Development Of Better Vaccines Research Articles

Analysis of SARS-CoV-2 isolates, namely the Wuhan strain, Delta variant, and Omicron variant, identifies differential immune profiles.

There is an urgent need to better understand the impact of different severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) variants on immune response and disease dynamics to facilitate better intervention strategies. Here, we show that SARS-CoV-2 variants differentially affect host immune responses. The magnitude and quantity of cytokines and chemokines were comparable in those infected with the Wuhan strain and the Delta variant. However, individuals infected with the Omicron variant had significantly lower levels of these mediators. We also found an elevation of plasma galectins (Gal-3, Gal-8, and Gal-9) in infected individuals, in particular, in those with the original strain. Soluble galectins exert a proinflammatory role in COVID-19 pathogenesis. This was illustrated by their correlation with the plasma levels of sCD14, sCD163, enhanced TNF-α/IL-6 secretion, and increased SARS-CoV-2 infectivity in vitro. Moreover, we observed enhanced CD4+ and CD8+ T cell activation in Wuhan strain-infected individuals. Surprisingly, there was a more pronounced T cell activation in those infected with the Omicron in comparison to the Delta variant. In line with T cell activation status, we observed a more pronounced expansion of T cells expressing different co-inhibitory receptors in patients infected with the Wuhan strain, followed by the Omicron and Delta variants. Individuals infected with the Wuhan strain or the Omicron variant had a similar pattern of plasma soluble immune checkpoints. Our results imply that a milder innate immune response might be beneficial and protective in those infected with the Omicron variant. Our results provide a novel insight into the differential impact of SARS-CoV-2 variants on host immunity. IMPORTANCE There is a need to better understand how different SARS-CoV-2 variants influence the immune system and disease dynamics to facilitate the development of better vaccines and therapies. We compared immune responses in 140 SARS-CoV-2-infected individuals with the Wuhan strain, the Delta variant, or the Omicron variant. All these patients were admitted to the intensive care unit and were SARS-CoV-2 vaccination naïve. We found that SARS-CoV-2 variants differentially affect the host immune response. This was done by measuring soluble biomarkers in their plasma and examining different immune cells. Overall, we found that the magnitude of cytokine storm in individuals infected with the Wuhan strain or the Delta variant was greater than in those infected with the Omicron variant. In light of enhanced cytokine release syndrome in individuals infected with the Wuhan strain or the Delta variant, we believe that a milder innate immune response might be beneficial and protective in those infected with the Omicron variant.

The SARS‐CoV‐2 Omicron Variant and its Multiple Sub‐lineages: Transmissibility, Vaccine Development, Antiviral Drugs, Monoclonal Antibodies, and Strategies for Infection Control – a Review

AbstractThe Omicron (B.1.1.529), fifth variant of concern (VOC) of SARS‐CoV‐2, initially identified following a steep increase in COVID‐19 cases in Southern Africa in November 2021. It is a highly‐mutated variant and is more contagious as compared with the Delta variant, however less deadly. Due to its high transmission rate, it spreads dramatically, and causing huge surges worldwide. It causes “mild infection”, with hospitalisations less likely to occur. However, this variant is known to show resistance to neutralizing antibodies (nAbs) generated through vaccination and/or prior infection as well as to monoclonal antibodies (mAbs) used to treat COVID‐19 patients. In many countries, booster doses of vaccines have been recommended to increase the protective levels of antibodies in vaccinated individuals. Along with the implementation of appropriate prevention and control strategy measures, current efforts are also focussed on the development of better vaccines and mAbs to counter this variant. This review highlights the global health concerns and challenges posed by the Omicron variant and present an update on its sub‐lineages.

