Immunogenicity of Adjuvanted Psoralen-Inactivated SARS-CoV-2 Vaccines and SARS-CoV-2 Spike Protein DNA Vaccines in BALB/c Mice.

The development of a safe and effective vaccine to protect against COVID-19 is a global priority due to the current high SARS-CoV-2 infection rate. Currently, there are over 160 SARS-CoV-2 vaccine candidates at the clinical or pre-clinical stages of development. Of these, there are only three whole-virus vaccine candidates produced using ß-propiolactone or formalin inactivation. Here, we prepared a whole-virus SARS-CoV-2 vaccine (SARS-CoV-2 PsIV) using a novel psoralen inactivation method and evaluated its immunogenicity in mice using two different adjuvants, alum and Advax-2. We compared the immunogenicity of SARS-CoV-2 PsIV against SARS-CoV-2 DNA vaccines expressing either full-length or truncated spike proteins. We also compared the psoralen-inactivated vaccine against a DNA prime, psoralen-inactivated vaccine boost regimen. After two doses, the psoralen-inactivated vaccine, when administered with alum or Advax-2 adjuvants, generated a dose-dependent neutralizing antibody responses in mice. Overall, the pattern of cytokine ELISPOT responses to antigen-stimulation observed in this study indicates that SARS-CoV-2 PsIV with the alum adjuvant promotes a Th2-type response, while SARS-CoV-2 PsIV with the Advax-2 adjuvant promotes a Th1-type response.

Tetravalent dengue DNA vaccine is not immunogenic when delivered by retrograde infusion into salivary glands.

INTRODUCTION AND BACKGROUND: A tetravalent DNA vaccine for Dengue virus is under development but has not yet achieved optimal immunogenicity. Salivary glands vaccination has been reported efficacious in rodents and dogs. We report on a pilot study testing the salivary gland as a platform for a Dengue DNA vaccine in a non-human primate model. MATERIALS AND METHODS: Four cynomolgus macaques were used in this study. Each macaque was pre-medicated with atropine and sedated with ketamine. Stensen's duct papilla was cannulated with a P10 polyethylene tube, linked to a 500ul syringe. On the first two infusions, all macaques were infused with 300ul of TVDV mixed with 2 mg of zinc. For the 3rd infusion, to increase transfection into salivary tissue, two animals received 100uL TVDV mixed with 400uL polyethylenimine 1µg/ml (PEI) and the other two animals received 500uL TVDV with zinc. Antibody titers were assessed 4 weeks following the second and third infusion. RESULTS AND CONCLUSIONS: SGRI through Stensen's duct is a well-tolerated, simple and easy to reproduce procedure. TVDV infused into macaques salivary glands elicited a significantly weaker antibody response than with different delivery methods.

Comparison of purified psoralen-inactivated and formalin-inactivated dengue vaccines in mice and nonhuman primates.

Dengue fever, caused by dengue viruses (DENV 1-4) is a leading cause of illness and death in the tropics and subtropics. Therefore, an effective vaccine is urgently needed. Currently, the only available licensed dengue vaccine is a chimeric live attenuated vaccine that shows varying efficacy depending on serotype, age and baseline DENV serostatus. Accordingly, a dengue vaccine that is effective in seronegative adults, children of all ages and in immunocompromised individuals is still needed. We are currently researching the use of psoralen to develop an inactivated tetravalent dengue vaccine. Unlike traditional formalin inactivation, psoralen inactivates pathogens at the nucleic acid level, potentially preserving envelope protein epitopes important for protective anti-dengue immune responses. We prepared highly purified monovalent vaccine lots of formalin- and psoralen-inactivated DENV 1-4, using Capto DeVirS and Capto Core 700 resin based column chromatography. Tetravalent psoralen-inactivated vaccines (PsIV) and formalin-inactivated vaccines (FIV) were prepared by combining the four monovalent vaccines. Mice were immunized with either a low or high dose of PsIV or FIV to evaluate the immunogenicity of monovalent as well as tetravalent formulations of each inactivation method. In general, the monovalent and tetravalent PsIVs elicited equivalent or higher titers of neutralizing antibodies to DENV than the FIV dengue vaccines and this response was dose dependent. The immunogenicity of tetravalent dengue PsIVs and FIVs were also evaluated in nonhuman primates (NHPs). Consistent with what was observed in mice, significantly higher neutralizing antibody titers for each dengue serotype were observed in the NHPs vaccinated with the tetravalent dengue PsIV compared to those vaccinated with the tetravalent dengue FIV, indicative of the importance of envelope protein epitope preservation during psoralen inactivation of DENV.

