Long-term protection against SIV-induced disease in macaques vaccinated with a live attenuated HIV-2 vaccine.

The aim of this study was to test the ability of a live attenuated human immunodeficiency virus type 2 (HIV-2) vaccine to protect cynomolgus monkeys against superinfection with a pathogenic simian immunodeficiency virus (SIVsm). This report is an update on our previously reported observation period of nine months. The new data here show that three of four monkeys vaccinated with live HIV-2 were protected against immunosuppression and SIV-induced disease during more than five years of follow-up. The quality of the immunity was permissive for infection, but monkeys that survived showed restricted viral replication in peripheral blood and lymph nodes. This study shows that it is possible to induce protection against a pathogenic heterologous primate lentivirus and to prevent disease in vaccinated monkeys even if infection is not prevented. These findings provide evidence that protection against AIDS can be achieved by immunization.

A monkey model for Epstein Barr virus-associated lymphomagenesis in human acquired immunodeficiency syndrome.

High-grade malignant nonHodgkin's lymphomas--five lymphoblastic, three pleomorphic, and two immunoblastic--developed in 10/25 cynomolgus monkeys (Macaca fascicularis) followed for up to 746 d after infection with simian immunodeficiency virus, strain SIVsm. These lymphomas were shown to be associated with an Epstein-Barr (EB)-like cynomolgus B-lymphotropic herpesvirus (CBLV) by electron microscopy, by Southern blot hybridization with probes against human EBV, and by the expression of antigens corresponding to EBV-associated nuclear antigens (EBNAs) involved in human B cells transformation. Southern blot demonstration of immunoglobulin gene rearrangements and homogeneous EBV episomes indicated that all the lymphomas were CBLV-associated monoclonal B cell proliferations. Our findings suggest that these tumors correspond to the EBV-associated malignant lymphomas in acquired immunodeficiency syndrome with respect to clinical, morphological, phenotypic, and genotypic characteristics. The particular susceptibility of SIVsm immunodeficient cynomolgus monkeys for CBLV-associated lymphomagenesis appears therefore a useful model for EBV-associated lymphomas in humans.

Enhancing adherence to antiretroviral therapy at the HIV clinic in resource constrained countries; the Tanzanian experience.

OBJECTIVE: To evaluate various strategies aimed at improving adherence to antiretroviral therapy (ART). METHODS: Patients initiated on ART at Muhimbili National Hospital HIV clinic were randomly assigned to either regular adherence counseling, regular counseling plus a calendar, or regular counseling and a treatment assistant. Patients were seen monthly; during these meetings self-reported adherence to treatment was recorded. Disease progression was monitored clinically and immunologically. RESULTS: Of the 621 patients randomized, 312 received regular counseling only, 242 regular counseling and calendars, while 67 had treatment assistants in addition to regular counseling. The mean (SD) follow-up time was 14.5 (4.6) months. During follow-up 20 (3.2%) patients died, and 102 (16.4%) were lost to follow-up; this was similar in all groups. In 94.8% of all visits, patients reported to have adhered to treatment. In only 39 (0.7%) visits did patients report a < or = 95% adherence. There were no differences in adherence (P = 0.573) or differences in CD4 count and weight changes over time in the interventions. CONCLUSIONS: Good adherence to ART is possible in resource constrained countries. Persistent adherence counseling in clinic settings by itself may be effective in improving adherence to ART.

HIVIS-DNA or HIVISopt-DNA priming followed by CMDR vaccinia-based boosts induce both humoral and cellular murine immune responses to HIV.