Impact of host genetic polymorphisms on response to inactivated influenza vaccine in children

In randomized controlled trials of influenza vaccination, 550 children received trivalent-inactivated influenza vaccine, permitting us to explore relationship between vaccine response and host single nucleotide polymorphisms (SNPs) in 23 candidate genes with adjustment of multiple testing. For host SNPs in TLR7–1817G/T (rs5741880), genotype GT was associated with lower odds (OR: 0.22, 95% CI: 0.09, 0.53) of have post-vaccination hemagglutination-inhibiting (HAI) titers ≥40, compared with genotype GG and TT combined under the over-dominant model. For host SNPs in TLR8–129G/C (rs3764879), genotype GT was associated with lower odds (OR: 0.47; 95% CI: 0.28, 0.80) of have post vaccination HAI titers ≥40 compared with genotype GG and AA combined under the over-dominant model. Our results could contribute to the development of better vaccines that may offer improved protection to all recipients.

Mucosal exposure to non-tuberculous mycobacteria elicits B cell-mediated immunity against pulmonary tuberculosis

Bacille Calmette-Guerin (BCG) is the only licensed vaccine against Mycobacterium tuberculosis (Mtb), the causative agent of tuberculosis (TB) disease. However, BCG has limited efficacy, necessitating the development of better vaccines. Non-tuberculous mycobacteria (NTMs) are opportunistic pathogens present ubiquitously in the environment. TB endemic countries experience higher exposure to NTMs, but previous studies have not elucidated the relationship between NTM exposure and BCG efficacy against TB. Therefore, we develop a mouse model (BCG+ NTM) to simulate human BCG immunization regime and continuous NTM exposure. BCG+ NTM mice exhibit superior and prolonged protection against pulmonary TB, with increased B cell influx and anti-Mtb antibodies in serum and airways, compared with BCG alone. Notably, spatial transcriptomics and immunohistochemistry reveal that BCG+ NTM mice formed B cell aggregates with features of germinal center development, which correlate with reduced Mtb burden. Our studies suggest a direct relationship between NTM exposure and TB protection, with B cells playing a crucial role.

The Immune Correlates of Orthohantavirus Vaccine.

Zoonotic transmission of orthohantaviruses from rodent reservoirs to humans has been the cause of severe fatalities. Human infections are reported worldwide, but vaccines have been approved only in China and Korea. Orthohantavirus vaccine development has been pursued with no sense of urgency due to the relative paucity of cases in countries outside China and Korea. However, the orthohantaviruses continuously evolve in hosts and thus the current vaccine may not work as well against some variants. Therefore, a more effective vaccine should be prepared against the orthohantaviruses. In this review, we discuss the issues caused by the orthohantavirus vaccine. Given the pros and cons of the orthohantavirus vaccine, we suggest strategies for the development of better vaccines in terms of pandemic preparedness.

Functional and in silico Characterization of Neutralizing Interactions Between Antibodies and the Foot-and-Mouth Disease Virus Immunodominant Antigenic Site.

Molecular knowledge of virus–antibody interactions is essential for the development of better vaccines and for a timely assessment of the spread and severity of epidemics. For foot-and-mouth disease virus (FMDV) research, in particular, computational methods for antigen–antibody (Ag–Ab) interaction, and cross-antigenicity characterization and prediction are critical to design engineered vaccines with robust, long-lasting, and wider response against different strains. We integrated existing structural modeling and prediction algorithms to study the surface properties of FMDV Ags and Abs and their interaction. First, we explored four modeling and two Ag–Ab docking methods and implemented a computational pipeline based on a reference Ag–Ab structure for FMDV of serotype C, to be used as a source protocol for the study of unknown interaction pairs of Ag–Ab. Next, we obtained the variable region sequence of two monoclonal IgM and IgG antibodies that recognize and neutralize antigenic site A (AgSA) epitopes from South America serotype A FMDV and developed two peptide ELISAs for their fine epitope mapping. Then, we applied the previous Ag–Ab molecular structure modeling and docking protocol further scored by functional peptide ELISA data. This work highlights a possible different behavior in the immune response of IgG and IgM Ab isotypes. The present method yielded reliable Ab models with differential paratopes and Ag interaction topologies in concordance with their isotype classes. Moreover, it demonstrates the applicability of computational prediction techniques to the interaction phenomena between the FMDV immunodominant AgSA and Abs, and points out their potential utility as a metric for virus-related, massive Ab repertoire analysis or as a starting point for recombinant vaccine design.

