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1.  Vaccine-Induced IgG Antibodies to V1V2 Regions of Multiple HIV-1 Subtypes Correlate with Decreased Risk of HIV-1 Infection 
PLoS ONE  2014;9(2):e87572.
In the RV144 HIV-1 vaccine efficacy trial, IgG antibody (Ab) binding levels to variable regions 1 and 2 (V1V2) of the HIV-1 envelope glycoprotein gp120 were an inverse correlate of risk of HIV-1 infection. To determine if V1V2-specific Abs cross-react with V1V2 from different HIV-1 subtypes, if the nature of the V1V2 antigen used to asses cross-reactivity influenced infection risk, and to identify immune assays for upcoming HIV-1 vaccine efficacy trials, new V1V2-scaffold antigens were designed and tested. Protein scaffold antigens carrying the V1V2 regions from HIV-1 subtypes A, B, C, D or CRF01_AE were assayed in pilot studies, and six were selected to assess cross-reactive Abs in the plasma from the original RV144 case-control cohort (41 infected vaccinees, 205 frequency-matched uninfected vaccinees, and 40 placebo recipients) using ELISA and a binding Ab multiplex assay. IgG levels to these antigens were assessed as correlates of risk in vaccine recipients using weighted logistic regression models. Levels of Abs reactive with subtype A, B, C and CRF01_AE V1V2-scaffold antigens were all significant inverse correlates of risk (p-values of 0.0008–0.05; estimated odds ratios of 0.53–0.68 per 1 standard deviation increase). Thus, levels of vaccine-induced IgG Abs recognizing V1V2 regions from multiple HIV-1 subtypes, and presented on different scaffolds, constitute inverse correlates of risk for HIV-1 infection in the RV144 vaccine trial. The V1V2 antigens provide a link between RV144 and upcoming HIV-1 vaccine trials, and identify reagents and methods for evaluating V1V2 Abs as possible correlates of protection against HIV-1 infection.
Trial Registration NCT00223080
PMCID: PMC3913641  PMID: 24504509
2.  Vaccine Induction of Antibodies Against a Structurally Heterogeneous Site of Immune Pressure within HIV-1 Envelope Protein Variable Regions 1 and 2 
Immunity  2013;38(1):176-186.
The RV144 HIV-1 trial of the canary pox vector (ALVAC-HIV) plus the gp120 AIDSVAX B/E vaccine demonstrated an estimated efficacy of 31%, that correlated directly with antibodies to HIV-1 envelope variable regions 1 and 2 (V1–V2). Genetic analysis of trial viruses revealed increased vaccine efficacy against viruses matching the vaccine strain at V2 residue 169. Here, we isolated four V2 monoclonal antibodies from RV144 vaccinees that recognize residue 169, neutralize laboratory-adapted HIV-1, and mediate killing of field isolate HIV-1-infected CD4+ T cells. Crystal structures of two of the V2 antibodies demonstrated residue 169 can exist within divergent helical and loop conformations, which contrasted dramatically with the beta strand conformation previously observed with a broadly neutralizing antibody PG9. Thus, RV144 vaccine-induced immune pressure appears to target a region that may be both sequence variable and structurally polymorphic. Variation may signal sites of HIV-1 envelope vulnerability, providing vaccine designers with new options.
PMCID: PMC3569735  PMID: 23313589
3.  Establishment of a Shigella sonnei human challenge model in Thailand☆ 
Vaccine  2012;30(49):7040-7045.
In order to establish a human challenge model of Shigella related disease for vaccine testing, a dose-escalating inpatient trial was performed. Three groups of 12 healthy adult volunteers were orally challenged with 93,440 and 1680 CFU of Shigella sonnei strain 53G. Subjects were admitted to the Vaccine Trial Centre (VTC) at Mahidol University in Bangkok, Thailand. The primary purpose of this study was to identify the dose of S. sonnei 53G required to elicit clinical disease in at least 70% of Thai adult subjects. At the highest dose of 1680 CFU, the attack rate was 75%, while at the two lower doses, the attack rate was approximately 50%. This human challenge model, which is the first of its kind in an endemic region, will provide an opportunity for S. sonnei vaccine evaluation in endemic populations.
PMCID: PMC3732056  PMID: 23069701
Shigella; Human challenge model; Shigella vaccine
4.  The Thai Phase III HIV Type 1 Vaccine Trial (RV144) Regimen Induces Antibodies That Target Conserved Regions Within the V2 Loop of gp120 
AIDS Research and Human Retroviruses  2012;28(11):1444-1457.