BACKGROUND: In order to develop a more effective prophylactic HIV-1 vaccine it is important optimize the components, improve Envelope glycoprotein immunogenicity as well as to explore prime-boost immunization schedules. It is also valuable to include several HIV-1 subtype antigens representing the world-wide epidemic. METHODS: HIVIS-DNA plasmids which include Env genes of subtypes A, B and C together with Gag subtypes A and B and RTmut/Rev of subtype B were modified as follows: the Envelope sequences were shortened, codon optimized, provided with an FT4 sequence and an immunodominant region mutated. The reverse transcriptase (RT) gene was shortened to contain the most immunogenic N-terminal fragment and fused with an inactivated viral protease vPR gene. HIVISopt-DNA thus contains fewer plasmids but additional PR epitopes compared to the native HIVIS-DNA. DNA components were delivered intradermally to young Balb/c mice once, using a needle-free Biojector® immediately followed by dermal electroporation. Vaccinia-based MVA-CMDR boosts including Env gene E and Gag-RT genes A were delivered intramuscularly by needle, once or twice. RESULTS: Both HIVIS-DNA and HIVISopt-DNA primed humoral and cell mediated responses well. When boosted with heterologous MVA-CMDR (subtypes A and E) virus inhibitory neutralizing antibodies were obtained to HIV-1 subtypes A, B, C and AE. Both plasmid compositions boosted with MVA-CMDR generated HIV-1 specific cellular responses directed against HIV-1 Env, Gag and Pol, as measured by IFNγ ELISpot. It was shown that DNA priming augmented the vector MVA immunological boosting effects, the HIVISopt-DNA with a trend to improved (Env) neutralization, the HIVIS-DNA with a trend to better (Gag) cell mediated immune reponses. CONCLUSIONS: HIVIS-DNA was modified to obtain HIVISopt-DNA that had fewer plasmids, and additional epitopes. Even with one DNA prime followed by two MVA-CMDR boosts, humoral and cell-mediated immune responses were readily induced by priming with either DNA construct composition. Priming by HIV-DNA augmented neutralizing antibody responses revealed by boosting with the vaccinia-based heterologous sequences. Cellular and antibody responses covered selected strains representing HIV-1 subtypes A, B, C and CRF01_AE. We assume this is related to the inclusion of heterologous full genes in the vaccine schedule.

Immunohistopathology of lymph nodes in HTLV-III infected homosexuals with persistent adenopathy or AIDS.

Lymph node biopsies from 43 male homosexuals with persistent generalized lymphadenopathy and from ten acquired immunodeficiency syndrome patients, all with serum antibodies to human T-cell leukemia virus III, were studied with regard to histopathology, immunohistology, and T-cell subsets in cell suspensions. All acquired immunodeficiency syndrome biopsies except one with Kaposi's sarcoma had the same histopathological pattern of follicular depletion, whereas the persistent generalized lymphadenopathy nodes showed a spectrum of changes characterized as follicular hyperplasia, involution with follicular fragmentation, or involution with follicular atrophy. Immunohistology showed a temporal and structural relation between follicular involution, disappearance of follicular dendritic reticulum cells, and follicular invasion by T-cells. These observations suggest elimination of dendritic reticulum cells as part of a pathogenic mechanism in follicular involution. Angiogenesis measured by staining of endothelial cells with antibodies to Factor VIII was increased in many biopsies in stages of involution and depletion. Our observations indicate the occurrence of marked changes not only in T-cells but also in the B-cell compartment of patients with persistent generalized lymphadenopathy or acquired immunodeficiency syndrome. The possibility of staging lymph nodes of these patients by combined histopathology and immunohistology is indicated. This might improve the evaluation of prognosis in these patients. A possible importance of angiogenesis for the tumorigenesis of Kaposi's sarcoma is suggested.

HTLV-III infection in homosexuals and hemophiliacs in Sweden.

Two hundred and three homosexual (HS) men and 114 hemophiliacs in Sweden were examined for serum antibodies to human T-lymphotropic virus type III (HTLV-III) and for alterations of T-lymphocyte subsets. Sera were screened for HTLV-III antibodies by an enzyme-linked immunosorbent assay and/or a dot immunobinding assay, and positive reactions were confirmed by Western blotting. HTLV-III antibodies were demonstrated in 13 of 13 (100%) HS men with acquired immune deficiency syndrome, in 63 of 67 (94%) HS men with persistent generalized lymphadenopathy, in 17 of 45 (38%) symptomatic HS men, and in 6 of 78 (8%) asymptomatic HS men but in none of 108 male blood donors. Seropositive HS men had significantly lower T4/T8 (helper/suppressor) cell ratios and T4 cell numbers than had seronegative HS men. Seronegative HS men had decreased T-cell ratios compared to controls but not decreased T4 cell numbers. Among hemophilia A patients, HTLV III antibodies were demonstrated in 40 of 48 (83%) cases treated with American factor VIII concentrate and in 17 of 29 (59%) cases treated with both American and Swedish concentrates but in none of 13 cases treated exclusively with Swedish factor VIII. Twenty-one hemophilia B patients treated with Swedish factor IX concentrates were all seronegative, whereas one of 3 hemophilia B cases treated with imported factor IX was seropositive. T4/T8 cell ratios were significantly lower in seropositive as compared to seronegative hemophilia A patients.

Is there a difference in the efficacy of peripartum antiretroviral regimens in reducing mother-to-child transmission of HIV in Africa?

