Paul U Cameron

Publications of Paul U Cameron

• The role of naïve T-cells in HIV-1 pathogenesis: an emerging key player.

  Authors: Gabriela Khoury, Reena Rajasuriar, Paul U Cameron, Sharon R Lewin

  Clinical immunology (Orlando, Fla.). 12/2011; 141(3):253-67.

  Functional naïve T-cells are critical for an effective immune response to multiple pathogens. HIV leads to a significant reduction in CD4+ naïve T-cell number and impaired function and there isFunctional naïve T-cells are critical for an effective immune response to multiple pathogens. HIV leads to a significant reduction in CD4+ naïve T-cell number and impaired function and there is incomplete recovery following combination antiretroviral therapy (cART). Here we review the basic homeostatic mechanisms that maintain naïve CD4+ T-cells and discuss recent developments in understanding the impact of HIV infection on naïve CD4+ T-cells. Finally we review therapeutic interventions in HIV-infected individuals aimed at specifically enhancing recovery of naïve CD4+ T-cells.

• Early events of HIV-1 infection: can signaling be the next therapeutic target?

  Authors: Kate L Jones, Redmond P Smyth, Cândida F Pereira, Paul U Cameron, Sharon R Lewin, Anthony Jaworowski, Johnson Mak

  Journal of neuroimmune pharmacology : the official journal of the Society on NeuroImmune Pharmacology. 03/2011; 6(2):269-83.

  Intracellular signaling events are signposts of biological processes, which govern the direction and action of biological activities. Through millions of years of evolution, pathogens, such asIntracellular signaling events are signposts of biological processes, which govern the direction and action of biological activities. Through millions of years of evolution, pathogens, such as viruses, have evolved to hijack host cell machinery to infect their targets and are therefore dependent on host cell signaling for replication. This review will detail our current understanding of the signaling events that are important for the early steps of HIV-1 replication. More specifically, the therapeutic potential of signaling events associated with chemokine coreceptors, virus entry, viral synapses, and post-entry processes will be discussed. We argue that these pathways may represent novel targets for antiviral therapy.

• Differential expression of CD163 on monocyte subsets in healthy and HIV-1 infected individuals.

  Authors: Emma Tippett, Wan-Jung Cheng, Clare Westhorpe, Paul U Cameron, Bruce J Brew, Sharon R Lewin, Anthony Jaworowski, Suzanne M Crowe

  PloS one. 01/2011; 6(5):e19968.

  CD163, a haptoglobin-hemoglobin (Hp-Hb) scavenger receptor, expressed by monocytes and macrophages, is important in resolution of inflammation. Age-related non-AIDS co-morbidities in HIV-infectedCD163, a haptoglobin-hemoglobin (Hp-Hb) scavenger receptor, expressed by monocytes and macrophages, is important in resolution of inflammation. Age-related non-AIDS co-morbidities in HIV-infected individuals, particularly dementia and cardiovascular disease, result in part from effects of HIV-1 infection on monocyte and macrophage biology. CD163 co-expression on CD14+CD16++ monocytes has been proposed as a useful biomarker for HIV-1 disease progression and the presence of HIV associated dementia. Here we investigated CD163 expression on monocyte subsets ex vivo, on cultured macrophages, and soluble in plasma, in the setting of HIV-1 infection. Whole blood immunophenotyping revealed CD163 expression on CD14++CD16- monocytes but not on CD14+CD16++ monocytes (P = 0.004), supported by CD163 mRNA levels. Incubation with M-CSF induced CD163 protein expression on CD14+CD16++ monocytes to the same extent as CD14++CD16- monocytes. CD163 expression on CD14++CD16+ monocytes from HIV-infected subjects was significantly higher than from uninfected individuals, with a trend towards increased expression on CD14++CD16- monocytes (P = 0.019 and 0.069 respectively), which is accounted for by HIV-1 therapy including protease inhibitors. Shedding of CD163 was shown to predominantly occur from the CD14++CD16- subset after Ficoll isolation and LPS stimulation. Soluble CD163 concentration in plasma from HIV-1 infected donors was similar to HIV-1 uninfected donors. Monocyte CD163 expression in HIV-1 infected patients showed a complicated relationship with classical measures of disease progression. Our findings clarify technical issues regarding CD163 expression on monocyte subsets and further elucidates its role in HIV-associated inflammation by demonstrating that CD163 is readily lost from CD14++CD16- monocytes and induced in pro-inflammatory CD14+CD16++ monocytes by M-CSF. Our data show that all monocyte subsets are potentially capable of differentiating into CD163-expressing anti-inflammatory macrophages given appropriate stimuli. Levels of CD163 expression on monocytes may be a potential biomarker reflecting efforts by the immune system to resolve immune activation and inflammation in HIV-infected individuals.

