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Dive into the research topics where Eugene Kroon is active.

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Featured researches published by Eugene Kroon.


PLOS Pathogens | 2014

Initiation of ART during early acute HIV infection preserves mucosal Th17 function and reverses HIV-related immune activation.

Alexandra Schuetz; Claire Deleage; Irini Sereti; Rungsun Rerknimitr; Nittaya Phanuphak; Yuwadee Phuang-Ngern; Jacob D. Estes; Netanya G. Sandler; Suchada Sukhumvittaya; Mary Marovich; Surat Jongrakthaitae; Siriwat Akapirat; James L. K. Fletscher; Eugene Kroon; Robin L. Dewar; Rapee Trichavaroj; Nitiya Chomchey; Robert J. O’Connell; Viseth Ngauy; Merlin L. Robb; Praphan Phanuphak; Nelson L. Michael; Jean-Louis Excler; Jerome H. Kim; Mark S. de Souza; Jintanat Ananworanich; Search Study Groups

Mucosal Th17 cells play an important role in maintaining gut epithelium integrity and thus prevent microbial translocation. Chronic HIV infection is characterized by mucosal Th17 cell depletion, microbial translocation and subsequent immune-activation, which remain elevated despite antiretroviral therapy (ART) correlating with increased mortality. However, when Th17 depletion occurs following HIV infection is unknown. We analyzed mucosal Th17 cells in 42 acute HIV infection (AHI) subjects (Fiebig (F) stage I-V) with a median duration of infection of 16 days and the short-term impact of early initiation of ART. Th17 cells were defined as IL-17+ CD4+ T cells and their function was assessed by the co-expression of IL-22, IL-2 and IFNγ. While intact during FI/II, depletion of mucosal Th17 cell numbers and function was observed during FIII correlating with local and systemic markers of immune-activation. ART initiated at FI/II prevented loss of Th17 cell numbers and function, while initiation at FIII restored Th17 cell numbers but not their polyfunctionality. Furthermore, early initiation of ART in FI/II fully reversed the initially observed mucosal and systemic immune-activation. In contrast, patients treated later during AHI maintained elevated mucosal and systemic CD8+ T-cell activation post initiation of ART. These data support a loss of Th17 cells at early stages of acute HIV infection, and highlight that studies of ART initiation during early AHI should be further explored to assess the underlying mechanism of mucosal Th17 function preservation.


The New England Journal of Medicine | 2016

Prospective Study of Acute HIV-1 Infection in Adults in East Africa and Thailand

Merlin L. Robb; Leigh Anne Eller; Hannah Kibuuka; Kathleen Rono; Lucas Maganga; Sorachai Nitayaphan; Eugene Kroon; Fred Sawe; Samuel Sinei; Somchai Sriplienchan; Linda L. Jagodzinski; Jennifer A. Malia; Mark M. Manak; Mark S. de Souza; Sodsai Tovanabutra; Eric Sanders-Buell; Morgane Rolland; Julie Dorsey-Spitz; Michael A. Eller; Mark Milazzo; Qun Li; Andrew Lewandowski; Hao Wu; Edith Swann; Robert J. O'Connell; Sheila A. Peel; Peter Dawson; Jerome H. Kim; Nelson L. Michael

BACKGROUND Acute human immunodeficiency virus type 1 (HIV-1) infection is a major contributor to transmission of HIV-1. An understanding of acute HIV-1 infection may be important in the development of treatment strategies to eradicate HIV-1 or achieve a functional cure. METHODS We performed twice-weekly qualitative plasma HIV-1 RNA nucleic acid testing in 2276 volunteers who were at high risk for HIV-1 infection. For participants in whom acute HIV-1 infection was detected, clinical observations, quantitative measurements of plasma HIV-1 RNA levels (to assess viremia) and HIV antibodies, and results of immunophenotyping of lymphocytes were obtained twice weekly. RESULTS Fifty of 112 volunteers with acute HIV-1 infection had two or more blood samples collected before HIV-1 antibodies were detected. The median peak viremia (6.7 log10 copies per milliliter) occurred 13 days after the first sample showed reactivity on nucleic acid testing. Reactivity on an enzyme immunoassay occurred at a median of 14 days. The nadir of viremia (4.3 log10 copies per milliliter) occurred at a median of 31 days and was nearly equivalent to the viral-load set point, the steady-state viremia that persists durably after resolution of acute viremia (median plasma HIV-1 RNA level, 4.4 log10 copies per milliliter). The peak viremia and downslope were correlated with the viral-load set point. Clinical manifestations of acute HIV-1 infection were most common just before and at the time of peak viremia. A median of one symptom of acute HIV-1 infection was recorded at a median of two study visits, and a median of one sign of acute HIV-1 infection was recorded at a median of three visits. CONCLUSIONS The viral-load set point occurred at a median of 31 days after the first detection of plasma viremia and correlated with peak viremia. Few symptoms and signs were observed during acute HIV-1 infection, and they were most common before peak viremia. (Funded by the Department of Defense and the National Institute of Allergy and Infectious Diseases.).