Anti-influenza immune plasma for the treatment of patients with severe influenza A: a randomised, double-blind, phase 3 trial.

BACKGROUND: Infection with influenza virus causes substantial morbidity and mortality globally, although antiviral treatments are available. Previous studies have suggested that anti-influenza immune plasma could be beneficial as treatment, but they were not designed as randomised, blinded, placebo-controlled trials. Therefore, we aimed to prospectively evaluate the clinical efficacy of high-titre immune plasma compared with standard low-titre plasma to improve outcomes in patients with severe influenza A infection. METHODS: We did this randomised, double-blind, phase 3 trial at 41 US medical centres to assess the efficacy of high-titre anti-influenza plasma (haemagglutination inhibition antibody titre ≥1:80) compared with low-titre plasma (≤1:10). Children and adults with PCR-confirmed influenza A infection, a National Early Warning score of 3 or greater, and onset of illness within 6 days before randomisation were eligible. Patients were randomly assigned (2:1) using an interactive web response system to receive either two units (or paediatric equivalent) of high-titre plasma (high-titre group) or low-titre plasma (low-titre group), and were followed up for 28 days from randomisation. High-titre and low-titre plasma had the same appearance. Randomisation was stratified by severity (in intensive care unit, not in intensive care but requiring supplemental oxygen, or not in intensive care and not requiring supplemental oxygen) and age (<18 years and ≥18 years). All participants, site staff, and the study team were masked to treatment allocation until after the final database lock. The primary endpoint was clinical status assessed by a six-point ordinal scale on day 7 (death, in intensive care, hospitalised but requiring supplemental oxygen, hospitalised not requiring supplemental oxygen, discharged but unable to resume normal activities, and discharged with full resumption of normal activities) analysed in a proportional odds model (an odds ratio [OR] >1 indicates improvement in clinical status across all categories for the high-titre vs the low-titre group). The primary analysis was done in the intention-to-treat population, excluding two participants who did not receive plasma. This trial is registered with ClinicalTrials.gov, NCT02572817. FINDINGS: Participants were recruited between Jan 26, 2016, and April 19, 2018. Of 200 participants enrolled (177 adults and 23 children), 140 met the criteria for randomisation and were assigned to the high-titre group (n=92) or to the control low-titre group (n=48). One participant from each group did not receive plasma. At baseline, 60 (43%) of 138 participants were in intensive care and 55 (71%) of 78 participants who were not in intensive care required oxygen. 93% of planned plasma infusions were completed. The study was terminated in July, 2018, when independent efficacy analysis showed low conditional power to detect an effect of high-titre plasma even if full accrual (150 participants) was achieved. The proportional OR for improved clinical status on day 7 was 1·22 (95% CI 0·65-2·29, p=0·54). 47 (34%) of 138 participants experienced 88 serious adverse events: 32 (35%) with 60 events in the high-titre group and 15 (32%) with 28 events in the low-titre group. The most common serious adverse events were acute respiratory distress syndrome (ARDS; four [4%] vs two [4%]), allergic transfusion reactions (two [2%] vs two [4%]), and respiratory distress (three [3%] vs none). 65 (47%) participants experienced 183 adverse events: 42 (46%) with 126 events in the high-titre group and 23 (49%) with 57 events in the low-titre group. The most common adverse events were anaemia (four [3%] vs two [4%]) and ARDS (four [3%] vs three [5%]). Ten patients died during the study (six [7%] in the high-titre group vs four [9%] in the low-titre group, p=0·73). The most common cause of death was worsening of acute respiratory distress syndrome (two [2%] vs two [4%] patients). INTERPRETATION: High-titre anti-influenza plasma conferred no significant benefit over non-immune plasma. Although our study did not have the precision to rule out a small, clinically relevant effect, the benefit is insufficient to justify the use of immune plasma for treating patients with severe influenza A. FUNDING: National Institute of Allergy and Infectious Diseases of the National Institutes of Health (Bethesda, MD, USA).

Enhanced immunogenicity and protective efficacy of a tetravalent dengue DNA vaccine using electroporation and intradermal delivery.

