Publications by authors named "Paul B Keiser"

Background: Zika virus infection is a threat to at-risk populations, causing major birth defects and serious neurological complications. Development of a safe and efficacious Zika virus vaccine is, therefore, a global health priority. Assessment of heterologous flavivirus vaccination is important given co-circulation of Japanese encephalitis virus and yellow fever virus with Zika virus.

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Background: Dengue is a global health problem and the development of a tetravalent dengue vaccine with durable protection is a high priority. A heterologous prime-boost strategy has the advantage of eliciting immune responses through different mechanisms and therefore may be superior to homologous prime-boost strategies for generating durable tetravalent immunity.

Methods: In this phase 1 first-in-human heterologous prime-boost study, 80 volunteers were assigned to 4 groups and received a tetravalent dengue virus (DENV-1-4) purified inactivated vaccine (TDENV-PIV) with alum adjuvant and a tetravalent dengue virus (DENV-1-4) live attenuated vaccine (TDENV-LAV) in different orders and dosing schedules (28 or 180 days apart).

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Dengue disease and its causative agents, the dengue viruses (DENV-1-4), cause high morbidity in tropical and subtropical regions. We evaluated three dosing regimens of the investigational tetravalent AS03-adjuvanted dengue-purified inactivated vaccine (DPIV+AS03). In this phase 1/2, observer-blind, placebo-controlled study (NCT02421367), 140 healthy adults were randomized 1:1:2 to receive DPIV+AS03 according to the following regimens: 0-1 month (M), 0-1-6 M, or 0-3 M.

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Background: The World Health Organization recommends intradermal (ID) administration of rabies vaccine for preexposure prophylaxis.

Methods: In a randomized trial in adults assigned to 1 of 6 treatment groups (ID vs intramuscular [IM], 2 vs 3 doses, and controls), rabies neutralizing antibody titers were measured to 1 year postvaccination.

Results: ID vaccination produced acceptable antibody levels in all subjects (2- and 3-dose groups).

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Background: Chloroquine can impair the immune responses to intradermal rabies vaccination. Current guidelines recommend an extra intramuscular dose be given for postexposure prophylaxis in previously unvaccinated persons taking any antimalarial drug.

Methods: We conducted a randomized, open-label, single-site study in 103 previously unvaccinated healthy adults age ≥18 to ≤60 years old to evaluate the effects of chloroquine, atovaquone/proguanil (Malarone), and doxycycline on the antibody response to a purified chick embryo cell vaccine, given on a postexposure prophylaxis schedule.

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Background: Vesiviruses (family Caliciviridae) had been shown capable of invading a variety of host species, raising concern of their zoonotic potential. Since the 1980's, several canine caliciviruses (CaCV) isolates have been reported and are phylogenetically related to the vesiviruses with features distinct from both Vesicular exanthema of swine virus (VESV) and Feline calicivirus (FCV) species in phylogeny, serology and cell culture specificities. Etiological studies of canine diseases in dogs used for military services and laboratory studies were conducted in 1963-1978 at the Walter Reed Army Institute of Research.

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Certain occupational and geographical exposures have been associated with an increased risk of lung disease. As a baseline for future studies, we sought to characterize the upper respiratory microbiomes of healthy military personnel in a garrison environment. Nasal, oropharyngeal, and nasopharyngeal swabs were collected from 50 healthy active duty volunteers eight times over the course of one year (1107 swabs, completion rate = 92.

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A candidate new canine picornavirus was isolated from a respiratory swab collected from an American foxhound () in 1968. The assembled genome sequence of strain A128thr is 7,618 bases in length, comprising a complete protein-coding sequence of the 2,213-amino-acid polyprotein and partial terminal untranslated sequences.

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Human adenoviruses (HAdV), in particular types 4 and 7, frequently cause acute respiratory disease (ARD) during basic military training. HAdV4 and HAdV7 vaccines reduced the ARD risk in U.S.

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A 20-y-old male presented with symptoms of meningococcal sepsis and died despite appropriate medical interventions. Blood cultures grew N. meningitidis serogroup Y.

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Background: Shigella flexneri 2a lipopolysaccharide 50 is a nasally delivered subunit vaccine consisting of a macromolecular complex composed of LPS, IpaB, IpaC and IpaD. The current study examined vaccine safety and immunogenicity across a dose range and the clinical performance of a new intranasal delivery device.

Methods: Volunteers (N=36) were randomized to receive vaccine via the Dolphin™ (Valois of America, Congers, New York) intranasal spray device at one of three doses (240, 480, and 690 μg) on days 0, 14, and 28.