EBioMedicine | 2016

HIV DNA Set Point is Rapidly Established in Acute HIV Infection and Dramatically Reduced by Early ART

Jintanat Ananworanich; Nicolas Chomont; Leigh Ann Eller; Eugene Kroon; Sodsai Tovanabutra; Meera Bose; Martin Nau; James L. K. Fletcher; Somporn Tipsuk; Claire Vandergeeten; Robert J. O'Connell; Suteeraporn Pinyakorn; Nelson L. Michael; Nittaya Phanuphak; Merlin L. Robb

HIV DNA is a marker of HIV persistence that predicts HIV progression and remission, but its kinetics in early acute HIV infection (AHI) is poorly understood. We longitudinally measured the frequency of peripheral blood mononuclear cells harboring total and integrated HIV DNA in 19 untreated and 71 treated AHI participants, for whom 50 were in the earliest Fiebig I/II (HIV IgM −) stage, that is ≤ 2 weeks from infection. Without antiretroviral therapy (ART), HIV DNA peaked at 2 weeks after enrollment, reaching a set-point 2 weeks later with little change thereafter. There was a marked divergence of HIV DNA values between the untreated and treated groups that occurred within the first 2 weeks of ART and increased with time. ART reduced total HIV DNA levels by 20-fold after 2 weeks and 316-fold after 3 years. Therefore, very early ART offers the opportunity to significantly reduce the frequency of cells harboring HIV DNA.


AIDS | 2000

A randomized controlled 24-week study of intermittent subcutaneous interleukin-2 in HIV-1 infected patients in Thailand.

Kiat Ruxrungtham; Surapol Suwanagool; Jorge A. Tavel; Mena Chuenyam; Eugene Kroon; Sasiwimol Ubolyam; Supranee Buranapraditkun; Wichai Techasathit; Yeuming Li; Sean Emery; Richard T. Davey; Lisa Fosdick; Chaiyos Kunanusont; H. Clifford Lane; Praphan Phanuphak

ObjectivesTo assess the immunological and virological effects, safety profile and feasibility of subcutaneous interleukin-2 (scIL-2) therapy in an HIV-infected Thai population. DesignSeventy-two patients with baseline CD4 cell count of ⩾ 350 × 106/l and no history of opportunistic infection were randomized to receive antiretroviral therapy plus scIL-2 (scIL-2 group) or antiretroviral therapy alone (control group). scIL-2 was administered at one of three doses for at least 24 weeks. The main measure of treatment efficacy was change in CD4 cell count. ResultsThe time-weighted mean change in CD4 cell count from baseline to week 24 was + 252 × 106/l for the scIL-2 group compared with + 42 × 106/l for the control group (P < 0.0001). Changes in plasma HIV RNA were not significantly different between the groups over the same time period: there was a 0.83 log10 copies/ml decrease for the scIL-2 group and a 0.70 log copies/ml decrease for the control group (P = 0.362). ConclusionsThis study provides the most extensive experience of scIL-2 therapy in HIV-1 infected women and Asians, and demonstrates the immunological efficacy, tolerability and feasability of scIL-2 therapy in this population. Data from this study were instrumental in guiding the selection of the scIL-2 dosing regimen for ongoing phase III trials.


AIDS | 2000

A randomized, dose-finding study with didanosine plus stavudine versus didanosine alone in antiviral-naive, HIV-infected Thai patients.

Kiat Ruxrungtham; Eugene Kroon; Chaiwat Ungsedhapand; Somsong Teeratakulpisarn; Sasiwimol Ubolyam; Supranee Buranapraditkun; R. van Leeuwen; Gerrit-Jan Weverling; Chaiyos Kunanusont; J. M. A. Lange; David A. Cooper; Praphan Phanuphak

