HIV-1 and HIV-2 prevalence and associated risk factors among postnatal women in Harare, Zimbabwe.

Studies of antenatal women form the predominant source of data on HIV-1 prevalence in Africa. Identifying factors associated with prevalent HIV is important in targeting diagnostic services and care. Between November 1997 and January 2000, 14,110 postnatal women from Harare, Zimbabwe were tested by ELISAs reactive to both HIV-1 and HIV-2; a subset of positive samples was confirmed with assays specific for HIV-1 and HIV-2. Baseline characteristics were elicited and modelled to identify risk factors for prevalent HIV infection. HIV-1 and HIV-2 prevalences were 32.0% (95% CI 31.2-32.8) and 1.3% (95% CI 1.1-1.5), respectively; 4% of HIV-1-positive and 99% of HIV-2-positive women were co-infected. HIV-1 prevalence increased from 0% among 14-year-olds to >45% among women aged 29-31 years, then fell to <20% among those aged>40 years. In multivariate analyses, prevalence increased with parity, was lower in married women than in single women, divorcees and widows, and higher in women with the lowest incomes and those professing no religion. Adjusted HIV-1 prevalence increased during 1998 and decreased during 1999. Age modified the effects of parity, home ownership and parental education. Among older women, prevalence was greater for women who were not homeowners. Among younger women, prevalence increased with parity and low parental education. None of these factors distinguished women co-infected with HIV-2 from those infected with HIV-1 alone. Prevalent HIV-1 infection is associated with financial insecurity and weak psychosocial support. The ZVITAMBO study apparently spanned the peak of the HIV-1 epidemic among reproductive women in Harare.

A pilot study to assess the immunologic and virologic efficacy of generic nevirapine, zidovudine and lamivudine in the treatment of HIV-1 infected women with pre-exposure to single dose nevirapine or short course zidovudine and their spouses in Chitungwiza, Zimbabwe.

OBJECTIVE: A pilot study to assess effectiveness of generic Nevirapine (NVP)+Zidovudine (AZT)+Lamivudine (3TC) as potent antiretroviral therapy (ART) in women exposed to either SD NVP or short course (SC) AZT through participation in prevention of mother-to-child transmission of HIV-1 (pMTCT) interventions, and their spouses. DESIGN: A pilot study of antiretroviral treatment of adults with AIDS. SETTING: Primary health care clinics; Seke North and St Mary's in Chitungwiza, Zimbabwe. SUBJECTS: Women with pre-exposure to SD NVP or SC AZT and their spouses with CD4 count < 200 cells/ INTERVENTIONS: Generic AZT/3TC twice daily plus NVP daily for the first 14 days and then twice a day thereafter, administered to the cohort. MAIN OUTCOME MEASURES: The baseline median CD4 count for women and men was 128.5 and 119.0 cells/ microL respectively. The geomean virus load was similar for the women and men. At weeks 16, 24 and 48, 82.8%, 85.1% and 73.8% had < 400 copies/ml of HIV RNA respectively. Only at 16 weeks, was the proportion of women (75.9%) with undetectable virus significantly lower than that for men (93.9%), p = 0.031. Median CD4 count for both men and women increased significantly, p < 0.001. There were no significant differences in virologic responses between the women with pre-exposure to SD NVP and SC AZT. The mean adherence for women and men was similar, > 98%. CONCLUSION: Women showed a significantly reduced response top ART relative to men only at 16. However, prior exposure to SD NVP for PMTCT was no more likely to negatively influence responses to ART than use of SC AZT.

Survival pattern among infants born to human immunodeficiency virus type-1 infected mothers and uninfected mothers in Harare, Zimbabwe.

OBJECTIVES: To determine the mother-to-child transmission (MTCT) rate of HIV-1 and to compare the survival patterns among infants born to HIV-1 infected and seronegative mothers. DESIGN: A two year prospective study from 1991 to 1995. METHODS: 345 HIV-1 infected mothers and 351 seronegative mothers and their infants were examined at regular intervals up to 24 months of age. RESULTS: The intermediate estimate of MTCT rate of HIV-1 was found to be 31.9%; (95% confidence interval (CI) 26.9 to 37.1). Of infants born to HIV-1 infected mothers 17% died compared with 2% of infants born to seronegative mothers. Forty six (43%) of the 107 HIV-1 infected infants died compared with 16 (219%) of the 559 uninfected infants. In a multivariate analysis, risk factors independently associated with infant mortality were low birth weight (hazard ratio (HR) 2.80; CI 1.52 to 5.13), HIV infected infant (HR 10.50; CI 5.48 to 20.15), HIV infected mother (HR 3.23; CI 3.17 to 15.85) and maternal death (HR 2.77; CI (1.09 to 7.06). CONCLUSION: The estimated MTCT rate of HIV-1 is comparable with rates of 25% to 45% reported from the African region. The poor survival of HIV-1 infected infants indicates the necessity for effective and comprehensive HIV/AIDS control strategies in Zimbabwe.

