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Biomedical subjects

G Biberfeld

Publications and source records attributed to G Biberfeld.

At least 37 records · Page 2Linked to original sources
PubMed2000

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.

Acquired Immunodeficiency Syndrome↗
PubMed2000

Diagnosis of primary HIV-1 infection and duration of follow-up after HIV exposure. Karolinska Institute Primary HIV Infection Study Group.

OBJECTIVE: To determine the sensitivity of 33 currently available and seven earlier tests for the detection of HIV or HIV antibody in primary HIV-1 infection, to estimate the duration of the 'window period' and the influence of early initiated antiretroviral treatment (ART). DESIGN: A prospective cohort study of 38 patients with primary HIV-1 infection. ART was initiated at a median time of 13 (range 0-23) days after the onset of symptoms in 10 patients. MAIN OUTCOME MEASURES: The time from infection to onset of symptoms and from onset of symptoms to the appearance of HIV antibody as measured by 36 different tests, and the start and duration of viraemia, as detected by four different tests. RESULTS: The illness appeared 13-15 days after infection in 12 of 15 determinable cases, and seroconversion was detected within 1-2 weeks after the onset of illness by 27 of 30 currently available tests for HIV antibody, in contrast to the 2-7 weeks or more needed by the old tests. HIV RNA appeared during the week preceding the onset of illness and was detected in all subsequent samples, except when ART had been initiated, which also induced a delay of the antibody response. CONCLUSION: Many tests for HIV or HIV antibody can now be employed for an early confirmation of primary HIV infection (PHI). Currently available screening tests proved much more sensitive than older tests, and seroconversion was usually detected within one month after infection. Consequently, in Sweden we now recommend only 3 months of follow-up after most cases of HIV exposure.

Follow-Up Studies↗
PubMed2000

Cell-mediated immunity to low doses of SIVsm in cynomolgus macaques did not confer protection against mucosal rechallenge.

Simian immunodeficiency virus (SIV) infection of macaques is a useful model for studies of the roles of different immune responses against viruses that cause (AIDS). In this study, six cynomolgus macaques were inoculated intrarectally with subinfectious or infectious doses of SIVsm to assess the SIV specific immunity, in particular protective immunity against subsequent challenge with a higher dose of SIVsm. Following the first inoculation with SIVsm, the two monkeys given the highest doses of cell-free SIVsm stock and one monkey given the intermediate dose became infected. In the three remaining animals, one animal inoculated with an intermediate dose and two animals given low doses of SIVsm, no overt infection occurred. Nevertheless, SIV specific cytotoxic T-cells against Gag/Pol and Nef proteins and T-cell proliferative responses against HIV-2 whole viral lysate, native HIV-2 gp125, recombinant SIV gp140 and SIV Env synthetic peptides were detected. After intrarectal rechallenge of the uninfected macaques with a higher dose of SIVsm all the animals became infected. These results demonstrate that cell mediated immunity can occur in the absence of detectable infection in monkeys inoculated with a low dose of SIVsm. Despite the presence of cellular immune responses, the animals were not protected when challenged with a higher dose of virus later.

Administration, Rectal↗
PubMed2000

Monitoring of HIV-1 infection prevalence and trends in the general population using pregnant women as a sentinel population: 9 years experience from the Kagera region of Tanzania.