ObjectivesTo evaluate the safety and efficacy of four different regimens of didanosine (ddI) + stavudine (d4T) in HIV-infected Thais. DesignProspective, open-label, randomized study. MethodsPatients were randomized to four regimens of high and low doses of ddI and d4T or to ddI alone. D4T was added to the ddI-alone arm after week 24. The duration of study was 48 weeks. ResultsSeventy-eight patients were randomized (mean CD4 cell count, 255 × 106/l; mean plasma HIV-1 RNA; 4.3 log10 copies/ml). In the intent-to-treat analysis, 78% of patients in the pooled combination arms and 20% of the patients in the ddI alone arm (to which d4T was added after 24 weeks) showed plasma HIV-1 RNA < 500 copies/ml at week 24 (P  < 0.001), and 59% versus 53% at week 48, respectively. In addition, the proportion of patients with < 50 HIV-1 RNA copies/ml was 13% versus 7% at week 24 (P  = 0.5) and 17% versus 20% at week 48 respectively. At week 24, median CD4 cell count increases from baseline were 101 × 106/l in the pooled combination versus 76 × 106/l in the ddI alone arm (P  = 0.78). Logistic regression modeling suggested a correlation between receiving high dose ddI and achieving HIV-1 RNA < 500 copies/ml at week 48 (P  = 0.07). ConclusionsThe d4T/ddI combination was superior to ddI alone in producing HIV-1 viral suppression. At week 48, > 60% of patients treated with this combination reached HIV-1 RNA levels < 500 copies/ml. Receiving high dose ddI but not d4T may correlate with a better viral suppression.


AIDS | 2000

A randomized, double-blind trial of half versus standard dose of zidovudine plus zalcitabine in Thai HIV-1-infected patients (study HIV-NAT 001)

Eugene Kroon; Chaiwat Ungsedhapand; Kiat Ruxrungtham; M. Chuenyam; Sasiwimol Ubolyam; M. Newell; R. van Leeuwen; Chaiyos Kunanusont; S. Buranapraditkul; Sunee Sirivichayakul; J. M. A. Lange; David A. Cooper; Praphan Phanuphak

BackgroundTriple combination antiretroviral therapy, recommended as standard of care, is unaffordable for much of the developing world. ObjectivesTo establish whether half doses of zidovudine (AZT) and zalcitabine (ddC) are as effective as standard doses in a Thai population with lower body weight than Western populations and predominantly infected with HIV-1 subtype E. MethodsA group of 116 antiretroviral naive patients, with CD4 cell counts 100–500 × 106 cells/l, were randomized to: AZT 200 mg three times daily plus ddC 0.75 mg three times daily versus AZT 100 mg three times daily plus ddC 0.375 mg three times daily and followed-up regularly for 48 weeks. ResultsThe study enrolled 111 patients: 59 men and 52 women, body weight (mean ± standard deviation) 56.4 ± 12.3 kg, mean CD4 cell count 324 × 106 cells/l, mean HIV RNA 4.7 log10 copies/ml. There were no significant differences between the two groups. Twelve patients discontinued, including two deaths that were unrelated to study medication. No significant differences in adverse events were seen. Week 48 data for the standard dose and half dose arms, respectively, were mean CD4 cell count increases of 52 and 78 × 106 cells/l (P  = 0.34), mean plasma HIV-1 RNA reduction of 1.4 and 1.1 log10 copies/ml (P  = 0.10), HIV RNA of < 400 copies/ml in 52 and 20%{ (P  = 0.001). Participants with higher than mean baseline CD8 cell counts (mean 1062 × 106 cells/l) showed greater decline in CD8 cells on standard doses. Further analysis showed improved reduction in HIV RNA (P <  0.0001) and in the percentage with undetectable HIV RNA (P  = 0.0137) in the standard dose arm, corrected for baseline HIV RNA, which if < 4.75 log10 copies/ml significantly correlated with HIV RNA < 400 copies/ml at week 48. ConclusionAt week 48, the proportion with HIV RNA < 400 copies/ml was significantly higher in the standard dose arm; lower baseline HIV RNA correlated with better HIV RNA outcome at 48 weeks. The arms did not differ in CD4 cell response but standard doses correlated with greater CD8 cell decline.


AIDS | 2015

Impact of nucleic acid testing relative to antigen/antibody combination immunoassay on the detection of acute HIV infection.

Mark S. de Souza; Nittaya Phanuphak; Suteeraporn Pinyakorn; Rapee Trichavaroj; Supanit Pattanachaiwit; Nitiya Chomchey; James L. K. Fletcher; Eugene Kroon; Nelson L. Michael; Praphan Phanuphak; Jerome H. Kim; Jintanat Ananworanich