The Thai Phase III clinical trial (RV144) showed modest efficacy in preventing HIV-1 acquisition. Plasma collected from HIV-1-uninfected trial participants completing all injections with ALVAC-HIV (vCP1521) prime and AIDSVAX B/E boost were tested for antibody responses against HIV-1 gp120 envelope (Env). Peptide microarray analysis from six HIV-1 subtypes and group M consensus showed that vaccination induced antibody responses to the second variable (V2) loop of gp120 of multiple subtypes. We further evaluated V2 responses by ELISA and surface plasmon resonance using cyclic (Cyc) and linear V2 loop peptides. Thirty-one of 32 vaccine recipients tested (97%) had antibody responses against Cyc V2 at 2 weeks postimmunization with a reciprocal geometric mean titer (GMT) of 1100 (range: 200–3200). The frequency of detecting plasma V2 antibodies declined to 19% at 28 weeks post-last injection (GMT: 110, range: 100–200). Antibody responses targeted the mid-region of the V2 loop that contains conserved epitopes and has the amino acid sequence KQKVHALFYKLDIVPI (HXB2 Numbering sequence 169–184). Valine at position 172 was critical for antibody binding. The frequency of V3 responses at 2 weeks postimmunization was modest (18/32, 56%) with a GMT of 185 (range: 100–800). In contrast, naturally infected HIV-1 individuals had a lower frequency of antibody responses to V2 (10/20, 50%; p=0.003) and a higher frequency of responses to V3 (19/20, 95%), with GMTs of 400 (range: 100–3200) and 3570 (range: 200–12,800), respectively. RV144 vaccination induced antibodies that targeted a region of the V2 loop that contains conserved epitopes. Early HIV-1 transmission events involve V2 loop interactions, raising the possibility that anti-V2 antibodies in RV144 may have contributed to viral inhibition.
PMCID: PMC3484815  PMID: 23035746
5.  Plasma IgG to Linear Epitopes in the V2 and V3 Regions of HIV-1 gp120 Correlate with a Reduced Risk of Infection in the RV144 Vaccine Efficacy Trial 
PLoS ONE  2013;8(9):e75665.
Neutralizing and non-neutralizing antibodies to linear epitopes on HIV-1 envelope glycoproteins have potential to mediate antiviral effector functions that could be beneficial to vaccine-induced protection. Here, plasma IgG responses were assessed in three HIV-1 gp120 vaccine efficacy trials (RV144, Vax003, Vax004) and in HIV-1-infected individuals by using arrays of overlapping peptides spanning the entire consensus gp160 of all major genetic subtypes and circulating recombinant forms (CRFs) of the virus. In RV144, where 31.2% efficacy against HIV-1 infection was seen, dominant responses targeted the C1, V2, V3 and C5 regions of gp120. An analysis of RV144 case-control samples showed that IgG to V2 CRF01_AE significantly inversely correlated with infection risk (OR= 0.54, p=0.0042), as did the response to other V2 subtypes (OR=0.60-0.63, p=0.016-0.025). The response to V3 CRF01_AE also inversely correlated with infection risk but only in vaccine recipients who had lower levels of other antibodies, especially Env-specific plasma IgA (OR=0.49, p=0.007) and neutralizing antibodies (OR=0.5, p=0.008). Responses to C1 and C5 showed no significant correlation with infection risk. In Vax003 and Vax004, where no significant protection was seen, serum IgG responses targeted the same epitopes as in RV144 with the exception of an additional C1 reactivity in Vax003 and infrequent V2 reactivity in Vax004. In HIV-1 infected subjects, dominant responses targeted the V3 and C5 regions of gp120, as well as the immunodominant domain, heptad repeat 1 (HR-1) and membrane proximal external region (MPER) of gp41. These results highlight the presence of several dominant linear B cell epitopes on the HIV-1 envelope glycoproteins. They also generate the hypothesis that IgG to linear epitopes in the V2 and V3 regions of gp120 are part of a complex interplay of immune responses that contributed to protection in RV144.
PMCID: PMC3784573  PMID: 24086607
6.  Clinical Factors for Severity of Plasmodium falciparum Malaria in Hospitalized Adults in Thailand 
PLoS ONE  2013;8(8):e71503.
