Age-related changes in expression of CXCR4 and CCR5 on peripheral blood leukocytes from uninfected infants born to human immunodeficiency virus type 1-infected mothers

Cross-sectional analysis of human immunodeficiency virus-exposed, uninfected infants revealed high proportions of CXCR4-expressing cells in their cord blood, which declined at 4.5 months and increased between 9 and 15 months to levels approaching those of uninfected adults. Proportions of CCR5-expressing cells, however, were very low in cord blood and subsequently increased with age.

Age-related changes in polymorphonuclear neutrophil characteristics in infants born to human immunodeficiency virus type 1 seropositive mothers

In infants, the major components of the innate immune system appear weakened, and it has been shown that both polymorphonuclear neutrophil (PMN) production and function are immature. This study was conducted to assess the expression of a number of receptors important to normal PMN function and the integrity of PMN degranulation in cord blood and in uninfected children of varying ages born to human immunodeficiency virus type 1 (HIV-1) seropositive mothers. Although the expression of l-selectin (CD62L) on PMN did not differ between the infants aged 12, 15 and 18 months, the expression of the interleukin-8 (IL-8) receptors CXCR1 and CXCR2, and the complement 5a (C5a) receptor CD88 displayed a similar pattern, with the highest levels expressed on PMN from infants in the 12 month old age group, and declining with age. It was also observed that PMN from a substantial proportion of the younger infants were unresponsive to a variety of stimuli including IL-8, C5a, stromal cell-derived factor (SDF)-1alpha, SDF-1beta, and phorbol 12-myristate 13-acetate (PMA), with the proportions of children showing positive (adult-like) PMN degranulation responses increasing with age. Exposure to HIV-1 did not appear to be the cause of impaired degranulation responses, since a similar proportion of cord blood PMN from uninfected infants born to HIV-1 infected and HIV-1 uninfected mothers were unresponsive. The altered expression of these important receptors and inefficient agonist-induced degranulation in early life may contribute to the increased susceptibility of infants to secondary microbial infections.

Evolution and diversity of HIV-1 in Africa--a review

The HIV/AIDS pandemic represents a major development crisis for the African continent, which is the worst affected region in the world. Currently, almost 30 of the 42 million people infected with HIV worldwide live in Africa. AIDS in humans is caused by two lentiviruses, HIV-1 and HIV-2, which entered the human population by zoonotic transmissions from at least two different African primate species. Extensive phylogenetic analyses of partial and full-length genome sequences have helped to gain insights into the evolutionary biology and population dynamics of HIV. One of the major characteristics of HIV is its rapid evolution, which has resulted in substantial genetic diversity amongst different isolates, the majority of which are represented in Africa. Genetic variability of HIV and any consequent phenotypic variation poses a significant challenge to disease control and surveillance in different geographic regions of Africa. This review focuses on the origins and evolution of HIV, current classification and diversity of HIV isolates in Africa and provides an extensive account of the geographic distribution of HIV types, groups, and subtypes in each of the 49 African countries. Numerous epidemiological studies have provided a picture of HIV distribution patterns in most countries in Africa, and these show increasing evidence of the importance of HIV-1 recombinants. In particular, this review highlights that our current understanding of HIV distribution in Africa is incomplete and inadequately represents the diversity of the virus, and underscores the need for ongoing surveillance.

Respiratory syncytial virus nucleoprotein-specific cytotoxic T-cell epitopes in a South African population of diverse HLA types are conserved in circulating field strains

This study identifies memory cytotoxic T lymphocyte (CTL) epitopes to respiratory syncytial virus (RSV) in healthy South African adults and demonstrates the conservation of those epitopes in circulating field strains of RSV in South Africa. Thirty-seven healthy adults from a population with diverse HLA backgrounds were screened by gamma interferon (IFN-gamma) enzyme-linked immunospot for memory CTL activity in response to overlapping peptides representing the complete nucleoprotein (N) of RSV. Responses of more than 40 spot-forming cells/million cells were detectable in 21 individuals. The significant responses were further characterized, and 14-mer peptides were identified that induced cytolytic activity. Fine mapping of peptides with the highest cytolytic activity identified an HLA-B(*)08-restricted RSV-specific CTL epitope. The extended 14-mer peptide containing this epitope also induced lysis in the context of A(*)02-restricted target cells in some individuals. These HLA types are common in the target population; thus, the epitope is useful for studies of CTL responses to RSV in humans. The epitope was detected in healthy adults, reflecting the response generated in the course of previous natural RSV infection. We obtained a large panel of naturally occurring isolates of RSV to determine whether there was evidence of escape from CTL activity in circulating strains. We found that this epitope and a previously identified B(*)07-restricted N protein epitope were conserved in RSV field strains representing the diversity of circulating genotypes. This work suggests that escape from CTL activity is not common for this acute respiratory infection.