Objective:To assess the addition of HIV nucleic acid testing (NAT) to fourth-generation (4thG) HIV antigen/antibody combination immunoassay in improving detection of acute HIV infection (AHI). Methods:Participants attending a major voluntary counseling and testing site in Thailand were screened for AHI using 4thG HIV antigen/antibody immunoassay and sequential less sensitive HIV antibody immunoassay. Samples nonreactive by 4thG antigen/antibody immunoassay were further screened using pooled NAT to identify additional AHI. HIV infection status was verified following enrollment into an AHI study with follow-up visits and additional diagnostic tests. Results:Among 74 334 clients screened for HIV infection, HIV prevalence was 10.9% and the overall incidence of AHI (N = 112) was 2.2 per 100 person-years. The inclusion of pooled NAT in the testing algorithm increased the number of acutely infected patients detected, from 81 to 112 (38%), relative to 4thG HIV antigen/antibody immunoassay. Follow-up testing within 5 days of screening marginally improved the 4thG immunoassay detection rate (26%). The median CD4+ T-cell count at the enrollment visit was 353 cells/&mgr;l and HIV plasma viral load was 598 289 copies/ml. Conclusion:The incorporation of pooled NAT into the HIV testing algorithm in high-risk populations may be beneficial in the long term. The addition of pooled NAT testing resulted in an increase in screening costs of 22% to identify AHI: from


Clinical Infectious Diseases | 2016

Initiation of Antiretroviral Therapy During Acute HIV-1 Infection Leads to a High Rate of Nonreactive HIV Serology

Mark S. de Souza; Suteeraporn Pinyakorn; Siriwat Akapirat; Supanit Pattanachaiwit; James L. K. Fletcher; Nitiya Chomchey; Eugene Kroon; Sasiwimol Ubolyam; Nelson L. Michael; Merlin L. Robb; Praphan Phanuphak; Jerome H. Kim; Nittaya Phanuphak; Jintanat Ananworanich

8.33 per screened patient to


Neurology | 2016

Neurologic signs and symptoms frequently manifest in acute HIV infection

Joanna Hellmuth; James L. K. Fletcher; Victor Valcour; Eugene Kroon; Jintanat Ananworanich; Jintana Intasan; Sukalaya Lerdlum; Jared Narvid; Mantana Pothisri; Isabel E. Allen; Shelly J. Krebs; Bonnie M. Slike; Peeriya Prueksakaew; Linda L. Jagodzinski; Suwanna Puttamaswin; Nittaya Phanuphak; Serena Spudich

10.16. Risk factors of the testing population should be considered prior to NAT implementation given the additional testing complexity and costs.


Therapeutic Drug Monitoring | 2003

Population pharmacokinetics of itraconazole in Thai HIV-1-infected persons

Cees H. W. Koks; Alwin D. R. Huitema; Eugene Kroon; Theshinee Chuenyam; Rolf W. Sparidans; Joep M. A. Lange; Jos H. Beijnen

BACKGROUND Third- and fourth-generation immunoassays (IAs) are widely used in the diagnosis of human immunodeficiency virus (HIV) infection. Antiretroviral therapy (ART) during acute HIV infection (AHI) may impact HIV-specific antibodies, with failure to develop antibody or seroreversion. We report on the ability of diagnostic tests to detect HIV-specific antibodies in Thai participants initiating ART during AHI. METHODS Participants with detectable plasma HIV RNA but nonreactive HIV-specific immunoglobulin G, enrolled in an AHI study, were offered immediate initiation of ART. Participants were tested at initiation and at 12 and 24 weeks following treatment using standard second-, third-, and fourth-generation IAs and Western blot (WB). RESULTS Participants (N = 234) initiating ART at a median of 19 days (range, 1-62 days) from HIV exposure demonstrated different frequencies of reactivity prior to and following 24 weeks of ART depending on the IA. Third-generation IA nonreactivity prior to ART was 48%, which decreased to 4% following ART (P < .001). Fourth-generation IA nonreactivity was 18% prior to ART and 17% following ART (P = .720). Negative WB results were observed in 89% and 12% of participants prior to and following 24 weeks of ART, respectively (P < .001). Seroreversion to nonreactivity during ART was observed to at least one of the tests in 20% of participants, with fourth-generation IA demonstrating the highest frequency (11%) of seroreversion. CONCLUSIONS HIV-specific antibodies may fail to develop and, when detected, may decline when ART is initiated during AHI. Although fourth-generation IA was the most sensitive at detecting AHI prior to ART, third-generation IA was the most sensitive during treatment. CLINICAL TRIALS REGISTRATION NCT00796146 and NCT00796263.

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Jintanat Ananworanich

Henry M. Jackson Foundation for the Advancement of Military Medicine

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Merlin L. Robb

Walter Reed Army Institute of Research

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Suteeraporn Pinyakorn

Walter Reed Army Institute of Research

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Nelson L. Michael

Walter Reed Army Institute of Research

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Sasiwimol Ubolyam

Boston Children's Hospital

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Jerome H. Kim

International Vaccine Institute

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