In the Kagera region of Tanzania, a population-based study was initiated in 1987 followed by the establishment of antenatal-clinic-based sentinel surveillance system in the town of Bukoba in 1990. Repeat studies in both populations in Bukoba in 1993 and 1996 made it possible to study the dynamics of HIV infection prevalence and incidence in the area. This study aims at comparing the findings from this sentinel surveillance system with those of cross-sectional studies in the general population to assess its validity in estimating HIV prevalence and their trends in the general population. A multistage cluster sampling technique was used in the population-based studies whereas the antenatal-clinic-based population was obtained by consecutively recruiting antenatal care attenders coming for the first time during a given pregnancy. Antibodies against HIV infection were tested using two independent enzyme-linked immunosorbent assay (ELISA) antibody detection tests. Unlinked anonymous testing strategy was adopted for the sentinel population. Age-adjusted prevalence among antenatal care attenders decreased from 22.4% (95% confidence interval [CI], 20.6-25.2) in 1990 to 16.1% (95% CI, 15.9-18.8) in 1993 and further to 13.7% (95% CI, 11.8-14.3) in 1996. These results closely resemble those of the general population of adult women in the clinic's catchment area (the town of Bukoba) where the age-adjusted prevalence of 29.1% (95% CI, 24.4-34.6) in 1987 showed a decrease in the studies in 1993 18.7% (95% CI, 15.1-23.0) and in 1996 14.9% (95% CI, 12.0-17.1). The study indicates that general population trend estimates can be generated using sentinel surveillance data based on pregnant women visiting an antenatal clinic for the first time during a given pregnancy. The benefits of using this group outweigh its limitations that are brought about by possible selection bias. Continued surveillance of the epidemic based on antenatal care patients as a sentinel population is therefore recommended.

Adolescent↗
PubMed2000

The prevalence and incidence of HIV-1 infection and syphilis in a cohort of police officers in Dar es Salaam, Tanzania: a potential population for HIV vaccine trials.

OBJECTIVES: To assess the suitability of a cohort of police officers in Dar es Salaam for HIV vaccine trials by determining the prevalence and incidence of HIV-1 infection, active syphilis and their associated factors. DESIGN AND SETTING: An open cohort study of police officers in Dar es Salaam, Tanzania. METHODS: Recruitment of police officers began in 1994. A standardized questionnaire was completed at enrolment and subsequent visits. HIV antibodies were determined using two consecutive enzyme-linked immunosorbent assays. Samples repeatedly discordant on the two tests were tested by a Western blot assay. Treponema pallidum antibodies were first determined by Venereal Disease Research Laboratory (VDRL) test and reactive sera were confirmed by Treponema pallidum hemagglutination test. RESULTS: At the end of 1996 a total of 2850 police officers had been recruited of whom 2733 (96%) consented to be tested for HIV. The overall HIV-1 seroprevalence at recruitment was 13.8% (378 of 2733). Females had a significantly higher HIV-1 seroprevalence, 18.0% (55 of 306), as compared to males, 13.3% (323 of 2427), P< 0.05. From a total of 2215 married police officers, 585 (26.4%) responded to a question on extramarital sex within the previous 3 months of whom 36.2% (212 of 585) admitted to have had at least one extramarital sexual intercourse. Condoms were not used during these encounters by 178 of 212 (84.0%). As of 31st December 1998, among the 1524 males observed for 2553 person-years (PYAR), 50 had seroconverted and among 200 females observed for 357 PYAR, eight had seroconverted. The overall crude HIV-1 incidence was thus 19.9/1000 PYAR; 19.6 and 22.4/1000 PYAR for males and females, respectively. The overall prevalence and incidence of active syphilis were 3.1% (88 of 2850) and 8.6/1000 PYAR (26 of 3149), respectively. Males had a higher prevalence of active syphilis, 84 of 2525 (3.3%) than females, five of 325 (1.5%), P = 0.09. CONCLUSIONS: There was high risk sexual practice including low condom use in this cohort of police officers. The incidence and prevalence of HIV infection were high. Police officers in Dar es Salaam are therefore a potential population group for HIV vaccine evaluation.

AIDS Vaccines↗
PubMed2000

Recombinant bacillus Calmette-Guérin as a potential vector for preventive HIV type 1 vaccines.

In August 1997, the World Health Organization (WHO) and the Joint United Nations Programme on HIV/AIDS (UNAIDS) convened an expert working group to discuss current strategies for the development of HIV type 1 vaccines. Based on the recent findings of investigators from Japan's National Institute of Infectious Diseases (NIID) in Tokyo using recombinant bacillus Calmette-Guérin (rBCG) as a potential vectored vaccine for HIV, a recommendation was made that further work in this area is a priority. As a result, the working group reconvened in September 1998 to discuss the progress to date with this vaccine approach, as well as areas of related research to assess the feasibility of a BCG-vectored HIV vaccine. This report summarizes the discussions addressing the available scientific data on the potential use of rBCG as a vector for preventive HIV vaccines, the work necessary to move such candidate vaccines into Phase 1 clinical trials, and recommendations targeted at facilitating the long-term development of rBCG-vectored HIV vaccines.

