- Email: [email protected]
ANTI-HIV TESTING ON URGENT SPECIMENS
323 SLEEP DEPRIVATION, DIETING, AND DEPRESSION MARKERS
SIR,-Professor Carroll (Dec- 13, p 1390) criticises our study (Nov 8, p 1051) of the influence of sleep disruption and calorie restriction on biological markers for depression, claiming that we used inadequate measures to ask the wrong question in an inappropriate group of subjects. We asked whether sleep disruption and calorie restriction in normal volunteers influenced the results of the rapid-eye-movement (REM) latency test and dexamethasone suppression test (DST) in a similar manner to that reported in depressive disorders. The group of volunteers were appropriate to this question. The measures we used included the method for the DST, rating scales, and data analysis used by Carroll himself. Carroll quotes Kupfer’s review1 in support of his statement that "REM latency alone is not an adequate objective index of sleep in depression". Kupfer actually states that, though. there are a constellation of sleep changes in depression, the reduced REM latency is the most prominent and has "considerable replicability" and that "in almost all depressed states REM latency is shortened".1 It was for reasons such as these that we examined this variable. We did not attempt to reproduce "the many complex sleep disturbances that may be seen in depression", as Professor Mendlewicz challenges (Jan 10, p 105); we merely demonstrated that the changes in REM latency commonly claimed as a diagnostic marker could be reproduced in normal volunteers by mimicking one aspect of the sleep disorder so common in depression. We agree with Carroll and with Dr Schweitzer (Jan 10, p 105) that, on current evidence, it is not possible to conclude that weight loss accounts for all the abnormal DST findings in depressed patients. This does not, however, vitiate our contention that unless mild-to-moderate weight loss can be confidently excluded in the previous six months, the DST results become an unreliable diagnostic marker for depression. Carroll suggests that we are nihilists promoting clinical folklore in preference to the brave new laboratory technologies. We are merely sceptical-about our own research and that of others. We have the greatest respect for Professor Carroll and his contributions to biological psychiatry, but we have the temerity to approach even his work in this spirit of scepticism. Department of Psychological Medicine, University of Otago, Dunedin, New Zealand 1.
PAUL E. MULLEN CHRISTOPHER R. LINSELL
Kupfer DJ. Neurophysiological "markers"—EEG sleep measures. J Psychiat Res 1984; 18: 467-75.
condom failure when one partner is HIV infected are serious enough and the likelihood of failure sufficiently high that condom use by risk groups should not be described as "safe sex". Encouraging non-penetrative sexual activities that do not afford HIV an entry to the bloodstream is more difficult than simply recommending the use of condoms. However, the seriousness of the AIDS crisis is such that sexually active AIDS risk group members should be urged to refrain from penetrative sexual activities, especially anal intercourse, with or without condoms. Division
of Psychology, Department of Psychiatry and Human Behavior, University of Mississippi Medical Center, Jackson, Mississippi 39216, USA
JEFFREY A. KELLY JANET S. ST LAWRENCE
1. Stone KM, Grimes
DA, Madger LS. Primary prevention of sexually transmitted diseases: a primer for clinicians. JAMA 1986; 255: 1763-66. 2. Katchadourian HA, Lunde DT. Fundamentals of human sexuality. New York: Holt, Rinehart, and Winston, 1972. J, Bloom D, Pebley A. Correcting contraception failure rates for sample composition and sample selection bias. Soc Biol 1981; 28: 293-98. 4. Andersen RE, Levy JA. Prevalence of antibodies to AIDS-associated retrovirus in single men in San Francisco. Lancet 1985; i: 217. 5. Jaffe HW, Darrow WW, et al. The acquired immune deficiency syndrome in a cohort of homosexual men. Ann Intern Med 1985; 103; 210-14. 3. Trussell
ANTI-HIV TESTING ON URGENT SPECIMENS
SIR,--0ur laboratory provides a district HIV (human immunodeficiency virus) antibody testing service which is predominantly, but not exclusively, concerned with the urgent testing of tissue and organ donors. Commercial anti-HIV immuneassay kits are designed for batch testing and are not ideal for the rapid testing of small numbers of samples. One problem with the ’Wellcozyme’assay (Wellcome Diagnostics) relates to the clotting of blood specimens. When asked to do a rapid anti-HIV test we try to report the result within 120 min of the blood sample being taken. Unfortunately, sera aspirated from freshly clotted blood and subsequently shown to be anti-HIV negative often give false positive or equivocal results in the Wellcome Diagnostics assay. The manufacturers state that "Care should be taken to ensure that serum samples are fully clotted", and they say that plasma may be tested. We have compared results with the Wellcome assay on fresh plasma and serum.