Plasmodium falciparum is a major cause of severe malaria in Southeast Asia, however, there is limited information regarding clinical factors associated with the severity of falciparum malaria from this region. We performed a retrospective case-control study to compare clinical factors and outcomes between patients with severe and non-severe malaria, and to identify clinical factors associated with the requirement for intensive care unit (ICU) admission of patients with severe falciparum malaria among hospitalized adults in Southeast Asia. A total of 255 patients with falciparum malaria in the Hospital for Tropical Diseases in Bangkok, Thailand between 2006 and 2012 were included. We identified 104 patients with severe malaria (cases) and 151 patients with non-severe malaria (controls). Patients with falciparum malaria with following clinical and laboratory characteristics on admission (1) referrals, (2) no prior history of malaria, (3) body temperature of >38.5°C, (4) white blood cell counts >10×109/µL, (5) presence of schizonts in peripheral blood smears, and (6) albumin concentrations of <3.5 g/dL, were more likely to develop severe malaria (P<0.05). Among patients with severe malaria, patients who met ≥3 of the 2010 WHO criteria had sensitivity of 79.2% and specificity of 81.8% for requiring ICU admission. Multivariate analysis identified the following as independent associated factors for severe malaria requiring ICU admission; (1) ethnicity of Thai [odds ratio (OR) = 3.601, 95% confidence interval (CI) = 1.011–12.822] or Myanmar [OR = 3.610, 95% CI = 1.138–11.445]; (2) referrals [OR = 3.571, 95% CI = 1.306–9.762]; (3) no prior history of malaria [OR = 5.887, 95% CI = 1.354–25.594]; and (4) albumin concentrations of <3.5 g/dL [OR = 7.200, 95% CI = 1.802–28.759]. Our findings are important for the clinical management of patients with malaria because it can help early identification of patients that could develop severe malaria and require ICU admission. Early identification and the timely initiation of appropriate treatments may well improve the outcomes and reduce the mortality of these patients.
PMCID: PMC3741184  PMID: 23951178
7.  Antigenicity and Immunogenicity of RV144 Vaccine AIDSVAX Clade E Envelope Immunogen Is Enhanced by a gp120 N-Terminal Deletion 
Journal of Virology  2013;87(3):1554-1568.
An immune correlates analysis of the RV144 HIV-1 vaccine trial revealed that antibody responses to the gp120 V1/V2 region correlated inversely with infection risk. The RV144 protein immunogens (A244-rp120 and MN-rgp120) were modified by an N-terminal 11-amino-acid deletion (Δ11) and addition of a herpes simplex virus (HSV) gD protein-derived tag (gD). We investigated the effects of these modifications on gp120 expression, antigenicity, and immunogenicity by comparing unmodified A244 gp120 with both Δ11 deletion and gD tag and with Δ11 only. Analysis of A244 gp120, with or without Δ11 or gD, demonstrated that the Δ11 deletion, without the addition of gD, was sufficient for enhanced antigenicity to gp120 C1 region, conformational V2, and V1/V2 gp120 conformational epitopes. RV144 vaccinee serum IgGs bound more avidly to A244 gp120 Δ11 than to the unmodified gp120, and their binding was blocked by C1, V2, and V1/V2 antibodies. Rhesus macaques immunized with the three different forms of A244 gp120 proteins gave similar levels of gp120 antibody titers, although higher antibody titers developed earlier in A244 Δ11 gp120-immunized animals. Conformational V1/V2 monoclonal antibodies (MAbs) gave significantly higher levels of blocking of plasma IgG from A244 Δ11 gp120-immunized animals than IgG from animals immunized with unmodified A244 gp120, thus indicating a qualitative difference in the V1/V2 antibodies induced by A244 Δ11 gp120. These results demonstrate that deletion of N-terminal residues in the RV144 A244 gp120 immunogen improves both envelope antigenicity and immunogenicity.
PMCID: PMC3554162  PMID: 23175357
8.  Dengue and Other Common Causes of Acute Febrile Illness in Asia: An Active Surveillance Study in Children 
Common causes of acute febrile illness in tropical countries have similar symptoms, which often mimic those of dengue. Accurate clinical diagnosis can be difficult without laboratory confirmation and disease burden is generally under-reported. Accurate, population-based, laboratory-confirmed incidence data on dengue and other causes of acute fever in dengue-endemic Asian countries are needed.
Methods and principal findings
This prospective, multicenter, active fever surveillance, cohort study was conducted in selected centers in Indonesia, Malaysia, Philippines, Thailand and Vietnam to determine the incidence density of acute febrile episodes (≥38°C for ≥2 days) in 1,500 healthy children aged 2–14 years, followed for a mean 237 days. Causes of fever were assessed by testing acute and convalescent sera from febrile participants for dengue, chikungunya, hepatitis A, influenza A, leptospirosis, rickettsia, and Salmonella Typhi. Overall, 289 participants had acute fever, an incidence density of 33.6 per 100 person-years (95% CI: 30.0; 37.8); 57% were IgM-positive for at least one of these diseases. The most common causes of fever by IgM ELISA were chikungunya (in 35.0% of in febrile participants) and S. Typhi (in 29.4%). The overall incidence density of dengue per 100 person-years was 3.4 by nonstructural protein 1 (NS1) antigen positivity (95% CI: 2.4; 4.8) and 7.3 (95% CI: 5.7; 9.2) by serology. Dengue was diagnosed in 11.4% (95% CI: 8.0; 15.7) and 23.9% (95% CI: 19.1; 29.2) of febrile participants by NS1 positivity and serology, respectively. Of the febrile episodes not clinically diagnosed as dengue, 5.3% were dengue-positive by NS1 antigen testing and 16.0% were dengue-positive by serology.