Circulating levels of stromal cell-derived factor 1alpha and interleukin 7 in HIV type 1 infection and pulmonary tuberculosis are reciprocally related to CXCR4 expression on peripheral blood leukocytes

In sub-Saharan Africa the coincidence of HIV-1 and Mycobacterium tuberculosis coinfection is ever-increasing, this being associated with increased progression to disease and reduced patient survival. Raised plasma levels of stromal cell-derived factor (SDF)-1alpha and interleukin (IL)-7, cytokines important in T cell development, and in the modulation of surface CXCR4 expression, have been reported to be associated with HIV-1 disease progression. We have previously shown specific disease group-related down modulation in vivo of the SDF-1 ligand, CXCR4, in HIV-1-seropositive patients, patients with pulmonary tuberculosis, and patients coinfected with M. tuberculosis and HIV-1. In this study, both SDF-1alpha and IL-7 plasma levels were significantly elevated from normal in similar disease groups (p < 0.001). Both SDF-1alpha and IL-7 plasma levels correlated negatively with the percentage of all subsets of leukocytes expressing CXCR4, across the study groups regardless of the presence or absence of disease. This suggests that CXCR4 receptors are likely modulated in similar ways by increased levels of these cytokines, even though the underlying mechanism of their increased production is likely to be different. In addition, plasma levels of SDF-1alpha correlated negatively with percentage of CD4(+) T cells, and both SDF-1alpha and IL-7 levels correlated positively with plasma HIV-1 viral load. Collectively, these results confirm a role for SDF-1alpha and IL-7 in HIV-1 disease progression, and suggest that these cytokines play a role in the modulation of CXCR4.

Characterisation of near-full length genome sequences of three South African human immunodeficiency virus type 1 subtype C isolates

As subtype C is the most prevalent circulating human immunodeficiency virus type 1 (HIV-1) subtype internationally as well as locally in South Africa, more information on the biological nature and molecular characteristics of these viruses is required. Proviral DNA was isolated from primary cultures of three South African R5 isolates and the near-full length genome amplified by PCR. The resultant PCR product was cloned into the pCR-XL-TOPO vector and a representative clone from each isolate sequenced by primer walking. Phylogenetic analysis showed all three clones clustered within subtype C with a bootstrap value of 100%, and no recombination with other subtypes was identified by distance scan and bootscan analysis. Analysis of the potential coding regions revealed premature truncations of the second rev exon but no other potential structural distortions nor frameshift mutations in the open reading frames. All the clones contained three potential NF-kappaB binding sites, a feature unique to subtype C viruses. The tips of the V3 loops contained the GPGQ sequence motif characteristic of CCR5-utilising subtype C strains, as well as relatively low overall net positive charge characteristic of non-syncytium-inducing isolates. This information contributes to our overall knowledge of circulating strains in South Africa and to the making of effective vaccines and chemotherapeutic agents.

HIV-1 Subtype A, D, G, AG and unclassified sequences identified in South Africa

HIV-1 subtype C accounts for the vast majority of infections in South Africa. However, increasingly non-C subtypes are being detected. Here we report 10 viruses that contain sequences that group with subtypes A, D, and G as well as CRF02_AG and 1 that could not be classified. Most of these individuals were from other countries in Africa. Some of these sequences were in combination with subtype C, possibly indicating local recombination events. Although there is no indication of endemic spread of these viruses, continued monitoring is warranted to track genetic changes, which may impact on diagnostic testing, therapeutic responses to antiretroviral therapies, and vaccine design.

CD38 expression on CD8(+) T cells as a prognostic marker in vertically HIV-infected pediatric patients

Increased expression of CD38 on CD8(+) T cells is associated with activation of the immune system, progression of HIV disease, and death in adults. The prognostic significance of these cells in HIV-infected children, where the picture is complicated by age-related differences in CD38 expression, remains controversial. Measuring the unimodal expression of CD38 on CD8(+) T cells in adults and children by flow cytometry is best accomplished by quantitating the antigen on the cell surface. To our knowledge, this technique has not previously been reported in a pediatric population. Vertically HIV-infected children were age matched for mild (n = 26) and severe (n = 23) clinical disease. Eleven age-matched HIV-negative controls were included for comparison. Quantitation of CD38 on CD8(+) T cells was performed at baseline and 1 y later. The ages of the children in the three clinical groups did not differ significantly (p = 0.6004). HIV-infected children had significantly increased CD38 measurements in comparison with the HIV-negative controls (p = 0.0131), and the severe disease group tended to have higher measurements than the mild disease group. Increased CD38(+)CD8(+) T cells were significant predictors of death within the first year (p = 0.043). These findings support the view that increased CD38 expression on CD8(+) T cells has the same prognostic significance in pediatric as in adult HIV disease.