CAUTIONS ABOUT CONDOMS IN PREVENTION OF AIDS
SIR,-In programmes aimed
at
preventing
transmission of
human immunodeficiency virus (HIV) condom use has been emphasised by clinicians, public health agencies, and health organisations in the gay community as a "safe sex" method. Laboratory studies indicate the HIV does not permeate the membrane of intact, high-quality condoms.1 However, condoms have a substantial failure rate. 13-15% of women whose male partners use condoms as the sole method of contraception become pregnant within one year,2,3 and condoms are generally regarded as unreliable. Presumably, condoms fail because of tears or slippage or because they have not been used properly. Failure rates may be even higher during sexual activities between male homosexuals. The prevalence of HIV infection among sexually active homosexual males is 20-50% in many American cities4,s and the likelihood that a homosexual individual’s partner will be HIV infected is substantial. Given the failure rate of condoms in family planning, homosexuals who practise anal intercourse will still be at risk of HIV exposure even if they use condoms. The use of condoms during anal intercourse between homosexual men or vaginal intercourse between heterosexual partners if one of them is in an AIDS risk group may reduce the probability of HIV transmission, but only if the sheath remains intact. The possible consequences of
Duplicate samples of both untreated and lithium heparinised blood from an anti-HIV-negative volunteer were kept at 20°C or 37°C for varying times after venepuncture. The specimens were then centrifuged; the serum and plasma were recovered and tested. Serum aspirated from blood kept at 20°C for 20 min after venepuncture gave a false-positive result, and a similar sample at 30 min was still equivocal (table I). Clotting at 37°C seemed more efficient but gave false-positive results at least up to 10 min after venepuncture. Plasma samples were negative throughout. TABLE I-WELLCOZYME ANTI-HIV IMMUNOASSAY: OPTICAL DENSITY AT
I
I
450
run
I
I
Optical density values less than the cut-off of 0 724 should be regarded as positive. Values within 10% (0 652-0 796) of the cut-off are equivocal.
324 TABLE II-PARALLEL TITRATION OF SERUM AND PLASMA
SAMPLES
FROM AN ANTI-HIV-POSITIVE INDIVIDUAL TESTED BY WELLCOZYME ANTI-HIV IMMUNOASSAY
values less than cut-off of 0.577 should be within 10% (0 519-0 635) of cut-off are equivocal.
Optical density
regarded
as
positive. Values
Table l shows the results of parallel titration of serum and plasma samples from an anti-HIV-positive individual which were kept at 4°C overnight and then diluted in anti-HIV-negative serum and plasma. The specimens demonstrated antibody to an equivalent titre. We recommend that heparinised plasma be requested for urgent testing in the wellcozyme anti-HIV immunoassay and that the possibility of false reactivity of fresh blood samples be investigated in other commercial anti-HIV assays. This may prevent the unnecessary waste of an organ or blood donation. C. J. RONALDS P. C. A. GRINT A. E. HARDIMAN
Department of Virology, St Bartholomew’s Hospital, London ECIA 7BE
Optical density cut-off
EFFICACY OF FIVE ENZYME IMMUNOASSAYS FOR ANTIBODY TO HIV IN DETECTING ANTIBODY TO
Distribution patterns of responses in four HIV EIAs for samples positive for anti-HIV and samples positive for anti-HTLV-IV. For Wellcome assay cut-off/optical density values
see
Reesink et al .7
HTLV-IV
SlR,—A year ago we reported serological evidence for a virus related to simian T-lymphotropic retrovirus type III (STLV-III) in residents of West Mrica.1 Another new retrovirus (HTLV-IV) has also been isolated from STLV-III seropositive West Africans by Kanki et all The core antigens of the original human immunodeficiency virus type 1 (HIV-1, HTLV-III/LAV) and HTLV-IV share common epitopes and are highly cross-reactive. There is less cross-reactivity at the envelope encoded proteins. Another human retrovirus related to STLV-III is HIV-2 (LAV-2); this has been isolated from West African patients with AIDS.3 Although HTLV-IV and HIV-2 have major proteins of slightly different molecular weights and have different cytopathic effects in vitro they probably belong to a subgroup of West African human T-lymphotropic retroviruses characterised by serological relatedness to STLV-III. The respective roles of HTLV-IV and HIV-2 in the genesis of AIDS-related diseases remain to be evaluated. Since HTLV-IV and HIV-2 seropositive subjects have been found occasionally in Europe’--6 we have compared the performance of five HIV commercial EIAs in detecting antibody to HTLV-IV. We tested the Abbott, Organon, Pasteur (two wells), and Wellcome assays and the Abbott competitive immunoassay that makes use of recombinant DNA HIV proteins as antigen and tests for antibody to core or envelope proteins. The assays were evaluated in November, 1986. 26 sera from healthy West African residents that