Comparative evaluation and assessment of the diagnostic usefulness of four commercial HIV-1/HIV-2 antibody assays using two well-characterized serum panels from Blood Transfusion Service and the National Health Laboratory Services in Zimbabwe.

OBJECTIVE: To evaluate four Enzyme Linked Immunosorbent Assay (ELISA) HIV kits for possible use as a combination at the National Health Laboratory Services (NHLS) in Zimbabwe. DESIGN: Laboratory evaluation, sensitivity, specificity and cost effectiveness of HIV diagnostic kits. SETTING: Blood Transfusion Service (BTS) and Parirenyatwa Hospital in Zimbabwe. SUBJECTS: A total of 346 samples from 245 patients referred to Parirenyatwa Hospital and 101 blood donors at BTS. MAIN OUTCOME: The main goal was to come out with the best combination of ELISA kits in terms of sensitivity, specificity and cost effectiveness for use in diagnosis of HIV infection in Zimbabwe. RESULTS: The best combination kit was the Murex/Innotest with 100% sensitivity and 98.9% specificity, being slightly superior to the Genelavia/Vironostika combination kits in current use at NHLS. In addition, the Murex/Innotest combination has the shortest assay running time and requires fewer internal controls thereby increasing the number of test specimens per run. CONCLUSION: We recommend the use of the Murex/Innotest kits as a suitable combination for HIV infection diagnosis in Zimbabwe. The combination has a relatively low number of discordant results, drastically reducing the cost of running a third confirmatory test to resolve the discordant results. Most importantly, this combination maximizes HIV infection diagnosis by its ability to detect antibodies to HIV-1 groups M and O as well as HIV-2.

Evaluation of the prototype Roche DNA amplification kit incorporating the new SSK145 and SKCC1B primers in detection of human immunodeficiency virus type 1 DNA in Zimbabwe.

We assessed the sensitivity and specificity of a newly developed DNA PCR kit (Roche Diagnostic Corporation, Indianapolis, Ind.) that incorporates primers for all the group M viruses for the detection of human immunodeficiency virus (HIV) type 1 (HIV-1) infection in Zimbabwe. A total of 202 whole-blood samples from adults whose HIV status was known were studied. This included 100 HIV-1-positive and 102 HIV-1-negative samples selected on the basis of concordant results obtained with two enzyme-linked immunosorbent assay kits. The prototype Roche DNA PCR assay had a 100% sensitivity for the detection of HIV-1 DNA and a specificity of 100%. We conclude that the new Roche DNA PCR kit is accurate for the detection of HIV DNA in Zimbabwean samples, in which HIV-1 subtype C dominates.

Conformation-dependent platelet adhesion to collagen involving integrin alpha 2 beta 1-mediated and other mechanisms: multiple alpha 2 beta 1-recognition sites in collagen type I.

Platelet adhesion has been measured to type-I monomeric collagen, collagen fibres, alpha 1(I) and alpha 2(I) chains and the chain fragments alpha 1(I)CB3, alpha 1(I)CB6, alpha 1(I)CB7 and alpha 1(I)CB8, and alpha 2(I)CB3,5 and alpha 2(I)CB4. Little if any adhesion occurred to any denatured species at 37 degrees C, demonstrating the importance of the collagen helix. However, on coating at 4 degrees C to promote helix formation, and assaying at room temperature to avoid denaturation, adhesion was observed to both alpha-chain types and all fragments, the exact level of which depended on the identity of the species in question. Adhesion was strongly Mg(2+)-dependent. Antibodies against the integrin alpha 2 beta 1 partially inhibited adhesion to alpha-chains and all fragments except alpha 1(I)CB6, indicating a wide distribution of alpha 2 beta 1-binding sites in the collagen molecule. 'Activation-dependent' adhesion to monomeric collagen, totally secondary to alpha 2 beta 1-mediated adhesion, involved at least two mechanisms, one mediated by integrin alpha IIb beta 3 and insensitive to prostaglandin E1, the other inhibitable by prostaglandin E1 but independent of integrin alpha IIb beta 3. alpha IIb beta 3-mediated adhesion to fragments was, at least in part, independent of the alpha 2 beta 1-mediated adhesion. Adhesion to fibres was largely bivalent-cation-independent with only minor involvement of integrin alpha 2 beta 1. Some alpha IIb beta 3-mediated adhesion occurred but was independent of any alpha 2 beta 1-initiated adhesion. Total 'activation-dependent' adhesion to fibres was less than to monomeric collagen. Affinity chromatography revealed bivalent-cation-independent binding to fibres of three main platelet surface proteins, 90, 150 and 190 kDa in size.

Analysis of alpha 1 beta 1, alpha 2 beta 1 and alpha 3 beta 1 integrins in cell--collagen interactions: identification of conformation dependent alpha 1 beta 1 binding sites in collagen type I.