Phase 1 clinical trials with a DNA vaccine for dengue demonstrated that the vaccine is safe and well tolerated, however it produced less than optimal humoral immune responses. To determine if the immunogenicity of the tetravalent dengue DNA vaccine could be enhanced, we explored alternate, yet to be tested, methods of vaccine administration in non-human primates. Animals were vaccinated on days 0, 28 and 91 with either a low (1 mg) or high (5 mg) dose of vaccine by the intradermal or intramuscular route, using either needle-free injection or electroporation devices. Neutralizing antibody, IFN-γ T cell and memory B cell responses were compared to a high dose group vaccinated with a needle-free intramuscular injection delivery device similar to what had been used in previous preclinical and clinical studies. All previously untested vaccination methodologies elicited improved immune responses compared to the high dose needle-free intramuscular injection delivery group. The highest neutralizing antibody responses were observed in the group that was vaccinated with the high dose formulation via intradermal electroporation. The highest IFN-γ T cell responses were also observed in the high dose intradermal electroporation group and the CD8+ T cells were the dominant contributors for the IFNγ response. Memory B cells were detected for all four serotypes. More than a year after vaccination, groups were challenged with dengue-1 virus. Both the low and high dose intradermal electroporation groups had significantly fewer days of dengue-1 virus RNAemia compared to the control group. The results from this study demonstrate that using either an electroporation device and/or the intradermal route of delivery increases the immune response generated by this vaccine in non-human primates and should be explored in humans.

Nosocomial outbreak of influenza A H3N2 in an inpatient oncology unit related to health care workers presenting to work while ill.

OBJECTIVE: To describe an outbreak of influenza A in an oncology unit, highlighting infection control methods implemented, and examining reasons health care workers (HCWs) present to work with influenza-like illness (ILI). METHODS: Confirmed cases were defined by the presence of ILI and a positive nasopharyngeal polymerase chain reaction swab for influenza A H3. Probable cases were defined as exposed HCWs with ILI who were unavailable for polymerase chain reaction testing. Infection prevention measures included closing the ward for new admissions, oseltamivir prophylaxis for all exposed groups, and dismissal from work of HCWs with ILI until resolution of symptoms. An anonymous survey of the cases in our HCWs was conducted to better elucidate reasons behind presenteeism. RESULTS: Over the course of 8 days (November 16, 2017, to November 22, 2017), influenza was diagnosed in 7 of 10 inpatients on the oncology ward, 16 HCWs (14 confirmed, 2 probable), and 2 visitors. The suspected index case was an HCW. Of the surveyed HCWs, 64% presented to work despite feeling ill (ie, presenteeism). The most common reason was "sense of duty as a health care worker." CONCLUSIONS: This nosocomial outbreak of influenza highlights the challenges of protecting inpatients from viral respiratory tract infections. HCWs and patient visitors with ILI should avoid work or visiting until resolution of peak respiratory symptoms and adhere to strict respiratory etiquette.

Influence of sample collection tube method, anticoagulant-containing plasma versus serum, on influenza virus hemagglutination inhibition titer and microneutralization titer serological assays.

BACKGROUND: The hemagglutination-inhibition (HAI) assay is a critical component for measurement of immunogenicity in influenza vaccine development. It is unknown if the results can be influenced by sample type and anticoagulants. The purpose of this study was to evaluate the influence of different sample collection methods, in particular different anticoagulants, and choice of plasma or serum, on influenza virus serological assays. METHODS: Blood samples from thirty donors previously immunized against influenza viruses were collected using six different types of blood collection tubes, two of which collect serum and four of which contain various anticoagulants for collecting plasma. Serum: (1) serum separator tubes (SST); and (2) Plus Plastic serum "red-top serum" tubes. Plasma: (3) spray-coated K2 ethylenediaminetetraacetic acid (EDTA) tubes: (4) Sodium Heparin tubes; (5) Citrate tubes with 3.2% sodium citrate solution; and (6) Glass Blood Collection tubes with acid citrate dextrose. Samples were tested against three different influenza viruses (A/California/07/2009 (H1N1pdm09), A/Texas/50/2012 (H3N2), and B/Massachusetts/2/2012) for hemagglutination inhibition titer and virus neutralization titer via a microneutralization (MN) assay, and data compared to that obtained for standard serum sample collected in SST. RESULTS: HAI and MN titers against type A viruses were within two dilutions compared to SST collection method over 96% of the time irrespective of sample type or anticoagulant. However, HAI titers for type B virus were more variable across different collection methods. EDTA plasma samples were greater than two dilutions higher than SST serum samples 70% (21 of 30 samples) of the time. In contrast, MN titers were within two dilutions over 96% of the time, with the highest deviation noted in acid citrate dextrose plasma samples (3 of 30 samples tested, 10%). CONCLUSIONS: These data provide useful guidelines for sample collection and serology testing when screening: (i) influenza vaccine immunogenicity antibody response; (ii) antibody responses to newly emerging viral strains; and (iii) clinical samples for anti-influenza antibody activity.

