Drug Administration-approved Vaccines Research Articles

An Evidence-based Practical Guide to Vaccination for Hepatitis B Virus.

The hepatitis B virus (HBV) is highly infectious, with over 292 million chronically infected people worldwide and up to 2.4 million in the United States. Following infection, clinically silent liver damage can ensue, but symptoms or signs of advanced disease, including cirrhosis and hepatocellular carcinoma, can take decades to emerge. HBV has the heaviest public health burden of all hepatitis viruses and has now surpassed other major communicable diseases (eg, HIV, diarrheal disease, malaria, tuberculosis) as a leading cause of death globally. Preventing transmission is essential, and efforts are in place to reinforce screening, vaccination, and routine follow-up. Three safe and effective vaccines are available in the United States and other countries for HBV prevention, and the benefits of vaccination in preventing infection and its sequelae have been substantiated. For the first time in over 25 years, a new Food and Drug Administration-approved vaccine is available that offers a high degree of immunogenicity after 2, rather than 3, injections. Persistent challenges include the underutilization of vaccination, choice of vaccine, incomplete vaccinations, varying needs in different populations, management of nonresponders or those with undocumented or incompletely documented vaccination courses, and questions about whether and when booster injections may be needed. A panel of US academic hepatologists with expertise and experience in preventing and managing HBV infection have collaborated to write this practical clinical paper intended to guide clinicians in vaccinating for HBV and address questions that regularly arise in the clinic.

Quantitative Proteomic Analysis Reveals Unfolded-Protein Response Involved in Severe Fever with Thrombocytopenia Syndrome Virus Infection.

Severe fever with thrombocytopenia syndrome (SFTS) is an emerging, highly pathogenic, infectious disease caused by infection with a newly discovered tick-borne phlebovirus, SFTS virus (SFTSV). Limited information on the molecular mechanism of SFTSV infection and pathogenesis impedes the development of effective vaccines and drugs for SFTS prevention and treatment. In this study, an isobaric tag for relative and absolute quantification (iTRAQ)-based quantitative proteomic analysis of SFTSV-infected HEK 293 cells was performed to explore dynamic host cellular protein responses toward SFTSV infection. A total of 433 of 5,606 host proteins involved in different biological processes were differentially regulated by SFTSV infection. The proteomic results highlighted a potential role of endoplasmic reticular stress-triggered unfolded-protein response (UPR) in SFTSV infection. Further functional studies confirmed that all three major branches of the UPR, including the PKR-like endoplasmic reticulum kinase (PERK), the activating transcription factor-6 (ATF6), and the inositol-requiring protein-1 (IRE1)/X-box-binding protein 1 (XBP1) pathways, were activated by SFTSV. However, only the former two pathways play a crucial role in SFTSV infection. Furthermore, expression of SFTSV glycoprotein (GP) alone was sufficient to stimulate the UPR, whereas suppression of PERK and ATF6 notably decreased GP expression. Interestingly, two other newly discovered phleboviruses, Heartland virus and Guertu virus, also stimulated the UPR, suggesting a common mechanism shared by these genetically related phleboviruses. This study provides a global view to our knowledge on how host cells respond to SFTSV infection and highlights that host cell UPR plays an important role in phlebovirus infection.IMPORTANCE Severe fever with thrombocytopenia syndrome virus (SFTSV) is an emerging tick-borne bunyavirus that causes severe fever with thrombocytopenia syndrome in humans, with a mortality rate reaching up to 30% in some outbreaks. There are currently no U.S. Food and Drug Administration-approved vaccines or specific antivirals available against SFTSV. To comprehensively understand the molecular interactions occurring between SFTSV and the host cell, we exploit quantitative proteomic approach to investigate the dynamic host cellular responses to SFTSV infection. The results highlight multiple biological processes being regulated by SFTSV infection. Among these, we focused on exploration of the mechanism of how SFTSV infection stimulates the host cell's unfolded-protein response (UPR) and identified the UPR as a common feature shared by SFTSV-related new emerging phleboviruses. This study, for the first time to our knowledge, provides a global map for host cellular responses to SFTSV infection and highlighted potential host targets for further research.

A Bacteriophage T4 Nanoparticle-Based Dual Vaccine against Anthrax and Plague.