Distribution of the human immunodeficiency virus coreceptors CXCR4 and CCR5 on leukocytes of persons with human immunodeficiency virus type 1 infection and pulmonary tuberculosis: implications for pathogenesis

Expression of CXCR4 was significantly reduced from normal on all cell subsets of persons with pulmonary tuberculosis (TB group), with HIV-1 infection (HIV group), and those with both infections (HIV/TB group), except for on monocytes in the HIV group. The reductions were most notable in the two TB groups. Interestingly, the duration of antituberculosis treatment was significantly negatively correlated with the expression of CXCR4 on CD4+ and CD8+CD45RO+ cells, monocytes and NK cells, viral load, and proportions of CD38-expressing CD8+ lymphocytes, in HIV/TB patients. By contrast, CCR5 expression on most cell subsets analyzed was increased in all the disease groups, except for on monocytes in the two TB groups. There was no change in CCR5 expression on CD4+ cells when based on the disease groupings. However, higher proportions of CD4+CD45RA+ and CD8+ lymphocytes as well as B cells expressing CCR5 correlated with advancing HIV-1 disease, as did decreased proportions of CXCR4-expressing CD4+CD45RA+ cells.

Human immunodeficiency virus type 1 envelope-stimulated interleukin-2 production and survival of infected children with severe and mild clinical disease

Interleukin (IL)-2 production after stimulation with human immunodeficiency virus type 1 (HIV-1) envelope (Env) peptides, tetanus toxoid, and phytohemagglutinin was measured in peripheral blood mononuclear cells (PBMC) from 25 HIV-1-infected children with mild and 24 with severe clinical disease and from 15 uninfected children. Env-specific IL-2 production was detected in PBMC of 26.5% of HIV-1-infected children but in none of the uninfected. The absence of Env-specific responses at enrollment among infected children was associated with a 6-fold increased risk of mortality within a year, adjusting for clinical severity (P=.04). Among those with severe clinical disease, Env-stimulated IL-2 reactivity in PBMC was negatively correlated with HIV-1 RNA copy numbers in plasma at enrollment and was positively correlated with CD4 T cell percentages 1 year later. HIV-specific cellular immune responses may play a role in containing progression of HIV-1 infection in children, despite early deficits in cell-mediated immunity.

Genetic diversity and molecular epidemiology of respiratory syncytial virus over four consecutive seasons in South Africa: identification of new subgroup A and B genotypes

The molecular epidemiology of respiratory syncytial virus (RSV) was studied over four consecutive seasons (1997-2000) in a single tertiary hospital in South Africa: 225 isolates were subgrouped by RT-PCR and the resulting products sequenced. Subgroup A predominated in two seasons, while A and B co-circulated approximately equally in the other seasons. The nucleotide sequences of the C-terminal of the G-protein were compared to sequences representative of previously defined RSV genotypes. South African subgroup A and subgroup B isolates clustered into four and five genotypes respectively. One new subgroup A and three new subgroup B genotypes were identified. Different genotypes co-circulated in every season. Different circulation patterns were identified for group A and B isolates. Subgroup A revealed more variability and displacement of genotypes while subgroup B remained more consistent.

Altered expression of L-selectin (CD62L) on polymorphonuclear neutrophils of children vertically infected with human immunodeficiency virus type 1

The expression of the leukocyte adhesion molecule L-selectin (CD62L) on polymorphonuclear neutrophils (PMN) and circulating levels of the soluble form of the receptor (sCD62L) were determined for a group of HIV-1-infected children, categorized as having mild or severe disease, and a group of uninfected control children. The fluorescence intensity of CD62L on PMN was significantly reduced in the HIV-1-infected children with mild disease compared to the uninfected controls. The proportion of lymphocytes expressing CD62L, as well as their corresponding fluorescence intensities, was significantly reduced in both the mild and the severe disease groups compared to the uninfected children, while peripheral levels of sCD62L were significantly elevated in the HIV-1-infected children with mild and severe disease compared to the controls. Altered cell migration resulting from reduced expression of CD62L may be an important contributor to the increased susceptibility to secondary microbial infections seen in HIV-1-infected children.

Duration of sample storage dramatically alters expression of the human immunodeficiency virus coreceptors CXCR4 and CCR5

Expression of the chemokine receptors CXCR4 and CCR5 was monitored using EDTA-anticoagulated whole blood held for different time periods prior to fluorescent-antibody staining. When left overnight CXCR4 expression on leukocytes was substantially increased, whereas CCR5 expression was reduced. The results were similar when heparin and acid-citrate-dextrose were used as anticoagulants.

Altered expression of CD88 and associated impairment of complement 5a-induced neutrophil responses in human immunodeficiency virus type 1-infected patients with and without pulmonary tuberculosis

The effect of infection with human immunodeficiency virus type 1 (HIV patient group), infection with Mycobacterium tuberculosis (TB patient group), and coinfection with both of these organisms (HIV/TB patient group) on the expression of CD88 on polymorphonuclear leukocytes (PMNL) was determined by using a receptor-specific monoclonal antibody and flow cytometry. A significant reduction in the fluorescence intensity of CD88 on PMNL was observed in the HIV and HIV/TB groups, compared with both the healthy donor (HD) and TB groups. Furthermore, when degranulation of PMNL was induced by ligation of CD88 by complement 5a (C5a), a large proportion of patients in the HIV and the HIV/TB groups was found to have reciprocal degranulation responses. Patients in the 2 HIV groups also were found to have significantly reduced C5a-induced chemotactic responses and significantly elevated peripheral levels of C5a des Arg, compared with the HD and TB groups. These differences may contribute to the increased susceptibility of HIV-1-infected individuals to secondary microbial infections.