BACKGROUND: Peripartum antiretroviral regimens have been shown to prevent mother-to-child transmission of HIV (MTCT) in randomized clinical trials; however, direct comparison of published results is impossible given methodological and population differences. OBJECTIVE: To directly compare the efficacy of different antiretroviral regimens in reducing the risk of 6-week MTCT rate in African breastfeeding populations. METHODS: Pooled analysis including all mother-infant pairs from any relevant trial: West African ZDV-placebo trials, Petra ZDV+3TC [two regimens A (pre/intra/post-partum) and B (intra/post-partum), placebo from Uganda and Tanzania], SAINT (NVP and Petra arm B), HIVNET012 (NVP, ultra short ZDV pp) and the Vitamin A trial (as placebo arm in South Africa). Peripartum HIV infection was any positive RNA or DNA polymerase chain reaction test < day 60. The MTCT risk was estimated at 6 weeks for each treatment arm and compared with placebo or single-dose NVP using logistic regression adjusting for maternal CD4 cell count, breastfeeding and birthweight. RESULTS: Overall, 4125 singleton live-births were included; 3629 (88%) were assessed for HIV status at 6 weeks of age. In comparison with placebo, zidovudine + lamivudine (ZDV+3TC) arm A [adjusted odds ratio (AOR), 0.23; P < 0.0001], ZDV+3TC arm B (AOR, 0.49; P < 0.001), antenatal ZDV short (AOR, 0.55; P = 0.006) and nevirapine (NVP) (AOR, 0.60; P = 0.0007) significantly reduced MTCT. In comparison with NVP, only the longest regimen of ZDV+3TC (AOR, 0.39, P < 0.0005) was significantly more effective. CONCLUSION: These results are in line with current World Health Organisation guidelines suggesting equivalence of choice between single-dose NVP and short-course ZDV, and confirm the greater efficacy of ZDV+3TC than with any single antiretroviral drug.

Plasma viral load in HIV-1 and HIV-2 singly and dually infected individuals in Guinea-Bissau, West Africa: significantly lower plasma virus set point in HIV-2 infection than in HIV-1 infection.

BACKGROUND: The intriguing differences in the natural course, transmissibility, and epidemiological characteristics of human immunodeficiency virus type 1 (HIV-1) and HIV-2 are still insufficiently explained. Differences in plasma viral load are an obvious possibility, but this has been difficult to investigate because of the lack of tests for HIV-2 RNA. OBJECTIVE: To compare plasma HIV RNA load between individuals infected with HIV-1 and HIV-2 in Guinea-Bissau, a West African country with high prevalence and incidence of HIV-1 and HIV-2 infection. METHODS: A total of 102 participants were recruited from ongoing prospective cohort studies. These included 19 HIV-1 and 29 HIV-2 seroincident cases tested at a median of less than 2 years after seroconversion as well as seroprevalent cases with single (9 HIV-1 cases and 31 HIV-2 cases) or dual (n = 14) infections. Plasma HIV RNA levels were determined by a commercial HIV-1 assay and an experimental HIV-2 assay based on the same principles. RESULTS: The viral set point, ie, the semi-equilibrium reached after seronconversion, was 28-fold lower in recent HIV-2 seroconverters than in recent HIV-1 seroconverters (median, 2500 and 70,000 RNA copies per milliliter, respectively; P<. 001). This difference appeared to persist to symptomatic stages of the diseases. Dually infected individuals had lower plasma HIV-1 RNA levels than singly infected individuals. CONCLUSIONS: The differences between HIV-1 and HIV-2 infection are likely to be caused by differences in plasma viral set point and load, but the mechanisms through which HIV-2 infection is contained to a higher degree than HIV-1 remain to be identified. Arch Intern Med. 2000;160:3286-3293.

Evaluation of commercial enzyme immunoassays for anti-HIV-1 using East African sera.