Bacillus anthracis and Yersinia pestis, the causative agents of anthrax and plague, respectively, are two of the deadliest pathogenic bacteria that have been used as biological warfare agents. Although Biothrax is a licensed vaccine against anthrax, no Food and Drug Administration-approved vaccine exists for plague. Here, we report the development of a dual anthrax-plague nanoparticle vaccine employing bacteriophage (phage) T4 as a platform. Using an in vitro assembly system, the 120- by 86-nm heads (capsids) of phage T4 were arrayed with anthrax and plague antigens fused to the small outer capsid protein Soc (9 kDa). The antigens included the anthrax protective antigen (PA) (83 kDa) and the mutated (mut) capsular antigen F1 and the low-calcium-response V antigen of the type 3 secretion system from Y. pestis (F1mutV) (56 kDa). These viral nanoparticles elicited robust anthrax- and plague-specific immune responses and provided complete protection against inhalational anthrax and/or pneumonic plague in three animal challenge models, namely, mice, rats, and rabbits. Protection was demonstrated even when the animals were simultaneously challenged with lethal doses of both anthrax lethal toxin and Y. pestis CO92 bacteria. Unlike the traditional subunit vaccines, the phage T4 vaccine uses a highly stable nanoparticle scaffold, provides multivalency, requires no adjuvant, and elicits broad T-helper 1 and 2 immune responses that are essential for complete clearance of bacteria during infection. Therefore, phage T4 is a unique nanoparticle platform to formulate multivalent vaccines against high-risk pathogens for national preparedness against potential bioterror attacks and emerging infections.IMPORTANCE Following the deadly anthrax attacks of 2001, the Centers for Disease Control and Prevention (CDC) determined that Bacillus anthracis and Yersinia pestis that cause anthrax and plague, respectively, are two Tier 1 select agents that pose the greatest threat to the national security of the United States. Both cause rapid death, in 3 to 6 days, of exposed individuals. We engineered a virus nanoparticle vaccine using bacteriophage T4 by incorporating key antigens of both B. anthracis and Y. pestis into one formulation. Two doses of this vaccine provided complete protection against both inhalational anthrax and pneumonic plague in animal models. This dual anthrax-plague vaccine is a strong candidate for stockpiling against a potential bioterror attack involving either one or both of these biothreat agents. Further, our results establish the T4 nanoparticle as a novel platform to develop multivalent vaccines against pathogens of high public health significance.

A Proteomics Survey of Junín Virus Interactions with Human Proteins Reveals Host Factors Required for Arenavirus Replication.

Arenaviruses are negative-strand, enveloped RNA viruses that cause significant human disease. In particular, Junín mammarenavirus (JUNV) is the etiologic agent of Argentine hemorrhagic fever. At present, little is known about the cellular proteins that the arenavirus matrix protein (Z) hijacks to accomplish its various functions, including driving the process of virus release. Furthermore, there is little knowledge regarding host proteins incorporated into arenavirus particles and their importance for virion function. To address these deficiencies, we used mass spectrometry to identify human proteins that (i) interact with the JUNV matrix protein inside cells or within virus-like particles (VLPs) and/or (ii) are incorporated into bona fide JUNV strain Candid#1 particles. Bioinformatics analyses revealed that multiple classes of human proteins were overrepresented in the data sets, including ribosomal proteins, Ras superfamily proteins, and endosomal sorting complex required for transport (ESCRT) proteins. Several of these proteins were required for the propagation of JUNV (ADP ribosylation factor 1 [ARF1], ATPase, H+ transporting, lysosomal 38-kDa, V0 subunit d1 [ATP6V0D1], and peroxiredoxin 3 [PRDX3]), lymphocytic choriomeningitis mammarenavirus (LCMV) (Rab5c), or both viruses (ATP synthase, H+ transporting, mitochondrial F1 complex, beta polypeptide [ATP5B] and IMP dehydrogenase 2 [IMPDH2]). Furthermore, we show that the release of infectious JUNV particles, but not LCMV particles, requires a functional ESCRT pathway and that ATP5B and IMPDH2 are required for JUNV budding. In summary, we have provided a large-scale map of host machinery that associates with JUNV and identified key human proteins required for its propagation. This data set provides a resource for the field to guide antiviral target discovery and to better understand the biology of the arenavirus matrix protein and the importance of host proteins for virion function.IMPORTANCE Arenaviruses are deadly human pathogens for which there are no U.S. Food and Drug Administration-approved vaccines and only limited treatment options. Little is known about the host proteins that are incorporated into arenavirus particles or that associate with its multifunctional matrix protein. Using Junín mammarenavirus (JUNV), the causative agent of Argentine hemorrhagic fever, as a model organism, we mapped the human proteins that are incorporated into JUNV particles or that associate with the JUNV matrix protein. Functional analysis revealed host machinery that is required for JUNV propagation, including the cellular ESCRT pathway. This study improves our understanding of critical arenavirus-host interactions and provides a data set that will guide future studies to better understand arenavirus pathogenesis and identify novel host proteins that can be therapeutically targeted.