During the study period, the most common identified causes of pediatric acute febrile illness among the seven tested for were chikungunya, S. Typhi and dengue. Not all dengue cases were clinically diagnosed; laboratory confirmation is essential to refine disease burden estimates.
Author Summary
Acute febrile episodes are common in children living in tropical countries. Diagnosis can be challenging because symptoms of the more common infectious causes are similar and often mimic those of dengue. Asia Pacific has over 70% of the worldwide dengue disease burden, although dengue incidence is generally underestimated because most surveillance systems are passive or based on clinical diagnosis without laboratory confirmation. Understanding the local etiology of febrile illness and the incidence of dengue is important when planning large-scale vaccine trials. This prospective, active fever surveillance, cohort study was carried out in children in five dengue-endemic Asian countries – Indonesia, Malaysia, Philippines, Thailand and Vietnam – during 2010–2011. Acute febrile episodes occurred in 289 (19.3%) of the cohort of 1,500 children. Among the diseases for which antibodies were tested using commercial kits, the top three causes of acute fever were chikungunya, Salmonella Typhi and dengue, followed by influenza A, rickettsia and hepatitis A. Dengue was confirmed in 11.4% of the febrile children by viral protein detection and in 23.9% by serology. Clinical diagnosis was not sufficient to detect all dengue cases. These findings are of relevance to those planning clinical studies of vaccines against these infectious agents in Southeast Asia.
PMCID: PMC3723539  PMID: 23936565
9.  Infectious Virion Capture by HIV-1 gp120-Specific IgG from RV144 Vaccinees 
Journal of Virology  2013;87(14):7828-7836.
The detailed examination of the antibody repertoire from RV144 provides a unique template for understanding potentially protective antibody functions. Some potential immune correlates of protection were untested in the correlates analyses due to inherent assay limitations, as well as the need to keep the correlates analysis focused on a limited number of endpoints to achieve statistical power. In an RV144 pilot study, we determined that RV144 vaccination elicited antibodies that could bind infectious virions (including the vaccine strains HIV-1 CM244 and HIV-1 MN and an HIV-1 strain expressing transmitted/founder Env, B.WITO.c). Among vaccinees with the highest IgG binding antibody profile, the majority (78%) captured the infectious vaccine strain virus (CM244), while a smaller proportion of vaccinees (26%) captured HIV-1 transmitted/founder Env virus. We demonstrated that vaccine-elicited HIV-1 gp120 antibodies of multiple specificities (V3, V2, conformational C1, and gp120 conformational) mediated capture of infectious virions. Although capture of infectious HIV-1 correlated with other humoral immune responses, the extent of variation between these humoral responses and virion capture indicates that virion capture antibodies occupy unique immunological space.
PMCID: PMC3700223  PMID: 23658446
10.  Ad hoc analysis of behavior and time as co-variates of the Thai phase III efficacy trial: RV 144 
The Lancet infectious diseases  2012;12(7):531-537.
The Thai phase III HIV vaccine trial's modest efficacy (VE 31.2% 95% CI 1.1, 51.2) represents the first demonstration that a vaccine can protect against HIV acquisition. Baseline variables of age, gender, marital status, and risk did not modify vaccine efficacy (VE). Here we explore behavioral risk and efficacy at 6 monthly intervals following vaccination.
Behavioral risk was assessed with a self-administered questionnaire every 6 months during trial participation. Both the acquisition endpoint and the early viral load endpoint are examined for interactions with risk status over time and temporal effects following vaccination.
Risk for HIV acquisition is low in each risk group, but the majority of participants reported higher-risk behavior at least once during the study (N= 9187, 58%). In post-hoc analyses, comparing those participants categorized as high or rising risk at least once during study follow-up versus those who maintained low or medium risk behavior as a time-varying covariate, the interaction of risk status and acquisition efficacy is significant (P = 0.010) with greater benefit in the lower risk individuals. VE appears to peak early with an estimate of cumulative VE = 60% through 12 months after initial vaccination (95% CI 22 –80%), and declines quickly. Vaccination did not appear to affect viral load in either early or late infections.
Future HIV vaccine trials must recognize potential interactions between challenge intensity and risk heterogeneity in the population and treatment effects. The regimen tested in the Thai phase III trial may benefit from extended immunization schedules.