Glycomic Profiling Unveils Association Between Serum Glycosylation and Antibody Responses to Influenza Vaccines

Despite being the most powerful approach to tackle influenza infections, current influenza vaccines have a mixed record of protection across the population. In the 2019-2020 flu season, flu vaccines in the U.S. were ~ 40% effective. High-risk populations, such as the obese and elderly, tend to have weaker responses to influenza vaccines, the molecular mechanisms behind which remain poorly understood. Glycans play critical roles in the human immune system. In this study, we examined serum glycosylation of 160 Caucasian adults pre- and post-vaccination with the 2019 Fluzone® Quadrivalent Vaccine using an expanded version of our lectin microarray technology that included antibodies against innate immune lectins and select sera glycoproteins. Glycosylation profiles were examined in light of post-vaccination antibody responses. Results showed that obese participants who exhibited poor antibody responses (non-responders) to the vaccines had higher levels of pre-vaccination innate immune lectins and high mannose glycans, suggesting a potential role of pre-existing, lectin-mediated immunity in the determination of vaccination outcomes. We observed widespread shifts in glycosylation in all participants associated with vaccination, possibly a result of antibody production. Non-responders and responders showed strikingly similar degrees of glycosylation changes. However, we observed higher levels of β1,6-branched N-glycans in responders, indicating a correlation of this specific glycan epitope with effective antibody responses. Our findings reveal the association of serum glycosylation with antibody responses to vaccination for influenza and may point to new directions in the development of better vaccines.

Asymptomatic Malaria Infection and Their Antibodies Against Malaria: A Study in Abra de Ilog, Occidental Mindoro, Philippines

Abstract Human malaria, caused by four species of Plasmodium, namely P falciparum, P vivax, P malariae, and P ovale, remains a health problem of global concern, with one to two million deaths annually and risking about two billion people worldwide. Alternative ways of controlling the incidence of malaria through understanding the host’s immune response to monoinfection and the detection of the presence of asymptomatic malaria infection are the factors being addressed in this study. The determination of the possible existence of cross-antigenic stimulation is a matter of great significance for future research and development. The isolation of these antigenic structures may give the first step to the development of better vaccines that may protect the general population who are at risk of developing malaria. Prior to blood collection, a memorandum of agreement was signed between the researcher and the Iraya-Mangyan leaders of Abra de Ilog, Occidental Mindoro. A Certificate Precondition was issued by the National Commission of Indigenous Peoples, which was required by the Graduate School Ethics Review Committee. Determination of the presence of malaria parasite on blood samples of residents of two barangays in Abra de Ilog, Occidental Mindoro, was performed using two methods: microscopic examination of stained blood smears for the presence of malaria parasite and polymerase chain reaction. Blood smears were prepared and eventually stained using Giemsa and Dip Quick stains. The detection of 5 positive cases of malaria infection with ring/schizont stage among the 53 cases was a clear indication of positive asymptomatic cases. Nested PCR using Plasmodium spp.–specific primer as well as P falciparum–specific and P vivax–specific primers showed the absence of bands so that one of the recommendations in this study is the performance of real-time PRC using more sensitive primers. Levels of P falciparum and P vivax–specific immunoglobulin were measured using an enzyme-linked immunosorbent assay revealing a higher level of PF-specific IgG than PV-specific IgG. Whole blood samples were saved for future determinations such as real-time PCR, immunophenotypic analysis, and possible parasitic culture. Further similar studies may also be done by increasing the number of respondents as well as the areas of concern for a more extensive scope.

Moving from Empirical to Rational Vaccine Design in the 'Omics' Era.

An ideal vaccine provides long lasting protection against a pathogen by eliciting a well-rounded immune response which engages both innate and adaptive immunity. However, we have a limited understanding of how components of innate immunity, antibody and cell-mediated adaptive immunity interact and function together at a systems level. With advances in high-throughput ‘Omics’ methodologies it has become possible to capture global changes in the host, at a cellular and molecular level, that are induced by vaccination and infection. Analysis of these datasets has shown the promise of discovering mechanisms behind vaccine mediated protection, immunological memory, adverse effects as well as development of more efficient antigens and adjuvants. In this review, we will discuss how systems vaccinology takes advantage of new technology platforms and big data analysis, to enable the rational development of better vaccines.