Defective neutrophil degranulation induced by interleukin-8 and complement 5a and down-regulation of associated receptors in children vertically infected with human immunodeficiency virus type 1

The polymorphonuclear neutrophils (PMNs) of patients infected with human immunodeficiency virus type 1 (HIV-1) show impaired microbicidal responses. The present study assessed the functional integrity of PMN degranulation responses and the expression of specific receptors that mediate these responses in a group of children vertically infected with HIV-1. PMN degranulation in response to interleukin-8 (IL-8) and complement 5a (C5a) was measured in a group of HIV-1-infected children with mild and severe clinical disease and in an uninfected control group. In addition, the expression of CXCR1, CXCR2, and CD88 on whole-blood PMNs was quantified by flow cytometry. Although CXCR1 expression was found to be largely unaltered in the HIV-1-infected children relative to that in the control children, the intensity of CXCR2 expression was significantly reduced in those with severe disease. Furthermore, there was a significant reduction in the percentage of cells expressing CD88 and in the intensity of CD88 fluorescence in the HIV-1-infected children compared to that in control children, with CD88 fluorescence intensity more significantly reduced in the presence of severe disease. PMNs from a large proportion of the HIV-1-infected children either showed reciprocal degranulation responses or were unresponsive to IL-8 and C5a, whereas the PMNs from the uninfected children showed positive responses. Inefficient agonist-induced degranulation may contribute to the increased susceptibility of HIV-1-infected children to secondary microbial infections. Furthermore, reduced expression of CXCR2 and CD88 may be suggestive of defects in other functions of PMNs from HIV-1-infected children.

Interleukin-8 fails to induce human immunodeficiency virus-1 expression in chronically infected promonocytic U1 cells but differentially modulates induction by proinflammatory cytokines

This study addresses the role of interleukin (IL)-8, a CXC-chemokine, the level of which is reported to be raised in the peripheral circulation of human immunodeficiency virus-1 (HIV-1)-infected individuals, during the induction of HIV-1 expression from latency and during cytokine-mediated HIV-1 up-regulation. IL-8 at the higher concentrations tested (> or = 100 ng/ml) was unable to induce HIV-1 expression in the chronically infected promonocytic U1 cell line, as measured by p24 antigen enzyme-linked immunosorbent assay (ELISA), whereas at lower concentrations of 1 and 10 ng/ml, constitutive HIV-1 expression was only marginally reduced. HIV-1 replication in acutely infected U937 cells was also significantly reduced by IL-8. The potent up-regulation of HIV-1 expression in U1 cells by tumour necrosis factor-alpha (TNF-alpha) remained unaffected by the addition of IL-8. HIV-1 induction by IL-1beta, IL-6 and TNF-beta, cytokines grouped here as intermediate HIV-1 inducers, was suppressed by IL-8 at concentrations of 1 and 10 ng/ml. However, IL-8 at 100 ng/ml did not significantly alter the effect of IL-1beta, synergized with IL-6 in enhancing, and marginally suppressed TNF-beta-induced HIV-1 expression. IL-8 suppressed granulocyte-macrophage colony-stimulating factor (GM-CSF) and enhanced interferon-gamma (IFN-gamma)-induced HIV-1 expression in a dose-dependent manner. Pretreatment of U1 cells with IL-8 did not alter the IL-8-mediated effects on cytokine-induced HIV-1 expression, suggesting that this chemokine exerts its effect at the time of HIV-1 induction or at a postinduction stage. Furthermore, IL-8 was itself induced by cytokines that up-regulate HIV-1 expression in U1 cells and the levels produced correlated directly with the levels of p24 antigen produced, suggesting common pathways for cytokine induction of both HIV-1 and IL-8. These results show that IL-8, typically a non-inducer, can differentially modulate HIV-1 expression in U1 cells and that this is dependent on the inducing cytokine and on the concentration of IL-8.

Cytokine-induced interleukin-8 production is depressed in chronic as opposed to acute human immunodeficiency virus 1 infection of promonocytic cells

Spontaneous secretion of interleukin 8 (IL-8) was higher in latently infected U1 cells than in acutely infected or uninfected parental U937 cells. However, the induction of IL-8 by various cytokines (IL-1 alpha, TNF-alpha, IL-6, TNF-beta, GM-CSF, IFN-gamma) was significantly reduced in U1 cells. Cytokine modulation of IL-8 production in U937 cells acutely infected with a T cell-tropic strain (IIIB) or monocytotropic strain (ADA) of human immunodeficiency virus 1 (HIV-1) (HIV-1IIIB and HIV-1ADA) was variable and showed strain-specific differences. The obtained results showed that the in vitro induction of IL-8 is impaired in promonocytic cells latently infected with HIV-1 and is differently modulated under acute conditions of infection depending on the IL-8 inducing cytokine and on the infecting virus strain.