Sera from 622 blood donors collected in 1986 and 1987 in Tanzania were screened for antibodies to HIV-1 by seven different commercial enzyme-linked immunosorbent assay (ELISA) kits. All ELISA-positive sera were tested by Western blot analysis and many of them also by radioimmunoprecipitation assay (RIPA). Sixty-seven sera were confirmed positive. Eight sera, which were repeatedly positive on only one or two of the ELISA kits and showed weak, doubtful reactions on Western blot and RIPA, were considered indeterminate and were not included in the calculations of sensitivity and specificity of the various ELISA kits. The sensitivity of the ELISAs was as follows: Organon Vironostika: low cut-off 74.6%; Organon Vironostika: high cut-off 62.7%; Du Pont: 85.1%; Pasteur: 78.7%; Abbott: 80.8%; Abbott recombinant: 94.0%; Wellcozyme: 82.1%; Wellcozyme monoclonal: 98.5%. The specificity was as follows: Organon Vironostika: low and high cut-off 100%; Du Pont: 94.7%; Pasteur: 99.3%; Abbott: 100%; Abbott recombinant 98.7%; Wellcozyme: 99.8%; Wellcozyme monoclonal: 98.5%. In conclusion, the two new generation kits tested, Wellcozyme monoclonal and Abbott recombinant, had the highest sensitivity whereas the sensitivity of the first-generation tests was unexpectedly low.

Enzyme immunoassays for the demonstration of antibodies to HIV-2SBL-6669 and HTLV-IV (SIVmac).

Enzyme-linked immunosorbent assays (ELISA) were developed for the demonstration of antibodies to HIV-2 using disrupted virions of the SBL-6669 isolate of HIV-2 and the so-called human T-lymphotropic virus type IV (HTLV-IV), recently found to be identical with the simian immunodeficiency virus (SIVmac), as antigens. Three hundred sera from West African subjects, attending an outward clinic in Bissau for examination of suspected tuberculosis, were tested by these two assays as well as by a commercially available anti-HIV-2 ELISA (ELAVIA II). Fifty of these sera were positive in all three ELISAs as well as in Western blot tests against HTLV-IV. Thirty-eight of these positive sera were also tested by an anti-HIV-2 Western blot kit (LAV-Blot II) with positive results. The ELISAs based on SBL-6669 and HTLV-IV antigens had a specificity of 99.6% (one false positive among 250 negative sera) whereas the specificity of ELAVIA II was 94.6% using the recommended cut-off value and 98.4% using a higher cut-off value. Another 58 sera from West African patients, clinically suspected of having AIDS or HIV-related disease, were tested for HIV-2/HTLV-IV antibodies by Western blot and by ELISA against SBL-6669 and HTLV-IV antigens; all of the 30 sera which were positive by Western blot were found to be positive in both ELISAs.(ABSTRACT TRUNCATED AT 250 WORDS)

Field evaluation of alternative testing strategies for diagnosis and differentiation of HIV-1 and HIV-2 infections in an HIV-1 and HIV-2-prevalent area.

OBJECTIVE: To identify cost-efficient alternative antibody testing strategies for screening, confirmation and discrimination of HIV-1 and HIV-2 infections, including rapid simple tests (RST) as well as enzyme-linked immunosorbent assays (ELISA), in a HIV-1 and HIV-2-prevalent area. DESIGN: Evaluation and comparison of anti-HIV-1/2 assays, adhering to the World Health Organization recommendations for alternative confirmatory strategies, using banked and prospectively collected specimens in Guinea-Bissau. METHODS: A total of 1110 consecutive sera from Bissau were included in the first phase, of which 198 (17.8%) were HIV-seropositive: 52 (4.7%) HIV-1, 120 (10.8%) HIV-2, and 26 (2.3%) HIV-1/HIV-2 dually reactive. In addition, 95 selected HIV-positive specimens were included for study of sensitivity and cross-reactivity between HIV-1 and HIV-2. Western blot was used as a gold standard for confirming the reactivity of the specimens. All specimens were screened by two assays. Enzygnost ELISA and Capillus RST. Samples reactive by any of the screening assays were further tested by assays chosen for confirmation: UBI ELISA, Innotest ELISA Recombigen RST, Multispot RST and Immunocomb RST. The confirmatory RST as well as Wellcozyme Recombinant HIV-1 ELISA, PEPTI-LAV and INNO-LIA were also used to study differentiation between HIV-1 and HIV-2. RESULTS: The sensitivities of all assays were 100%. The specificities of the screening assays at initial and repeated testing were 98.0 and 99.7%, respectively, for Enzygnost and 99.8 and 99.9%, respectively, for Capillus. The various combinations of two or three assays showed specificities of 99.2-100%. Several possible combinations of assays were identified where a specificity of 100% and good differentiation between HIV-1 and HIV-2 was achieved. Significant differences in the capacity to discriminate were noted; Immunocomb and PEPTI-LAV had the lowest number of dual-reactive results. A follow-up study of 1501 consecutive samples tested with the strategy chosen for routine use showed a sensitivity and specificity comparable to ELISA and Western blot. CONCLUSION: High sensitivities and specificities were obtained with various combinations of assays including RST as well as ELISA, and these procedures are well suited for field use in Africa. Serodiagnostic strategies for HIV can be based on RST alone and differentiation between HIV-1 and HIV-2 can be achieved as part of these strategies. Large differences in the capacity of individual assays to discriminate between HIV-1 and HIV-2 were observed.