Associations of Initial Multiple Inactivated Vaccines with Later Allergies in JECS Children

Background: Although we recognise that immunization is indispensable to global elimination of various diseases, the adjuvants used in inactivated vaccines often upregulate type 2 immunity that is dominant in allergic diseases. On the other hand, BCG vaccine is known to induce type 1 immunity. We hypothesised that administration during infancy of a greater number of vaccines that contain adjuvants may influence the development of allergies later in life by changing the balance of type 1/type 2 immunity. Methods: We obtained information regarding vaccinations and allergic diseases by using questionnaires that were used in The Japan Environment and Children's Study (JECS), i.e., a nationwide, multicentre, prospective birth cohort study including 103,099 pregnant women and their children. We examined for associations between the history of vaccination before 6 months of age and symptoms related to allergies at 12 months of age. Findings: Our statistical analyses included 56,277 children. Physician-diagnosed asthma was associated with receiving 3 (aOR 1.395, 95% CI 1.028-1.893) or 4-5 different inactivated vaccines (aOR 1.544, 95% CI 1.149-2.075), compared with children who received only one inactivated vaccine. Similar results were found for two questionnaire-based symptoms, i.e., wheeze (aOR 1.238, 95% CI 1.094-1.401; 3 vaccines vs. a single vaccine) and eczema (aOR 1.144, 95% CI 1.007-1.299; 4 or 5 vaccines vs. a single vaccine). Interpretation: The prevalence of asthma, wheeze and eczema among children at 12 months of age was associated with having received a greater number of initial inactivated vaccines before 6 months of age. Although these results should be cautiously interpreted, we can at least postulate that development of better vaccines is needed to reduce the risk of later development of allergic diseases. Nevertheless, further studies should be conducted, and we are planning to extend the evaluation period until at least 13 years of age. Funding Statement: This study was funded and supported by the Ministry of the Environment, Japan. Declaration of Interests: All authors have no conflicts of interest related to this study. Ethics Approval Statement: The JECS protocol was reviewed and approved by the Ministry of the Environment’s Institutional Review Board on Epidemiological Studies and by the ethics committees of all participating institutions. Written informed consent was obtained from all participants (i.e. pregnant women or other caregivers). The JECS was conducted in accordance with the Helsinki Declaration and other nationally valid regulations and guidelines.

Bluetongue virus vaccine: conventional to modern approach.

Bluetongue (BT) is an economically important, infectious and non-contagious disease of ruminant animals. BT disease is caused by bluetongue virus (BTV) of the genus Orbivirus (the family Reoviridae). BTV is transmitted by certain species of biting midges of the genus Culicoides. Although originally BT was restricted to African continent, now it is present in all the continents except Antarctica. Conventional BT vaccines such as live attenuated and inactivated vaccines showed different degree of success in BT control. However, conventional vaccines have certain disadvantages of reversion to virulent strain and frequent booster dose requirement. Several BT outbreaks in India and the rest of the world open a new insight for development of better vaccines. The development in molecular biology techniques allowed the development and validation of several modern vaccines such as subunit vaccine, recombinant vector vaccine, disabled infections single cycle (DISC) vaccine, differentiating infected from vaccinated animals (DIVA) approach etc. Most of these vaccines are considered as safer, having better protective immune response and provided cross-protective immunization against more than one serotype. Keywords: bluetongue virus; live vaccine; inactivated vaccine; DISC; recombinant vaccine.

Alternative Strategy for a Quadrivalent Live Attenuated Influenza Virus Vaccine.