A Bivalent Anthrax-Plague Vaccine That Can Protect against Two Tier-1 Bioterror Pathogens, Bacillus anthracis and Yersinia pestis.

Bioterrorism remains as one of the biggest challenges to global security and public health. Since the deadly anthrax attacks of 2001 in the United States, Bacillus anthracis and Yersinia pestis, the causative agents of anthrax and plague, respectively, gained notoriety and were listed by the CDC as Tier-1 biothreat agents. Currently, there is no Food and Drug Administration-approved vaccine against either of these threats for mass vaccination to protect general public, let alone a bivalent vaccine. Here, we report the development of a single recombinant vaccine, a triple antigen consisting of all three target antigens, F1 and V from Y. pestis and PA from B. anthracis, in a structurally stable context. Properly folded and soluble, the triple antigen retained the functional and immunogenicity properties of all three antigens. Remarkably, two doses of this immunogen adjuvanted with Alhydrogel® elicited robust antibody responses in mice, rats, and rabbits and conferred complete protection against inhalational anthrax and pneumonic plague. No significant antigenic interference was observed. Furthermore, we report, for the first time, complete protection of animals against simultaneous challenge with Y. pestis and the lethal toxin of B. anthracis, demonstrating that a single biodefense vaccine can protect against a bioterror attack with weaponized B. anthracis and/or Y. pestis. This bivalent anthrax–plague vaccine is, therefore, a strong candidate for stockpiling, after demonstration of its safety and immunogenicity in human clinical trials, as part of national preparedness against two of the deadliest bioterror threats.

Longitudinal peripheral blood transcriptional analysis of a patient with severe Ebola virus disease.

The 2013-2015 outbreak of Ebola virus disease in Guinea, Liberia, and Sierra Leone was unprecedented in the number of documented cases, but there have been few published reports on immune responses in clinical cases and their relationships with the course of illness and severity of Ebola virus disease. Symptoms of Ebola virus disease can include severe headache, myalgia, asthenia, fever, fatigue, diarrhea, vomiting, abdominal pain, and hemorrhage. Although experimental treatments are in development, there are no current U.S. Food and Drug Administration-approved vaccines or therapies. We report a detailed study of host gene expression as measured by microarray in daily peripheral blood samples collected from a patient with severe Ebola virus disease. This individual was provided with supportive care without experimental therapies at the National Institutes of Health Clinical Center from before onset of critical illness to recovery. Pearson analysis of daily gene expression signatures revealed marked gene expression changes in peripheral blood leukocytes that correlated with changes in serum and peripheral blood leukocytes, viral load, antibody responses, coagulopathy, multiple organ dysfunction, and then recovery. This study revealed marked shifts in immune and antiviral responses that preceded changes in medical condition, indicating that clearance of replicating Ebola virus from peripheral blood leukocytes is likely important for systemic viral clearance.

Differential Cultivation of Francisella tularensis Induces Changes in the Immune Response to and Protective Efficacy of Whole Cell-Based Inactivated Vaccines.

Francisella tularensis (Ft) is a category A biothreat agent for which there is no Food and Drug Administration-approved vaccine. Ft can survive in a variety of habitats with a remarkable ability to adapt to changing environmental conditions. Furthermore, Ft expresses distinct sets of antigens (Ags) when inside of macrophages (its in vivo host) as compared to those grown in vitro with Mueller Hinton Broth (MHB). However, in contrast to MHB-grown Ft, Ft grown in Brain-Heart Infusion (BHI) more closely mimics the antigenic profile of macrophage-grown Ft. Thus, we anticipated that when used as a vaccine, BHI-grown Ft would provide better protection compared to MHB-grown Ft, primarily due to its greater antigenic similarity to Ft circulating inside the host (macrophages) during natural infection. Our investigation, however, revealed that inactivated Ft (iFt) grown in MHB (iFt-MHB) exhibited superior protective activity when used as a vaccine, as compared to iFt grown in BHI (iFt-BHI). The superior protection afforded by iFt-MHB compared to that of iFt-BHI was associated with significantly lower bacterial burden and inflammation in the lungs and spleens of vaccinated mice. Moreover, iFt-MHB also induced increased levels of Ft-specific IgG. Further evaluation of early immunological cues also revealed that iFt-MHB exhibits increased engagement of Ag-presenting cells including increased iFt binding to dendritic cells, increased expression of costimulatory markers, and increased secretion of pro-inflammatory cytokines. Importantly, these studies directly demonstrate that Ft growth conditions strongly impact Ft vaccine efficacy and that the growth medium used to produce whole cell vaccines to Ft must be a key consideration in the development of a tularemia vaccine.