AIDS Vaccines↗
PubMed2000

Evaluation of a prototype Amplicor PCR assay for detection of human immunodeficiency virus type 1 DNA in blood samples from Tanzanian adults infected with HIV-1 subtypes A, C and D.

BACKGROUND: In previous evaluations, the standard Amplicor HIV-1 DNA PCR test (Roche Diagnostic Systems) has been reported to have low sensitivity for the detection of some non-B HIV-1 subtypes. It has therefore become necessary to determine the performance of commercially available as well as prototype HIV-1 PCR assays for HIV-1 DNA detection in samples from various geographical settings, in order to assess their ability to detect the different HIV-1 genotypes. OBJECTIVES: To determine the performance of the prototype Roche Amplicor version 1.5 PCR test in comparison to that of the standard Roche Amplicor PCR test for the detection of HIV-1 DNA in blood samples from HIV-1 seropositive pregnant Tanzanian women infected with various HIV-1 subtypes. STUDY DESIGN: This was a cross-sectional study done on 161 blood samples collected from 106 HIV-1 seropositive and 55 seronegative asymptomatic pregnant women attending antenatal clinic in Dar es Salaam, Tanzania. METHODS: Cell pellets for PCR were prepared from EDTA blood by the Amplicor whole blood PCR sample preparation method. Plasma was used for HIV serology by enzyme linked immunosorbent assays. Subtyping was done by the heteroduplex mobility assay (HMA) using cell pellets and/or plasma. RESULTS: The sensitivities of the prototype PCR and the standard assays were 99.1% (105/106) and 97% (99/102), respectively. All samples from 55 HIV-1 seronegative women were negative by both PCR assays. Among the 101 samples subtyped by HMA, 48 (47%) were subtype A, 30 (30%) subtype C, 20 (20%) subtype D and 3 (3%) were indeterminate. In the standard DNA PCR assay, a statistically significantly higher proportion of subtype A samples had a low level of reactivity as measured as optical density compared with the subtypes C and D samples while in the prototype assay all three subtypes showed a high level of reactivity. CONCLUSIONS: The Amplicor version 1.5 DNA PCR test has a high sensitivity for the detection of HIV-1 DNA in blood samples from Tanzanian adults. Since performance of this assay does not appear to be influenced by differences in HIV-1 subtypes A, C and D, it has the potential for use in the detection of HIV-1 DNA in samples from geographic areas where these subtypes are prevalent.

Adult↗
PubMed2000

Recruitment of monocyte derived dendritic cells ex vivo from SIV infected and non-infected cynomolgus monkeys.

This study shows that characteristic dendritic, antigen presenting cells, can be generated from adherent peripheral blood mononuclear cells (PBMC)/monocytes of uninfected and SIVsm-infected cynomolgus monkeys after stimulation in vitro with granulocyte macrophage colony stimulating factor (GM-CSF) and interleukin (IL)-4. The recruitment of monocyte derived dendritic cells (MDDC) was usually possible irrespective of the level of immunodeficiency (CD4-level) and viremia. The cynomolgus MDDC closely resembled their human counterpart (immature MDDC) with regard to capacity to upregulate CD1a, CD40, CD86 and human leukocyte antigen (HLA)-DR and develop dendrites and veiled processes. Such MDDC also increased their capacity for antigen uptake (dextran endocytoses/macropinocytosis) and for induction of T-cell proliferation in mixed leukocyte reaction (MLR) assays. However, although no clear difference with regard to phenotype and morphology was seen between MDDC from SIV-infected and uninfected monkeys, a reduction in MLR responsiveness in MDDC from SIV infected monkeys was consistently detected within each experiment.