• Expression and reactivation of HIV in a chemokine induced model of HIV latency in primary resting CD4+ T cells.

  Authors: Suha Saleh, Fiona Wightman, Saumya Ramanayake, Marina Alexander, Nitasha Kumar, Gabriela Khoury, Cândida Pereira, Damian Purcell, Paul U Cameron, Sharon R Lewin

  Retrovirology. 01/2011; 8:80.

  We recently described that HIV latent infection can be established in vitro following incubation of resting CD4+ T-cells with chemokines that bind to CCR7. The main aim of this study was to fullyWe recently described that HIV latent infection can be established in vitro following incubation of resting CD4+ T-cells with chemokines that bind to CCR7. The main aim of this study was to fully define the post-integration blocks to virus replication in this model of CCL19-induced HIV latency. High levels of integrated HIV DNA but low production of reverse transcriptase (RT) was found in CCL19-treated CD4+ T-cells infected with either wild type (WT) NL4.3 or single round envelope deleted NL4.3 pseudotyped virus (NL4.3- Δenv). Supernatants from CCL19-treated cells infected with either WT NL4.3 or NL4.3- Δenv did not induce luciferase expression in TZM-bl cells, and there was no expression of intracellular p24. Following infection of CCL19-treated CD4+ T-cells with NL4.3 with enhanced green fluorescent protein (EGFP) inserted into the nef open reading frame (NL4.3- Δnef-EGFP), there was no EGFP expression detected. These data are consistent with non-productive latent infection of CCL19-treated infected CD4+ T-cells. Treatment of cells with phytohemagluttinin (PHA)/IL-2 or CCL19, prior to infection with WT NL4.3, resulted in a mean fold change in unspliced (US) RNA at day 4 compared to day 0 of 21.2 and 1.1 respectively (p = 0.01; n = 5), and the mean expression of multiply spliced (MS) RNA was 56,000, and 5,000 copies/million cells respectively (p = 0.01; n = 5). In CCL19-treated infected CD4+ T-cells, MS-RNA was detected in the nucleus and not in the cytoplasm; in contrast to PHA/IL-2 activated infected cells where MS RNA was detected in both. Virus could be recovered from CCL19-treated infected CD4+ T-cells following mitogen stimulation (with PHA and phorbyl myristate acetate (PMA)) as well as TNFα, IL-7, prostratin and vorinostat. In this model of CCL19-induced HIV latency, we demonstrate HIV integration without spontaneous production of infectious virus, detection of MS RNA in the nucleus only, and the induction of virus production with multiple activating stimuli. These data are consistent with ex vivo findings from latently infected CD4+ T-cells from patients on combination antiretroviral therapy, and therefore provide further support of this model as an excellent in vitro model of HIV latency.

• Thymic plasmacytoid dendritic cells are susceptible to productive HIV-1 infection and efficiently transfer R5 HIV-1 to thymocytes in vitro.

  Authors: Vanessa A Evans, Luxshimi Lal, Ramesh Akkina, Ajantha Solomon, Edwina Wright, Sharon R Lewin, Paul U Cameron

  Retrovirology. 01/2011; 8:43.