positive for antibody to HTLV-IV were tested with sera from seropositive healthy West African residents and 29 HIV seropositive healthy French individuals. Western blot analysis was
were
22 HIV
done with both HTLV-111 virions and HTLV-IV, 289 virions.!,2 Serotype specificity was determined according to differential reactivity to envelope glycoproteins of both viruses. Sera that reacted to gp41 of HTLV-IIIB were defined as HIV antibody
positive. Sera that were reactive to gp32 (the putative transmembrane glycoprotein) of HTLV-IV were defined as HTLV-IV antibody positive. In HTLV-IV antibody positive symptom-free individuals the Wellcome HIV EIA was the least sensitive (42% positive) and the Abbott competitive assay was the most sensitive (96 %) (table, figure). In agreement with Biberfeld et al5
we
think that the results with the Wellcome HIV kit
can
be
explained by the nature of this competitive EIA in which the affinity of cross-reacting HTLV-IV antibodies may not be sufficient to compete with the anti-HIV conjugate. HIV-2 positive AIDS patients from West Africa were reported not to have serological cross-reactivity with HIV-1.3.6This may be ascribable to lowantibody titres that are common in AIDS patients. Evaluation of the performance of HIV-1 EIA kits in detecting HTLV-IV/HIV-2 seropositive patients with AIDS-related symptoms is now required. Another finding in this study was that most of the EIAs seemed slightly less sensitive for the detection of HIV antibody positive sera
PERFORMANCE OF FIVE HIV ENZYME IMMUNOASSAYS IN DETECTING ANTIBODY TO HTLV-IV
SIR,-Professor Carroll (Dec- 13, p 1390) criticises our study (Nov 8, p 1051) of the influence of sleep disruption and calorie restriction on biological markers for depression, claiming that we used inadequate measures to ask the wrong question in an inappropriate group of subjects. We asked whether sleep disruption and calorie restriction in normal volunteers influenced the results of the rapid-eye-movement (REM) latency test and dexamethasone suppression test (DST) in a similar manner to that reported in depressive disorders. The group of volunteers were appropriate to this question. The measures we used included the method for the DST, rating scales, and data analysis used by Carroll himself. Carroll quotes Kupfer’s review1 in support of his statement that "REM latency alone is not an adequate objective index of sleep in depression". Kupfer actually states that, though. there are a constellation of sleep changes in depression, the reduced REM latency is the most prominent and has "considerable replicability" and that "in almost all depressed states REM latency is shortened".1 It was for reasons such as these that we examined this variable. We did not attempt to reproduce "the many complex sleep disturbances that may be seen in depression", as Professor Mendlewicz challenges (Jan 10, p 105); we merely demonstrated that the changes in REM latency commonly claimed as a diagnostic marker could be reproduced in normal volunteers by mimicking one aspect of the sleep disorder so common in depression. We agree with Carroll and with Dr Schweitzer (Jan 10, p 105) that, on current evidence, it is not possible to conclude that weight loss accounts for all the abnormal DST findings in depressed patients. This does not, however, vitiate our contention that unless mild-to-moderate weight loss can be confidently excluded in the previous six months, the DST results become an unreliable diagnostic marker for depression. Carroll suggests that we are nihilists promoting clinical folklore in preference to the brave new laboratory technologies. We are merely sceptical-about our own research and that of others. We have the greatest respect for Professor Carroll and his contributions to biological psychiatry, but we have the temerity to approach even his work in this spirit of scepticism. Department of Psychological Medicine, University of Otago, Dunedin, New Zealand 1.