Tularemia vaccine development: paralysis or progress?

Francisella tularensis (Ft) is a gram-negative intercellular pathogen and category A biothreat agent. However, despite 15 years of strong government investment and intense research focused on the development of a US Food and Drug Administration-approved vaccine against Ft, the primary goal remains elusive. This article reviews research efforts focused on developing an Ft vaccine, as well as a number of important factors, some only recently recognized as such, which can significantly impact the development and evaluation of Ft vaccine efficacy. Finally, an assessment is provided as to whether a US Food and Drug Administration-approved Ft vaccine is likely to be forthcoming and the potential means by which this might be achieved.

Thermostable ricin vaccine protects rhesus macaques against aerosolized ricin: Epitope-specific neutralizing antibodies correlate with protection

Ricin toxin (RT) is the second most lethal toxin known; it has been designated by the CDC as a select agent. RT is made by the castor bean plant; an estimated 50,000 tons of RT are produced annually as a by-product of castor oil. RT has two subunits, a ribotoxic A chain (RTA) and galactose-binding B chain (RTB). RT binds to all mammalian cells and once internalized, a single RTA catalytically inactivates all of the ribosomes in a cell. Administered as an aerosol, RT causes rapid lung damage and fibrosis followed by death. There are no Food and Drug Administration-approved vaccines and treatments are only effective in the first few hours after exposure. We have developed a recombinant RTA vaccine that has two mutations V76M/Y80A (RiVax). The protein is expressed in Escherichia coli and is nontoxic and immunogenic in mice, rabbits, and humans. When vaccinated mice are challenged with injected, aerosolized, or orally administered (gavaged) RT, they are completely protected. We have now developed a thermostable, aluminum-adjuvant-containing formulation of RiVax and tested it in rhesus macaques. After three injections, the animals developed antibodies that completely protected them from a lethal dose of aerosolized RT. These antibodies neutralized RT and competed to varying degrees with a panel of neutralizing and nonneutralizing mouse monoclonal antibodies known to recognize specific epitopes on native RTA. The resulting antibody competition profile could represent an immunologic signature of protection. Importantly, the same signature was observed using sera from RiVax-immunized humans.

The Ebola Virus Matrix Protein Penetrates into the Plasma Membrane

Ebola, a fatal virus in humans and non-human primates, has no Food and Drug Administration-approved vaccines or therapeutics. The virus from the Filoviridae family causes hemorrhagic fever, which rapidly progresses and in some cases has a fatality rate near 90%. The Ebola genome encodes seven genes, the most abundantly expressed of which is viral protein 40 (VP40), the major Ebola matrix protein that regulates assembly and egress of the virus. It is well established that VP40 assembles on the inner leaflet of the plasma membrane; however, the mechanistic details of plasma membrane association by VP40 are not well understood. In this study, we used an array of biophysical experiments and cellular assays along with mutagenesis of VP40 to investigate the role of membrane penetration in VP40 assembly and egress. Here we demonstrate that VP40 is able to penetrate specifically into the plasma membrane through an interface enriched in hydrophobic residues in its C-terminal domain. Mutagenesis of this hydrophobic region consisting of Leu(213), Ile(293), Leu(295), and Val(298) demonstrated that membrane penetration is critical to plasma membrane localization, VP40 oligomerization, and viral particle egress. Taken together, VP40 membrane penetration is an important step in the plasma membrane localization of the matrix protein where oligomerization and budding are defective in the absence of key hydrophobic interactions with the membrane.

Hypersensitivity Reactions to Vaccine Constituents

Vaccines are composed of immunogens, preservatives, adjuvants, antibiotics, and manufacturing by-products. Components of vaccines may rarely elicit adverse reactions in susceptible individuals, thus raising concerns regarding vaccine safety. In this report, we add to the medical literature 3 cases of cutaneous delayed-type hypersensitivity to the vaccine preservative aluminum. We provide a review of major constituents in vaccines that have elicited immediate-type or delayed-type hypersensitivity reactions and describe their clinical manifestations. We include a table of the Food and Drug Administration-approved vaccines, which lists the quantities of major components including ovalbumin (egg protein), gelatin, aluminum, neomycin, 2-phenoxyethanol, thimerosal, and formaldehyde. Our goals were to inform physicians on the variety of hypersensitivity reactions to common vaccines and to provide information on the choice of vaccines in patients with suspected hypersensitivity.

