dr Lafeuillade p 131) test the activity of zidovudine (AZT) against five collection strains of mycoplasma and show them to be susceptible to 10, l, and 0’ 1 )g/ml of the drug. Using the standard metabolism inhibition broth method of susceptibility testing for mycoplasma,l we tested three freshly isolated strains of Ureaplasma urealyticum against AZT in the

same

concentrations and found

no

SiR,—Your Aug 1 editorial (p 280) states that recent media speculation on HIV-negative AIDS was inspired by a press announcement from Dr Sudhir Gupta, and implies that he behaved irresponsibly by doing so. Not so. The story broke in an article in the popular American magazine Newsweek on July 27 featuring prominently Dr Jeffrey Laurence, whose work you subsequently published (Aug 1, p 273). As a result of the publicity created by Newsweek, the organisers of the VIIIth International Conference on AIDS, taken by surprise, were forced to give Dr Laurence a platform to announce his fmdings in a more responsible setting. Dr Gupta, bombarded by inquiries from the media, responded to the frenzy from Amsterdam by obtaining permission from Proceedings of the National Academy of Sciences to release his peer-reviewed

H. CANTALLOUBE

Springer, 1990: 267-95. Konig R, Huang LY, Germain RN. MHC class II interaction with CD4 mediated by a region analogous to the MHC class I binding site for CD8. Nature 1992; 356:

3. Ferreira

AIDS minus HIV?

paper earlier than scheduled. Whatever the merits or otherwise of that paper, Gupta did nothing to drive the publicity on HIV-

London:

2.

1 Senterfit LB. Antibiotic sensitivity testing of mycoplasmas. In: Tully JG, Razin S, eds Methods in mycoplasmology, vol 2. New York: Academic Press, 1983: 387-401 2. Madoff S, Hooper DC. Nongenitourinary infections caused by Mycoplasma hominis in adults. Rev Infect Dis 1988; 10: 602-13.

J.-F. ZAGURY J. BERNARD J.-P. MORNON

Brussels, Belgium 1. Paukovits

help.

SARABELLE MADOFF MARY JANE FERRARO DEBRA P. MERRILL MARTIN S. HIRSCH

inhibition of metabolic

activity. Similarly, four strains of Mycoplasma hominis (three of which were recently isolated from clinical specimens) showed no susceptibility to AZT in concentrations of 100,10,1, and 0 1 jg/ml. These tests were done with drug concentrations prepared from the pure AZT powder. They were then repeated with concentrations prepared from the standard parenteral AZT preparation. Growth of M hominis in arginine containing mycoplasma broth, as shown by distinct colour change, was confirmed by transfer to mycoplasma

Aaron Diamond AIDS Research Center, New York University School of Medicine, New York, NY 10016, USA

JOHN MOORE

Origin of HIV-1 SIR,-Billi Goldberg (June 20, p 1548) states categorically and without benefit of supporting evidence that the alleged origin of HIV-1 in Africa was the human diploid cell strain (HDCS) WI-38, developed by me at the Wistar Institute and used, among other things, for the preparation of poliovaccines. After this unqualified assertion Goldberg curiously relents and asks: "Is there any possibility at all that those poliovaccines [used in the then Belgian Congo] were developed in the human cell line? I can find no evidence for this but the possibility deserves an airing." The answers to Goldberg’s unsupported charge and to his query are that both are impossible. WI-38 cannot have been used for the preparation of the poliovaccine administered in the Belgian Congo "between August 1958,and April, I960,..."because WI-38 was not developed by me until June, 1962.1 However, in 1962 we did report on the safety and efficacy of a poliomyelitis vaccine produced in the WI-1 normal HDCS and fed to six full-term infants2 and to my children. No attenuated poliovirus vaccine ever produced in any HDCS at the Wistar Institute was ever given to recipients in Africa at that time. In an effort to underpin his guess that a poliovirus vaccine produced in WI-38 might be the origin of the HIV-1 epidemic in Africa, Goldberg makes an additional argument. He notes, correctly, that the seed virus used by me to produce the type 1 poliovirus vaccine was the CHAT strain that had been grown previously in primary monkey kidney cells. What-Goldberg fails to mention, however, is that before production of the vaccine, the type 1 CHAT seed virus was terminally diluted and triple plaque purified in high population doubling level (PDL) WI-I.2 This material was then used to produce the seed virus in WI-1and PDL 22.2 Although triple plaque purification is not a guarantee that a putative unwanted virus was removed, the possibility that HIV-1 or any other virus may have remained is vanishingly small. WI-38 has been used for the production of vaccines against

Striking identity between HIV-1 envelope glycoprotein gp120 and its CD4 receptor.

483 baseline23 has provided evidence that low dietary magnesium is predictive of IHD. 7-day weighed dietary records were kept by 665 men.4 Prevalent...
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