  HIV-1 infection of the thymus contributes to the defective regeneration and loss of CD4+ T cells in HIV-1-infected individuals. As thymic dendritic cells (DC) are permissive to infection by HIV-1, weHIV-1 infection of the thymus contributes to the defective regeneration and loss of CD4+ T cells in HIV-1-infected individuals. As thymic dendritic cells (DC) are permissive to infection by HIV-1, we examined the ability of thymic DC to enhance infection of thymocytes which may contribute to the overall depletion of CD4+ T cells. We compared productive infection in isolated human thymic and blood CD11c+ myeloid DC (mDC) and CD123+ plasmacytoid DC (pDC) using enhanced green fluorescent protein (EGFP) CCR5 (R5)-tropic NL(AD8) and CXCR4 (X4)-tropic NL4-3 HIV-1 reporter viruses. Transfer of productive HIV-1 infection from thymic mDC and pDC was determined by culturing these DC subsets either alone or with sorted thymocytes. Productive infection was observed in both thymic pDC and mDC following exposure to R5 HIV-1 and X4 HIV-1. Thymic pDC were more frequently productively infected by both R5 and X4 HIV-1 than thymic mDC (p = 0.03; n = 6). Thymic pDC efficiently transferred productive R5 HIV-1 infection to both CD3(hi) (p = 0.01; mean fold increase of 6.5; n = 6) and CD3(lo) thymocytes (mean fold increase of 1.6; n = 2). In comparison, transfer of productive infection by thymic mDC was not observed for either X4 or R5 HIV-1. The capacity of thymic pDC to efficiently transfer R5 HIV-1 to both mature and immature thymocytes that are otherwise refractory to R5 virus may represent a pathway to early infection and impaired production of thymocytes and CD4+ T cells in HIV-1-infected individuals.

• Clinical predictors of immune reconstitution following combination antiretroviral therapy in patients from the Australian HIV Observational Database.

  Authors: Reena Rajasuriar, Maelenn Gouillou, Tim Spelman, Tim Read, Jennifer Hoy, Matthew Law, Paul U Cameron, Kathy Petoumenos, Sharon R Lewin

  PloS one. 01/2011; 6(6):e20713.

  A small but significant number of patients do not achieve CD4 T-cell counts >500 cells/µl despite years of suppressive cART. These patients remain at risk of AIDS and non-AIDS defining illnesses. TheA small but significant number of patients do not achieve CD4 T-cell counts >500 cells/µl despite years of suppressive cART. These patients remain at risk of AIDS and non-AIDS defining illnesses. The aim of this study was to identify clinical factors associated with CD4 T-cell recovery following long-term cART. Patients with the following inclusion criteria were selected from the Australian HIV Observational Database (AHOD): cART as their first regimen initiated at CD4 T-cell count <500 cells/µl, HIV RNA<500 copies/ml after 6 months of cART and sustained for at least 12 months. The Cox proportional hazards model was used to identify determinants associated with time to achieve CD4 T-cell counts >500 cells/µl and >200 cells/µl. 501 patients were eligible for inclusion from AHOD (n = 2853). The median (IQR) age and baseline CD4 T-cell counts were 39 (32-47) years and 236 (130-350) cells/µl, respectively. A major strength of this study is the long follow-up duration, median (IQR) = 6.5(3-10) years. Most patients (80%) achieved CD4 T-cell counts >500 cells/µl, but in 8%, this took >5 years. Among the patients who failed to reach a CD4 T-cell count >500 cells/µl, 16% received cART for >10 years. In a multivariate analysis, faster time to achieve a CD4 T-cell count >500 cells/µl was associated with higher baseline CD4 T-cell counts (p<0.001), younger age (p = 0.019) and treatment initiation with a protease inhibitor (PI)-based regimen (vs. non-nucleoside reverse transcriptase inhibitor, NNRTI; p = 0.043). Factors associated with achieving CD4 T-cell counts >200 cells/µl included higher baseline CD4 T-cell count (p<0.001), not having a prior AIDS-defining illness (p = 0.018) and higher baseline HIV RNA (p<0.001). The time taken to achieve a CD4 T-cell count >500 cells/µl despite long-term cART is prolonged in a subset of patients in AHOD. Starting cART early with a PI-based regimen (vs. NNRTI-based regimen) is associated with more rapid recovery of a CD4 T-cell count >500 cells/µl.

• Splenectomy associated changes in IgM memory B cells in an adult spleen registry cohort.

  Authors: Paul U Cameron, Penelope Jones, Malgorzata Gorniak, Kate Dunster, Eldho Paul, Sharon Lewin, Ian Woolley, Denis Spelman

  PloS one. 01/2011; 6(8):e23164.