Impaired interleukin-8-induced degranulation of polymorphonuclear neutrophils from human immunodeficiency virus type 1-infected individuals

Degranulation of peripheral blood polymorphonuclear leukocytes (PMNLs) was monitored in human immunodeficiency virus (HIV) type 1 (HIV-1)-infected individuals with or without pulmonary tuberculosis (HIV/TB and HIV groups, respectively) by measuring the release of beta-glucuronidase induced by interleukin-8 (IL-8). This was increased in a dose-dependent manner in the control groups consisting of healthy blood donors and patients with pulmonary tuberculosis. In contrast, PMNLs from the HIV and HIV/TB groups responded reciprocally in the same assay; that is, higher IL-8 input concentrations resulted in the release of less enzyme than lower IL-8 input concentrations. The degranulation response of PMNLs from HIV-1-infected individuals was similarly altered for another agonist, N-formyl-methionyl-leucyl-phenylalanine, suggesting that impairment of the nonoxidative armature of PMNL was a more generalized phenomenon. However, impaired IL-8-induced degranulation was found to be associated with the reduced expression of both IL-8 receptors, A and B, on whole-blood PMNLs from HIV-1-infected patients compared with that on whole-blood PMNLs from healthy persons. The density of IL-8RA, in particular, was most reduced on the surfaces of PMNLs from those patients with the poorest degranulation in response to IL-8. Inefficient agonist-induced degranulation may contribute to the increased susceptibility of HIV-1-infected persons to secondary microbial infections, this being further exacerbated in HIV/TB patients who, in addition, display defects in phagocytosis and oxidative burst.

Dysregulated production of interleukin-8 in individuals infected with human immunodeficiency virus type 1 and Mycobacterium tuberculosis

Interleukin-8 (IL-8) production in vivo was monitored in four study groups: normal blood donors, patients with pulmonary tuberculosis (TB), patients with human immunodeficiency virus type 1 (HIV-1) infection, and dually infected (HIV/TB) patients. We show that whereas there was evidence of detectable levels of cell-associated IL-8 (mRNA and protein) in peripheral cells of healthy individuals, this was largely lost in the disease states studied. Coupled with this finding was significantly increased circulating levels of IL-8 in HIV-1-infected individuals with or without concomitant pulmonary TB (P < 0.001). On the other hand, the capacity of peripheral mononuclear cells to produce IL-8 spontaneously ex vivo was enhanced in HIV-1 and TB patients (P < 0.05) and many of the HIV/TB group, but their corresponding capacities to respond to various stimuli, in particular phytohemagglutinin, were significantly diminished compared to those of normal donors (P < 0.05). Circulating levels of IL-8 in a group of HIV/TB patients were significantly positively correlated with the percentage of polymorphonuclear leukocytes (PMN) in the peripheral circulation (r = 0.65; P = 0.01), the proportions of IL-8 receptor A (IL-8RA)-expressing (r = 0.86; P < 0.01) and IL-8RB-expressing (r = 0.77; P < 0.01) PMN, and the capacity of PMN to migrate in response to IL-8 as chemoattractant (r = 0.68; P < 0. 01). IL-8RB fluorescence intensity, however, was negatively correlated with plasma IL-8 levels (r = -0.73; P < 0.01). Our results suggest that altered regulation of IL-8 in HIV-1 may have important implications for antimicrobial defenses and for normal immune processes.

Effects of anticoagulants and temperature on expression of activation markers CD11b and HLA-DR on human leukocytes

A whole-blood model was used to evaluate the effects of temperature and anticoagulant on the expression of activation markers HLA-DR and CD11b on peripheral leukocytes. Venous blood, anticoagulated with either EDTA or heparin, was obtained from six healthy blood donors and 13 hospitalized patients (8 human immunodeficiency virus type 1-seropositive individuals with concurrent pulmonary tuberculosis and 5 patients with pneumonia). A preliminary evaluation was carried out with whole blood from two of the normal donors, and cells were stained immediately for HLA-DR and CD11b markers or stained after incubation at room temperature or 37 degreesC for 18 h with or without the addition of the cytokines gamma interferon (IFN-gamma), granulocyte-macrophage colony-stimulating factor (GM-CSF), IFN-gamma plus GM-CSF, tumor necrosis factor beta, or interleukin-6. Of the cytokines tested, the combination of IFN-gamma and GM-CSF had the most pronounced modulation of marker expression on polymorphonuclear neutrophils (PMN), in particular, HLA-DR expression, which required induction for its detection. These cytokines were therefore used in further evaluations that considered the above-mentioned effects in the presence of disease. Results indicated that the expression of activation markers on PMN and lymphocytes in whole blood are influenced by the temperature of incubation and the choice of anticoagulant and the effects noted were dependent on (i) the particular cell surface marker, (ii) the cell type being studied, and (iii) the presence or absence of disease. It is therefore recommended that ex vivo whole-blood models for evaluating phenotype or immune function be carefully evaluated for the above-mentioned effects.