Influenza virus infections continue to pose a major public health threat worldwide associated with seasonal epidemics and sporadic pandemics. Vaccination is considered the first line of defense against influenza. Live attenuated influenza virus vaccines (LAIVs) may provide superior responses compared to inactivated vaccines because the former can better elicit a combination of humoral and cellular responses by mimicking a natural infection. Unfortunately, during the 2013-2014, 2014-2015, and 2015-2016 seasons, concerns emerged about the effectiveness of the only LAIV approved in the United States that prevented the Advisory Committee on Immunization Practices (ACIP) from recommending its use. Such drawbacks open up the opportunity for alternative LAIV strategies that could overcome such concerns. Previously, we developed a combined strategy of temperature-sensitive mutations in the PB2 and PB1 segments and an epitope tag in the C terminus of PB1 that effectively attenuates influenza A viruses of avian and mammalian origin. More recently, we adopted a similar strategy for influenza B viruses. The resulting attenuated (att) influenza A and B viruses were safe, immunogenic, and protective against lethal influenza virus challenge in a variety of animal models. In this report, we provide evidence of the potential use of our att strategy in a quadrivalent LAIV (QIV) formulation carrying H3N2 and H1N1 influenza A virus subtype viruses and two antigenic lineages of influenza B viruses. In naive DBA/2J mice, two doses of the QIV elicited hemagglutination inhibition (HI) responses with HI titers of ≥40 and effectively protected against lethal challenge with prototypical pandemic H1N1 influenza A and influenza B virus strains.IMPORTANCE Seasonal influenza viruses infect 1 billion people worldwide and are associated with ∼500,000 deaths annually. In addition, the never-ending emergence of zoonotic influenza viruses associated with lethal human infections and of pandemic concern calls for the development of better vaccines and/or vaccination strategies against influenza virus. Regardless of the strategy, novel influenza virus vaccines must aim at providing protection against both seasonal influenza A and B viruses. In this study, we tested an alternative quadrivalent live attenuated influenza virus vaccine (QIV) formulation whose individual components have been previously shown to provide protection. We demonstrate in proof-of principle studies in mice that the QIV provides effective protection against lethal challenge with either influenza A or B virus.

Unravelling how adjuvants work, and what their roles are in vaccination and allergy

The development of safe and effective vaccines is essential to tackling a variety of infectious diseases. Vaccines fall into a variety of different types, depending on how they are produced. The inclusions of live attenuated, inactivated, toxoid, subunit or conjugate vaccines contain key antigens which are used in the vaccines to encourage the immune system to mount an immune response. This response will eventually trigger the creation of targeted memory B cells that persist and can quickly multiple and tackle future interactions with the disease agent. This is the cornerstone of our adaptive immune system, protecting us against getting many diseases more than once. Vaccines often contain more than just the antigen. They also commonly contain a facilitating agent known as an adjuvant. Adjuvants enhance the effect of the vaccine, making it more likely to work and to work well, however, it has long been thought that they themselves confer no immunity if presented to the immune system without the antigen. One of the biggest mysteries in immunology is how exactly adjuvants function. They certainly do function, often making the difference between an ineffectual vaccine and one that can help tackle a disease. However, answering the question of 'how?' may well prove key to the development of better vaccines and even treatments in other fields of human disease. Investigating the mode of action of adjuvants is Dr Etsushi Kuroda, Senior Researcher at NIBIOHN, Japan. He works in the Center for Vaccine and Adjuvant Research under Dr Ken J. Ishii in a large lab with multiple researchers focussing on a different aspect of adjuvants. Kuroda's field of interest is the role of pollution particulates as adjuvants to allergy and asthma. Kuroda explains his area of research in greater detail: 'Particle pollutants that we focused on are also thought to be adjuvants and induce inflammation when they are inhaled. There are pros and cons in adjuvants, and excessive activation of immune cells by adjuvant might induce immune-related diseases such as allergic inflammation.'

Isolation and characterization of Infectious bursal disease virus VP2 gene isolated from Tirupati region of Andhra Pradesh, India.