Small-Molecule Inhibitor Leads of Ribosome-Inactivating Proteins Developed Using the Doorstop Approach

Ribosome-inactivating proteins (RIPs) are toxic because they bind to 28S rRNA and depurinate a specific adenine residue from the α-sarcin/ricin loop (SRL), thereby inhibiting protein synthesis. Shiga-like toxins (Stx1 and Stx2), produced by Escherichia coli, are RIPs that cause outbreaks of foodborne diseases with significant morbidity and mortality. Ricin, produced by the castor bean plant, is another RIP lethal to mammals. Currently, no US Food and Drug Administration-approved vaccines nor therapeutics exist to protect against ricin, Shiga-like toxins, or other RIPs. Development of effective small-molecule RIP inhibitors as therapeutics is challenging because strong electrostatic interactions at the RIP•SRL interface make drug-like molecules ineffective in competing with the rRNA for binding to RIPs. Herein, we report small molecules that show up to 20% cell protection against ricin or Stx2 at a drug concentration of 300 nM. These molecules were discovered using the doorstop approach, a new approach to protein•polynucleotide inhibitors that identifies small molecules as doorstops to prevent an active-site residue of an RIP (e.g., Tyr80 of ricin or Tyr77 of Stx2) from adopting an active conformation thereby blocking the function of the protein rather than contenders in the competition for binding to the RIP. This work offers promising leads for developing RIP therapeutics. The results suggest that the doorstop approach might also be applicable in the development of other protein•polynucleotide inhibitors as antiviral agents such as inhibitors of the Z-DNA binding proteins in poxviruses. This work also calls for careful chemical and biological characterization of drug leads obtained from chemical screens to avoid the identification of irrelevant chemical structures and to avoid the interference caused by direct interactions between the chemicals being screened and the luciferase reporter used in screening assays.

Plague in Guinea Pigs and Its Prevention by Subunit Vaccines

Human pneumonic plague is a devastating and transmissible disease for which a Food and Drug Administration-approved vaccine is not available. Suitable animal models may be adopted as a surrogate for human plague to fulfill regulatory requirements for vaccine efficacy testing. To develop an alternative to pneumonic plague in nonhuman primates, we explored guinea pigs as a model system. On intranasal instillation of a fully virulent strain, Yersinia pestis CO92, guinea pigs developed lethal lung infections with hemorrhagic necrosis, massive bacterial replication in the respiratory system, and blood-borne dissemination to other organ systems. Expression of the Y. pestis F1 capsule was not required for the development of pulmonary infection; however, the capsule seemed to be important for the establishment of bubonic plague. The mean lethal dose (MLD) for pneumonic plague in guinea pigs was estimated to be 1000 colony-forming units. Immunization of guinea pigs with the recombinant forms of LcrV, a protein that resides at the tip of Yersinia type III secretion needles, or F1 capsule generated robust humoral immune responses. Whereas LcrV immunization resulted in partial protection against pneumonic plague challenge with 250 MLD Y. pestis CO92, immunization with recombinant F1 did not. rV10, a vaccine variant lacking LcrV residues 271-300, elicited protection against pneumonic plague, which seemed to be based on conformational antibodies directed against LcrV.

Parainfluenza virus type 3 expressing the native or soluble fusion (F) Protein of Respiratory Syncytial Virus (RSV) confers protection from RSV infection in African green monkeys.

Respiratory syncytial virus (RSV) causes respiratory disease in young children, the elderly, and immunocompromised individuals, often resulting in hospitalization and/or death. After more than 40 years of research, a Food and Drug Administration-approved vaccine for RSV is still not available. In this study, a chimeric bovine/human (b/h) parainfluenza virus type 3 (PIV3) expressing the human PIV3 (hPIV3) fusion (F) and hemagglutinin-neuraminidase (HN) proteins from an otherwise bovine PIV3 (bPIV3) genome was employed as a vector for RSV antigen expression with the aim of generating novel RSV vaccines. b/h PIV3 vaccine candidates expressing native or soluble RSV F proteins were evaluated for efficacy and immunogenicity in a nonhuman primate model. b/h PIV3 is suited for development of pediatric vaccines since bPIV3 had already been evaluated in clinical studies in 1- and 2-month-old infants and was found to be safe, immunogenic, and nontransmissible in a day care setting (Karron et al., Pediatr. Infect. Dis. J. 15:650-654, 1996; Lee et al., J. Infect. Dis. 184:909-913, 2001). African green monkeys immunized with b/h PIV3 expressing either the native or soluble RSV F protein were protected from challenge with wild-type RSV and produced RSV neutralizing and RSV F-protein specific immunoglobulin G serum antibodies. The PIV3-vectored RSV vaccines evaluated here further underscore the utility of this vector system for developing safe and immunogenic pediatric respiratory virus vaccines.