PMCID: PMC3530398  PMID: 22652344
11.  The Thai Phase III Trial (RV144) Vaccine Regimen Induces T Cell Responses that Preferentially Target Epitopes within the V2 Region of HIV-1 Envelope 
The Thai HIV phase III prime-boost trial (RV144) using ALVAC-HIV® (vCP1521) and AIDSVAX B/E® was, to our knowledge, the first to demonstrate acquisition efficacy. Vaccine-induced, cell-mediated immune responses were assessed. T cell epitope mapping studies using IFN-γ ELISPOT were performed on PBMC from HIV-1 uninfected vaccine (N=61) and placebo (N=10) recipients using HIV-1 Env peptides. Positive responses were measured in 25 (41%) vaccinees and were predominantly CD4+ T cell mediated. Responses were targeted within the HIV Env region, with 15/25 (60%) of vaccinees recognizing peptides derived from the V2 region of HIV-1 Env, which includes the α4β7 integrin binding site. Intracellular cytokine staining confirmed that Env responses predominated (19/30; 63% of vaccine recipients) and were mediated by polyfunctional effector memory CD4+ T cells, with the majority of responders producing both IL-2 and IFN-γ (12/19; 63%). HIV-Env Ab titers were higher in subjects with IL-2 compared to those without IL-2 secreting HIV-Env specific effector memory T cells. Proliferation assays revealed that HIV Ag-specific T cells were CD4+ with the majority (80%) expressing CD107a. HIV-specific T cell lines obtained from vaccine recipients confirmed V2 specificity, polyfunctionality and functional cytolytic capacity. While the RV144 T cell responses were modest in frequency compared to humoral immune responses, the CD4+ T cell response was directed to HIV-1 Env and more particularly the V2 region.
PMCID: PMC3383859  PMID: 22529301
Human; Vaccination; Viral; AIDS; HIV-1; T cells
12.  Antibody-Dependent Cellular Cytotoxicity-Mediating Antibodies from an HIV-1 Vaccine Efficacy Trial Target Multiple Epitopes and Preferentially Use the VH1 Gene Family 
Journal of Virology  2012;86(21):11521-11532.
The ALVAC-HIV/AIDSVAX-B/E RV144 vaccine trial showed an estimated efficacy of 31%. RV144 secondary immune correlate analysis demonstrated that the combination of low plasma anti-HIV-1 Env IgA antibodies and high levels of antibody-dependent cellular cytotoxicity (ADCC) inversely correlate with infection risk. One hypothesis is that the observed protection in RV144 is partially due to ADCC-mediating antibodies. We found that the majority (73 to 90%) of a representative group of vaccinees displayed plasma ADCC activity, usually (96.2%) blocked by competition with the C1 region-specific A32 Fab fragment. Using memory B-cell cultures and antigen-specific B-cell sorting, we isolated 23 ADCC-mediating nonclonally related antibodies from 6 vaccine recipients. These antibodies targeted A32-blockable conformational epitopes (n = 19), a non-A32-blockable conformational epitope (n = 1), and the gp120 Env variable loops (n = 3). Fourteen antibodies mediated cross-clade target cell killing. ADCC-mediating antibodies displayed modest levels of V-heavy (VH) chain somatic mutation (0.5 to 1.5%) and also displayed a disproportionate usage of VH1 family genes (74%), a phenomenon recently described for CD4-binding site broadly neutralizing antibodies (bNAbs). Maximal ADCC activity of VH1 antibodies correlated with mutation frequency. The polyclonality and low mutation frequency of these VH1 antibodies reveal fundamental differences in the regulation and maturation of these ADCC-mediating responses compared to VH1 bNAbs.
PMCID: PMC3486290  PMID: 22896626
13.  Immune-Correlates Analysis of an HIV-1 Vaccine Efficacy Trial 
The New England Journal of Medicine  2012;366(14):1275-1286.
In the RV144 trial, the estimated efficacy of a vaccine regimen against human immunodeficiency virus type 1 (HIV-1) was 31.2%. We performed a case–control analysis to identify antibody and cellular immune correlates of infection risk.
In pilot studies conducted with RV144 blood samples, 17 antibody or cellular assays met prespecified criteria, of which 6 were chosen for primary analysis to determine the roles of T-cell, IgG antibody, and IgA antibody responses in the modulation of infection risk. Assays were performed on samples from 41 vaccinees who became infected and 205 uninfected vaccinees, obtained 2 weeks after final immunization, to evaluate whether immune-response variables predicted HIV-1 infection through 42 months of follow-up.
Of six primary variables, two correlated significantly with infection risk: the binding of IgG antibodies to variable regions 1 and 2 (V1V2) of HIV-1 envelope proteins (Env) correlated inversely with the rate of HIV-1 infection (estimated odds ratio, 0.57 per 1-SD increase; P = 0.02; q = 0.08), and the binding of plasma IgA antibodies to Env correlated directly with the rate of infection (estimated odds ratio, 1.54 per 1-SD increase; P = 0.03; q = 0.08). Neither low levels of V1V2 antibodies nor high levels of Env-specific IgA antibodies were associated with higher rates of infection than were found in the placebo group. Secondary analyses suggested that Env-specific IgA antibodies may mitigate the effects of potentially protective antibodies.
