Carrie M. Rosenberger

Generation and Protective Ability of Influenza Virus–Specific Antibody-Dependent Cellular Cytotoxicity in Humans Elicited by Vaccination, Natural Infection, and Experimental Challenge

BACKGROUND Nonneutralizing antibodies (Abs) involved in antibody-dependent cellular cytotoxicity (ADCC) may provide some protection from influenza virus infection. The ability of influenza vaccines to induce ADCC-mediating Abs (ADCC-Abs) in adults and children is unclear. METHODS We quantified ADCC-Abs in serum samples from adults who received a dose of inactivated subunit vaccine (ISV) targeting monovalent 2009 pandemic influenza A(H1N1) virus or live-attenuated influenza vaccine (LAIV) or who had laboratory-confirmed influenza A(H1N1) virus infection. We also measured ADCC-Abs in children who either received a dose of trivalent seasonal ISV followed by trivalent seasonal LAIV or 2 doses of LAIV. Finally, we assessed the ability of low and high ADCC-Ab titers to protect adults from experimental challenge with influenza A/Wisconsin/67/131/2005(H3N2) virus. RESULTS Adults and children who received a dose of ISV had a robust increase in ADCC-Ab titers to both recombinant hemagglutinin (rHA) protein and homologous virus-infected cells. There was no detectable increase in titers of ADCC-Abs to rHA or virus-infected cells in adults and children who received LAIV. Higher titers (≥320) of preexisting ADCC-Abs were associated with lower virus replication and a significant reduction in total symptom scores in experimentally infected adults. CONCLUSIONS ADCC-Ab titers increased following experimental influenza virus infection in adults and after ISV administration in both children and adults.

SNP-mediated disruption of CTCF binding at the IFITM3 promoter is associated with risk of severe influenza in humans

Previous studies have reported associations of IFITM3 SNP rs12252 with severe influenza, but evidence of association and the mechanism by which risk is conferred remain controversial. We prioritized SNPs in IFITM3 on the basis of putative biological function and identified rs34481144 in the 5′ UTR. We found evidence of a new association of rs34481144 with severe influenza in three influenza-infected cohorts characterized by different levels of influenza illness severity. We determined a role for rs34481144 as an expression quantitative trait locus (eQTL) for IFITM3, with the risk allele associated with lower mRNA expression. The risk allele was found to have decreased IRF3 binding and increased CTCF binding in promoter-binding assays, and risk allele carriage diminished transcriptional correlations among IFITM3-neighboring genes, indicative of CTCF boundary activity. Furthermore, the risk allele disrupts a CpG site that undergoes differential methylation in CD8+ T cell subsets. Carriers of the risk allele had reduced numbers of CD8+ T cells in their airways during natural influenza infection, consistent with IFITM3 promoting accumulation of CD8+ T cells in airways and indicating that a critical function for IFITM3 may be to promote immune cell persistence at mucosal sites.Our study identifies a new regulator of IFITM3 expression that associates with CD8+ T cell levels in the airways and a spectrum of clinical outcomes.

A comprehensive collection of systems biology data characterizing the host response to viral infection

The Systems Biology for Infectious Diseases Research program was established by the U.S. National Institute of Allergy and Infectious Diseases to investigate host-pathogen interactions at a systems level. This program generated 47 transcriptomic and proteomic datasets from 30 studies that investigate in vivo and in vitro host responses to viral infections. Human pathogens in the Orthomyxoviridae and Coronaviridae families, especially pandemic H1N1 and avian H5N1 influenza A viruses and severe acute respiratory syndrome coronavirus (SARS-CoV), were investigated. Study validation was demonstrated via experimental quality control measures and meta-analysis of independent experiments performed under similar conditions. Primary assay results are archived at the GEO and PeptideAtlas public repositories, while processed statistical results together with standardized metadata are publically available at the Influenza Research Database (www.fludb.org) and the Virus Pathogen Resource (www.viprbrc.org). By comparing data from mutant versus wild-type virus and host strains, RNA versus protein differential expression, and infection with genetically similar strains, these data can be used to further investigate genetic and physiological determinants of host responses to viral infection.

Pharmacokinetics and pharmacodynamics of DSTA4637A: A novel THIOMAB™ antibody antibiotic conjugate against Staphylococcus aureus in mice

ABSTRACT DSTA4637A, a novel THIOMAB™ antibody antibiotic conjugate (TAC) against Staphylococcus aureus (S. aureus), is currently being investigated as a potential therapy against S. aureus infections. Structurally, TAC is composed of an anti-S. aureus antibody linked to a potent antibiotic, dmDNA31. The goal of the current study was to characterize the pharmacokinetics (PK) of TAC in mice, assess the effect of S. aureus infection on its PK, and evaluate its pharmacodynamics (PD) by measuring the bacterial load in various organs at different timepoints following TAC treatment. Plasma concentrations of 3 analytes, total antibody (TAb), antibody-conjugated dmDNA31 (ac-dmDNA31), and unconjugated dmDNA31, were measured in these studies. In non-infected mice (target antigen absent), following intravenous (IV) administration of a single dose of TAC, systemic concentration-time profiles of both TAb and ac-dmDNA31 were bi-exponential and characterized by a short distribution phase and a long elimination phase as expected for a monoclonal antibody-based therapeutic. Systemic exposures of both TAb and ac-dmDNA31 were dose proportional over the dose range tested (5 to 50 mg/kg). In a mouse model of systemic S. aureus infection (target antigen present), a single IV dose of TAC demonstrated PK behavior similar to that in the non-infected mice, and substantially reduced bacterial load in the heart, kidney, and bones on 7 and 14 d post dosing. These findings have increased our understanding of the PK and PK/PD of this novel molecule, and have shown that at efficacious dose levels the presence of S. aureus infection had minimal effect on TAC PK.

