SciCombinator

Discover the most talked about and latest scientific content & concepts.

Journal: NPJ vaccines

490

Mycobacterium are among the oldest co-evolutionary partners of humans. The attenuated Mycobacterium bovis Bacillus Calmette Guérin (BCG) strain has been administered globally for 100 years as a vaccine against tuberculosis. BCG also shows promise as treatment for numerous inflammatory and autoimmune diseases. Here, we report on a randomized 8-year long prospective examination of type 1 diabetic subjects with long-term disease who received two doses of the BCG vaccine. After year 3, BCG lowered hemoglobin A1c to near normal levels for the next 5 years. The BCG impact on blood sugars appeared to be driven by a novel systemic and blood sugar lowering mechanism in diabetes. We observe a systemic shift in glucose metabolism from oxidative phosphorylation to aerobic glycolysis, a state of high glucose utilization. Confirmation is gained by metabolomics, mRNAseq, and functional assays of cellular glucose uptake after BCG vaccinations. To prove BCG could induce a systemic change to promote accelerated glucose utilization and impact blood sugars, murine data demonstrated reduced blood sugars and aerobic induction in non-autoimmune mice made chemically diabetic. BCG via epigenetics also resets six central T-regulatory genes for genetic re-programming of tolerance. These findings set the stage for further testing of a known safe vaccine therapy for improved blood sugar control through changes in metabolism and durability with epigenetic changes even in advanced Type 1 diabetes.

135

Seasonal vaccines are currently the most effective countermeasure against influenza. However, seasonal vaccines are only effective against strains closely related to the influenza strains contained in the vaccine. Recently a new hemagglutinin (HA) stem-based antigen, the so-called “mini-HA”, has been shown to induce a cross-protective immune response in influenza-naive mice and non-human primates (NHP). However, prior exposure to influenza can have a profound effect on the immune response to subsequent influenza infection and the protective efficacy of vaccination. Here we show that mini-HA, compared to a trivalent influenza vaccine (TIV), elicits a broadened influenza-specific humoral immune response in NHP previously exposed to influenza. Serum transfer experiments showed that antibodies induced by both mini-HA and seasonal vaccine protected mice against lethal challenge with a H1N1 influenza strain heterologous to the H1 HA included in the TIV. However, antibodies elicited by mini-HA showed an additional benefit of protecting mice against lethal heterosubtypic H5N1 influenza challenge, associated with H5 HA-specific functional antibodies.

10

Zika virus (ZIKV), a mosquito-borne flavivirus, was first identified in the 1940s in Uganda in Africa and emerged in the Americas in Brazil in May 2015. In the 30 months since ZIKV emerged as a major public health problem, spectacular progress has been made with vaccine development cumulating with the publication of three reports of phase 1 clinical trials in the 4th quarter of 2017. Clinical trials involving candidate DNA and purified inactivated virus vaccines showed all were safe and well-tolerated in the small number of volunteers and all induced neutralizing antibodies, although these varied by vaccine candidate and dosing regimen. These results suggest that a Zika vaccine can be developed and that phase 2 clinical trials are warranted. However, it is difficult to compare the results from the different phase 1 studies or with neutralizing antibodies induced by licensed flavivirus vaccines (Japanese encephalitis, tick-borne encephalitis, and yellow fever) as neutralizing antibody assays vary and, unfortunately, there are no standards for Zika virus neutralizing antibodies. In addition to clinical studies, substantial progress continues to be made in nonclinical development, particularly in terms of the ability of candidate vaccines to protect reproductive tissues, and the potential use of monoclonal antibodies for passive prophylaxis.

10

Sustained elimination of leprosy as a global health concern likely requires a vaccine. The current standard, BCG, confers only partial protection and precipitates paucibacillary (PB) disease in some instances. When injected into mice with the T helper 1 (Th1)-biasing adjuvant formulation Glucopyranosyl Lipid Adjuvant in stable emulsion (GLA-SE), a cocktail of three prioritized antigens (ML2055, ML2380 and ML2028) reducedM. lepraeinfection levels. Recognition and protective efficacy of a single chimeric fusion protein incorporating these antigens, LEP-F1, was confirmed in similar experiments. The impact of post-exposure immunization was then assessed in nine-banded armadillos that demonstrate a functional recapitulation of leprosy. Armadillos were infected withM. leprae1 month before the initiation of post-exposure prophylaxis. While BCG precipitated motor nerve conduction abnormalities more rapidly and severely than observed for control infected armadillos, motor nerve injury in armadillos treated three times, at monthly intervals with LepVax was appreciably delayed. Biopsy of cutaneous nerves indicated that epidermal nerve fiber density was not significantly altered inM. leprae-infected animals although Remak Schwann cells of the cutaneous nerves in the distal leg were denser in the infected armadillos. Importantly, LepVax immunization did not exacerbate cutaneous nerve involvement due toM. lepraeinfection, indicating its safe use. There was no intraneural inflammation but a reduction of intra axonal edema suggested that LepVax treatment might restore some early sensory axonal function. These data indicate that post-exposure prophylaxis with LepVax not only appears safe but, unlike BCG, alleviates and delays the neurologic disruptions caused byM. lepraeinfection.