Safety and tolerability of a novel, polyclonal human anti-MERS coronavirus antibody produced from transchromosomic cattle: a phase 1 randomised, double-blind, single-dose-escalation study.

BACKGROUND: Middle East respiratory syndrome (MERS) is a severe respiratory illness with an overall mortality of 35%. There is no licensed or proven treatment. Passive immunotherapy approaches are being developed to prevent and treat several human medical conditions where alternative therapeutic options are absent. We report the safety of a fully human polyclonal IgG antibody (SAB-301) produced from the hyperimmune plasma of transchromosomic cattle immunised with a MERS coronavirus vaccine. METHODS: We did a phase 1 double-blind, placebo-controlled, single-dose escalation trial at the National Institutes of Health Clinical Center. We recruited healthy participants aged 18-60 years who had normal laboratory parameters at enrolment, a body-mass index of 19-32 kg/m2, and a creatinine clearance of 70 mL/min or more, and who did not have any chronic medical problems that required daily oral medications, a positive rheumatoid factor (≥15 IU/mL), IgA deficiency (<7 mg/dL), or history of allergy to intravenous immunoglobulin or human blood products. Participants were randomly assigned by a computer-generated table, made by a masked pharmacist, to one of six cohorts (containing between three and ten participants each). Cohorts 1 and 2 had three participants, randomly assigned 2:1 to receive active drug SAB-301 versus normal saline placebo; cohorts 3 and 4 had six participants randomised 2:1; and cohorts 5 and 6 had ten participants, randomised 4:1. Participants received 1 mg/kg, 2·5 mg/kg, 5 mg/kg, 10 mg/kg, 20 mg/kg, or 50 mg/kg of SAB-301, or equivalent volume placebo (saline control), on day 0, and were followed up by clinical, laboratory, and pharmacokinetic assessments on days 1, 3, 7, 21, 42, and 90. The primary outcome was safety, and immunogenicity was a secondary outcome. We analysed the intention-to-treat population. This trial is registered with ClinicalTrials.gov, number NCT02788188. FINDINGS: Between June 2, 2016, and Jan 4, 2017, we screened 43 participants, of whom 38 were eligible and randomly assigned to receive SAB-301 (n=28) or placebo (n=10). 97 adverse events were reported: 64 adverse events occurred in 23 (82%) of 28 participants receiving SAB-301 (mean 2·3 adverse events per participant). 33 adverse events occurred in all ten participants receiving placebo (mean 3·3 adverse events per participant). The most common adverse events were headache (n=6 [21%] in participants who received SAB-301 and n=2 [20%] in those receiving placebo), albuminuria (n=5 [18%] vs n=2 [20%]), myalgia (n=3 [11%] vs n=1 [10%]), increased creatine kinase (n=3 [11%] vs 1 [10%]), and common cold (n=3 [11%] vs n=2 [20%]). There was one serious adverse event (hospital admission for suicide attempt) in one participant who received 50 mg/kg of SAB-301. The area under the concentration-time curve (AUC) in the 50 mg/kg dose (27 498 µg × days per mL) is comparable to the AUC that was associated with efficacy in a preclinical model. INTERPRETATION: Single infusions of SAB-301 up to 50 mg/kg appear to be safe and well tolerated in healthy participants. Human immunoglobulin derived from transchromosomic cattle could offer a new platform technology to produce fully human polyclonal IgG antibodies for other medical conditions. FUNDING: National Institute of Allergy and Infectious Diseases, National Institutes of Health, and Biomedical Advanced Research and Development Authority.

Safety and Immunogenicity of a Tetravalent Dengue DNA Vaccine Administered with a Cationic Lipid-Based Adjuvant in a Phase 1 Clinical Trial.