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Analysis of the specificity of bactericidal antibodies in normal, convalescent, and postvaccination human sera is important in understanding human immunity to meningococcal infections and can aid in the design of an effective group B vaccine. A collection of human sera, including group C and group B convalescent-phase sera, normal sera with naturally occurring cross-reactive bactericidal activity, and some postvaccination sera, was analyzed to determine the specificity of cross-reactive bactericidal antibodies. Analysis of human sera using a bactericidal antibody depletion assay demonstrated that a significant portion of the bactericidal activity could be removed by purified lipopolysaccharide (LPS).

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Meningococcal disease has historically been associated with military populations, particularly during periods of mobilization. Although the U.S.

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This phase 1 clinical trial assessed the safety and immunogenicity of a native outer membrane vesicle (NOMV) vaccine prepared from a lpxL2(-) synX(-) mutant of strain 44/76 with opcA expression stabilized. Thirty-four volunteers were assigned to one of the three dose groups (25 mcg, 25 mcg with aluminum hydroxide adjuvant, and 50 mcg) to receive three intramuscular injections at 0, 6 and 24 weeks. Specific local and systemic adverse events (AEs) were solicited by diary and at visits on days 1, 2, 7 and 14 after each vaccination and at the end of the study at 30 weeks.

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A vaccine based on native outer membrane vesicles (NOMV) that has potential to provide safe, broad based protection against group B strains of Neisseria meningitidis has been developed. Three antigenically diverse group B strains of N. meningitidis were chosen and genetically modified to improve safety and expression of desirable antigens.

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Endotoxin in vaccines has long been recognized as a cause of adverse events and is generally regarded as a contaminant. However there are now a number of vaccine candidates that contain endotoxin as either antigen or adjuvant, particularly vaccines for Neisseria meningitidis based on native outer membrane vesicles (NOMV). Vaccines containing meningococcal endotoxin are not new.

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Bacterial endotoxin interacts with the human immune system via complex immunological pathways. The evaluation of endotoxicity is important in the development of safe vaccines and immunomodulatory therapeutics. The Limulus amebocyte lysate (LAL) assay is generally accepted by the FDA for use for the quantification of lipopolysaccharide (LPS), while the rabbit pyrogen test (RPT) is used to estimate pyrogenicity during early development and production.

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Several studies have shown plasma fibrinogen increases following some vaccinations, but the specific triggers and the kinetics of this response are not well understood. We conducted a phase I trial of an outer membrane vesicle vaccine for Neisseria meningitidis. Plasma fibrinogen was measured on days 0, 2 and 14 following each of 3 doses.

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Wolbachiae are bacterial endosymbionts of insects and many filarial nematodes whose products trigger inflammation in filarial infections. The dependence of the parasites on their endosymbionts has also led to the use of antibiotics directed against the Wolbachiae, therapy that has been demonstrated to have a profound salutary effect on filarial infections. The identification of Wolbachiae in Mansonella species has been conclusively shown for Mansonella ozzardi (Mo), but not for Mansonella perstans (Mp).

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Monocyte dysfunction in filarial infection has been proposed as one mechanism underlying the diminished antigen-specific T-cell response seen in patent lymphatic filariasis. Cytokine/chemokine production and gene expression in monocytes from filaria-infected patients and uninfected healthy donors were assessed unstimulated and in response to stimulation with Staphylococcus aureus Cowan I bacteria plus gamma interferon both before and 8 months following treatment. Monocytes from filaria-infected individuals were studded with intracellular microfilarial antigens.

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Strongyloides stercoralis causes chronic asymptomatic infections which can be maintained in the human host for many decades. Identification and treatment of S. stercoralis-infected individuals is required because immunosuppression can lead to fatal hyperinfection.

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Protective immunity to larval Strongyloides stercoralis in mice has been shown to be dependent on antibody, complement, and granulocytes. The goals of the present study was to determine the following: (1) whether human serum could passively transfer immunity to mice, (2) the mechanism by which the serum mediated killing, and (3) whether the antigens (Ags) recognized by the protective human antibody could induce protective immunity in mice. Immunoglobulin G (IgG) from a S.

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Strongyloides stercoralis is an intestinal nematode of humans that infects tens of millions of people worldwide. S. stercoralis is unique among intestinal nematodes in its ability to complete its life cycle within the host through an asexual autoinfective cycle, allowing the infection to persist in the host indefinitely.

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