Reduced expression of interleukin-8 receptors A and B on polymorphonuclear neutrophils from persons with human immunodeficiency virus type 1 disease and pulmonary tuberculosis

The expression of the two human interleukin (IL)-8 receptors, designated IL-8RA (CXCR-1) and IL-8RB (CXCR-2), on the surface of whole blood polymorphonuclear leukocytes (PMNL) was determined by use of receptor-specific monoclonal antibodies and flow cytometry. Sixteen subjects each were included in 4 study groups: healthy blood donors (ND), patients with pulmonary tuberculosis (TB), human immunodeficiency virus type 1-seropositive patients (HIV), and HIV-1-seropositive subjects with pulmonary tuberculosis (HIV/TB). A significant reduction in the percentage of PMNL expressing IL-8RA and IL-8RB and in their respective fluorescence intensities was found in TB, HIV, and HIV/TB groups compared with that obtained for the ND group. The greatest down-regulation of both receptors occurred in the HIV/TB group. Furthermore, associated with this reduced expression of IL-8 receptors was impairment of both intracellular calcium flux and migration of PMNL in response to IL-8 in a group of HIV/TB patients compared with that in healthy persons.

Depressed phagocytosis and oxidative burst in polymorphonuclear leukocytes from individuals with pulmonary tuberculosis with or without human immunodeficiency virus type 1 infection

Phagocytosis and oxidative burst in whole-blood granulocytes were assessed by flow cytometry with Phagotest and Bursttest kits, respectively. Seventy individuals were included in this study: 15 healthy, normal donors, 18 human immunodeficiency virus (HIV) type 1 (HIV-1)-seropositive patients, 19 patients with pulmonary tuberculosis (TB), and 18 patients co-infected with Mycobacterium tuberculosis and HIV-1 (TB-HIV). Granulocyte phagocytosis was assessed by incubating whole blood with fluorescence-labelled Escherichia coli and measuring the proportion of granulocytes with ingested bacteria and the capacity (fluorescence intensity) of each cell to phagocytose E. coli. The percentage of granulocytes converting nonfluorescent dihydrorhodamine to fluorescent rhodamine 123 on production of reactive oxygen intermediates (ROIs) and the mean channel shift were assessed as a measure of oxidative burst. No differences in the proportion of granulocytes that were capable of phagocytosing or producing ROIs in response to E. coli were observed between any of the study groups. Phagocytosis was significantly enhanced in granulocytes from HIV-1-infected individuals. On the other hand, granulocytes from individuals infected with M. tuberculosis alone or in combination with HIV-1 had a significantly reduced capacity to phagocytose E. coli and to produce ROIs in response to E. coli as an agonist. These results provide evidence that granulocytes from individuals with pulmonary TB with or without concomitant infection with HIV-1 have an impaired ability to phagocytose and to undergo oxidative burst, possibly contributing to the enhanced susceptibility to opportunistic infections in these patients.

Interleukin-4 regulation of cytokine-induced HIV1 and interleukin-8 expression in promonocytic U1 cells is concentration- and cytokine-dependent

IL4 has been shown to differentially modulate HIV1 replication in primary cells of the monocyte/macrophage lineage. Its effects on chronic HIV1 infection, however, are unknown. To address IL4-mediated effects on promonocytic cells chronically infected with HIV1, U1 cells were incubated in the presence or absence of IL4 together with cytokines that are known to induce both HIV1 and IL8 expression. IL4 enhanced IL1 beta-induced HIV1 and IL8 expression in promonocytic U1 cells, whereas it suppressed their expression induced by cytokines IL6, GM-CSF and to a small extent, TNF alpha. IL4 suppressed IFN gamma-induced IL8 production with increasing IL4 concentration, while HIV1 p24 core antigen production was suppressed at low IL4 input (0.1 and 1 U/ml) but was substantially enhanced at a high IL4 input concentration (10 U/ml). Results showed that the immunosuppressive cytokine IL4 can behave variably in modulating HIV1 and IL8 expression, depending on both the inducing cytokine and the input concentration of IL4.

Altered expression of Fc gammaRIII (CD16) on polymorphonuclear neutrophils from individuals with human immunodeficiency virus type 1 disease and pulmonary tuberculosis

Fc gammaRIII (CD16) expression on the surfaces of polymorphonuclear neutrophils was significantly reduced in human immunodeficiency virus type 1-seropositive patients with pulmonary tuberculosis compared to that in individuals with either disease alone or in healthy blood donors. This downregulation of Fc gammaRIII may contribute to the enhanced susceptibility of coinfected individuals to opportunistic infections.