This immune-correlates study generated the hypotheses that V1V2 antibodies may have contributed to protection against HIV-1 infection, whereas high levels of Env-specific IgA antibodies may have mitigated the effects of protective antibodies. Vaccines that are designed to induce higher levels of V1V2 antibodies and lower levels of Env-specific IgA antibodies than are induced by the RV144 vaccine may have improved efficacy against HIV-1 infection.
PMCID: PMC3371689  PMID: 22475592
14.  Magnitude and Breadth of the Neutralizing Antibody Response in the RV144 and Vax003 HIV-1 Vaccine Efficacy Trials 
The Journal of Infectious Diseases  2012;206(3):431-441.
Background. A recombinant canarypox vector expressing human immunodeficiency virus type 1 (HIV-1) Gag, Pro, and membrane-linked gp120 (vCP1521), combined with a bivalent gp120 protein boost (AIDSVAX B/E), provided modest protection against HIV-1 infection in a community-based population in Thailand (RV144 trial). No protection was observed in Thai injection drug users who received AIDSVAX B/E alone (Vax003 trial). We compared the neutralizing antibody response in these 2 trials.
Methods. Neutralization was assessed with tier 1 and tier 2 strains of virus in TZM-bl and A3R5 cells.
Results. Neutralization of several tier 1 viruses was detected in both RV144 and Vax003. Peak titers were higher in Vax003 and waned rapidly in both trials. The response in RV144 was targeted in part to V3 of gp120.vCP1521 priming plus 2 boosts with gp120 protein was superior to 2 gp120 protein inoculations alone, confirming a priming effect for vCP1521. Sporadic weak neutralization of tier 2 viruses was detected only in Vax003 and A3R5 cells.
Conclusion. The results suggest either that weak neutralizing antibody responses can be partially protective against HIV-1 in low-risk heterosexual populations or that the modest efficacy seen in RV144 was mediated by other immune responses, either alone or in combination with neutralizing antibodies.
PMCID: PMC3392187  PMID: 22634875
15.  Safety and Immunogenicity of the MRKAd5 gag HIV Type 1 Vaccine in a Worldwide Phase 1 Study of Healthy Adults 
The safety and immunogenicity of the MRK adenovirus type 5 (Ad5) HIV-1 clade B gag vaccine was assessed in an international Phase I trial. Three-hundred and sixty healthy HIV-uninfected adults were enrolled on five continents. Subjects received placebo or 1 × 109 or 1 × 1010 viral particles (vp) per dose of the MRKAd5 HIV-1 gag vaccine at day 1, week 4, and week 26. Immunogenicity was evaluated using an IFN-γ ELISPOT gag 15-mer assay with positive responses defined as ≥55 SFC/106 PBMCs and ≥4-fold over mock control. The vaccine was well tolerated. The most common adverse events were injection site reactions, headache, pyrexia, diarrhea, fatigue, and myalgia. At week 30, geometric mean ELISPOT responses were 24, 114, and 226 SFC/106 PBMCs in the placebo, 1 × 109 vp/dose, and 1 × 1010 vp/dose groups, respectively. Overall, responses to 1 × 1010 vp were 85% and 68% in subjects with low (≤200) and high (>200) baseline Ad5 titers, respectively. The MRKAd5 HIV-1 gag vaccine was immunogenic in diverse geographic regions. Gag ELISPOT responses were greater in the 1 × 1010 vp/dose groups than in the 1 × 109 vp/dose groups. Data from this first international study indicate that adenovirus-vectored vaccines are well tolerated and may be immunogenic in subjects from regions with high prevalence of preexisting Ad5 immunity.
PMCID: PMC3422055  PMID: 20854108
16.  Safety and Reactogenicity of Canarypox ALVAC-HIV (vCP1521) and HIV-1 gp120 AIDSVAX B/E Vaccination in an Efficacy Trial in Thailand 
PLoS ONE  2011;6(12):e27837.
A prime-boost vaccination regimen with ALVAC-HIV (vCP1521) administered intramuscularly at 0, 4, 12, and 24 weeks and gp120 AIDSVAX B/E at 12 and 24 weeks demonstrated modest efficacy of 31.2% for prevention of HIV acquisition in HIV-uninfected adults participating in a community-based efficacy trial in Thailand.