Integrins can mediate the attachment of cells to collagen type I. In the present study we have investigated the possible differences in collagen type I recognition sites for the alpha 1 beta 1 and alpha 2 beta 1 integrins. Different cyanogen bromide (CB) fragments of the alpha 1 (I) collagen chain were used in cell attachment experiments with three rat cell types, defined with regard to expression of collagen binding integrins. Primary rat hepatocytes expressed alpha 1 beta 1, primary rat cardiac fibroblasts alpha 1 beta 1 and alpha 2 beta 1, and Rat-1 cells only alpha 2 beta 1. All three cell types expressed alpha 3 beta 1 but this integrin did not bind to collagen--Sepharose or to immobilized collagen type I in a radioreceptor assay. Hepatocytes and cardiac fibroblasts attached to substrata coated with alpha 1(I)CB3 and alpha 1(I)CB8; Rat-1 cells attached to alpha 1(I)CB3 but only poorly to alpha 1(I)CB8-coated substrata. Cardiac fibroblasts and Rat-1 cells spread and formed beta 1-integrin-containing focal adhesions when grown on substrata coated with native collagen or alpha 1(I)CB3; focal adhesions were also detected in cardiac fibroblasts cultured on alpha 1(I)CB8. The rat alpha 1 specific monoclonal antibody 3A3 completely inhibited hepatocyte attachment to alpha 1(I)CB3 and alpha 1(I)CB8, as well as the attachment of cardiac fibroblasts to alpha 1(I)CB8, but only partially inhibited the attachment of cardiac fibroblasts to alpha 1(I)CB3. 3A3 IgG did not inhibit the attachment of Rat-1 cells to collagen type I or to alpha 1(I)CB3.(ABSTRACT TRUNCATED AT 250 WORDS)

Platelet-reactive sites in human collagens I and III: evidence for cell-recognition sites in collagen unrelated to RGD and like sequences.

Following fragmentation of the collagen molecule with cyanogen bromide (CB), two major platelet-aggregatory sites were detected with human platelets in the alpha 1(I)-chain of human collagen I corresponding to those detected previously in bovine alpha 1(I)-chains. Two main sites were also detected in the human alpha 1(III)-chain, at locations different from those in the alpha 1(I)-chain. Only one of these had been previously recognised. The new site was found in the peptide alpha 1(III)CB3, the amino acid sequence of which does not contain the cell-recognition site RGD nor comparable sequences that might be supposed to serve this function such as KGD, RGE or KGE. The peptide does, however, contain the sequence GRPGRPGER which reflects a spacing of basic residues (at positions 2 and 9) we have previously postulated to be essential for collagen to cause platelet aggregation. None of the CB-derived peptides was able to cause an aggregation of rabbit platelets. Human platelet secretion, as aggregation, was only induced by CB-derived fragments in triple-helical, polymeric form. One fragment, peptide alpha 1(III)CB8, was able to induce secretion although lacking aggregatory activity. Platelet adhesion occurred to all of the fragments, including those lacking aggregatory activity. Adhesion also occurred to the collagen-like polypeptide (PGP) n. However, inhibition studies suggested that the GPP sequence which occurs frequently along the length of the collagen molecule is not responsible for platelet adhesion to collagen.

Platelet adhesion to collagen. Factors affecting Mg2(+)-dependent and bivalent-cation-independent adhesion.

Platelet adhesion to collagens immobilized on plastic has been measured, with the following results. (1) Human, but not rabbit, platelets adhered readily to pepsin-extracted monomeric collagens in an Mg2(+)-dependent manner. (2) Rabbit platelets adhered to a monomeric collagen extracted without pepsin by a process that was cation-independent; human platelet adhesion to this collagen exhibited a cation-independent element. (3) Human platelet adhesion to polymeric collagens, including intact native fibres and those reconstituted from pepsin-extracted monomeric collagens, exhibited appreciable cation-independence; adhesion of rabbit platelets to these collagens occurred only by a cation-independent process; pepsin treatment of the intact fibres caused a reduction in cation-independent binding. Two mechanisms of adhesion can therefore be distinguished, one Mg2(+)-dependent, expressed by human, but not rabbit, platelets, the other cation-independent and exhibited by platelets of both species. Mg2(+)-dependent and cation-independent adhesion sites are located within the triple helix of collagen, but the latter sites are only expressed in collagen in polymeric form. In neither case is the helical conformation of the sites essential for their binding activity. Cation-independent adhesion sites are also located in the pepsin-sensitive non-helical telopeptides of collagen and can be expressed in both monomeric and polymeric collagens. Chemical modification of collagen lysine residues indicates that specific lysine residues may be involved in Mg2(+)-dependent adhesion. Adhesion using human citrated platelet-rich plasma is Mg2(+)-independent. Plasma contains factors, conceivably the adhesive proteins fibronectin and von Willebrand factor, that promote the Mg2(+)-independent mechanism.