Evaluation of glycoconjugate antigens as vaccine candidates against group A Streptococcus and human immunodeficiency virus infections

This PhD thesis discusses the rationale for design and use of synthetic oligosaccharides for the development of glycoconjugate vaccines and the role of physicochemical methods in the characterization of these vaccines. The study concerns two infectious diseases that represent a serious problem for the national healthcare programs: human immunodeficiency virus (HIV) and Group A Streptococcus (GAS) infections. Both pathogens possess distinctive carbohydrate structures that have been described as suitable targets for the vaccine design. The Group A Streptococcus cell membrane polysaccharide (GAS-PS) is an attractive vaccine antigen candidate based on its conserved, constant expression pattern and the ability to confer immunoprotection in a relevant mouse model. Analysis of the immunogenic response within at-risk populations suggests an inverse correlation between high anti-GAS-PS antibody titres and GAS infection cases. Recent studies show that a chemically synthesized core polysaccharide-based antigen may represent an antigenic structural determinant of the large polysaccharide. Based on GAS-PS structural analysis, the study evaluates the potential to exploit a synthetic design approach to GAS vaccine development and compares the efficiency of synthetic antigens with the long isolated GAS polysaccharide. Synthetic GAS-PS structural analogues were specifically designed and generated to explore the impact of antigen length and terminal residue composition. For the HIV-1 glycoantigens, the dense glycan shield on the surface of the envelope protein gp120 was chosen as a target. This shield masks conserved protein epitopes and facilitates virus spread via binding to glycan receptors on susceptible host cells. The broadly neutralizing monoclonal antibody 2G12 binds a cluster of high-mannose oligosaccharides on the gp120 subunit of HIV-1 Env protein. This oligomannose epitope has been a subject to the synthetic vaccine development. The cluster nature of the 2G12 epitope suggested that multivalent antigen presentation was important to develop a carbohydrate based vaccine candidate. I describe the development of neoglycoconjugates displaying clustered HIV-1 related oligomannose carbohydrates and their immunogenic properties.

Treatment modification in human immunodeficiency virus-infected individuals starting combination antiretroviral therapy between 2005 and 2008

Adverse effects of combination antiretroviral therapy (CART) commonly result in treatment modification and poor adherence.

Determinants of hepatitis A vaccine immunity in a cohort of human immunodeficiency virus-infected children living in Switzerland

Vaccination in HIV-infected children is often less effective than in healthy children. The goal of this study was to assess vaccine responses to hepatitis A virus (HAV) in HIV-infected children. Children of the Swiss Mother and Child HIV Cohort Study (MoCHiV) were enrolled prospectively. Recommendations for initial, catch-up, and additional HAV immunizations were based upon baseline antibody concentrations and vaccine history. HAV IgG was assessed by enzyme-linked immunosorbent assay (ELISA) with a protective cutoff value defined as ≥10 mIU/ml. Eighty-seven patients were included (median age, 11 years; range, 3.4 to 21.2 years). Forty-two patients were seropositive (48.3%) for HAV. Among 45 (51.7%) seronegative patients, 36 had not received any HAV vaccine dose and were considered naïve. Vaccine responses were assessed after the first dose in 29/35 naïve patients and after the second dose in 33/39 children (25 initially naïve patients, 4 seronegative patients, and 4 seropositive patients that had already received 1 dose of vaccine). Seroconversion was 86% after 1 dose and 97% after 2 doses, with a geometric mean concentration of 962 mIU/ml after the second dose. A baseline CD4(+) T cell count below 750 cells/μl significantly reduced the post-2nd-dose response (P = 0.005). Despite a high rate of seroconversion, patients with CD4(+) T cell counts of <750/μl had lower anti-HAV antibody concentrations. This may translate into a shorter protection time. Hence, monitoring humoral immunity may be necessary to provide supplementary doses as needed.