Phase 2 Randomized Trial of the Safety and Efficacy of MHAA4549A, a Broadly Neutralizing Monoclonal Antibody, in a Human Influenza A Virus Challenge Model

ABSTRACT MHAA4549A, a human monoclonal antibody targeting the hemagglutinin stalk region of influenza A virus (IAV), is being developed as a therapeutic for patients hospitalized with severe IAV infection. The safety and efficacy of MHAA4549A were assessed in a randomized, double-blind, placebo-controlled, dose-ranging study in a human IAV challenge model. One hundred healthy volunteers were inoculated with A/Wisconsin/67/2005 (H3N2) IAV and, 24 to 36 h later, administered a single intravenous dose of either placebo, MHAA4549A (400, 1,200, or 3,600 mg), or a standard oral dose of oseltamivir. Subjects were assessed for safety, pharmacokinetics (PK), and immunogenicity. The intent-to-treat-infected (ITTI) population was assessed for changes in viral load, influenza symptoms, and inflammatory biomarkers. MHAA4549A was well tolerated in all IAV challenge subjects. The 3,600-mg dose of MHAA4549A significantly reduced the viral burden relative to that of the placebo as determined by the area under the curve (AUC) of nasopharyngeal virus infection, quantified using quantitative PCR (98%) and 50% tissue culture infective dose (TCID50) (100%) assays. Peak viral load, duration of viral shedding, influenza symptom scores, mucus weight, and inflammatory biomarkers were also reduced. Serum PK was linear with a half-life of ∼23 days. No MHAA4549A-treated subjects developed anti-drug antibodies. In conclusion, MHAA4549A was well tolerated and demonstrated statistically significant and substantial antiviral activity in an IAV challenge model. (This study has been registered at ClinicalTrials.gov under identifier NCT01980966.)

Phase 2 Randomized, Double-Blind, Placebo-Controlled Trial of RG7667, a Combination Monoclonal Antibody, for Prevention of Cytomegalovirus Infection in High-Risk Kidney Transplant Recipients

ABSTRACT Cytomegalovirus (CMV) infection is a significant complication after kidney transplantation. We examined the ability of RG7667, a combination of two monoclonal antibodies, to prevent CMV infection in high-risk kidney transplant recipients in a randomized, double-blind, placebo-controlled trial. CMV-seronegative recipients of a kidney transplant from a CMV-seropositive donor (D+R−) were randomized to receive RG7667 (n = 60) or placebo (n = 60) at the time of transplant and 1, 4, and 8 weeks posttransplant. Patients were monitored for CMV viremia every 1 to 2 weeks posttransplant for 24 weeks. Patients who had seroconverted (D+R+) or withdrawn before dosing were excluded from the analysis (n = 4). CMV viremia occurred in 27 of 59 (45.8%) patients receiving RG7667 and 35 of 57 (61.4%) patients receiving placebo (stratum-adjusted difference, 15.3%; P = 0.100) within 12 weeks posttransplant and in 30 of 59 (50.8%) patients receiving RG7667 and 40 of 57 (70.2%) patients receiving placebo (stratum-adjusted difference, 19.3%; P = 0.040) within 24 weeks posttransplant. Median time to CMV viremia was 139 days in patients receiving RG7667 compared to 46 days in patients receiving placebo (hazard ratio, 0.53; P = 0.009). CMV disease was less common in the RG7667 than placebo group (3.4% versus 15.8%; P = 0.030). Adverse events were generally balanced between treatment groups. In high-risk kidney transplant recipients, RG7667 was well tolerated, numerically reduced the incidence of CMV infection within 12 and 24 weeks posttransplant, delayed time to CMV viremia, and was associated with less CMV disease than the placebo. (This study has been registered at ClinicalTrials.gov under registration no. NCT01753167.)

A Prognostic Model of Persistent Bacteremia and Mortality in Complicated Staphylococcus aureus Bloodstream Infection

BACKGROUND Staphylococcus aureus is a leading cause of bacteremia, yet there remains a significant knowledge gap in the identification of relevant biomarkers that predict clinical outcomes. Heterogeneity in the host response to invasive S. aureus infection suggests that specific biomarker signatures could be utilized to differentiate patients prone to severe disease, thereby facilitating earlier implementation of more aggressive therapies. METHODS To further elucidate the inflammatory correlates of poor clinical outcomes in patients with S. aureus bacteremia, we evaluated the association between a panel of blood proteins at initial presentation of bacteremia and disease severity outcomes using 2 cohorts of patients with S. aureus bacteremia (n = 32 and n = 124). RESULTS We identified 13 candidate proteins that were correlated with mortality and persistent bacteremia. Prognostic modeling identified interleukin (IL)-8 and CCL2 as the strongest individual predictors of mortality, with the combination of these biomarkers classifying fatal outcome with 89% sensitivity and 77% specificity (P < .0001). Baseline IL-17A levels were elevated in patients with persistent bacteremia (P < .0001), endovascular (P = .026) and metastatic tissue infections (P = .012). CONCLUSIONS These results demonstrate the potential utility of selected biomarkers to distinguish patients with the highest risk for treatment failure and bacteremia-related complications, providing a valuable tool for clinicians in the management of S. aureus bacteremia. Additionally, these biomarkers could identify patients with the greatest potential to benefit from novel therapies in clinical trials.