Methodology/Principal Findings
Reactogenicity was recorded for 3 days following vaccination. Adverse events were monitored every 6 months for 3.5 years, during which pregnancy outcomes were recorded. Of the 16,402 volunteers, 69% of the participants reported an adverse event any time after the first dose. Only 32.9% experienced an AE within 30 days following any vaccination. Overall adverse event rates and attribution of relatedness did not differ between groups. The frequency of serious adverse events was similar in vaccine (14.3%) and placebo (14.9%) recipients (p = 0.33). None of the 160 deaths (85 in vaccine and 75 in placebo recipients, p = 0.43) was assessed as related to vaccine. The most common cause of death was trauma or traffic accident. Approximately 30% of female participants reported a pregnancy during the study. Abnormal pregnancy outcomes were experienced in 17.1% of vaccine and 14.6% (p = 0.13) of placebo recipients. When the conception occurred within 3 months (estimated) of a vaccination, the majority of these abnormal outcomes were spontaneous or elective abortions among 22.2% and 15.3% of vaccine and placebo pregnant recipients, respectively (p = 0.08). Local reactions occurred in 88.0% of vaccine and 61.0% of placebo recipients (p<0.001) and were more frequent after ALVAC-HIV than AIDSVAX B/E vaccination. Systemic reactions were more frequent in vaccine than placebo recipients (77.2% vs. 59.8%, p<0.001). Local and systemic reactions were mostly mild to moderate, resolving within 3 days.
The ALVAC-HIV and AIDSVAX B/E vaccine regimen was found to be safe, well tolerated and suitable for potential large-scale use in Thailand.
Trial Registration NCT00223080
PMCID: PMC3244387  PMID: 22205930
18.  AIDS Vaccine for Asia Network (AVAN): Expanding the Regional Role in Developing HIV Vaccines 
PLoS Medicine  2010;7(9):e1000331.
Yiming Shao and colleagues describe the work of AVAN, the AIDS Vaccine for Asia Network, which aims to strengthen its regional efforts in finding an AIDS vaccine.
PMCID: PMC2943436  PMID: 20877474
19.  Human Immunodeficiency Virus Type 1 Elite Neutralizers: Individuals with Broad and Potent Neutralizing Activity Identified by Using a High-Throughput Neutralization Assay together with an Analytical Selection Algorithm▿ † 
Journal of Virology  2009;83(14):7337-7348.
The development of a rapid and efficient system to identify human immunodeficiency virus type 1 (HIV-1)-infected individuals with broad and potent HIV-1-specific neutralizing antibody responses is an important step toward the discovery of critical neutralization targets for rational AIDS vaccine design. In this study, samples from HIV-1-infected volunteers from diverse epidemiological regions were screened for neutralization responses using pseudovirus panels composed of clades A, B, C, and D and circulating recombinant forms (CRFs). Initially, 463 serum and plasma samples from Australia, Rwanda, Uganda, the United Kingdom, and Zambia were screened to explore neutralization patterns and selection ranking algorithms. Samples were identified that neutralized representative isolates from at least four clade/CRF groups with titers above prespecified thresholds and ranked based on a weighted average of their log-transformed neutralization titers. Linear regression methods selected a five-pseudovirus subset, representing clades A, B, and C and one CRF01_AE, that could identify top-ranking samples with 50% inhibitory concentration (IC50) neutralization titers of ≥100 to multiple isolates within at least four clade groups. This reduced panel was then used to screen 1,234 new samples from the Ivory Coast, Kenya, South Africa, Thailand, and the United States, and 1% were identified as elite neutralizers. Elite activity is defined as the ability to neutralize, on average, more than one pseudovirus at an IC50 titer of 300 within a clade group and across at least four clade groups. These elite neutralizers provide promising starting material for the isolation of broadly neutralizing monoclonal antibodies to assist in HIV-1 vaccine design.
PMCID: PMC2704778  PMID: 19439467
20.  Pregnancy Outcomes Among HIV-Infected Women Undergoing Antiretroviral Therapy 
The Open AIDS Journal  2009;3:8-13.
The use of antiretroviral drugs (ARV) to prevent mother-to-child HIV transmission (PMTCT) promises to be effective. However, limited data on the adverse effects of ARV among pregnant women and pregnancy outcomes have been reported in clinical practice.
This study aimed to assess adverse effects and outcomes among pregnant HIV-infected women receiving antiretroviral drugs for either antiretroviral therapy (ART) or PMTCT.
Study Design:
This cohort study was at Chonburi Hospital, Thailand, in 2002-2006.