Animals↗
PubMed2000

Prevalence of HIV type 1 infection, associated clinical features and mortality among hospitalized children in Dar es Salaam, Tanzania.

The aim of this study was to determine the prevalence of HIV-1 infection, the clinical spectrum of HIV-1-associated conditions and HIV-1-associated mortality among children hospitalized in the medical paediatric wards at Muhimbili Medical Centre (MMC), Dar es Salaam, Tanzania. All children admitted to the medical paediatric wards of MMC between August 1995 and January 1996 were eligible for the study. Testing for HIV antibodies was done using 2 consecutive enzyme linked immunosorbent assays (ELISAs). ELISA-reactive samples from children aged 18 months and below were further tested by a recently developed heat-denatured p24 antigen assay. The prevalence of HIV-1 infection among the 2015 children studied was 19.2%. When present for 14 days or more, fever, cough, diarrhoea, ear discharge, oral ulcers and skin rash were all significantly more common in HIV-1-infected than in HIV-uninfected children (p < 0.001). In the multivariate analysis cough, ear discharge, oropharyngeal ulcers and skin rash were found to be the most important symptoms. Clinical signs found to be significantly associated with HIV-1 infection in the univariate analysis were wasting, stunting, hair changes, oral thrush, oropharyngeal ulcers, lymphadenopathy, lung consolidation and lung crepitations (p < 0.001). In the multivariate analysis, oral thrush, lung crepitations, cervical lymphadenopathy, wasting and inguinal lymphadenopathy were found to be the most important signs. The 3 most common diagnoses in HIV-1-infected children were acute respiratory infection (ARI) (39.4%), malnutrition (38.1%) and tuberculosis (19.3%), while in HIV-uninfected children they were malaria (47.0%), ARI (25.0%) and malnutrition (16.1%). The mortality rate was 21.4% in HIV-1-infected children and 8.4% in HIV-uninfected children (p < 0.001). In conclusion, the prevalence of HIV-1 infection among hospitalized children at the main hospital in Dar es Salaam was high and associated with high mortality. Many symptoms and signs are indicative of HIV-1 infection, but appropriate laboratory testing is required for diagnosis.

Acquired Immunodeficiency Syndrome↗
PubMed2000

Isoniazid prophylaxis for tuberculosis prevention among HIV infected police officers in Dar es Salaam.

OBJECTIVE: To determine the acceptability, compliance and side effects of isoniazid (INH) prophylaxis against tuberculosis among HIV infected police officers (PO) in Dar es Salaam. DESIGN: A nested study from a prospective follow up of a cohort of police officers. SETTING: Dar es Salaam, Tanzania. SUBJECTS: One hundred and forty three HIV-1 infected police officers. MAIN OUTCOME MEASURES: Acceptance and compliance to INH prophylaxis. RESULTS: Of the 400 HIV-1 infected officers, 143 (35.7%) came forward for post-test counselling and HIV test results. Sixty per cent (87/143) of them accepted to be on INH prophylaxis. However only 42.5% (37/87) came forward for evaluation regarding their suitability for INH prophylaxis. During the evaluation, eight (21.6%) of 37 otherwise asymptomatic PO were found to have active pulmonary tuberculosis (TB). Eventually only 29 PO were actually started on INH, and only 16 (55.2%) of them completed the six months course. No serious side effects were observed. One PO developed TB two months after loss to follow up before completing the six months. CONCLUSIONS: There was low acceptability of and poor compliance with INH prophylaxis among the HIV-1 infected PO despite being educated on the benefits of prophylaxis. The prevalence of PTB among asymptomatic HIV-1 infected PO was high, and therefore persons with HIV infection should be examined for TB even in the absence of symptoms.

Adult↗
PubMed2000

Three-year follow-up of patients with pulmonary tuberculosis in Guinea-Bissau, West Africa.

