DIVERSE TROPISM OF HUMAN B-LYMPHOTROPIC VIRUS (HUMAN HERPESVIRUS 6)

743 SEROLOGICAL FINDINGS IN FIVE CASES OF PSITTACOSIS

*Outbreak

serially propagated the agent in human embryonic kidney cells, by use of trypsin-containing media3 for propagation of human astroviruses. Electronmicroscopy on stool material from a volunteer given MCA (sent to us by Dr H. B. Greenberg, Stanford University, Palo Alto) suggested that the virus was an astrovirus. In immune-electronmicroscopic (IEM) studies the virus in stool reacted only with antisera (rabbit) prepared against astrovirus type 5 (reference sera to astrovirus types 1-5 provided by Dr J. B. Kurtz, John Radcliffe Hospital, Oxford). Acute We have isolated and

from November, 1985, to March, 1986. test; FAB = indirect immunofluorescence antibody test with the enzootic abortion of EWES (EAE) strain of C psittaci ; IFA=indirect immunofluorescence assay; ELISA enzyme-linked immunosorbent assay ran

tCFT=complement fixation

=

A further 6 weeks later, an elderly man (case 5) living next door to the index case had influenza-like symptoms with cough and sputum production. His convalescent phase serum sample had a C psittaci antibody titre of 256. He had had no contact with birds but worked with case 2 and had visited him in hospital on the day of his admission. Serological fmdings are summarised in the table. C psittaci was isolated from both cloacal specimens from Joey, from all seven other birds tested at the original breeder’s premises, and from one of the two specimens taken from the birds at the caravan. Specimens from birds in the aviary at the caravan site were

negative. Cases 1—4

were

probably

associated with

Joey

but

case

related

to

contact

with

birds.

However,

careful

epidemiological investigation of cases presenting this year has shown that a bird contact, directly or indirectly, is present in up to half of the cases. Person-to-person spread may be more important than has been generally accepted. Psittacosis should be made a notifiable disease, to strengthen the powers available to this potentially fatal infection. We thank Dr E. 0. Caul (Bristol Public Health Laboratory) for the immunofluorescent assays and Miss Vicky Robinson for the ELI SA tests.

Cambridge Health Authority, Fulboum Hospital, Cambridge CB1 5EF

R. B. BUTTERY

Clinical Microbiology and Public Health Laboratory, Cambridge

T. G. WREGHITT

Nagington J. Psittacosis/ornithosis

m

Cambridgeshire 1975-1983. J Hyg 1984;

92:

9-19.

MARIN COUNTY AGENT, AN ASTROVIRUS

SIR,—The relative importance of some of the enteric viruses as of gastroenteritis is often difficult to establish because of the lack of suitable cultivation and/or identification techniques. One such virus, the Marin County agent (MCA), was first associated with an outbreak of gastroenteritis in a convalescent home in 19811 and it was thought to be a member of the Norwalk virus group. Lately there has been speculation that MCA might be an causes

astrovirus.2

RICHARD W. HUDSON NEIL R. BLACKLOW

Public Health Laboratory and Department of Microbiology, Central Middlesex Hospital, London NW10

W. DAVID CUBITT

1. Oshiro LS, Haley CE, Roberto RR, et al. A 27-nm virus isolated during an outbreak of acute infectious nonbacterial gastroenteritis in a convalescent hospital, a possible

serotype. J Infect Dis 1981; 143: 791-95. JB, Lee TW. Astroviruses: Human and animal. In: Bock G, Whelan J, eds. Novel diarrhoeal viruses (Ciba Found Symp 128). Chichester: John Wiley, 1987:

new

5 is

revealing psittacosis in a large proportion (1. B. Griffiths, personal communication). Nagington1 found that in Cambridgeshire only 17 % of cases

1.