A total of 246 pregnant HIV-infected women with the median age (range) of 27 (16-41) years were included in this study. ART was initiated in 16.3% for treatment during ANC, 66.7% for PMTCT during ANC, and 17.1% for PMTCT in labor. Adverse effects, especially anemia, were significantly associated with continuing combined ART in pregnancy (p<0.001). 88.9% delivered normal-term neonates. The prevalence of pre-term delivery was 10.2%. Overall, 24 adverse events from 21 pregnant women (8.5%) were noted. A significantly higher prevalence of pre-term delivery was noted in the groups continuing combined ART, or initiating of PMTCT during labor rather than ANC (p=0.02). The incidence of low Apgar scores was 3.6%, and these were associated with initiation of PMTCT during labor (p=0.004).
Adverse ARV events were more numerous among the pregnant women who needed ART than PMTCT. ANC is beneficial and strongly recommended for all pregnant HIV-infected women for better pregnancy outcomes.
PMCID: PMC2695603  PMID: 19543534
HIV; Adverse effects; antiretroviral drugs; pregnancy; PMTCT.
22.  Estimation of the Total Parasite Biomass in Acute Falciparum Malaria from Plasma PfHRP2 
PLoS Medicine  2005;2(8):e204.
In falciparum malaria sequestration of erythrocytes containing mature forms of Plasmodium falciparum in the microvasculature of vital organs is central to pathology, but quantitation of this hidden sequestered parasite load in vivo has not previously been possible. The peripheral blood parasite count measures only the circulating, relatively non-pathogenic parasite numbers. P. falciparum releases a specific histidine-rich protein (PfHRP2) into plasma. Quantitative measurement of plasma PfHRP2 concentrations may reflect the total parasite biomass in falciparum malaria.
Methods and Findings
We measured plasma concentrations of PfHRP2, using a quantitative antigen-capture enzyme-linked immunosorbent assay, in 337 adult patients with falciparum malaria of varying severity hospitalised on the Thai–Burmese border. Based on in vitro production rates, we constructed a model to link this measure to the total parasite burden in the patient. The estimated geometric mean parasite burden was 7 × 1011 (95% confidence interval [CI] 5.8 × 1011 to 8.5 × 1011) parasites per body, and was over six times higher in severe malaria (geometric mean 1.7 × 1012, 95% CI 1.3 × 1012 to 2.3 × 1012) than in patients hospitalised without signs of severity (geometric mean 2.8 × 1011, 95% CI 2.3 × 1011 to 3.5 × 1011; p < 0.001). Parasite burden was highest in patients who died (geometric mean 3.4 × 1012, 95% CI 1.9 × 1012 to 6.3 × 1012; p = 0.03). The calculated number of sequestered parasites increased with disease severity and was higher in patients with late developmental stages of P. falciparum present on peripheral blood smears. Comparing model and laboratory estimates of the time of sequestration suggested that admission to hospital with uncomplicated malaria often follows schizogony—but in severe malaria is unrelated to stage of parasite development.
Plasma PfHRP2 concentrations may be used to estimate the total body parasite biomass in acute falciparum malaria. Severe malaria results from extensive sequestration of parasitised erythrocytes.
Measuring sequestered parasites using plasma PfHRP2 concentrations may provide a more accurate estimate of total parasite mass and hence severity in falciparum malaria.
PMCID: PMC1188247  PMID: 16104831
23.  Development and Evaluation of Rapid Urinary Antigen Detection Tests for Diagnosis of Penicilliosis Marneffei 
Journal of Clinical Microbiology  2002;40(9):3179-3183.
Penicilliosis, caused by the dimorphic fungus Penicillium marneffei, is an important opportunistic systemic fungal infection affecting immunocompromised individuals living in areas where penicilliosis is endemic. We have demonstrated previously that a urinary enzyme-linked immunosorbent assay (ELISA) with purified rabbit polyclonal antibody against killed whole-fission-form arthroconidia of P. marneffei was specific and highly sensitive for the diagnosis of penicilliosis. In this study, a dot blot ELISA and a latex agglutination (LA) test were developed with the same polyclonal antibody and compared with the ELISA for the detection of P. marneffei urinary antigen. Urine specimens from 37 patients with culture-proven penicilliosis and 300 controls (52 healthy subjects and 248 hospitalized patients without penicilliosis) were tested. Antigen was detected in urine from all 37 (100%) penicilliosis patients by the LA test, 35 (94.6%) penicilliosis patients by the dot blot ELISA, and 36 (97.3%) penicilliosis patients by the ELISA. False-positive results were found by the three assays for 2 (0.7%), 8 (2.7%), and 6 (2%) of 300 controls, respectively. The overall sensitivities of the diagnostic tests were as follows: dot blot ELISA, 94.6%; ELISA, 97.3%; and LA test, 100% (specificities, 97.3, 98, and 99.3%, respectively). The LA test is simple, robust, rapid, and convenient and should prove to be an important addition to the existing diagnostic tests for penicilliosis.
PMCID: PMC130715  PMID: 12202550

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