PIP: Western blot (WB) is the most widely used serological confirmatory test of ELISA and rapid simple tests (RST) to detect infection with HIV. WB tests, however, are expensive, time-consuming, and have technical disadvantages. The authors therefore conducted a study to identify cost-efficient alternative strategies for HIV-antibody screening, confirmation, and discrimination of HIV-1 and HIV-2 infections in a HIV-1 and HIV-2 prevalent area. 1110 consecutively collected blood sera from Guinea-Bissau were included in the first phase of the study, of which 198 (17.8%) were known to be HIV-seropositive; 52 with HIV-1, 120 with HIV-2, and 26 being HIV-1/HIV-2 dually reactive. 95 selected HIV-positive specimens were included for study of sensitivity and cross-reactivity between HIV-1 and HIV-2, with WB used to confirm specimen reactivity. All specimens were screened by Enzygnost ELISA and Capillus RST, with reactive samples further tested by the following assays for confirmation: UBI ELISA, Innotest ELISA, Recombigen RST, Multispot RST, and Immunocomb RST. The confirmatory RST, Wellcozyme Recombinant HIV-1 ELISA, PEPTI-LAV, and INNO-LIA were also used to study differentiation between HIV-1 and HIV-2. All assays were 100% sensitive. The specificities of the screening assays at initial and repeated testing were 98.0% and 99.7%, respectively, for Enzygnost and 99.8% and 99.9%, respectively, for Capillus. Various combinations of 2-3 assays yielded specificities of 99.2-100%. Screening with Enzygnost ELISA and confirmation and differentiation between HIV-1 and HIV-2 with Capillus RST and Multispot RST was adopted for routine use at Guinea-Bissau's National Public Health Laboratory. A field trial of the approach conducted in 1996 involving 1501 sera found a sensitivity and specificity comparable to ELISA and WB.

A prospective study of vertical transmission of HIV-2 in Bissau, Guinea-Bissau.

OBJECTIVES: To determine the vertical transmission rate of HIV-2 and clinical findings associated with vertically transmitted HIV-2 infection. DESIGN: A prospective study of HIV-2 transmission in children of HIV-2-seropositive mothers, and a comparison of clinical findings between children of seropositive and seronegative mothers. SETTING: Recruitment of women delivering at the national hospital in Bissau, Guinea-Bissau. Follow-up by home visits. SUBJECTS AND METHODS: Eighty-six newborns of 82 HIV-2-seropositive mothers and a control group of 102 newborns of HIV-seronegative mothers were followed-up clinically and by HIV serology until the children reached the age of 20 months. RESULTS: Of the 86 children of seropositive mothers, 51 had a complete follow-up, 22 died and 13 were lost due to change of residence. Of the 102 children of seronegative mothers, 63 had a complete follow-up, 13 died and 26 were lost due to change of residence. None of 51 children of seropositive mothers had serological evidence of HIV-2 infection at the end of the follow-up period. There was no significant difference in the frequency of clinical symptoms between the children in the study group and the children in the control group. The mortality during the first year of life was not significantly different between the children of seropositive and seronegative mothers (13 out of 80 and 11 out of 94, respectively, P > 0.05, excluding children lost to follow-up). Only three of the dead children of seropositive mothers and one of the dead children of seronegative mothers had any symptoms that might be related to HIV-2 infection (diarrhoea > 1 month). CONCLUSION: Vertical transmission of HIV-2 appears to be rare.