  Asplenic patients have a lifelong risk of overwhelming post-splenectomy infection and have been reported to have low numbers of peripheral blood IgM memory B cells. The clinical value of quantitationAsplenic patients have a lifelong risk of overwhelming post-splenectomy infection and have been reported to have low numbers of peripheral blood IgM memory B cells. The clinical value of quantitation of memory B cells as an indicator of splenic abnormality or risk of infection has been unclear. To assess changes in B cell sub-populations after splenectomy we studied patients recruited to a spleen registry (n = 591). A subset of 209 adult asplenic or hyposplenic subjects, and normal controls (n = 140) were tested for IgM memory B cells. We also determined a) changes in IgM memory B cells with time after splenectomy using the cross-sectional data from patients on the registry and b) the kinetics of changes in haematological markers associated with splenectomy(n = 45). Total B cells in splenectomy patients did not differ from controls, but memory B cells, IgM memory B cells and switched B cells were significantly (p<0.001) reduced. The reduction was similar for different indications for splenectomy. Changes of asplenia in routine blood films including presence of Howell-Jolly bodies (HJB), occurred early (median 25 days) and splenectomy associated thrombocytosis and lymphocytosis peaked by 50 days. There was a more gradual decrease in IgM memory B cells reaching a stable level within 6 months after splenectomy. IgM memory B cells as proportion of B cells was the best discriminator between splenectomized patients and normal controls and at the optimal cut-off of 4.53, showed a true positive rate of 95% and false positive rate of 20%. In a survey of 152 registry patients stratified by IgM memory B cells around this cut-off there was no association with minor infections and no registry patients experienced OPSI during the study. Despite significant changes after splenectomy, conventional measures of IgM memory cells have limited clinical utility in this population.

• The influence of splenectomy on the infectious complications and outcomes of people with HIV: marked, sustained elevation in risk of severe infection with bacteria including Streptococcus pneumoniae.

  Authors: Mark N Polizzotto, Penelope Jones, Paul U Cameron, Denis Spelman, Ian J Woolley

  Journal of acquired immune deficiency syndromes (1999). 11/2010; 55(3):e24-6.

• Both CD31(+) and CD31⁻ naive CD4(+) T cells are persistent HIV type 1-infected reservoirs in individuals receiving antiretroviral therapy.

  Authors: Fiona Wightman, Ajantha Solomon, Gabriela Khoury, Justin A Green, Lachlan Gray, Paul R Gorry, Yung Shwen Ho, Nitin K Saksena, Jennifer Hoy, Suzanne M Crowe, Paul U Cameron, Sharon R Lewin

  The Journal of infectious diseases. 10/2010; 202(11):1738-48.

  Naive T cell recovery is critical for successful immune reconstitution after antiretroviral therapy (ART), but the relative contribution of CD31(+) and CD31⁻ naive T cells to immune reconstitutionNaive T cell recovery is critical for successful immune reconstitution after antiretroviral therapy (ART), but the relative contribution of CD31(+) and CD31⁻ naive T cells to immune reconstitution and viral persistence is unknown. In a cross-sectional (n = 94) and longitudinal (n = 10) study of human immunodeficiency virus (HIV)-infected patients before and after ART, we examined the ratio of CD31(+) to CD31⁻ naive CD4(+) T cells. In the longitudinal cohort we then quantified the concentration of HIV-1 DNA in each cell subset and performed single-genome amplification of virus from memory and naive T cells. Patients receiving ART had a higher proportion of CD31(+) CD4(+) T cells than HIV-1-infected individuals naive to ART and uninfected control subjects (P < .001 and .007, respectively). After 24 months of ART, the proportion of CD31(+) naive CD4(+) T cells did not change, the concentration of HIV-1 DNA in memory CD4(+) T cells significantly decreased over time (P < .001), and there was no change in the concentration of HIV-1 DNA in CD31(+) or CD31⁻ naive CD4(+) T cells (P = .751 and .251, respectively). Single-genome amplification showed no evidence of virus compartmentalization in memory and naive T cell subsets before or after ART. After ART, both CD31(+) and CD31⁻ naive CD4(+) T cells expand, and both subsets represent a stable, persistent reservoir of HIV-1.

• Establishment of HIV-1 latency in resting CD4+ T cells depends on chemokine-induced changes in the actin cytoskeleton.

  Authors: Paul U Cameron, Suha Saleh, Georgina Sallmann, Ajantha Solomon, Fiona Wightman, Vanessa A Evans, Genevieve Boucher, Elias K Haddad, Rafick-Pierre Sekaly, Andrew N Harman, Jenny L Anderson, Kate L Jones, Johnson Mak, Anthony L Cunningham, Anthony Jaworowski, Sharon R Lewin

  Proceedings of the National Academy of Sciences of the United States of America. 09/2010; 107(39):16934-9.