Orosomucoid (alpha1-acid glycoprotein) plasma concentration and genetic variants: effects on human immunodeficiency virus protease inhibitor clearance and cellular accumulation

BACKGROUND AND OBJECTIVE: Protease inhibitors are highly bound to orosomucoid (ORM) (alpha1-acid glycoprotein), an acute-phase plasma protein encoded by 2 polymorphic genes, which may modulate their disposition. Our objective was to determine the influence of ORM concentration and phenotype on indinavir, lopinavir, and nelfinavir apparent clearance (CL(app)) and cellular accumulation. Efavirenz, mainly bound to albumin, was included as a control drug. METHODS: Plasma and cells samples were collected from 434 human immunodeficiency virus-infected patients. Total plasma and cellular drug concentrations and ORM concentrations and phenotypes were determined. RESULTS: Indinavir CL(app) was strongly influenced by ORM concentration (n = 36) (r2 = 0.47 [P = .00004]), particularly in the presence of ritonavir (r2 = 0.54 [P = .004]). Lopinavir CL(app) was weakly influenced by ORM concentration (n = 81) (r2 = 0.18 [P = .0001]). For both drugs, the ORM1 S variant concentration mainly explained this influence (r2 = 0.55 [P = .00004] and r2 = 0.23 [P = .0002], respectively). Indinavir CL(app) was significantly higher in F1F1 individuals than in F1S and SS patients (41.3, 23.4, and 10.3 L/h [P = .0004] without ritonavir and 21.1, 13.2, and 10.1 L/h [P = .05] with ritonavir, respectively). Lopinavir cellular exposure was not influenced by ORM abundance and phenotype. Finally, ORM concentration or phenotype did not influence nelfinavir (n = 153) or efavirenz (n = 198) pharmacokinetics. CONCLUSION: ORM concentration and phenotype modulate indinavir pharmacokinetics and, to a lesser extent, lopinavir pharmacokinetics but without influencing their cellular exposure. This confounding influence of ORM should be taken into account for appropriate interpretation of therapeutic drug monitoring results. Further studies are needed to investigate whether the measure of unbound drug plasma concentration gives more meaningful information than total drug concentration for indinavir and lopinavir.

A randomized clinical trial of mupirocin in the eradication of Staphylococcus aureus nasal carriage in human immunodeficiency virus disease

Seventy-six human immunodeficiency virus (HIV)-infected patients with Staphylococcus aureus nasal carriage were randomized to treatment groups receiving intranasal mupirocin or placebo twice daily for 5 days. Nasal cultures for S. aureus were obtained at 1, 2, 6, and 10 weeks after therapy. At 1 week, 88% of mupirocin-treated patients had negative nasal cultures compared with 8% in placebo patients (P<.001). The percentage of mupirocin-treated patients with persistently negative nasal cultures decreased over time (63%, 45%, and 29% at 2, 6, and 10 weeks, respectively) but remained significantly greater than the placebo group (3% at 2, 6, and 10 weeks). In mupirocin-treated patients, most (16/19) instances of nasal recolonization were with pretreatment strains (determined by means of by pulsed field gel electrophoresis); mupirocin resistance was not observed. Five days of treatment with mupirocin eliminated S. aureus nasal carriage in HIV-infected patients for several weeks; however, since the effect waned over time, intermittent dosing regimens should be considered for long-term eradication.

Determinants of vaccine immunity in the cohort of human immunodeficiency virus-infected children living in Switzerland

BACKGROUND: Human immunodeficiency virus (HIV)-infected children are at increased risk of infections caused by vaccine preventable pathogens, and specific immunization recommendations have been issued. METHODS: A prospective national multicenter study assessed how these recommendations are followed in Switzerland and how immunization history correlates with vaccine immunity. RESULTS: Among 87 HIV-infected children (mean age: 11.1 years) followed in the 5 Swiss university hospitals and 1 regional hospital, most (76%) had CD4 T cells >25%, were receiving highly active antiretroviral treatment (79%) and had undetectable viral load (60%). Immunization coverage was lower than in the general population and many lacked serum antibodies to vaccine-preventable pathogens, including measles (54%), varicella (39%), and hepatitis B (65%). The presence of vaccine antibodies correlated most significantly with having an up-to-date immunization history (P<0.05). An up-to-date immunization history was not related to age, immunologic stage, or viremia but to the referral medical center. CONCLUSIONS: All pediatricians in charge of HIV-infected children are urged to identify missing immunizations in this high-risk population.