PIP: Between May 1987 and December 1988 in Guinea-Bissau, health workers followed 86 HIV-2 seropositive mothers and their infants delivered at the National Hospital Simao-Mendes in Bissau for 20 months to learn the HIV-2 vertical transmission rate and to compare their clinical findings with those of 102 infants of HIV-2 seronegative women. The ELISA and Western Blot analysis used antigen-purified virions of the SBL-6669 strain of HIV-2 grown on U937:2 cells. During the enrollment period, hospital workers tested 3246 women; tests confirmed that 211 (6.5%) and 3 (0.1%) were HIV-2 seropositive, respectively. 1 HIV-2 seronegative mother seroconverted during the study, but none of the infants of HIV-2 seronegative mothers seroconverted. Infant mortality of cases did not differ significantly from that of controls (16.2% vs. 11.7%). After 1 year of age, however, children of HIV-2 seropositive mothers were significantly more likely to die than the controls (15% vs. 3%; p .05). When the researchers added the children lost to follow up, there no longer was a significant difference in mortality after 1 year (23.9% vs. 24.1%). Just 3 of the deceased infants of the HIV-2 seropositive mothers and 1 of the deceased infants of seronegative mothers suffered from symptoms from symptoms that may have been related to HIV-2 infection. 1 of these deceased infants was HIV-2 seropositive at 12 months. These symptoms included prolonged fever, vomiting, diarrhea, and respiratory symptoms. Children in the study group did not experience more frequent clinical symptoms of HIV-2 infection than did the controls during the 3rd and 4th home visits. At the last visit (i.e., 4th visit; when the children were older than 17 months), none of the children of the HIV-2 seropositive mothers tested positive for HIV- 2. Vertical transmission of HIV-2 infection may be rare.

Prevalence of HIV-1 infection in the Kagera region of Tanzania: a population-based study.

A population-based survey was carried out in the Kagera region of the United Republic of Tanzania in 1987 to determine the magnitude of HIV-1 infection and to study associated risk factors. The region was divided into one urban and three rural zones. A multistage cluster sampling technique was adopted. Antibodies to HIV-1 were determined by enzyme-linked immunosorbent assay and confirmed by Western blot analysis. A total of 2,475 adults (aged 15-54 years) and 1,961 children (aged 0-14 years) was studied. The overall prevalence of HIV-1 infection among adults was 9.6%, with a higher prevalence in the urban zone (24.2%) than in the three rural zones (10.0, 4.5 and 0.4%, respectively). The corresponding figures for children were 1.3% overall: 3.9% in the urban area and for the rural areas 1.2, 0.8 and 0.0%, respectively. The age-specific seroprevalence for adults was highest in the age group 25-34 years. The age-standardized sex-specific prevalence was higher among women than men in the urban zone, while it was the same in the rural zones. Change of sexual partners among adults was associated with an increased risk of HIV-1 seropositivity. Travelling outside the region but within the country was also found to be associated with increased risk of HIV-1 infection but only in the rural population.

HIV-2 infection in hospitalized patients in Bissau, Guinea-Bissau.

During 11 months in 1989-1990, 1009 consecutive hospitalized adult patients admitted to the medical wards of the National Hospital in Bissau were interviewed, examined clinically, and tested for antibodies to HIV-1 and HIV-2. The prevalence of HIV-2 infection was 20.4% (206 out of 1009) and of HIV-2-associated AIDS 4.4% (44 out of 1009). HIV-2 infection was more frequent in women (25%, 110 out of 440) than in men (16.9%, 96 out of 569). HIV-1 infection was diagnosed in one patient only, and one patient (with AIDS) had reactivity to both HIV-1 and HIV-2. Among HIV-2-seropositive patients, AIDS was demonstrated in 21.3% and AIDS-related symptoms (not fulfilling the AIDS criteria) in 19.4%. The frequency of AIDS-associated symptoms was significantly higher in HIV-2-seropositive patients than in seronegative patients. The clinical profile of the HIV-2-associated AIDS cases was very similar to that described in HIV-1-associated AIDS cases in Africa. Seven out of 51 patients fulfilling the clinical criteria for AIDS were HIV-seronegative. The World Health Organization (WHO) clinical case definition for AIDS in Africa had a specificity of 99% and a positive predictive value of 86%. Tuberculosis was more common in HIV-2-seropositive patients (6.3%) than in HIV-2-seronegative patients (2.2%). A history of blood transfusion was a significant risk factor for HIV-2 infection. HIV-2 infection and AIDS are public health problems in Guinea-Bissau.

Clinical features and predictive markers of disease progression in cynomolgus monkeys experimentally infected with simian immunodeficiency virus.