Adenovirus 41 replication: cell-related differences in viral gene transcription

Adenovirus 41 infection of human embryo fibroblasts (HEF cells) leads to an abortive replication cycle whereas semi-permissive infection of Chang cells and permissive infection of 293 cells leads to the production of infectious particles. The aim of this study was to delineate where in the viral life cycle the block in replication occurs in non-permissive cells. DNA replication marks the onset of the late stage of the replication cycle but synthesis of DNA could only be detected when cultures were co-infected with Ad2, suggesting an early block in Ad41 replication. In order to map Ad41-specific transcripts produced following infection of HEF, Chang and 293 cells, tentative transcription units (determined by alignment with the Ad2 and Ad40 transcription maps) were first assigned to various plasmids carrying Pstl fragments. These plasmids were used as probes to detect Ad41 transcripts that map to these regions. Only transcripts mapping to the region between 0 and 12 map units were detected in Ad41 infected HEF cells. The level of late transcription was found to be low even in Chang and 293 cells and we therefore employed a more sensitive method to detect major late transcripts in Ad41 infected HEF cells. Transcripts carrying 59 kDa-fibre gene-specific sequences could be detected using RT-PCR at earlier times in 293 cells when compared to Chang cells but were present over a much longer time period in the latter cells, and could not be detected in HEF cells. These results are in agreement with the results from DNA synthesis in Ad41 infected HEF cells and mapping of transcripts to specific regions of the Ad41 genome, confirming that the Ad41 block in replication occurs within the early phase of the infectious cycle.

Detection and typing of subgroup F adenoviruses using the polymerase chain reaction

A DNA amplification test was developed for the sensitive detection of the diarrhoea-associated subgroup F adenoviruses in clinical specimens. The test was made highly specific for serotypes 40 and 41 by using a region of the genome (the long-fiber gene) which is not significantly homologous to other human adenoviruses, but which is highly conserved between Ad40 and Ad41. A positive subgroup F adenovirus diagnosis was characterized by the presence of an amplification product of 152 base pairs, which could be digested into products of predictable length by restriction enzymes XbaI and SpeI. The viruses were typed as either Ad40 or Ad41 by digestion of the amplification product with a restriction enzyme which digested only Ad40 DNA. The specificity of the test was assessed using DNA from other adenoviruses, from human and simian cells, and from bacteria commonly found in the human intestine. There was a strong correlation between results of typing obtained with PCR and restriction enzyme typing of Ad40 and Ad41, and also positivity using subgroup F specific probes in dot blot hybridizations.

Adenovirus type 40 and 41 growth in vitro: host range diversity reflected by differences in patterns of DNA replication

Subgroup F adenoviruses adapt poorly to cell culture, but the reasons for their fastidious nature are as yet ill defined. In an attempt to gain an overview of the differences in replication between adenovirus type 2 (Ad2) and representative strains of Ad40 and Ad41, cell lines which show different degrees of permissiveness to Ad40 and Ad41 were infected and examined with respect to three key functions in the Ad2 life cycle: host protein shutoff, DNA synthesis, and late antigen synthesis. The complexity of growth patterns exhibited by the subgroup F adenoviruses suggests that defectiveness is a multifactorial phenomenon not easily explainable by a single aberrant function. Furthermore, results suggest that there may be replicative defects in subgroup F adenoviruses which are not shared by both serotypes or by all strains.

Characterization of a single SA7-like VA RNA gene in subgroup F adenoviruses

The virus-associated (VA) RNA gene regions of the human subgroup F adenoviruses (types 40 and 41) were amplified using primers corresponding to flanking open reading frames of human and simian (SA7) adenovirus sequences previously published. The subgroup F adeno-viruses, like human Ad12 (subgroup A) and SA7, were found to have only one VA RNA gene at this locus (map unit 30). The type 40 and type 41 VA RNA genes have primary sequence characteristics in common with other known VA RNA genes, have high cross-identity (93%), and show appreciably higher identity to the single VA RNA gene present in SA7 (77% and 81%, respectively) than to any of the VA RNA genes of Ad2, Ad7 or Ad12 (< 61%). These findings may have implications for explaining the evolution and growth peculiarities of human subgroup F adenoviruses.

Sensitivity of subgroup F adenoviruses to interferon

The subgroup F adenoviruses were tested for their ability to induce interferon in semi-permissive human cells (Chang conjunctiva) and non-permissive cells (HEF, human embryo lung fibroblasts). These cells did not produce interferon spontaneously or in response to infection by either of these adenoviruses. It was concluded that interferon induction in response to subgroup F adenovirus infection is not a likely explanation of limited virus growth in culture. Adenovirus 40 and Ad41, unlike Ad2, were found to be sensitive to human lymphoblastoid interferon in Chang conjunctival cells. The addition of Ad2 to cells before pretreatment with interferon resulted in the partial and complete abrogation of Ad40 and Ad41 interferon sensitivity, respectively. The suppressive effect of Ad2 on the inhibitory action of interferon and the modulatory function of Ad2 in mixed infection with either Ad40 or Ad41 suggests the inadequate functioning of a subgroup F adenovirus gene product or products involved in suppression of the interferon-induced antiviral state.

Subgroup F adenovirus growth in foetal intestinal organ cultures

An in vitro foetal intestinal organ culture system was employed to determine the permissiveness of human intestinal cells for subgroup F adenovirus infection. Ad40 and Ad41 growth, monitored through group-specific hexon antigen production, was poor in comparison to that of Ad2 in these cultures, further demonstrating their fastidious nature in most human cells. The low growth capability of these viruses in culture, in relation to their association with gastrointestinal disease is discussed.