<p>Infectious bursal disease (IBD) is a highly contagious viral disease of birds characterized by lesions in the bursa of Fabricius, immunosuppression, severe morbidity and mortality. Due to amino acids substitutions in this region results in change in the topography of hyper variable region of VP2, where most of the neutralizing epitopes are present. Cloning and characterization of hyper variable region of prevalent strains of IBDV in this part of the country will provide basis for development of better vaccine for future. In the present study, we cloned four full length sequences of IBDV-VP2 with hyper variable region and found that all the cloned sequences have similar epitopes. Phylogenetic analysis showed that they are closely related to each other and are also closely related to strains of Luxembourg, China, and USA. This study will enhance the knowledge on IBDV circulating strains in this part of the country.</p>

Whole-Cell Cancer Vaccines Induce Large Antibody Responses to Carbohydrates and Glycoproteins

Whole-cell cancer vaccines are a promising strategy for treating cancer, but the characteristics of a favorable immune response are not fully understood. New insights could enable development of better vaccines, discovery of new antigens, and identification of biomarkers of efficacy. Using glyco-antigen microarrays, we demonstrate that GVAX Pancreas (a granulocyte macrophage colony-stimulating factor-modified whole-cell tumor vaccine) induces large immunoglobulin G and immunoglobulin M responses to many antigens, including tumor-associated carbohydrates, blood group antigens, α-Gal, and bovine fetuin. Antibody responses to α-Gal, a glycan found in fetal bovine serum (FBS) used to produce the vaccine, correlated inversely with overall survival and appear to compete with productive responses to the vaccine. H1299 lysate vaccine, produced with FBS, also induced responses to α-Gal and fetuin but not K562-GM, which is produced in serum-free medium. Our results provide new potential biomarkers to evaluate productive/unproductive immune responses and suggest that removal/reduction of FBS could improve the efficacy of whole-cell vaccines.

Machine Learning for Predicting Vaccine Immunogenicity

The ability to predict how different individuals will respond to vaccination and to understand what best protects individuals from infection greatly facilitates developing next-generation vaccines. It facilitates both the rapid design and evaluation of new and emerging vaccines and identifies individuals unlikely to be protected by vaccine. We describe a general-purpose machine-learning framework, DAMIP, for discovering gene signatures that can predict vaccine immunity and efficacy. DAMIP is a multiple-group, concurrent classifier that offers unique features not present in other models: a nonlinear data transformation to manage the curse of dimensionality and noise; a reserved-judgment region that handles fuzzy entities; and constraints on the allowed percentage of misclassifications. Using DAMIP, implemented results for yellow fever demonstrated that, for the first time, a vaccine’s ability to immunize a patient could be successfully predicted (with accuracy of greater than 90 percent) within one week after vaccination. A gene identified by DAMIP, EIF2AK4, decrypted a seven-decade-old mystery of vaccination. Results for flu vaccine demonstrated DAMIP’s applicability to both live-attenuated and inactivated vaccines. Results in a malaria study enabled targeted delivery to individual patients. Our project’s methods and findings permit highlighting and probabilistically prioritizing hypothesis design to enhance biological discovery. Moreover, they guide the rapid development of better vaccines to fight emerging infections, and improve monitoring for poor responses in the elderly, infants, or others with weakened immune systems. In addition, the project’s work should help with universal flu-vaccine design.

Introduction: 2015 Daniel H. Wagner Prize for Excellence in Operations Research Practice

Competition for the 2015 Daniel H. Wagner Prize for Excellence in Operations Research Practice provided the five finalist papers featured in this special issue of Interfaces. The prestigious Wagner Prize—awarded for achievement in implemented operations research, management science, and advanced analytics—emphasizes quality and originality of mathematical models and clarity of written and oral exposition. Researchers from Georgia Institute of Technology, Emory University, the University of São Paulo, and a major client organization—Centers for Disease Control and Prevention—won the competition for their invention and successful laboratory testing of original methods that will guide the rapid development of better vaccines to protect against pandemic-causing viruses. The remaining finalist papers describe work to improve repair and maintenance of railroad locomotives, testing of new-model automotive vehicles, location of products on shelves in supermarket stores, and organization of a national postal service.