OBJECTIVE: To study the pathogenicity of simian immunodeficiency virus (SIVsm) in cynomolgus monkeys in order to establish an animal model for human AIDS. METHODS: Thirty-three cynomolgus monkeys were monitored for more than 2 years following experimental infection with SIVsm. RESULTS: All the macaques became SIV-infected, as demonstrated by virus recovery from peripheral blood lymphocytes and by the appearance of viral antibodies. SIVsm was found to be pathogenic, killing 29 out of the 33 monkeys (88%) within 26 months. Clinically, infected monkeys developed lymphadenopathy, splenomegaly, diarrhoea, weight loss, neurological symptoms and a remarkably high incidence (39%) of malignant lymphomas. All lymphomas were high-grade malignant and of B-cell origin. Disease progression was associated with low CD4+ lymphocyte count, involution of initially hyperplastic follicular B-cell areas in lymph nodes, reappearance of viral antigen in serum, loss of anti-Gag antibodies and development of systemic giant cell disease in 55% of the monkeys. CONCLUSIONS: There are many similarities between SIVsm-induced AIDS in cynomolgus monkeys and human AIDS with regard to clinical, virological, immunological and pathological manifestations.

Infection of cynomolgus monkeys with HIV-2 protects against pathogenic consequences of a subsequent simian immunodeficiency virus infection.

Simian immunodeficiency virus (SIV) infection in cynomolgus macaques leads to severe immunodeficiency with a fatal outcome. In contrast, HIV-2 infects these primates without apparently causing any immunological abnormalities. In this study three cynomolgus monkeys were experimentally infected with HIV-2 strain SBL-K135 and 168 days later challenged with 10-100 animal infectious doses of the closely related SIV strain SM to study protective immunity. At the time of SIV challenge the HIV-2-infected monkeys had neutralizing antibodies against HIV-2, but virus could no longer be recovered from their peripheral blood mononuclear cells (PBMCs) and no clinical symptoms or decrease in CD4+ lymphocytes were observed. Follow-up for 9 months after challenge with SIV showed that the HIV-2-infected monkeys were protected against SIV-induced immunodeficiency (no decrease of CD4+ lymphocytes) and lymphadenopathy. However, they were not resistant to SIV infection since virus could be recovered from their PBMCs and they developed anamnestic antibody responses. Four naive control monkeys which were inoculated with the same dose of SIV became persistently infected and developed a decrease of the absolute numbers of CD4+ cells and showed a marked lymphadenopathy. Two out of four control animals died 58-265 days postinfection with an immunosuppressive disease. Immunohistochemical examination showed abundant viral antigen in lymph-node biopsies from the SIV-infected control monkeys but absence of SIV or HIV-2 antigens in the biopsies from the three HIV-2-preinfected and SIV-superinfected monkeys. The present study demonstrates possibilities for induction of immunity against immunodeficiency induced by a primate lentivirus, a concept with application also to HIV infection and AIDS in man.

Site-directed enzyme-linked immunosorbent assay with a synthetic simian immunodeficiency virus SIVmac peptide identifying antibodies against the HIV-2 transmembrane glycoprotein.

A 23-amino-acid-long peptide (AIEKYLEDQAQLNAWGCAFRQVC) representing the transmembranous protein gp32 in SIVmac was used in site-directed enzyme-linked immunosorbent assay (ELISA) for detection of HIV-2-specific antibodies in 567 sera from Bissau, Guinea Bissau. Ninety out of the 567 sera were identified to contain HIV-2 antibodies by whole antigen ELISA and Western blot assays. The peptide ELISA correctly identified 89 out of these 90 seropositives (sensitivity 98.9%). Three sera falsely interpreted to be positive were encountered (specificity 99.4%). The HIV-2 peptide was also used for testing of 93 HIV-1-positive Swedish sera. None of these sera reacted. Site-directed serology employing synthetic peptides should be considered for application as a screening assay.

PIP: HIV-1 is predominant in Central and East Africa, while HIV-2 is predominant in West Africa. The HIV-2 virus, originally described as human T-lymphotropic virus type IV, is identical to the simian immunodeficiency virus SIV-mac. Whole-antigen enzyme-linked immunosorbent assay (ELISA) can detect heterotypic antigens in 80% of sera, but separate tests are required for detecting HIV-1 and HIV-2. Site-directed ELISA using amino acids 586-620 of the synthetic transmembranous protein gp41 as antigen has been used for type-specific antibody determination in HIV-1. The homologous site on the 23-amino-acid-long peptide AIEKYLEDQAQLNAWGCAFRQVC representing the transmembranous protein gp32 in the simian immunodeficiency virus SIV-mac is WGCAFR, which can be used in site-directed serology of HIV-2. This approach was tested on sera from 567 Africans in Guinea-Bissau and 49 suspected AIDS patients. None of these sera had HIV-1 antibodies. 93 HIV-1-positive sera from Sweden were used as controls. The HIV-2 peptide ELISA correctly identified 89 of the 90 HIV-2 seropositives out of the sample of 567. The peptide ELISA also correctly identified all of the 93 HIV-1-positive sera as HIV-2-negative. Use of HIV-2-specific ELISA in combination with an HIV-1-specific ELISA can efficiently screen blood for both types of HIV.