SETTING: Raoul Follereau Hospital, Bissau, Guinea-Bissau. OBJECTIVE: To study the long-term outcome of patients with bacteriologically verified tuberculosis (TB), with or without human immunodeficiency virus (HIV) co-infection. DESIGN: Sputum samples were collected from all patients referred to the hospital with clinical symptoms of pulmonary tuberculosis. Direct microscopy and culture was performed at the Health Laboratory. Patients with a culture positive for Mycobacterium tuberculosis were followed for 3 years, and underlying factors were analysed regarding the outcome of treatment. A group of sex and age-matched HIV-negative individuals was used as controls. RESULTS: Of 206 bacteriologically verified pulmonary TB patients, 168 were followed up. Antibodies to HIV-2 were found in 33 patients (19.6%); eight patients (4.8%) had antibodies to HIV-1 or showed dual reactivity. Of 149 patients discharged to follow ambulatory treatment, the survival rate of HIV-2-positive patients was 42.3% (11/26) and for HIV-negative patients it was 81.9% (95/116). The difference in survival between HIV-2-positive and HIV-negative patients was highly significant (P < 0.00001). HIV-negative TB patients had a significantly higher mortality than their controls (mortality ratio 3.75, 95% confidence interval 1.58-8.90). Most patients who survived, regardless of HIV status, also became free from symptoms compatible wtih pulmonary TB. CONCLUSION: Although the mortality rate among HIV-positive TB patients was very much higher than among HIV-negative patients, there are weighty arguments for active contact tracing and effective treatment of all TB patients.

AIDS-Related Opportunistic Infections↗
PubMed1999

Molecular characterization of human immunodeficiency virus (HIV)-1 and -2 in individuals from guinea-bissau with single or dual infections: predominance of a distinct HIV-1 subtype A/G recombinant in West Africa.

Guinea-Bissau in West Africa has the highest prevalence of human immunodeficiency virus (HIV)-2 infection in the world, but recently the HIV-1 prevalence increased rapidly with the subsequent appearance of HIV-1 and HIV-2 dual infections. Information about the genetic subtypes of HIV in the region is limited. Therefore, we characterized the env V3 region of HIV-1 and HIV-2 variants through direct DNA sequencing of peripheral blood mononuclear cell samples from 18 individuals with HIV-1 only and 9 individuals with dual infection. Phylogenetic analyses of these new sequences and database sequences from other West African countries showed that all HIV-1 and HIV-2 sequences from singly as well as dually infected individuals, except one, clustered among HIV-1 subtype A and HIV-2 subtype A, respectively. Importantly, a majority of the HIV-1 sequences from Guinea-Bissau and neighbouring countries were closely related with the isolates IbNG, DJ263, and DJ264, which share a common subtype A/G recombination pattern. Analysis of pol gene sequences from selected HIV-1 variants showed that "IbNG-like" viruses in Guinea-Bissau are also recombinant, indicating that the HIV-1 epidemic in Guinea-Bissau and neighbouring countries is dominated by an epidemic spread of a distinct subtype A/G recombinant, which is strikingly similar to the epidemic spread of a subtype A/E recombinant in Southeast Asia. Furthermore, the HIV-1 and HIV-2 variants carried by individuals with dual infection were intermixed with variants from singly infected individuals, indicating that variants involved in dual and single infections have common epidemiological histories.

Adult↗
PubMed1999

High concordance between polymerase chain reaction and antibody testing of specimens from individuals dually infected with HIV types 1 and 2 in Guinea-Bissau, West Africa.