  Eradication of HIV-1 with highly active antiretroviral therapy (HAART) is not possible due to the persistence of long-lived, latently infected resting memory CD4(+) T cells. We now show that HIV-1Eradication of HIV-1 with highly active antiretroviral therapy (HAART) is not possible due to the persistence of long-lived, latently infected resting memory CD4(+) T cells. We now show that HIV-1 latency can be established in resting CD4(+) T cells infected with HIV-1 after exposure to ligands for CCR7 (CCL19), CXCR3 (CXCL9 and CXCL10), and CCR6 (CCL20) but not in unactivated CD4(+) T cells. The mechanism did not involve cell activation or significant changes in gene expression, but was associated with rapid dephosphorylation of cofilin and changes in filamentous actin. Incubation with chemokine before infection led to efficient HIV-1 nuclear localization and integration and this was inhibited by the actin stabilizer jasplakinolide. We propose a unique pathway for establishment of latency by direct HIV-1 infection of resting CD4(+) T cells during normal chemokine-directed recirculation of CD4(+) T cells between blood and tissue.

• HIV inhibits early signal transduction events triggered by CD16 cross-linking on NK cells, which are important for antibody-dependent cellular cytotoxicity.

  Authors: Gregor F Lichtfuss, Aislin C Meehan, Wan-Jung Cheng, Paul U Cameron, Sharon R Lewin, Suzanne M Crowe, Anthony Jaworowski

  Journal of leukocyte biology. 09/2010; 89(1):149-58.

  Measurement of NK cell cytolytic activity in the setting of chronic viral infection is important for determining viral pathogenicity. Mobilization of LAMP-1 (CD107a) to the NK cell surface is aMeasurement of NK cell cytolytic activity in the setting of chronic viral infection is important for determining viral pathogenicity. Mobilization of LAMP-1 (CD107a) to the NK cell surface is a surrogate marker for cytotoxic granule release and hence, NK cell cytotoxicity. We have developed a convenient, rapid, whole blood flow cytometric assay for measuring CD107a mobilization in response to CD16 cross-linking, a surrogate for NK cell ADCC activity ex vivo, which can be performed using small volumes of patient whole blood. Using this assay, we show that CD107a mobilization, in response to CD16 cross-linking, is triggered in CD56(dim) but not CD56(bright) NK cells, requiring Syk/Zap70 tyrosine kinase activity, and that there is a significant correlation between CD107a mobilization and pSyk/Zap70 in response to CD16 cross-linking. We compared whole blood from treatment-naïve, HIV-infected patients with age- and sex-matched HIV-uninfected control subjects and found a significant reduction in CD16-dependent pSyk/Zap70 (median=32.7% compared with 67.8%; P=0.0002) and CD107a mobilization (median=9.72% compared with 32.9%; P=0.046) in NK cells. Reduction of both correlated strongly with reduced CD16 surface expression on NK cells of HIV-infected individuals (P<0.01). These data suggest that ADCC is inhibited in NK cells from therapy-naïve, HIV-infected individuals at the level of early events in CD16 signal transduction, associated with low CD16R expression, and our method is a useful and reliable tool to detect pathological defects in NK cell degranulation.

• Genetic modulation of TLR8 response following bacterial phagocytosis.

  Authors: Michael P Gantier, Aaron T Irving, Maria Kaparakis-Liaskos, Dakang Xu, Vanessa A Evans, Paul U Cameron, James A Bourne, Richard L Ferrero, Matthias John, Mark A Behlke, Bryan R G Williams

  Human mutation. 09/2010; 31(9):1069-79.

  Human Toll-like receptors (TLRs) TLR7, TLR8, and TLR9 are important immune sensors of foreign nucleic acids encountered by phagocytes. Although there is growing evidence implicating TLR7 and TLR9 inHuman Toll-like receptors (TLRs) TLR7, TLR8, and TLR9 are important immune sensors of foreign nucleic acids encountered by phagocytes. Although there is growing evidence implicating TLR7 and TLR9 in the detection of intracellular pathogenic bacteria, characterization of such a role for TLR8 is currently lacking. A recent genetic study has correlated the presence of a TLR8 single nucleotide polymorphism (SNP) (rs3764880:A>G; p.Met1Val) with the development of active tuberculosis, suggesting a role for TLR8 in the detection of phagosomal bacteria. Here we provide the first direct evidence that TLR8 sensing is activated in human monocytic cells following Helicobacter pylori phagocytosis. In addition, we show that rs3764880 fine tunes translation of the two TLR8 main isoforms, without affecting protein function. Although we show that TLR8 variant 2 (TLR8v2) is the prevalent form of TLR8 contributing to TLR8 function, we also uncover a role for the TLR8 long isoform (TLR8v1) in the positive regulation of TLR8 function in CD16(+)CD14(+) differentiated monocytes. Thus, TLR8 sensing can be activated following bacterial phagocytosis, and rs3764880 may play a role in the modulation of TLR8-dependent microbicidal response of infected macrophages.