We conducted an open label, dose escalation Phase 1 clinical trial of a tetravalent dengue DNA vaccine (TVDV) formulated in Vaxfectin® to assess safety and immunogenicity. A total of 40 dengue- and flavivirus-naive volunteers received either low-dose (1 mg) TVDV alone (N = 10, group 1), low-dose TVDV (1 mg) formulated in Vaxfectin (N = 10, group 2), or high-dose TVDV (2 mg, group 3) formulated in Vaxfectin® (N = 20). Subjects were immunized intramuscularly with three doses on a 0-, 30-, 90-day schedule and monitored. Blood samples were obtained after each immunization and various time points thereafter to assess anti-dengue antibody and interferon gamma (IFNγ) T-cell immune responses. The most common adverse events (AEs) across all groups included mild to moderate pain and tenderness at the injection site, which typically resolved within 7 days. Common solicited signs and symptoms included fatigue (42.5%), headache (45%), and myalgias (47.5%). There were no serious AEs related to the vaccine or study procedures. No anti-dengue antibody responses were detected in group 1 subjects who received all three immunizations. There were minimal enzyme-linked immunosorbent assay and neutralizing antibody responses among groups 2 and 3 subjects who completed the immunization schedule. By contrast, IFNγ T-cell responses, regardless of serotype specificity, occurred in 70%, 50%, and 79% of subjects in groups 1, 2, and 3, respectively. The largest IFNγ T-cell responses were among group 3 subjects. We conclude that TVDV was safe and well-tolerated and elicited predominately anti-dengue T-cell IFNγ responses in a dose-related fashion.

Antibody-dependent NK cell degranulation as a marker for assessing antibody-dependent cytotoxicity against pandemic 2009 influenza A(H1N1) infection in human plasma and influenza-vaccinated transchromosomic bovine intravenous immunoglobulin therapy.

This study describes an antibody-dependent NK cell degranulation assay, as a biomarker to assess antibody-dependent cellular cytotoxicity (ADCC) response in influenza plasma and for antibody therapies against influenza infection. The concentration of neutralizing antibodies (NAbs) against the hemagglutinin receptor of influenza viruses is a current determinant in protection against infection, particularly following receipt of the seasonal influenza vaccine. However, this is a limited assessment of protection, because: (i) NAb titers that incur full protection vary; and (ii) NAb titers do not account for the entire breadth of antibody responses against viral infection. Previous reports have indicated that antibodies that prime ADCC play a vital role in controlling influenza infections, and thus should be quantified for assessing protection against influenza. This report demonstrates a non-radioactive assay that assesses NK cell activation as a marker of ADCC, in which NK cells interact with opsonized viral antigen expressed on the surface of infected Raji target cells resulting in effector cell degranulation (surrogate CD107a expression). A positive correlation was determined between HAI titers and sustained NK cell activation, although NK cell activation was seen in plasma samples with HAI titers below 40 and varied amongst samples with high HAI titers. Furthermore, sustained NK cell degranulation was determined for influenza-vaccinated transchromosomic bovine intravenous immunoglobulin, indicating the potential utility of this therapy for influenza treatment. We conclude that this assay is reproducible and relevant.

Antibody Preparations from Human Transchromosomic Cows Exhibit Prophylactic and Therapeutic Efficacy against Venezuelan Equine Encephalitis Virus.