In this study we have evaluated the concordance between serology, using five commercially available antibody assays designed to discriminate between HIV-1 and HIV-2, and the polymerase chain reaction (PCR) for the detection of HIV-1 and HIV-2 dual infection. Thirty-seven HIV-1 and HIV-2 dually reactive serum samples from individuals in Guinea-Bissau with total CD4+ T lymphocyte counts ranging from 9 to 948 x 10(6)/liter were included in the study. All samples were tested by Multispot, Pepti-LAV, and Immunocomb HIV-1 and HIV-2 discriminatory antibody assays. Thirty-two of the 37 samples were also tested by a combination of two HIV type-specific antibody enzyme-linked immunosorbent assays (ELISA; Wellcozyme HIV-1 and Murex HIV-2). Each sample showed dual reactivity in all or any of these assays. A nested PCR based on primer systems in the vif and pol regions of HIV-1 and in the gag and LTR regions of HIV-2 was used to evaluate the serological results. Thirty samples from HIV-1 antibody-positive individuals and 30 samples from HIV-2 antibody-positive individuals were all PCR positive with their corresponding primer systems. The type specificity was 100% for all of the primer systems. The concordance between dual HIV-1 and HIV-2 reactivity on the serological assays and PCR was 77.7% for Multispot, 80% for Pepti-LAV, 81.8% for Immunocomb, and 85.7% for the two ELISAs used in combination. Thus the majority of individuals included in this study appeared to be truly dually infected. The study shows that it is possible, through a careful selection of assays, to reach a high concordance between serological assays and PCR in studying HIV-1 and HIV-2 dual infections.

CD4 Lymphocyte Count↗
PubMed1999

Child survival in children born to HIV-2 infected women in Guinea-Bissau, West Africa.

We have retrospectively studied the effect of maternal HIV-2 infection and other risk factors on child survival at a family planning centre in Bissau, Guinea-Bissau. A total of 2109 women were included, and the seroprevalence of HIV-2 was 5.7%. Overall child mortality of all live births (n=5912) reported by the women (standardized for age of the mother) was slightly higher among children of HIV-2 seropositive mothers (16.3%) compared with children of HIV seronegative women (14.6%) (not significant). There was a significant association between low level of maternal education and increased child mortality, but no difference in the level of education was found between HIV-2 seropositive and seronegative women.

Adult↗
PubMed1999

Trends and interaction of HIV-1 and HIV-2 in Guinea-Bissau, west Africa: no protection of HIV-2 against HIV-1 infection.

OBJECTIVES: To study trends in the prevalence and incidence of HIV-1 and HIV-2 infections in Guinea-Bissau over the last 7 years, and to evaluate the protective effect of HIV-2 against HIV-1 infection. DESIGN: Prospective follow-up of a cohort of police officers in Guinea-Bissau, and sentinel surveillance of pregnant women in Bissau. METHODS: Participants in the police cohort were tested regularly for antibodies to HIV and Treponema pallidum, and information about sexual risk behaviour and a history of sexually transmitted diseases was obtained. Simultaneously, pregnant women at the maternity wards at the National Hospital in Bissau were screened annually for HIV antibodies. To evaluate changes in prevalence and incidence of HIV in the police cohort, the study period was divided into three time strata with 2-3 years in each stratum. For the evaluation of a protective effect of HIV-2 on subsequent HIV-1 infection, two multivariate Poisson regression models were constructed, adjusting for different selected confounding variables. RESULTS: Between 1990 and 1997, 2637 police officers were included in the cohort study, 90.7% of whom were male. The overall prevalence of HIV-1 was 0.9%, of HIV-2 it was 9.7% and of HIV-1 and HIV-2 dual reactivity it was 0.5%. For pregnant women the prevalence rates were 0.9, 5.5 and 0.2% for HIV-1, HIV-2 and dual reactivity respectively. The prevalence of HIV-1 increased significantly whereas the prevalence of HIV-2 declined significantly during the study period, among both police officers and pregnant women. The total incidence of HIV-1 and HIV-2 was 0.74 and 0.83 per 100 person-years respectively in the police cohort. The incidence of HIV-1 increased slightly from 0.62 to 0.78 per 100 person-years (not significant), whereas the incidence of HIV-2 declined significantly from 0.90 to 0.35 per 100 person-years over the study period. Seven police officers seroconverted from HIV-2 to dual reactivity (1.22 per 100 person-years). The adjusted incidence ratio of acquiring HIV-1 infection among HIV-2-positive subjects compared with HIV-negative subjects was 1.65 [95% confidence interval (CI), 0.73-3.74] and 1.98 (95% CI, 0.80-4.87), depending on the confounding variables included. CONCLUSIONS: Our study shows an increasing prevalence of HIV-1 and a decreasing prevalence of HIV-2 in Guinea-Bissau. The incidence of HIV-2 declined significantly whereas the incidence of HIV-1 was relatively stable over the study period. No protective effect of HIV-2 against subsequent HIV-1 infection was observed, instead HIV-2-positive subjects had a tendency towards higher risk of acquiring HIV-1 infection compared with seronegative subjects.