• A novel, rapid method to detect infectious HIV-1 from plasma of persons infected with HIV-1.

  Authors: Alyssa Cornall, Laveena Sharma, Ajantha Solomon, Paul R Gorry, Suzanne M Crowe, Paul U Cameron, Sharon R Lewin

  Journal of virological methods. 04/2010; 165(1):90-6.

  Efficient isolation of replication-competent virus from plasma of patients infected with HIV-1 is needed to characterize important clinical parameters of virus. However, addition of plasma to inEfficient isolation of replication-competent virus from plasma of patients infected with HIV-1 is needed to characterize important clinical parameters of virus. However, addition of plasma to in vitro cultures results in clot formation. Blood from HIV-1 infected patients was collected in the presence of three commonly used anticoagulants (ACD, heparin and EDTA) and plasma was isolated. Plasma was then used to infect HIV-1 indicator cell lines (TZM-bl and GHOST) with spinoculation in the presence or absence of additional heparin and positively charged polymers. The presence of additional heparin during inoculation significantly reduced clot formation without affecting the sensitivity of HIV-1 infection in the GHOST cell line. However, heparin reduced the frequency of HIV-1 infection of the TZM-bl cell line. Using plasma from patients with HIV RNA>1000 copies/ml (n=58), the frequency of HIV-1 isolation was 92% in GHOST (n=51) and 54% in TZM-bl (n=26) cell lines. A sensitive method was developed for rapid isolation of infectious HIV-1 from plasma of patients with HIV RNA>1000 copies/ml that includes spinoculation and the addition of heparin during infection of GHOST cells. This technique could be used for rapid evaluation of viral fitness, co-receptor usage or drug resistance without the need for viral amplification.

• Coinfection of hepatic cell lines with human immunodeficiency virus and hepatitis B virus leads to an increase in intracellular hepatitis B surface antigen.

  Authors: David M Iser, Nadia Warner, Peter A Revill, Ajantha Solomon, Fiona Wightman, Suha Saleh, Megan Crane, Paul U Cameron, Scott Bowden, Tin Nguyen, Cândida F Pereira, Paul V Desmond, Stephen A Locarnini, Sharon R Lewin

  Journal of virology. 03/2010; 84(12):5860-7.

  Liver-related mortality is increased in the setting of HIV-hepatitis B virus (HBV) coinfection. However, interactions between HIV and HBV to explain this observation have not been described. WeLiver-related mortality is increased in the setting of HIV-hepatitis B virus (HBV) coinfection. However, interactions between HIV and HBV to explain this observation have not been described. We hypothesized that HIV infection of hepatocytes directly affects the life cycle of HBV. We infected human hepatic cell lines expressing HBV (Hep3B and AD38 cells) or not expressing HBV (Huh7, HepG2, and AD43 cells) with laboratory strains of HIV (NL4-3 and AD8), as well as a vesicular stomatitis virus (VSV)-pseudotyped HIV expressing enhanced green fluorescent protein (EGFP). Following HIV infection with NL4-3 or AD8 in hepatic cell lines, we observed a significant increase in HIV reverse transcriptase activity which was infectious. Despite no detection of surface CD4, CCR5, and CXCR4 by flow cytometry, AD8 infection of AD38 cells was inhibited by maraviroc and NL4-3 was inhibited by AMD3100, demonstrating that HIV enters AD38 hepatic cell lines via CCR5 or CXCR4. High-level infection of AD38 cells (50%) was achieved using VSV-pseudotyped HIV. Coinfection of the AD38 cell line with HIV did not alter the HBV DNA amount or species as determined by Southern blotting or nucleic acid signal amplification. However, coinfection with HIV was associated with a significant increase in intracellular HBsAg when measured by Western blotting, quantitative HBsAg, and fluorescence microscopy. We conclude that HIV infection of HBV-infected hepatic cell lines significantly increased intracellular HBsAg but not HBV DNA synthesis and that increased intrahepatic HBsAg secondary to direct infection by HIV may contribute to accelerated liver disease in HIV-HBV-coinfected individuals.