Venezuelan equine encephalitis virus (VEEV) is a mosquito-borne RNA virus that causes low mortality but high morbidity rates in humans. In addition to natural outbreaks, there is the potential for exposure to VEEV via aerosolized virus particles. There are currently no FDA-licensed vaccines or antiviral therapies for VEEV. Passive immunotherapy is an approved method used to protect individuals against several pathogens and toxins. Human polyclonal antibodies (PAbs) are ideal, but this is dependent upon serum from convalescent human donors, which is in limited supply. Non-human-derived PAbs can have serious immunoreactivity complications, and when "humanized," these antibodies may exhibit reduced neutralization efficiency. To address these issues, transchromosomic (Tc) bovines have been created, which can produce potent neutralizing human antibodies in response to hyperimmunization. In these studies, we have immunized these bovines with different VEEV immunogens and evaluated the protective efficacy of purified preparations of the resultant human polyclonal antisera against low- and high-dose VEEV challenges. These studies demonstrate that prophylactic or therapeutic administration of the polyclonal antibody preparations (TcPAbs) can protect mice against lethal subcutaneous or aerosol challenge with VEEV. Furthermore, significant protection against unrelated coinfecting viral pathogens can be conferred by combining individual virus-specific TcPAb preparations.IMPORTANCE With the globalization and spread or potential aerosol release of emerging infectious diseases, it will be critical to develop platforms that are able to produce therapeutics in a short time frame. By using a transchromosomic (Tc) bovine platform, it is theoretically possible to produce antigen-specific highly neutralizing therapeutic polyclonal human antibody (TcPAb) preparations in 6 months or less. In this study, we demonstrate that Tc bovine-derived Venezuelan equine encephalitis virus (VEEV)-specific TcPAbs are highly effective against VEEV infection that mimics not only the natural route of infection but also infection via aerosol exposure. Additionally, we show that combinatorial TcPAb preparations can be used to treat coinfections with divergent pathogens, demonstrating that the Tc bovine platform could be beneficial in areas where multiple infectious diseases occur contemporaneously or in the case of multipathogen release.

Immune plasma for the treatment of severe influenza: an open-label, multicentre, phase 2 randomised study.

BACKGROUND: Influenza causes substantial morbidity and mortality despite available treatments. Anecdotal reports suggest that plasma with high antibody titres to influenza might be of benefit in the treatment of severe influenza. METHODS: In this randomised, open-label, multicentre, phase 2 trial, 29 academic medical centres in the USA assessed the safety and efficacy of anti-influenza plasma with haemagglutination inhibition antibody titres of 1:80 or more to the infecting strain. Hospitalised children and adults (including pregnant women) with severe influenza A or B (defined as the presence of hypoxia or tachypnoea) were randomly assigned to receive either two units (or paediatric equivalent) of anti-influenza plasma plus standard care, versus standard care alone, and were followed up for 28 days. The primary endpoint was time to normalisation of patients' respiratory status (respiratory rate of ≤20 breaths per min for adults or age-defined thresholds of 20-38 breaths per min for children) and a room air oxygen saturation of 93% or more. This study is registered with ClinicalTrials.gov, number NCT01052480. FINDINGS: Between Jan 13, 2011, and March 2, 2015, 113 participants were screened for eligibility and 98 were randomly assigned from 20 out of 29 participating sites. Of the participants with confirmed influenza (by PCR), 28 (67%) of 42 in the plasma plus standard care group normalised their respiratory status by day 28 compared with 24 (53%) of 45 participants on standard care alone (p=0·069). The hazard ratio (HR) comparing plasma plus standard care with standard care alone was 1·71 (95% CI 0·96-3·06). Six participants died, one (2%) from the plasma plus standard care group and five (10%) from the standard care group (HR 0·19 [95% CI 0·02-1·65], p=0·093). Participants in the plasma plus standard care group had non-significant reductions in days in hospital (median 6 days [IQR 4-16] vs 11 days [5-25], p=0·13) and days on mechanical ventilation (median 0 days [IQR 0-6] vs 3 days [0-14], p=0·14). Fewer plasma plus standard care participants had serious adverse events compared with standard care alone recipients (nine [20%] of 46 vs 20 [38%] of 52, p=0·041), the most frequent of which were acute respiratory distress syndrome (one [2%] vs two [4%] patients) and stroke (one [2%] vs two [4%] patients). INTERPRETATION: Although there was no significant effect of plasma treatment on the primary endpoint, the treatment seemed safe and well tolerated. A phase 3 randomised trial is now underway to further assess this intervention. FUNDING: National Institute of Allergy and Infectious Diseases, US National Institutes of Health.

DNA Vaccine Delivery and Improved Immunogenicity.

The promise of DNA vaccines is as compelling today as it was more than a decade ago. Ease of manufacture, stability at ambient temperatures without the need for a cold chain and its ability to mimic natural infections and elicit appropriate immune responses makes this vaccine platform extremely attractive. Although, human clinical trials of DNA vaccines have yielded less than optimal results, the approval and licensing of a few veterinary vaccines is testimony to the proof-of-concept and the hope that licensed DNA vaccines for human use may not be too far away. Delivery and targeting of immunologically relevant cells appears to be the major hurdle in maximizing the immunogenicity of DNA vaccines. Several different approaches that are currently pursued in achieving this objective are discussed.