Africa↗
PubMed1999

Proliferation and apoptosis-related gene expression in experimental acquired immunodeficiency syndrome-related simian lymphoma.

Lymphomas in 10 cynomolgus monkeys infected with a simian immunodeficiency virus (SIVsm) were studied with regard to proliferative activity and apoptosis-related gene expression. All were diffuse large-cell lymphomas, showed mono or oligoclonality and a 9/10 diploid cellular DNA content. Expression of a simian homologue to Epstein-Barr virus (HVMF-1) was shown in nine cases. The lymphomas showed moderate to high proliferative activity by Ki67 immunostaining and DNA flow cytometry, and a low number of apoptotic cells detected by TdT-mediated dUTP nick-end labeling (TUNEL). Immunohistochemistry showed abundant tumor infiltrating TIA-1(+) cytotoxic lymphocytes (CTL) and macrophages. Bcl-2, Mcl-1, and also Bax and Bak, but not p53 were demonstrable in the tumor cells by immunostaining. Our findings suggest a causal relationship between HVMF-1 infection and a low apoptotic index of the lymphomas due to the expression of Bcl-2. The apparent inefficient function of tumor-infiltrating CTL could be due to inactivation of CTL and/or resistance of the lymphoma cells to CTL effects. The tumors showed immunoreactivity for CD18, CD29, and CD49d, but not for CD11a, mimicking the phenotype of human Epstein-Barr virus (EBV)-related lymphomas. In summary, our observations indicate a high similarity between this simian model of acquired immunodeficiency syndrome (AIDS)-related lymphomas (ARL) and human ARL and other immunosuppression-related lymphomas.

Animals↗
PubMed1999

The accuracy of an alternative confirmatory strategy for detection of antibodies to HIV-1: experience from a regional laboratory in Kagera, Tanzania.

BACKGROUND: Constant improvement of HIV tests often results in withdrawal of poorer quality tests by the manufacturing companies. It is thus often necessary to evaluate new HIV testing kits and modify the existing testing strategies. OBJECTIVES: To evaluate an alternative HIV antibody testing strategy which involves consecutive testing of sera by two enzyme-linked immunosorbent assays (ELISA), which both are recombinant antigen-based but utilise different test principles, followed by re-testing of sera giving discordant results. STUDY DESIGN: Sera (n = 1558) from a cross-sectional study of the HIV-1 seroprevalence in the Kagera region of Tanzania were tested using two ELISAs in parallel: Enzygnost anti-HIV-1/2 plus and Wellcozyme HIV-1 recombinant. Western blot analysis was done on all concordantly reactive and repeatedly discordant reactive samples as well as on 10% of concordantly ELISA negative sera. RESULTS: Two hundred and four sera (13.1%) were confirmed HIV-1-antibody positive. Both ELISAs had a sensitivity of 100%. The specificities of the ELISAs at initial and repeated testing were 99.8 and 99.9%, respectively, for Enzygnost and 97.7 and 99.5%, respectively, for Wellcozyme. None of the sera was concordantly false positive in both ELISAs. The mean ratio of the optical density of a sample to the cut off value of the test run (OD/CO ratio) was lower for samples giving false positive reactions than for confirmed HIV-1-antibody-positive samples. It is therefore important to interpret with caution HIV antibody ELISA test results on samples giving low OD/CO ratios. None of 10% of randomly selected concordantly ELISA negative sera gave a positive Western blot reaction. CONCLUSIONS: This field evaluation of an HIV antibody testing strategy involving the use of a recombinant antigen-based sandwich ELISA (Enzygnost) followed by a recombinant antigen-based competitive ELISA (Wellcozyme) showed that it had a sensitivity and specificity of 100%.

AIDS Serodiagnosis↗