The role of substance abuse treatment in preventing human immunodeficiency virus transmission among injecting drug users

This exploratory study assesses the utility of substance abuse treatment as a strategy for preventing human immunodeficiency virus (HIV) transmission among injecting drug users (IDUs). Data analyzed in this study were collected in San Antonio, TX, 1989 through 1995 using both qualitative and quantitative methods. Qualitative data included ethnographic interviews with 234 active IDUs; quantitative data included baseline risk assessments and HIV screening plus interviews follow-up interviews administered approximately six months later to 823 IDUs participating in a Federally-funded AIDS community outreach demonstration project.^ Findings that have particularly important implications for substance abuse treatment as an HIV prevention strategy for IDUs are listed below. (1) IDUs who wanted treatment were significantly more likely to be daily heroin users. (2) IDUs who want treatment were significantly more likely to have been to treatment previously. (3) IDUs who wanted treatment at baseline reported significantly higher levels of HIV risk than IDUs who did not want treatment. (4) IDUs who went to treatment between their baseline and follow-up interviews reported significantly higher levels of HIV risk at baseline than IDUs who did not go to treatment. (5) IDUs who went to treatment between their baseline and follow-up interviews reported significantly greater decreases in injection-related HIV risk behaviors. (6) IDUs who went to treatment reported significantly greater decreases in sexual HIV risk behaviors than IDUs who did not go to treatment.^ This study also noted a number of factors that may limit the effectiveness of substance abuse treatment in reducing HIV risk among IDUs. Findings suggest that the impact of methadone maintenance on HIV risk behaviors among opioid dependent IDUs may be limited by the negative manner in which it is perceived by IDUs as well as other elements of society. One consequence of the negative perception of methadone maintenance held by many elements of society may be an unwillingness to provide public funding for an adequate number of methadone maintenance slots. Thus many IDUs who would be willing to enter methadone maintenance are unable to enter it and many IDUs who do enter it are forced to drop out prematurely. ^

Distribution of human immunodeficiency virus (HIV) in the CNS of children with severe HIV encephalomyelopathy

The presence and distribution of human immunodeficiency virus (HIV) were examined in the CNS of two children with severe HIV encephalitis and myelitis. Using polymerase chain reaction-mediated DNA amplification and subsequent Southern analysis, proviral HIV gag sequences were identified in brain tissue of both patients. In situ hybridization using antisense oligonucleotide probes revealed abundant HIV gag and env/nef RNAs selectively in areas with histopathological evidence for HIV-induced tissue damage. The spinal cord of one patient exhibited a striking subpial accumulation of HIV RNAs strongly suggestive of a liquorigenic spread of the infection. HIV RNAs were typically associated with cells of the monocyte/macrophage lineage, as shown by a combined immunohistochemical and in situ hybridization procedure. The present study supports the view that the pattern and distribution of HIV-induced brain lesions is largely determined by the extent of focal HIV replication within the CNS.

Prognostic factors for advanced-stage human immunodeficiency virus-associated classical Hodgkin lymphoma treated with doxorubicin, bleomycin, vinblastine, and dacarbazine plus combined antiretroviral therapy: A multi-institutional retrospective study.

BACKGROUND The treatment and outcomes of patients with human immunodeficiency virus (HIV)-associated Hodgkin lymphoma (HL) continue to evolve. The International Prognostic Score (IPS) is used to predict the survival of patients with advanced-stage HL, but it has not been validated in patients with HIV infection. METHODS This was a multi-institutional, retrospective study of 229 patients with HIV-associated, advanced-stage, classical HL who received doxorubicin, bleomycin, vinblastine, and dacarbazine (ABVD) plus combination antiretroviral therapy. Their clinical characteristics were presented descriptively, and multivariate analyses were performed to identify the factors that were predictive of response and prognostic of progression-free survival (PFS) and overall survival (OS). RESULTS The overall and complete response rates to ABVD in patients with HIV-associated HL were 91% and 83%, respectively. After a median follow-up of 5 years, the 5-year PFS and OS rates were 69% and 78%, respectively. In multivariate analyses, there was a trend toward an IPS score >3 as an adverse factor for PFS (hazard ratio [HR], 1.49; P=.15) and OS (HR, 1.84; P=.06). A cluster of differentiation 4 (CD4)-positive (T-helper) cell count <200 cells/μL was associated independently with both PFS (HR, 2.60; P=.002) and OS (HR, 2.04; P=.04). The CD4-positive cell count was associated with an increased incidence of death from other causes (HR, 2.64; P=.04) but not with death from HL-related causes (HR, 1.55; P=.32). CONCLUSIONS The current results indicate excellent response and survival rates in patients with HIV-associated, advanced-stage, classical HL who receive ABVD and combination antiretroviral therapy as well as the prognostic value of the CD4-positive cell count at the time of lymphoma diagnosis for PFS and OS. Cancer 2014. © 2014 American Cancer Society.

Increased mortality after a first myocardial infarction in human immunodeficiency virus-infected patients; a nested cohort study.