Feasibility of Using Convalescent Plasma Immunotherapy for MERS-CoV Infection, Saudi Arabia.

We explored the feasibility of collecting convalescent plasma for passive immunotherapy of Middle East respiratory syndrome coronavirus (MERS-CoV) infection by using ELISA to screen serum samples from 443 potential plasma donors: 196 patients with suspected or laboratory-confirmed MERS-CoV infection, 230 healthcare workers, and 17 household contacts exposed to MERS-CoV. ELISA-reactive samples were further tested by indirect fluorescent antibody and microneutralization assays. Of the 443 tested samples, 12 (2.7%) had a reactive ELISA result, and 9 of the 12 had reactive indirect fluorescent antibody and microneutralization assay titers. Undertaking clinical trials of convalescent plasma for passive immunotherapy of MERS-CoV infection may be feasible, but such trials would be challenging because of the small pool of potential donors with sufficiently high antibody titers. Alternative strategies to identify convalescent plasma donors with adequate antibody titers should be explored, including the sampling of serum from patients with more severe disease and sampling at earlier points during illness.

Human polyclonal immunoglobulin G from transchromosomic bovines inhibits MERS-CoV in vivo.

As of 13 November 2015, 1618 laboratory-confirmed human cases of Middle East respiratory syndrome coronavirus (MERS-CoV) infection, including 579 deaths, had been reported to the World Health Organization. No specific preventive or therapeutic agent of proven value against MERS-CoV is currently available. Public Health England and the International Severe Acute Respiratory and Emerging Infection Consortium identified passive immunotherapy with neutralizing antibodies as a treatment approach that warrants priority study. Two experimental MERS-CoV vaccines were used to vaccinate two groups of transchromosomic (Tc) bovines that were genetically modified to produce large quantities of fully human polyclonal immunoglobulin G (IgG) antibodies. Vaccination with a clade A γ-irradiated whole killed virion vaccine (Jordan strain) or a clade B spike protein nanoparticle vaccine (Al-Hasa strain) resulted in Tc bovine sera with high enzyme-linked immunosorbent assay (ELISA) and neutralizing antibody titers in vitro. Two purified Tc bovine human IgG immunoglobulins (Tc hIgG), SAB-300 (produced after Jordan strain vaccination) and SAB-301 (produced after Al-Hasa strain vaccination), also had high ELISA and neutralizing antibody titers without antibody-dependent enhancement in vitro. SAB-301 was selected for in vivo and preclinical studies. Administration of single doses of SAB-301 12 hours before or 24 and 48 hours after MERS-CoV infection (Erasmus Medical Center 2012 strain) of Ad5-hDPP4 receptor-transduced mice rapidly resulted in viral lung titers near or below the limit of detection. Tc bovines, combined with the ability to quickly produce Tc hIgG and develop in vitro assays and animal model(s), potentially offer a platform to rapidly produce a therapeutic to prevent and/or treat MERS-CoV infection and/or other emerging infectious diseases.

Nucleic acid (DNA) immunization as a platform for dengue vaccine development.

Since the early 1990s, DNA immunization has been used as a platform for developing a tetravalent dengue vaccine in response to the high priority need for protecting military personnel deployed to dengue endemic regions of the world. Several approaches have been explored ranging from naked DNA immunization to the use of live virus vectors to deliver the targeted genes for expression. Pre-clinical animal studies were largely successful in generating anti-dengue cellular and humoral immune responses that were protective either completely or partially against challenge with live dengue virus. However, Phase 1 clinical evaluation of a prototype monovalent dengue 1 DNA vaccine expressing prM and E genes revealed anti-dengue T cell IFNγ responses, but poor neutralizing antibody responses. These less than optimal results are thought to be due to poor uptake and expression of the DNA vaccine plasmids. Because DNA immunization as a vaccine platform has the advantages of ease of manufacture, flexible genetic manipulation and enhanced stability, efforts continue to improve the immunogenicity of these vaccines using a variety of methods.

Self-administration of intranasal influenza vaccine: Immunogenicity and volunteer acceptance.