PAUL E. MULLEN CHRISTOPHER R. LINSELL
Kupfer DJ. Neurophysiological "markers"—EEG sleep measures. J Psychiat Res 1984; 18: 467-75.
condom failure when one partner is HIV infected are serious enough and the likelihood of failure sufficiently high that condom use by risk groups should not be described as "safe sex". Encouraging non-penetrative sexual activities that do not afford HIV an entry to the bloodstream is more difficult than simply recommending the use of condoms. However, the seriousness of the AIDS crisis is such that sexually active AIDS risk group members should be urged to refrain from penetrative sexual activities, especially anal intercourse, with or without condoms. Division
of Psychology, Department of Psychiatry and Human Behavior, University of Mississippi Medical Center, Jackson, Mississippi 39216, USA
JEFFREY A. KELLY JANET S. ST LAWRENCE
1. Stone KM, Grimes
DA, Madger LS. Primary prevention of sexually transmitted diseases: a primer for clinicians. JAMA 1986; 255: 1763-66. 2. Katchadourian HA, Lunde DT. Fundamentals of human sexuality. New York: Holt, Rinehart, and Winston, 1972. J, Bloom D, Pebley A. Correcting contraception failure rates for sample composition and sample selection bias. Soc Biol 1981; 28: 293-98. 4. Andersen RE, Levy JA. Prevalence of antibodies to AIDS-associated retrovirus in single men in San Francisco. Lancet 1985; i: 217. 5. Jaffe HW, Darrow WW, et al. The acquired immune deficiency syndrome in a cohort of homosexual men. Ann Intern Med 1985; 103; 210-14. 3. Trussell
ANTI-HIV TESTING ON URGENT SPECIMENS
SIR,--0ur laboratory provides a district HIV (human immunodeficiency virus) antibody testing service which is predominantly, but not exclusively, concerned with the urgent testing of tissue and organ donors. Commercial anti-HIV immuneassay kits are designed for batch testing and are not ideal for the rapid testing of small numbers of samples. One problem with the ’Wellcozyme’assay (Wellcome Diagnostics) relates to the clotting of blood specimens. When asked to do a rapid anti-HIV test we try to report the result within 120 min of the blood sample being taken. Unfortunately, sera aspirated from freshly clotted blood and subsequently shown to be anti-HIV negative often give false positive or equivocal results in the Wellcome Diagnostics assay. The manufacturers state that "Care should be taken to ensure that serum samples are fully clotted", and they say that plasma may be tested. We have compared results with the Wellcome assay on fresh plasma and serum.
CAUTIONS ABOUT CONDOMS IN PREVENTION OF AIDS
SIR,-In programmes aimed
at
preventing
transmission of
human immunodeficiency virus (HIV) condom use has been emphasised by clinicians, public health agencies, and health organisations in the gay community as a "safe sex" method. Laboratory studies indicate the HIV does not permeate the membrane of intact, high-quality condoms.1 However, condoms have a substantial failure rate. 13-15% of women whose male partners use condoms as the sole method of contraception become pregnant within one year,2,3 and condoms are generally regarded as unreliable. Presumably, condoms fail because of tears or slippage or because they have not been used properly. Failure rates may be even higher during sexual activities between male homosexuals. The prevalence of HIV infection among sexually active homosexual males is 20-50% in many American cities4,s and the likelihood that a homosexual individual’s partner will be HIV infected is substantial. Given the failure rate of condoms in family planning, homosexuals who practise anal intercourse will still be at risk of HIV exposure even if they use condoms. The use of condoms during anal intercourse between homosexual men or vaginal intercourse between heterosexual partners if one of them is in an AIDS risk group may reduce the probability of HIV transmission, but only if the sheath remains intact. The possible consequences of
Duplicate samples of both untreated and lithium heparinised blood from an anti-HIV-negative volunteer were kept at 20°C or 37°C for varying times after venepuncture. The specimens were then centrifuged; the serum and plasma were recovered and tested. Serum aspirated from blood kept at 20°C for 20 min after venepuncture gave a false-positive result, and a similar sample at 30 min was still equivocal (table I). Clotting at 37°C seemed more efficient but gave false-positive results at least up to 10 min after venepuncture. Plasma samples were negative throughout. TABLE I-WELLCOZYME ANTI-HIV IMMUNOASSAY: OPTICAL DENSITY AT
I
I
450
run
I
I
Optical density values less than the cut-off of 0 724 should be regarded as positive. Values within 10% (0 652-0 796) of the cut-off are equivocal.