Replicative capacity of HIV-2, like HIV-1, correlates with severity of immunodeficiency.

We have obtained 15 HIV-2 isolates from the peripheral blood mononuclear cells (PBMCs) of 24 HIV-2-infected west African people. The frequency of virus isolation correlated with the severity of HIV-2 infection; only three isolates were obtained from 11 asymptomatic individuals, whereas virus was isolated from nearly all (12 of 13) individuals with symptoms. The HIV-2 isolates showed distinct replicative and cytopathic characteristics and, similarly to HIV-1 isolates, could be divided into two major groups: rapid/high and slow/low. Rapid/high isolates, i.e. isolates with the ability to replicate in tumour cell lines, were obtained from individuals with symptomatic HIV-2 infection and CD4+ lymphocyte counts less than 360/microliters blood; these isolates induced syncytia in PBMC cultures. HIV-2 isolates unable to replicate continuously in tumour cell lines (slow/low isolates) induced small syncytia, cell death, or no cytopathic effect at all. All HIV-2 isolates obtained from asymptomatic individuals showed a slow/low replication pattern.

Selection of primers of optimal sensitivity for the detection of HIV-1 from Africa and Europe by polymerase chain reaction.

In order to facilitate the detection of integrated HIV-1 proviral DNA from African as well as European patients, four new primer pairs for use in the polymerase chain reaction (PCR), localised in the gag, pol, vif and env genes of HIV-1, were constructed. The primer pairs were compared to all accessible HIV-1 sequences from African and European isolates and to some of the earlier published and most commonly used primer pairs. HIV-1 DNA was detected in blood drawn from 13 out of 13 individuals infected in Africa, in three out of three Tanzanian HIV-1 isolates and in three out of three asymptomatic Swedes infected in Europe. The new selection of primer pairs can be used as an alternative to enhance the detection of HIV-1 of different origins.

PIP: In order to facilitate the detection of integrated HIV-1 proviral DNA from African as well as European patients, 4 new primer pairs for use in the polymerase chain reaction (PCR), localized in the gag, pool, vif, and env genes of HIV-1, were constructed. The primer pairs were compared to all accessible HIV-1 sequences from African and European isolates and to some of the earlier published and most commonly used primer pairs. HIV-1 DNA was detected in blood drawn from 13 infected individuals in Africa, in 3 Tanzanian HIV-1 isolates, and in the 3 asymptomatic Swedes infected in Europe. The new selection of primer parts can be used as an alternative to enhance the detection of HIV-1 of different origins.

Prevalence of HIV infection in healthy subjects and groups of patients in Tanzania.

During 1986 sera from 2508 individuals representing various groups of healthy subjects and patients in Dar es Salaam (the capital city of Tanzania), Bukoba (the capital of Kagera region in the northwest corner of Tanzania), Arusha (in the northeast of Tanzania) and Mbeya (in the southwest of Tanzania) were screened for antibodies to HIV by enzyme-linked immunosorbent assay (ELISA). All ELISA-positive sera were also tested by Western blot analysis. In Dar es Salaam HIV antibodies were demonstrated in 3.6% of 192 pregnant women, 5.2% of 784 blood donors, 29.0% of 224 barmaids, 8.0% of 50 male bar workers, 9.25% of 400 male and 12.2% of 90 female patients attending a clinic for sexually transmitted diseases (STDs), 85.7% of 35 patients with herpes zoster and in 97.6% of 84 patients clinically suspected of AIDS. Among the barmaids the seropositivity rate was higher in younger women (45%) than in middle-aged women (11%). Only three (4.6%) out of 65 HIV-seropositive barmaids had HIV-related symptoms. The prevalence of HIV seropositivity among healthy low-risk subjects was highest in Bukoba, namely 16% of 100 pregnant women and 13.9% of 36 blood donors, while in Arusha only one (0.7%) of the 144 pregnant women and none of 41 bar workers, none of 42 blood donors and none of 61 patients with STD were positive. In Mbeya, 3.4% of 118 pregnant women and 11.8% of 34 men with STD were seropositive. Thus the prevalence of HIV infection differs considerably in various population groups and in various parts of Tanzania.