BACKGROUND: In outbreak settings, mass vaccination strategies could maximize health protection of military personnel. Self-administration of live attenuated influenza vaccine (LAIV) may be a means to vaccinate large numbers of people and achieve deployment readiness while sparing the use of human resources. METHODS: A phase IV, open-label, randomized controlled trial evaluating the immunogenicity and acceptance of self-administered (SA) LAIV was conducted from 2012 to 2014. SA subjects were randomized to either individual self-administration or self-administration in a group setting. Control randomized subjects received healthcare worker-administered (HCWA) LAIV. Anti-hemagglutinin (HAI) antibody concentrations were measured pre- and post-vaccination. The primary endpoint was immunogenicity non-inferiority between SA and HCWA groups. Subjects were surveyed on preferred administration method. RESULTS: A total of 1077 subjects consented and were randomized (529 SA, 548 HCWA). Subject characteristics were very similar between groups, though SA subjects were younger, more likely to be white and on active duty. The per-protocol analysis included 1024 subjects (501 SA, 523 HCWA). Post-vaccination geometric mean titers by vaccine strain and by study group (HCWA vs. SA) were: A/H1N1 (45.8 vs. 48.7, respectively; p=0.43), A/H3N2 (45.5 vs. 46.4; p=0.80), B/Yamagata (17.2 vs. 17.8; p=0.55). Seroresponses to A components were high (∼67%), while seroresponses to B components were lower (∼25%). Seroresponse did not differ by administration method. Baseline preference for administration method was similar between groups, with the majority in each group expressing no preference. At follow-up, the majority (64%) of SA subjects preferred SA vaccine. CONCLUSIONS: LAIV immunogenicity was similar for HCWA and SA vaccines. SA was well-tolerated and preferred to HCWA among those who performed SA.

Dengue serosurvey in Sint Eustatius.

Four distinct serotypes of dengue viruses (DENV) are the cause of re-emerging dengue fever (DF) and dengue hemorrhagic fever (DHF). Dengue circulation in the Caribbean has gone from none or single serotype to multiple serotypes co-circulating with reports of continuing cycles of progressively more severe disease in the region. Few studies have investigated dengue on Sint Eustatius. Blood samples were collected to determine the prevalence of antibodies against dengue in the Sint Eustatius population. Greater than 90% of the serum samples (184 of 204) were positive for anti-flavivirus antibodies by enzyme linked immunosorbance assay (ELISA). Plaque reduction neutralization test (PRNT), specific for dengue viruses, showed that 171 of these 184 flavivirus antibody positive sera had a neutralization titer against one or more DENV serotypes. A majority of the sera (62%) had neutralizing antibody to all four dengue serotypes. Only 26 PRNT positive sera (15%) had monotypic dengue virus neutralizing antibody, most of which (20 of 26) were against DENV2. Evidence of infection with all four serotypes was observed across all age groups except in the youngest age group (10-19 years) which contained only DENV2 positive individuals. In a multiple logistic regression model, only the length of residence on the island was a predictor of a positive dengue PRNT50 result. To our knowledge this is the first dengue serosurveillance study conducted on Sint Eustatius since the 1970s. The lack of antibodies to the DEN1, 3, and 4 in the samples collected from participants under 20 years of age suggests that only DEN2 has circulated on island since the early 1990s. The high prevalence of antibodies against dengue (83.8%) and the observation that the length of time on the island was the strongest predictor of infection suggests dengue is endemic on Sint Eustatius and a public health concern that warrants further investigation.

Full-genome sequence of human betacoronavirus 2c jordan-n3/2012 after serial passage in Mammalian cells.

Middle East respiratory syndrome coronavirus (MERS-CoV) is the etiologic agent of a highly lethal pneumonia. Here, we report the full-genome sequence of the Jordan-N3/2012 strain after serial passage in two distinct mammalian cell lines. The genome exhibits noteworthy stability, which may inform the development of vaccines and therapeutics used to treat infection with this virus.

Tetravalent DNA vaccine product as a vaccine candidate against dengue.

Dengue is the most important arbovirus worldwide and is the virus that causes dengue fever and the more severe dengue hemorrhagic fever. There are four serotypes of dengue with each possessing the ability to cause disease. Developing a preventive vaccine is the most efficient and effective way to prevent these diseases, and because immunity to one serotype does not protect against the other serotypes, a vaccine must provide tetravalent protection. We used DNA immunization as a platform to develop a tetravalent vaccine. In this chapter, we describe the laboratory, regulatory, and clinical methodology for evaluating a candidate tetravalent vaccine in a Phase 1 clinical trial.