Unconjugated Multi-Epitope Peptides Adjuvanted with ALFQ Induce Durable and Broadly Reactive Antibodies to Human and Avian Influenza Viruses.

An unconjugated composite peptide vaccine targeting multiple conserved influenza epitopes from hemagglutinin, neuraminidase, and matrix protein and formulated with a safe and highly potent adjuvant, Army Liposome formulation (ALFQ), generated broad and durable immune responses in outbred mice. The antibodies recognized specific epitopes in influenza peptides and several human, avian, and swine influenza viruses. Comparable antibody responses to influenza viruses were observed with intramuscular and intradermal routes of vaccine administration. The peptide vaccine induced cross-reactive antibodies that recognized influenza virus subtypes A/H1N1, A/H3N2, A/H5N1, B/Victoria, and B/Yamagata. In addition, immune sera neutralized seasonal and pandemic influenza strains (Group 1 and Group 2). This composite multi-epitope peptide vaccine, formulated with ALFQ and administered via intramuscular and intradermal routes, provides a high-performance supra-seasonal vaccine that would be cost-effective and easily scalable, thus moving us closer to a viable strategy for a universal influenza vaccine and pandemic preparedness.

Conserved Influenza Hemagglutinin, Neuraminidase and Matrix Peptides Adjuvanted with ALFQ Induce Broadly Neutralizing Antibodies.

A universal influenza candidate vaccine that targets multiple conserved influenza virus epitopes from hemagglutinin (HA), neuraminidase (NA) and matrix (M2e) proteins was combined with the potent Army liposomal adjuvant (ALFQ) to promote induction of broad immunity to seasonal and pandemic influenza strains. The unconjugated and CRM-conjugated composite peptides formulated with ALFQ were highly immunogenic and induced both humoral and cellular immune responses in mice. Broadly reactive serum antibodies were induced across various IgG isotypes. Mice immunized with the unconjugated composite peptide developed antibody responses earlier than mice immunized with conjugated peptides, and the IgG antibodies were broadly reactive and neutralizing across Groups 1 and 2 influenza viruses. Multi-epitope unconjugated influenza composite peptides formulated with ALFQ provide a novel strategy for the development of a universal influenza vaccine. These synthetic peptide vaccines avoid the pitfalls of egg-produced influenza vaccines and production can be scaled up rapidly and economically.

Erratum to "Opsonic monoclonal antibodies enhance phagocytic killing activity and clearance of Mycobacterium tuberculosis from blood in a quantitative qPCR mouse model" [Heliyon 5 (9), (September 2019), e02260].

[This corrects the article DOI: 10.1016/j.heliyon.2019.e02260.].

Opsonic monoclonal antibodies enhance phagocytic killing activity and clearance of Mycobacterium tuberculosis from blood in a quantitative qPCR mouse model.

BACKGROUND: Patients with impaired immunity often have rapid progression of tuberculosis (TB) which can lead to highly lethal Mycobacterium tuberculosis (MTB) sepsis. Opsonic monoclonal antibodies (MABs) directed against MTB that enhance phagocytic killing activity and clearance of MTB from blood may be useful to enhance TB immunity. METHODS: BALB/c mice were immunized with ethanol-killed MTB (EK-MTB) and MABs were produced and screened by ELISA for binding to killed and live Mycobacterium smegmatis (SMEG) and MTB. MAB opsonophagocytic killing activity (OPKA) was examined using SMEG with HL60 and U-937 cells and MTB with U-937 cells. Clearance of MTB from blood was evaluated in Institute of Cancer Research (ICR) mice given opsonic anti-MTB MABs or saline (control) 24 h prior to intravenous infusion with 108 CFUs gamma-irradiated MTB (HN878). MTB levels in murine blood collected 0.25, 4 and 24 h post-challenge were assessed by qPCR. MAB binding to peptidoglycan (PGN) was examined by ELISA using PGN cell wall mixture and ultra-pure PGN. RESULTS: Two MABs (GG9 and JG7) bound to killed and live SMEG and MTB (susceptible and resistant), and promoted OPKA with live MTB. MAB JG7 significantly enhanced OPKA of MTB. Both MABs significantly enhanced clearance of killed MTB from murine blood at 4 and 24 h as measured by qPCR. These opsonic MABs bound to PGN, a major cell wall constituent. CONCLUSIONS: Anti-MTB MABs that promote bactericidal phagocytic activity of MTB and enhance clearance of killed MTB from the blood, may offer an immunotherapeutic approach for treatment of MTB bacteremia or sepsis, and augment treatment of multi-drug resistant (MDR) or extensively drug resistant (XDR) TB.

Safety and pharmacokinetics of a chimerized anti-lipoteichoic acid monoclonal antibody in healthy adults.

A chimerized (murine/human) monoclonal antibody (pagibaximab) against lipoteichoic acid (LTA) and protective in animal models for coagulase-negative staphylococci (CONS) and Staphylococcus aureus bacteremia, was developed for prevention of staphylococcal infection in high-risk populations. This open label two-dose study of a single intravenous dose of 3 or 10 mg/kg of pagibaximab evaluated the safety/tolerability, pharmacokinetics, and opsonophagocytic activity of pagibaximab in healthy adults. Eight participants were enrolled (four in each dose group). No infusion, drug, or dose related adverse events occurred. Serum anti-LTA levels were dose-related; mean concentrations peaked at 87.75 and 259.24 microg/mL for 3 and 10 mg/kg groups, respectively. The half-life (beta) of pagibaximab was approximately 33 days. Opsonophagocytic activity of serum samples on a human clinical isolate of Staphylococcus epidermidis in a standard bacterial killing assay was dose-related, and peaked at a mean of 88.5 and 95.5% at 1:90 dilution for 3 and 10 mg/kg groups, respectively. Serum anti-LTA and opsonophagocytic activity levels exhibited statistically significant correlation. The results suggest that pagibaximab at 3 and 10 mg/kg administered as a single intravenous dose in healthy adults appears to: 1) provide preliminary safety and tolerability data, 2) produce dose-related serum anti-LTA and opsonophagocytic activity levels, 3) have a half-life similar to other immunoglobulin G1 antibodies, 4) exhibit statistically significant correlation between serum anti-LTA and opsonophagocytic activity levels. This study supports conducting safety and pharmacokinetic trials of pagibaximab in populations at high-risk of developing CONS infection.

Identification of antigenic components of Staphylococcus epidermidis expressed during human infection.

A spectrum of in vivo-expressed Staphylococcus epidermidis antigens was identified by probing a bacteriophage lambda library of S. epidermidis genomic DNA with human serum from infected and uninfected individuals. This analysis resulted in identification of 53 antigen-encoding loci. Six antigenic polypeptides were expressed from these loci and purified. These polypeptides were the propeptide, mature amidase, and repeat sequence domains of the major autolysin AtlE, GehD (lipase), and two members of a conserved family of surface proteins (ScaA [AaE] and ScaB). AtlE, ScaA, and ScaB all exhibit human ligand binding capacity. Screening a bank of human serum samples revealed that there were significant increases in the amounts of reactive immunoglobulin G in infected individuals compared to the amounts in healthy individuals for the repeat sequence and mature amidase domains of AtlE, ScaB, and GehD. Vaccination of mice with recombinant antigens stimulated an immune response which in vitro opsonized S. epidermidis. In this study we identified prospective candidate antigens for prophylaxis or immunotherapy to control disease.