JOHN E. HERRMANN

Division of Infectious Diseases, University of Massachusetts Medical School, Worcester, Massachusetts 01605, USA

2. Kurtz

difficult to explain. However, since no other cases of C psittaci infection were diagnosed in this south Cambridgeshire village, case 5 may have been associated indirectly with Joey, possibly by person-to-person transmission. This outbreak is a reminder of the health risk associated with psittacine birds. In 1986 there were another 43 cases of psittacosis in this health district, and two previously fit women living in Cambridgeshire have died of the disease. Legal powers aimed at preventing the spread of infection are exercised only when poultry is at risk. In 1985, 24 792 psittacines were imported into the UK; during the statutory 3 weeks’ quarantine 14-9% died, necropsy

were

and convalescent sera obtained from the volunteer showed seroconversion by IEM to MCA in stool, to astrovirus type 1 in stool, and to cell-cultivated astrovirus type 5. Immunofluorescence of MCA-infected cells showed positive reactions with type 5 antiserum and at a lower dilution with type 1 antiserum. By an ELISA test of cell-cultivated virus, only type 5 antiserum was positive. Thus, MCA can now be classified as an astrovirus of serotype 54 with cross-reactivity in some tests with type 1. These findings provide a means for assessing the role of MCA along with other astroviruses in viral gastroenteritis.

92-107. 3. Lee TW, Kurtz 4.

JB. Serial propagation of astrovirus in tissue culture with trypsin. J Gen Virol 1981; 57: 421-24. Kurtz JB, Lee TW. Human astrovirus serotypes. Lancet 1984; ii: 1405.

the aid of

DIVERSE TROPISM OF HUMAN B-LYMPHOTROPIC

VIRUS (HUMAN HERPESVIRUS 6) SIR,—The human B-lymphotropic virus (HBLV, human herpesvirus 6) was recently isolated from patients affected by several haematological disorders,l,2 and descriptions of HBLV have lately appeared in the letters pages of The Lancet (Aug 15, pp 390-91 ; July 4, p 36). On the basis primarily of the characterisation of infected cells in peripheral blood from patients, tropism for B lymphoid cells was reported.1 However, in vitro studies on fresh leucocytes from healthy donors and established cell lines demonstrate a broader range of target cells for HBLV. We have developed optimum culture conditions for the in-vitro propagation of purified HBLV in normal human peripheral blood, umbilical cord blood, and bone marrow leucocytes. A detailed immunological and molecular analysis of the target cells was done on a cell population that was more than 90% infected, as demonstrated by in-situ hybridisation with the HBLV probe pZVH143 or by indirect immunofluorescence using positive sera from patients.! Although B-cell-associated antigens were occasionally observed, the vast majority of HBLV-infected cells from the different tissues displayed features of immature T lymphocytes. Single and double staining immunofluorescence analysis, utilising anti-HBLV-positive human sera and a wide panel of monoclonal antibodies, defmed the predominant phenotype of HBLV-infected cells in vitro as CD7 (Leu-9), CD2 (OKT11), CD4 (OKT4) positive, and CD19 (B4), CD20 (Bl), surface and cytoplasmic immunoglobulins negative. These results were confirmed by radioimmunoprecipitation assay. The CD3 (OKT3) antigen, appearing during the last phase of intrathymic T-cell differentiation,’ was not detectable on the cell membrane and was only very weakly expressed in the cytoplasm of infected cells. 20-40% of infected cells coexpressed the CD4 (OKT4) and CD8 (OKT8) molecules on the surface membrane. The molecular analysis of immunoglobulin heavy chain and T-cell-receptor B-chain gene configuration and expression, by Southern and northern blot techniques, is in progress to confirm the Tlymphocytic origin of these cells.