AIMS HIV infection may be associated with an increased recurrence rate of myocardial infarction. Our aim was to determine whether HIV infection is a risk factor for worse outcomes in patients with coronaray artery disease. METHODS We compared data aggregated from two ongoing cohorts: (i) the Acute Myocardial Infarction in Switzerland (AMIS) registry, which includes patients with acute myocardial infarction (AMI), and (ii) the Swiss HIV Cohort Study (SHCS), a prospective registry of HIV-positive (HIV+) patients. We included all patients who survived an incident AMI occurring on or after 1st January 2005. Our primary outcome measure was all-cause mortality at one year; secondary outcomes included AMI recurrence and cardiovascular-related hospitalisations. Comparisons used Cox and logistic regression analyses, respectively. RESULTS There were 133 HIV+, (SHCS) and 5,328 HIV-negative [HIV-] (AMIS) individuals with incident AMI. In the SHCS and AMIS registries, patients were predominantly male (72% and 85% male, respectively), with a median age of 51 years (interquartile range [IQR] 46-57) and 64 years (IQR 55-74), respectively. Nearly all (90%) of HIV+ individuals were on successful antiretroviral therapy. During the first year of follow-up, 5 (3.6%) HIV+ and 135 (2.5%) HIV- individuals died. At one year, HIV+ status after adjustment for age, sex, calendar year of AMI, smoking status, hypertension and diabetes was associated with a higher risk of death (HR 4.42, 95% CI 1.73-11.27). There were no significant differences in recurrent AMIs (4 [3.0%] HIV+ and 146 [3.0%] HIV- individuals, OR 1.16, 95% CI 0.41-3.27) or in hospitalization rates (OR 0.68 [95% CI 0.42-1.11]). CONCLUSIONS HIV infection was associated with a significantly increased risk of all-cause mortality one year after incident AMI.

Cryptococcal Antigenemia in Immunocompromised Human Immunodeficiency Virus Patients in Rural Tanzania: A Preventable Cause of Early Mortality

Background.  Cryptococcal meningitis is a leading cause of death in people living with human immunodeficiency virus (HIV)/acquired immune deficiency syndrome. The World Health Organizations recommends pre-antiretroviral treatment (ART) cryptococcal antigen (CRAG) screening in persons with CD4 below 100 cells/µL. We assessed the prevalence and outcome of cryptococcal antigenemia in rural southern Tanzania. Methods.  We conducted a retrospective study including all ART-naive adults with CD4 <150 cells/µL prospectively enrolled in the Kilombero and Ulanga Antiretroviral Cohort between 2008 and 2012. Cryptococcal antigen was assessed in cryopreserved pre-ART plasma. Cox regression estimated the composite outcome of death or loss to follow-up (LFU) by CRAG status and fluconazole use. Results.  Of 750 ART-naive adults, 28 (3.7%) were CRAG-positive, corresponding to a prevalence of 4.4% (23 of 520) in CD4 <100 and 2.2% (5 of 230) in CD4 100-150 cells/µL. Within 1 year, 75% (21 of 28) of CRAG-positive and 42% (302 of 722) of CRAG-negative patients were dead or LFU (P<.001), with no differences across CD4 strata. Cryptococcal antigen positivity was an independent predictor of death or LFU after adjusting for relevant confounders (hazard ratio [HR], 2.50; 95% confidence interval [CI], 1.29-4.83; P = .006). Cryptococcal meningitis occurred in 39% (11 of 28) of CRAG-positive patients, with similar retention-in-care regardless of meningitis diagnosis (P = .8). Cryptococcal antigen titer >1:160 was associated with meningitis development (odds ratio, 4.83; 95% CI, 1.24-8.41; P = .008). Fluconazole receipt decreased death or LFU in CRAG-positive patients (HR, 0.18; 95% CI, .04-.78; P = .022). Conclusions.  Cryptococcal antigenemia predicted mortality or LFU among ART-naive HIV-infected persons with CD4 <150 cells/µL, and fluconazole increased survival or retention-in-care, suggesting that targeted pre-ART CRAG screening may decrease early mortality or LFU. A CRAG screening threshold of CD4 <100 cells/µL missed 18% of CRAG-positive patients, suggesting guidelines should consider a higher threshold.

Strong Impact of Smoking on Multimorbidity and Cardiovascular Risk Among Human Immunodeficiency Virus-Infected Individuals in Comparison With the General Population.