Fiber sequence heterogeneity in subgroup F adenoviruses

The fiber gene of adenovirus type 41 was sequenced and compared to the fiber gene sequence of adenovirus type 40 (A. H. Kidd and M. J. Erasmus, 1989, Virology 172, 134-144), the other known member of subgroup F. The open reading frame, from map units 87 through 92 with transcription from the r-strand, comprised 1686 bases and was 45 bases longer than its counterpart on the Ad40 genome. The 45-base difference appears to have resulted from a block deletion on the Ad40 sequence. Apart from this one region, the Ad40 and Ad41 fiber genes showed remarkably high homology (95.6%), indicating a relatively recent evolutionary divergence. The deduced amino acid sequence of the Ad41 fiber polypeptide was analyzed according to the model of N. M. Green et al. (1983, EMBO J. 2, 1357-1365) for the structure of the adenovirus fiber. Ad41 had one more 15-residue repeat in the shaft region than Ad40, there being 22 repeat motifs. A detailed study of various Ad40 and Ad41 strains with proven genome differences indicated that the 15-amino acid difference in polypeptide length at the 14th repeat motif is a type-specific difference among the subgroup F adenoviruses. However, two uncommon Ad41 strains belonging to 2 of the 16 Ad41 genome types tested had a 15-amino acid block deletion which was different to that of the Ad40 polypeptide. The implication from this work is that the Ad40 fiber gene probably arose from its Ad41 counterpart, but the fiber gene sequences of both types of subgroup F adenovirus are so similar that genetic recombination between strains could occur with some frequency.

Adenovirus 41 growth in semi-permissive cells shows multiple-hit kinetics

Adenovirus type 41 infection of semi-permissive Chang conjunctival cells, monitored by fluorescent focus assay, followed multiple-hit kinetics. In non-permissive human cells, type 41 showed infectivity with two-hit kinetics in the presence of type 2. Type 41 infectivity was seen to be directly proportional to input concentration (one-hit) only in 293 cells, a continuous human line expressing Ad 5 E1 products.

Infection by enteric adenoviruses, rotaviruses, and other agents in a rural African environment

From February 1985 to January 1986, 432 stool samples, 310 from rural African children with diarrhea and 122 from controls, were analysed for the presence of enteric viruses known to be associated with diarrhea. Group A rotavirus ELISA indicated 12.9% positivity among patients and 2.5% positivity among controls. Only 23 of the 43 rotavirus ELISA-positive stools were also positive by electron microscopy. Nine children, three of whom were controls, were found to be shedding coronavirus-like particles, detected by electron microscopy. Stools from all but one of the nine children had been taken within 1 month of each other. Dot-blot hybridization tests for the presence of Ad40 or Ad41 DNA revealed 44 positive stools, 41 of which were from patients (13.2% positivity). Only three of the Ad40-or Ad41-positive stools by DNA hybridization were positive by electron microscopy, and only these three strains could be grown in semipermissive Chang conjunctival cells and their identity checked by restriction enzyme analysis. Further attempts to rescue the other strains using a helper virus failed, but nine of the stools proved positive by ELISA using a subgroup F-specific monoclonal antibody. On the basis of the DNA hybridization results alone, subgroup F adenoviruses were encountered as frequently as rotavirus in the study and were significantly associated with diarrhea, although the viability and intactness of virus particles by the time of laboratory analysis appeared to be very low.

Helper function of adenovirus 2 for adenovirus 41 antigen synthesis in semi-permissive and non-permissive cells

Using a fluorescent focus assay, complementation and interference effects of Ad2 and Ad41 on each other in mixed infection were investigated. Ad2 provided a helper function for Ad41 late antigen synthesis in cells normally non-permissive for Ad41 growth (HEF cells), and enhanced Ad41 late antigen synthesis in semi-permissive Chang conjunctival cells. The degree of complementation by Ad2 was dependent on its input concentration. In addition, interference by Ad41 on Ad2 replication was seen in HEF cells. The degree of interference by Ad41 was dependent on the relative time of infection by each serotype. The complementation results in HEF cells suggest an absolute dependency of Ad41 on an adenovirus helper function in these cells. The results presented are consistent with the postulated helper function provided in trans by 293 cells, which are transformed by Ad5 early region 1.

Characterization of rotaviruses and subgroup F adenoviruses from acute summer gastroenteritis in South Africa

Six hundred and sixteen specimens were collected from black children hospitalised with acute gastroenteritis during the summer and autumn of 1982-1983 (October to May). Eighty-five children (13.8%) shed rotavirus and at least 40 (6.5%) shed adenovirus (Ad) type 40 or 41 belonging to subgroup F. The highest monthly prevalence of shedding subgroup F adenoviruses (10.1%) coincided with a peak in admissions in midsummer, whereas the highest monthly prevalence of shedding rotaviruses (41.9%) coincided with a peak in admissions in autumn. There were at least five genome types of rotavirus, at least three genome types of Ad40, and at least five genome types of Ad41 circulating in the Johannesburg-Soweto area during the study period. The high rate of rotavirus shedding in autumn could not be attributed to an upsurge in infections by any particular rotavirus strain.