Stakeholders’ perceptions of 10 years of the Global Action Plan for Influenza Vaccines (GAP) – Results from a survey

Ten years after the launch of the Global Action Plan for Influenza Vaccines (GAP), the World Health Organization (WHO) surveyed stakeholders to understand their perceptions of what the programme had achieved. This article provides a summary of the findings; the full report will be available on-line on the GAP website in November 2016 (http://www.who.int/influenza_vaccines_plan/en/). Seventy-seven responses were received from stakeholders including medical doctors, national influenza center officials, country immunization programme teams, surveillance and disease centers, policy-makers, researchers, vaccine manufacturers, and non-governmental organizations from 28 countries, representing all six WHO regions.Respondents cited GAP’s biggest successes as capacity building in developing countries; raising international awareness of global needs in the event of a pandemic; and collaborative alignment of influenza stakeholders. The most commonly reported challenges were the limited progress in development of a broadly protective or universal vaccine and the perceived absence of a major increase in seasonal demand. These findings aligned with the perception that less global progress had been made under the third GAP objective, focused on research and development of better vaccines, than on increasing seasonal vaccine use (objective 1) and pandemic vaccine production capacity (objective 2). Respondents explained what they saw as the major challenges to development of better vaccines, including to development of a universal influenza vaccine. The majority of respondents agreed that the goal chosen at the GAP II consultation is still relevant. Results highlighted the importance of promoting research and development of better vaccines, both for facilitating uptake of seasonal vaccines and for ensuring timely vaccine availability in the event of a pandemic. As the GAP concludes its mandate this year, these findings will contribute to discussions on the impact of programme closure and how to address the key issues facing influenza stakeholders thereafter.

Type IV secretion system of Brucella spp. and its effectors.

Brucella spp. are intracellular bacterial pathogens that cause infection in domestic and wild animals. They are often used as model organisms to study intracellular bacterial infections. Brucella VirB T4SS is a key virulence factor that plays important roles in mediating intracellular survival and manipulating host immune response to infection. In this review, we discuss the roles of Brucella VirB T4SS and 15 effectors that are proposed to be crucial for Brucella pathogenesis. VirB T4SS regulates the inflammation response and manipulates vesicle trafficking inside host cells. VirB T4SS also plays crucial roles in the inhibition of the host immune response and intracellular survival during infection. Here, we list the key molecular events in the intracellular life cycle of Brucella that are potentially targeted by the VirB T4SS effectors. Elucidating the functions of these effectors will help clarify the molecular role of T4SS during infection. Furthermore, studying the effectors secreted by Brucella spp. might provide insights into the mechanisms used by the bacteria to hijack the host signaling pathways and aid in the development of better vaccines and therapies against brucellosis.

Pneumococal Surface Protein A (PspA) Regulates Programmed Death Ligand 1 Expression on Dendritic Cells in a Toll-Like Receptor 2 and Calcium Dependent Manner

Pneumonia leads to high mortality in children under the age of five years worldwide, resulting in close to 20 percent of all deaths in this age group. Therefore, investigations into host-pathogen interactions during Streptococcus pneumoniae infection are key in devising strategies towards the development of better vaccines and drugs. To that end, in this study we investigated the role of S. pneumoniae and its surface antigen Pneumococcal surface protein A (PspA) in modulating the expression of co-stimulatory molecule Programmed Death Ligand 1 (PD-L1) expression on dendritic cells (DCs) and the subsequent effects of increased PD-L1 on key defence responses. Our data indicate that stimulation of DCs with PspA increases the surface expression of PD-L1 in a time and dose dependent manner. Characterization of mechanisms involved in PspA induced expression of PD-L1 indicate the involvement of Toll-Like Receptor 2 (TLR2) and calcium homeostasis. While calcium release from intracellular stores positively regulated PD-L1 expression, calcium influx from external milieu negatively regulated PD-L1 expression. Increase in PD-L1 expression, when costimulated with PspA and through TLR2 was higher than when stimulated with PspA or through TLR2. Further, knockdown of TLR2 and the intermediates in the TLR signaling machinery pointed towards the involvement of a MyD88 dependent pathway in PspA induced PD-L1 expression. Incubation of DCs with S. pneumoniae resulted in the up-regulation of PD-L1 expression, while infection with a strain lacking surface PspA failed to do so. Our data also suggests the role of PspA in ROS generation. These results suggest a novel and specific role for PspA in modulating immune responses against S. pneumoniae by regulating PD-L1 expression.