Background.  Although acquired immune deficiency syndrome-associated morbidity has diminished due to excellent viral control, multimorbidity may be increasing among human immunodeficiency virus (HIV)-infected persons compared with the general population. Methods.  We assessed the prevalence of comorbidities and multimorbidity in participants of the Swiss HIV Cohort Study (SHCS) compared with the population-based CoLaus study and the primary care-based FIRE (Family Medicine ICPC-Research using Electronic Medical Records) records. The incidence of the respective endpoints were assessed among SHCS and CoLaus participants. Poisson regression models were adjusted for age, sex, body mass index, and smoking. Results.  Overall, 74 291 participants contributed data to prevalence analyses (3230 HIV-infected; 71 061 controls). In CoLaus, FIRE, and SHCS, multimorbidity was present among 26%, 13%, and 27% of participants. Compared with nonsmoking individuals from CoLaus, the incidence of cardiovascular disease was elevated among smoking individuals but independent of HIV status (HIV-negative smoking: incidence rate ratio [IRR] = 1.7, 95% confidence interval [CI] = 1.2-2.5; HIV-positive smoking: IRR = 1.7, 95% CI = 1.1-2.6; HIV-positive nonsmoking: IRR = 0.79, 95% CI = 0.44-1.4). Compared with nonsmoking HIV-negative persons, multivariable Poisson regression identified associations of HIV infection with hypertension (nonsmoking: IRR = 1.9, 95% CI = 1.5-2.4; smoking: IRR = 2.0, 95% CI = 1.6-2.4), kidney (nonsmoking: IRR = 2.7, 95% CI = 1.9-3.8; smoking: IRR = 2.6, 95% CI = 1.9-3.6), and liver disease (nonsmoking: IRR = 1.8, 95% CI = 1.4-2.4; smoking: IRR = 1.7, 95% CI = 1.4-2.2). No evidence was found for an association of HIV-infection or smoking with diabetes mellitus. Conclusions.  Multimorbidity is more prevalent and incident in HIV-positive compared with HIV-negative individuals. Smoking, but not HIV status, has a strong impact on cardiovascular risk and multimorbidity.

Absence of Active Hepatitis C Virus Infection in Human Immunodeficiency Virus Clinics in Zambia and Mozambique.

Few studies have evaluated the prevalence of replicating hepatitis C virus (HCV) infection in sub-Saharan Africa. Among 1812 individuals infected with human immunodeficiency virus, no patient in rural Mozambique and 4 patients in urban Zambia were positive for anti-HCV antibodies. Of these, none had confirmed HCV replication.

Correlation of tuberculosis and human immunodeficiency virus in Harris County, Texas from 2009 through 2010 using Geographic Information Systems

A population based ecological study was conducted to identify areas with a high number of TB and HIV new diagnoses in Harris County, Texas from 2009 through 2010 by applying Geographic Information Systems to determine whether distinguished spatial patterns exist at the census tract level through the use of exploratory mapping. As of 2010, Texas has the fourth highest occurrence of new diagnoses of HIV/AIDS and TB.[31] The Texas Department of State Health Services (DSHS) has identified HIV infected persons as a high risk population for TB in Harris County.[29] In order to explore this relationship further, GIS was utilized to identify spatial trends. ^ The specific aims were to map TB and HIV new diagnoses rates and spatially identify hotspots and high value clusters at the census tract level. The potential association between HIV and TB was analyzed using spatial autocorrelation and linear regression analysis. The spatial statistics used were ArcGIS 9.3 Hotspot Analysis and Cluster and Outlier Analysis. Spatial autocorrelation was determined through Global Moran's I and linear regression analysis. ^ Hotspots and clusters of TB and HIV are located within the same spatial areas of Harris County. The areas with high value clusters and hotspots for each infection are located within the central downtown area of the city of Houston. There is an additional hotspot area of TB located directly north of I-10 and a hotspot area of HIV northeast of Interstate 610. ^ The Moran's I Index of 0.17 (Z score = 3.6 standard deviations, p-value = 0.01) suggests that TB is statistically clustered with a less than 1% chance that this pattern is due to random chance. However, there were a high number of features with no neighbors which may invalidate the statistical properties of the test. Linear regression analysis indicated that HIV new diagnoses rates (β=−0.006, SE=0.147, p=0.970) and census tracts (β=0.000, SE=0.000, p=0.866) were not significant predictors of TB new diagnoses rates. ^ Mapping products indicate that census tracts with overlapping hotspots and high value clusters of TB and HIV should be a targeted focus for prevention efforts, most particularly within central Harris County. While the statistical association was not confirmed, evidence suggests that there is a relationship between HIV and TB within this two year period.^