• Spleen registry may help reduce the incidence of overwhelming postsplenectomy infection in Victoria.

  Authors: Justin T Denholm, Penelope A Jones, Denis W Spelman, Paul U Cameron, Ian J Woolley

  The Medical journal of Australia. 01/2010; 192(1):49-50.

• Differential dynamics of donor DC and non-DC peripheral blood mononuclear cell microchimerism in lung transplantation.

  Authors: Joel Van der Meulen, Nicole A Mifsud, Diahnn Abud, Eldho Paul, Michael D Varney, Sharon R Lewin, Paul U Cameron, Tom C Kotsimbos

  Clinical immunology (Orlando, Fla.). 09/2009;

  Donor cell microchimerism induces tolerance in animal models and may increase graft survival in man. Since dendritic cells (DC) are critical for induction of both tolerance and alloreactivity weDonor cell microchimerism induces tolerance in animal models and may increase graft survival in man. Since dendritic cells (DC) are critical for induction of both tolerance and alloreactivity we developed a method to quantitate microchimerism in donor DC and non-DC in peripheral blood mononuclear cells (PBMC) after lung transplantation. Longitudinal analysis of donor cell microchimerism in eleven sex mismatched lung transplant recipients (LTR) up to 12 months post-transplant used Y chromosome based real-time PCR on sorted cells. Total DC or a proportion of DC subsets in PBMC did not change but there were heterogeneous and dynamic changes in microchimerism in DC and non-DC. Analysis of changes in DC using a mixed model analysis showed significantly less reduction in DC compared to non-DC over time (0.49, p=0.001). Preferential DC persistence compared to non-DC may indicate tolerance induction but future studies are required to determine if DC microchimerism after transplantation affects clinical outcomes.

• IMPAIRED QUALITY OF THE HBV-SPECIFIC T-CELL RESPONSE IN HIV-1-HBV CO-INFECTION.

  Authors: J Judy Chang, Sunee Sirivichayakul, Anchalee Avihingsanon, Alex J V Thompson, Peter Revill, David Iser, John Slavin, Supranee Buranapraditkun, Pip Marks, Gail Matthews, David A Cooper, Stephen J Kent, Paul U Cameron, Joe Sasadeusz, Paul Desmond, Stephen Locarnini, Gregory J Dore, Kiat Ruxrungtham, Sharon R Lewin

  Journal of virology. 06/2009;

  HBV-specific T-cells play a key role in both the control of HBV replication and in the pathogenesis of liver disease. HIV-1 co-infection and the presence or absence of HBeAg significantly alters theHBV-specific T-cells play a key role in both the control of HBV replication and in the pathogenesis of liver disease. HIV-1 co-infection and the presence or absence of HBeAg significantly alters the natural history of chronic HBV infection. We examined the HBV-specific T-cell responses in treatment naïve HBeAg-positive and HBeAg-negative HIV-1-HBV co-infected (n = 24) and HBV mono-infected (n = 39) Asian patients. Peripheral blood was stimulated with an overlapping peptide library to the whole HBV genome and TNF-alpha and IFN-gamma cytokine expression in CD8(+) T-cells was measured by intracellular cytokine staining and flow cytometry. There was no difference in the overall magnitude of the HBV-specific T-cell responses but the quality of the response was significantly impaired in HIV-1-HBV co-infected patients compared with mono-infected patients. In co-infected patients, HBV-specific T-cells rarely produced more than one cytokine and responded to fewer HBV proteins than in mono-infected patients. Overall, the frequency and quality of the HBV-specific T-cell responses increased with a higher CD4(+) T-cell count (p = 0.018 and 0.032 respectively). There was no relationship between circulating HBV-specific T-cells and liver damage as measured by activity and fibrosis scores and the HBV-specific T-cell response was not significantly different in patients with either HBeAg-positive or HBeAg-negative disease. The quality of the HBV-specific T-cell response is impaired in the setting of HIV-1-HBV co-infection and is related to the CD4(+) T-cell count.

• Virologic determinants of success after structured treatment interruptions of antiretrovirals in acute HIV-1 infection.

  Authors: Sharon R Lewin, John M Murray, Ajantha Solomon, Fiona Wightman, Paul U Cameron, Damian J Purcell, John J Zaunders, Pat Grey, Mark Bloch, Don Smith, David A Cooper, Anthony D Kelleher

  Journal of acquired immune deficiency syndromes (1999). 03/2008; 47(2):140-47.