-

744 We have shown that HBLV can infect several permanent human cell lines, including megakaryocytes, glioblastoma cells, B cells, and T cells at different stages of maturation.s This evidence for an expanded HBLV tropism in vitro suggests the possible direct role of the virus in various haematological and neurological disorders. In accordance with the published provisional classification of human herpesviruses, we suggest that HBLV should be designated human

herpesvirus-6 (HHV-6). Laboratory of Tumor Cell Biology, National Cancer Institute, National Institutes of Health, Bethesda, Maryland 20892, USA

Bionetics Research, Inc,

Rockville, Maryland

P. LUSSO S. Z. SALAHUDDIN D. V. ABLASHI R. C. GALLO F. DI MARZO VERONESE P. D. MARKHAM

SZ, Ablashi DV, Markham PD, et al. Isolation of a new virus, HBLV, in patients with lymphoproliferative disorders. Science 1986, 234: 596-600. 2. Biberfeld P, Kramarsky B, Salahuddin SZ, Gallo RC Ultrastructural characterization of a new human B lymphotropic DNA virus (HBLV) isolated from patients with lymphoproliferative disease. J Natl Cancer Inst (in press). 3. Josephs SF, Salahuddin SZ, Ablashi DV, Schachter F, Wong-Staal F, Gallo RC. Genomic analysis of the human B-lymphotropic virus (HBLV). Science 1986; 234: 601-03. 4. Reinherz EL, Kung PC, Goldstein G, Levey RC, Schlossman SF. Discrete stages of human intrathymic differentiation: analysis of normal thymocytes and leukemic lymphoblasts of T cell lineage. Proc Natl Acad Sci USA 1980; 77: 1588. 5. Ablashi DV, Salahuddin SZ, Josephs SF, et al. HBLV (HHV-6) in human cell lines. Nature (in press). 1. Salahuddin

IMMUNE BASIS FOR PRE-ECLAMPSIA: EVIDENCE FROM OOCYTE RECIPIENTS

SIR,—The evidence that pre-eclampsia may be a disorder of the mechanism involved in the normal fetomatemal host response includes an association with primigravidae, the protection afforded in subsequent pregnancies of the same paternity, the possibility of pre-eclampsia occurring in a subsequent pregnancy by a different consort, and the protective role of blood transfusions, previous abortions, and prolonged exposure to spermatozoa in primigravidae. All these features indicated that exposure to paternal antigens is protective. Further evidence comes from our experience with oocyte donation. Five out of the first ten patients successfully treated for infertility with oocyte donation developed pre-eclampsia. Of this group, all of whom were normotensive before treatment, two had a twin gestation. One of these two patients had fulminating pre-eclampsia and was delivered by caesarean section at 32 weeks. She subsequently required dialysis and now awaits transplantation. The other had massive oedema and proteinuria with moderate hypertension and then became nephrotic (serum albumin below 25 g/1) and underwent caesarean section at 34 weeks. The three patients having singleton pregnancies had hypertension, oedema, and proteinuria and were each delivered before 35 weeks. In all instances the babies did well. In oocyte donation the father and the woman donating the eggs provide the haplotype of their major histocompatibility antigens to the conceptus, creating a unique model for investigating the immunological aetiology of pre-eclampsia. Immunological tolerance between two genetically dissimilar tissues (matemal and fetal) is needed for successful reproduction. The fetus is said to be protected from maternal rejection by the low-grade antigenicity of the trophoblastic tissue, by the masking of trophoblast antigens by surface coat sialomucin, and by "blocking antibodies". It has been suggested that in pregnancy maternal exposure to allelic antigens in the fetus normally induces blocking antibodies which block reactivity to paternal antigens. However, in pre-eclampsia, when paternal and maternal HLA or other antigens are similar, the antigenic stimulus for production of blocking antibodies may be inadequate. Jenkins et all found an unusual frequency of HLA matching between pre-eclamptics and their husbands, and the immunological activity of lymphocytes of pre-eclamptic women has been shown to be reduced in vitro. In a second pregnancy by the same partner the long-lived cross-reactive blocking antibodies seem to be immunoprotective. Antigen specific and non-specific suppressor T cells induced by the first pregnancy