324 TABLE II-PARALLEL TITRATION OF SERUM AND PLASMA
SAMPLES
FROM AN ANTI-HIV-POSITIVE INDIVIDUAL TESTED BY WELLCOZYME ANTI-HIV IMMUNOASSAY
values less than cut-off of 0.577 should be within 10% (0 519-0 635) of cut-off are equivocal.
Optical density
regarded
as
positive. Values
Table l shows the results of parallel titration of serum and plasma samples from an anti-HIV-positive individual which were kept at 4°C overnight and then diluted in anti-HIV-negative serum and plasma. The specimens demonstrated antibody to an equivalent titre. We recommend that heparinised plasma be requested for urgent testing in the wellcozyme anti-HIV immunoassay and that the possibility of false reactivity of fresh blood samples be investigated in other commercial anti-HIV assays. This may prevent the unnecessary waste of an organ or blood donation. C. J. RONALDS P. C. A. GRINT A. E. HARDIMAN
Department of Virology, St Bartholomew’s Hospital, London ECIA 7BE
Optical density cut-off
EFFICACY OF FIVE ENZYME IMMUNOASSAYS FOR ANTIBODY TO HIV IN DETECTING ANTIBODY TO
Distribution patterns of responses in four HIV EIAs for samples positive for anti-HIV and samples positive for anti-HTLV-IV. For Wellcome assay cut-off/optical density values
see
Reesink et al .7
HTLV-IV
SlR,—A year ago we reported serological evidence for a virus related to simian T-lymphotropic retrovirus type III (STLV-III) in residents of West Mrica.1 Another new retrovirus (HTLV-IV) has also been isolated from STLV-III seropositive West Africans by Kanki et all The core antigens of the original human immunodeficiency virus type 1 (HIV-1, HTLV-III/LAV) and HTLV-IV share common epitopes and are highly cross-reactive. There is less cross-reactivity at the envelope encoded proteins. Another human retrovirus related to STLV-III is HIV-2 (LAV-2); this has been isolated from West African patients with AIDS.3 Although HTLV-IV and HIV-2 have major proteins of slightly different molecular weights and have different cytopathic effects in vitro they probably belong to a subgroup of West African human T-lymphotropic retroviruses characterised by serological relatedness to STLV-III. The respective roles of HTLV-IV and HIV-2 in the genesis of AIDS-related diseases remain to be evaluated. Since HTLV-IV and HIV-2 seropositive subjects have been found occasionally in Europe’--6 we have compared the performance of five HIV commercial EIAs in detecting antibody to HTLV-IV. We tested the Abbott, Organon, Pasteur (two wells), and Wellcome assays and the Abbott competitive immunoassay that makes use of recombinant DNA HIV proteins as antigen and tests for antibody to core or envelope proteins. The assays were evaluated in November, 1986. 26 sera from healthy West African residents that
positive for antibody to HTLV-IV were tested with sera from seropositive healthy West African residents and 29 HIV seropositive healthy French individuals. Western blot analysis was
were
22 HIV
done with both HTLV-111 virions and HTLV-IV, 289 virions.!,2 Serotype specificity was determined according to differential reactivity to envelope glycoproteins of both viruses. Sera that reacted to gp41 of HTLV-IIIB were defined as HIV antibody
positive. Sera that were reactive to gp32 (the putative transmembrane glycoprotein) of HTLV-IV were defined as HTLV-IV antibody positive. In HTLV-IV antibody positive symptom-free individuals the Wellcome HIV EIA was the least sensitive (42% positive) and the Abbott competitive assay was the most sensitive (96 %) (table, figure). In agreement with Biberfeld et al5
we
think that the results with the Wellcome HIV kit
can
be
explained by the nature of this competitive EIA in which the affinity of cross-reacting HTLV-IV antibodies may not be sufficient to compete with the anti-HIV conjugate. HIV-2 positive AIDS patients from West Africa were reported not to have serological cross-reactivity with HIV-1.3.6This may be ascribable to lowantibody titres that are common in AIDS patients. Evaluation of the performance of HIV-1 EIA kits in detecting HTLV-IV/HIV-2 seropositive patients with AIDS-related symptoms is now required. Another finding in this study was that most of the EIAs seemed slightly less sensitive for the detection of HIV antibody positive sera
PERFORMANCE OF FIVE HIV ENZYME IMMUNOASSAYS IN DETECTING ANTIBODY TO HTLV-IV