  BACKGROUND: Latently infected resting memory CD4 T cells are thought to be the major reservoir that contributes to rebound viremia after cessation of antiretrovirals (ARVs). Commencing ARVs duringBACKGROUND: Latently infected resting memory CD4 T cells are thought to be the major reservoir that contributes to rebound viremia after cessation of antiretrovirals (ARVs). Commencing ARVs during primary HIV-1 infection (PHI) may limit the size of the latent pool and lead to improved control of viral replication during structured treatment interruption (STI). METHODS: Individuals with PHI (n = 59) were randomized to receive ARVs with or without hydroxyurea. After STI, a good response was defined as maintenance of HIV-1 RNA <5000 copies/mL for 24 weeks off therapy. In a detailed prospective virologic substudy (n = 19), integrated HIV-1 DNA, total HIV-1 DNA, and cell-associated HIV-1 unspliced (US) RNA were quantified using a real-time polymerase chain reaction assay. RESULTS: The plasma HIV-1 RNA 12 weeks after the initiation of ARVs was significantly lower in good responders (n = 7) compared with poor responders (n = 12) (P = 0.005). There were no significant differences between good and poor responders in integrated HIV-1 DNA, HIV-1 DNA, and HIV-1 US RNA. Integrated HIV-1 DNA before initiation of ARVs was strongly correlated with plasma HIV-1 RNA at week 12 (P = 0.006, r = 0.81). CONCLUSION: HIV-1 RNA measured 12 weeks after initiation of ARV was the only virologic variable associated with viral rebound after treatment interruption in PHI.

• Human thymic dendritic cells: regulators of T cell development in health and HIV-1 infection.

  Authors: Vanessa A Evans, Paul U Cameron, Sharon R Lewin

  Clinical immunology (Orlando, Fla.). 02/2008; 126(1):1-12.

  Thymic dendritic cells (DCs) are a unique subset of bone marrow-derived professional antigen presenting cells (APCs) that interact closely with developing thymocytes and play a crucial role in theThymic dendritic cells (DCs) are a unique subset of bone marrow-derived professional antigen presenting cells (APCs) that interact closely with developing thymocytes and play a crucial role in the process of negative selection and subsequent deletion of potential auto-reactive T cell clones. HIV-1 infection of the thymus has been implicated in the defective regeneration of the CD4(+) T cell pool in infected individuals. Thymic DCs are permissive to infection by HIV-1 and given their important role in T cell development, infected DCs within the thymus may contribute to the depletion of T cells. Here we review the phenotype and function of different DC subsets found within the human thymus and discuss potential mechanisms of how DCs may be important in CD4(+) T cell dysfunction in HIV-1 infection.

• CCR7 ligands CCL19 and CCL21 increase permissiveness of resting memory CD4+ T cells to HIV-1 infection: a novel model of HIV-1 latency.

  Authors: Suha Saleh, Ajantha Solomon, Fiona Wightman, Miranda Xhilaga, Paul U Cameron, Sharon R Lewin

  Blood. 01/2008; 110(13):4161-4.

  Latent HIV-1 infection of resting memory CD4(+) T cells represents the major barrier to HIV-1 eradication. To determine whether the CCR7 ligands involved in lymphocyte migration can alter HIV-1Latent HIV-1 infection of resting memory CD4(+) T cells represents the major barrier to HIV-1 eradication. To determine whether the CCR7 ligands involved in lymphocyte migration can alter HIV-1 infection of resting CD4(+) T cells, we infected purified resting CD4(+) T cells after incubation with the chemokines CCL19 and CCL21. Incubation with CCL19 or CCL21 did not alter markers of T-cell activation or proliferation. However, after HIV-1 infection of CCL19- or CCL21-treated CD4(+) T-cells, we observed low-level HIV-1 production but high concentrations of integrated HIV-1 DNA, approaching that seen in mitogen-stimulated T-cell blasts. Restimulation of CCL19-treated infected CD4(+) T cells resulted in virus production consistent with establishment of postintegration latency. CCR7 ligands facilitate efficient entry of HIV-1 into resting CD4(+) T cells. These studies demonstrate a unique action of the chemokines CCL19 and CCL21 and provide a novel model with which to study HIV-1 latency in vitro.