immunological

present in the second pregnancy. Such an immunoprotective role is not operative in the second pregnancy from a different partner, when the mother is exposed to a new set of histocompatibility antigens. Pregnancies achieved by donor sperm insemination have been shown to be associated with a significant increase in pre-eclampsia in multipara.1 Similar immunological processes have been implicated in recurrent spontaneous abortion. Couples with recurrent pregnancy wastage of unknown aetiology share MHC antigens at several loci3,4 and the blocking antibodies normally present in women’s serum during and after normal pregnancy are absent in habitual abortion.5 Women with recurrent abortion sharing multiple MHC antigens with their husbands have shown hyporeactivity in mixed lymphocyte culture when maternal lymphocytes responded to paternal cells as stimulators. No such hyporeactivity was demonstrated when third party HLA-incompatible stimulators were used. In an oocyte recipient immunological hyporesponsiveness can be explained either by an increased likelihood of HLA sharing between the mother and the two sets of paternal and donor egg histocompatability antigens or an excessive antigenic load overwhelming the responder state. Since previous exposure to paternal antigens may be protective it is tempting to speculate that immunotherapy might offer protection. Marti and Herman6 have shown that regular and natural inoculation of the female genital tract with allogeneic spermatozoa bearing histocompatability antigens of the male reduces the incidence of subsequent pre-eclampsia. In women with recurrent abortions pre-immunisation with paternal lymphocytes can result in immunoreactivity and normal term pregnancies. 3,7 Furthermore, immunological conditioning by giving donor-specific blood transfusions to the recipient before surgery is common practice in

are

kidney transplantation. The oocyte recipient setting affords an excellent opportunity to investigate the possibility of a disturbed immunological process in the aetiology of pre-eclampsia. If our finding is confirmed we will do detailed HLA analyses of oocyte donor and recipient and recipient’s husband, to establish the degree of HLA sharing. A controlled trial will then be undertaken to test the protective effect of active immunisation. So far no woman who has become pregnant after immunisation for recurrent abortion has had pre-eclampsia.8 Fertility &

IVF

Unit,

Humana

Hospital, Wellington Place, London NW8 9LE

PAUL F. SERHAL IAN CRAFT

Jenkins DM, Need JA, Scott, JS, Morris H, Pepper M. Human leucocyte antigens and mixed lymphocyte reaction in severe pre-eclampsia. Br Med J 1978; i 543 2. Need JA, Bell B, Meffin E, Jones WR. Pre-eclampsia in pregnancies from donor inseminations. J Reprod Immunol 1983; 5: 329. 3. Beer AE, Quebbeman JF, Ayers JWT, Haines RF. Major histocompatability complex antigens, maternal and gestational immune responses and chronic habitual abortions Am J Obstet Gynecol 1981; 141: 987. 4. Komlos L, Zamir R, Joshua H, Holbrecht I. Common HLA antigens in couples with repeated abortions Clin Immunol Immunopathol 1977; 7: 330. 5. Rocklin RE, Kitzmiller JL, Carpenter CB, Garovoy MR, David JR. Maternal-fetal relation. Absence of an immunologic blocking factor from the serum of women with chronic abortions. N Engl J Med 1976; 295: 1209. 6. Marti JJ, Herman U. Immunogenosis. A new aetiologic concept of "essential" EPH gestosis, with special reference to the primigravid patient Am J Obstet Gynecol 1977, 128: 483-93 7 Mowbray JF, Liddell H, Underwood JL, Gibbings C, Reginald PW, Beard RW Controlled trial of treatment of recurrent spontaneous abortion by immunisation 1.

with paternal cells Lancet 1985; i 941-43. 8. Beer AE, Ned JA. Immunological aspects of pre-eclampsia eclampsia. Birth Orig Art Ser 1985; 21: 131-54.

Defects

LEUCOERYTHROBLASTOSIS IN BREAST CARCINOMA

SIR,—The association of leucoerythroblastosis with metastasis to the bone marrow is well known but its occurrence in such diverse entities as asthma, inflammatory bowel disease, congestive heart failure, haemorrhage, haemolysis, and infection is not so well appreciated.l,2 This has led to some controversy, with assertions that leucoerythroblastosis is not a useful diagnostic signl,2 contrasting with statements that it is always a sign, or is virtually diagnostic of, bone marrow metastasis in patients with known cancer. 3,4