HIV-Nef enhances interleukin-2 production and phosphatidylinositol 3-kinase activity in a human T cell line.

OBJECTIVE: The Nef protein has a major influence on disease pathogenesis in HIV-infected individuals. The objective of the present study was to examine the effects of Nef on T lymphocyte activation and associated signalling events. DESIGN: A recombinant vaccinia expression system was used to express Nef in a human T cell line. Stimulation of these cells with anti-CD28 antibody, and either phorbol 12-myristate 13-acetate (PMA) or anti-CD3, activates signal transduction pathways and results in IL-2 production and IL-2 receptor alpha-chain (CD25) expression. Cellular responses were examined in cells expressing either Nef or an irrelevant control protein. METHODS: Activation of signalling was assessed by immunoblot analysis, or by in-vitro phosphatidylinositol 3-kinase (PI3K) assays. IL-2 production was measured by enzyme-linked immunosorbent assay, and CD25 cell surface expression was examined using flow cytometry. RESULTS: Infection of cells with recombinant vaccinia expressing HIV-nef resulted in a marked increase in the production of IL-2 when cells were activated. The enhanced IL-2 response was accompanied by an increase in the level of PI3K activity. IL-2 production remained sensitive to inhibition with the PI3K competitive inhibitor Ly294002, and to the fungal macrolide, rapamycin. In contrast, CD25 expression was not affected, and there were no measurable changes to nuclear factor kappaB (NFkappaB) activation pathways. CONCLUSION: Enhanced IL-2 production in stimulated T cells expressing HIV-Nef is associated with increased activation of PI3K-dependent signalling pathways. The results support a model in which Nef affects HIV disease progression by distorting T cell responses.

CCR5 promoter polymorphisms, CCR5 59029A and CCR5 59353C, are under represented in HIV-1-infected long-term non-progressors. The Australian Long-Term Non-Progressor Study Group.

OBJECTIVE: To determine the influence of CCR5 promoter polymorphisms on HIV-1 progression to AIDS and to evaluate the interaction between CCR5 structural polymorphisms and those occurring in the regulatory region of the same gene. PARTICIPANTS: Seventy-one HIV-1-infected long-term non-progressors with a CD4+ T cell count of > 500 x 10(6)/I more than 8 years after infection were compared with 75 HIV-1-infected individuals who had progressed to AIDS and/or death within 8 years and with a further 119 HIV-1-positive patients who had CD4+ T cell counts of 200-500 x 10(6)/l. An additional 92 HIV-negative individuals were also studied. METHODS: CCR5 delta32 genotype was determined by PCR with primers spanning the 32 base pair deletion. CCR2-64I, CCR5 59029A/G and CCR5 59353C/T genotypes were determined by PCR followed by restriction fragment length polymorphism analysis. RESULTS: Strong linkage disequilibrium between the CCR5 59029A and CCR5 59353C polymorphic variants was identified. CCR5 59029A and CCR5 59353C homozygotes were found to be significantly under-represented in the long-term non-progressor group as compared with the other HIV-1-positive groups, with the effect being more marked in the absence of the CCR5 delta32 and CCR2 64I mutations. CONCLUSIONS: This study provides the first evidence for an association between CCR5 promoter polymorphisms and long-term asymptomatic HIV-1 infection, with individuals lacking the CCR5 59029A/CCR5 59353C homozygous genotype likely to progress more slowly towards AIDS and/or death.

Bacterial, viral and parasitic aetiology of paediatric diarrhoea in the highlands of Papua New Guinea.

Enteropathogens and clinical features associated with diarrhoea were investigated in 1526 children admitted over a 5-year period to the paediatric ward of a hospital in the highlands of Papua New Guinea. Overall, a recognized pathogen was isolated from 39 per cent of the children admitted with diarrhoea. The most commonly isolated agents were rotavirus (23 per cent), Shigella spp. (13 per cent), Campylobacter spp. (12 per cent), Cryptosporidium parvum (10 per cent) and enteropathogenic Escherichia coli (8 per cent). The clearest clinical associations were rotavirus with vomiting, and Shigella with blood and pus in the stool. A control series of children admitted with other complaints was also included, and the odds ratios for diarrhoea for the above five pathogens were 18.2, 9.6, 3.7, 2.2, and 1.6, respectively.