Concepts: Immune system, Nervous system, Neuroanatomy, Action potential

4

There is a pressing need for safe and highly effective Plasmodium falciparum (Pf) malaria vaccines. The circumsporozoite protein (CS), expressed on sporozoites and during early hepatic stages, is a leading target vaccine candidate, but clinical efficacy has been modest so far. Conversely, whole-sporozoite (WSp) vaccines have consistently shown high levels of sterilizing immunity and constitute a promising approach to effective immunization against malaria. Here, we describe a novel WSp malaria vaccine that employs transgenic sporozoites of rodent P. berghei (Pb) parasites as cross-species immunizing agents and as platforms for expression and delivery of PfCS (PbVac). We show that both wild-type Pb and PbVac sporozoites unabatedly infect and develop in human hepatocytes while unable to establish an infection in human red blood cells. In a rabbit model, similarly susceptible to Pb hepatic but not blood infection, we show that PbVac elicits cross-species cellular immune responses, as well as PfCS-specific antibodies that efficiently inhibit Pf sporozoite liver invasion in human hepatocytes and in mice with humanized livers. Thus, PbVac is safe and induces functional immune responses in preclinical studies, warranting clinical testing and development.

4

Lassa fever (LF) is a zoonotic disease associated with acute and potentially fatal hemorrhagic illness caused by the Lassa virus (LASV), a member of the familyArenaviridae. It is generally assumed that a single infection with LASV will produce life-long protective immunity. This suggests that protective immunity induced by vaccination is an achievable goal and that cell-mediated immunity may play a more important role in protection, at least following natural infection. Seropositive individuals in endemic regions have been shown to have LASV-specific T cells recognizing epitopes for nucleocapsid protein (NP) and glycoprotein precursor (GPC), suggesting that these will be important vaccine immunogens. The role of neutralizing antibodies in protective immunity is still equivocal as recent studies suggest a role for neutralizing antibodies. There is extensive genetic heterogeneity among LASV strains that is of concern in the development of assays to detect and identify all four LASV lineages. Furthermore, the gene disparity may complicate the synthesis of effective vaccines that will provide protection across multiple lineages. Non-human primate models of LASV infection are considered the gold standard for recapitulation of human LF. The most promising vaccine candidates to date are the ML29 (a live attenuated reassortant of Mopeia and LASV), vesicular stomatitis virus (VSV) and vaccinia-vectored platforms based on their ability to induce protection following single doses, high rates of survival following challenge, and the use of live virus platforms. To date no LASV vaccine candidates have undergone clinical evaluation.

Concepts: Immune system, Antibody, Microbiology, Virus, Malaria, Vaccination, Viral hemorrhagic fever, Lassa fever

3

Current design of Zika virus (ZIKV) vaccine mainly considered envelope (E) as the major target antigen. Non-structural protein NS1 was seldom considered. Herein, we generated three adenovirus-vectored vaccines carrying E (Ad2-E), or premembrane/membrane (prM/M) with E (Ad2-prME), or NS1 in addition to prM/M with E (Ad2-prME-NS1). Ad2-prME induced higher neutralizing antibody response to ZIKV than Ad2-E, suggesting prM/M is important for the folding of immunogenic E. Most intriguingly, Ad2-prME-NS1 elicited the best viral inhibition when the immune sera were added to ZIKV-infected cells. In ZIKV-challenged neonatal mice born to maternally immunized dams, Ad2-prME-NS1 conferred the best protection in preventing weight loss, neurological disorders, and viral replication. Ad2-prME also conferred significant protection but was less effective than Ad2-prME-NS1, whereas Ad2-E only alleviated neurological symptoms but did not inhibit viral replication. Our study suggested that NS1 should be considered in the design of ZIKV vaccine in addition to prM/M and E.

2

Plasmodium falciparum reticulocyte-binding protein homolog 5 (PfRH5) is a leading asexual blood-stage vaccine candidate for malaria. In preparation for clinical trials, a full-length PfRH5 protein vaccine called “RH5.1” was produced as a soluble product under cGMP using the ExpreS2 platform (based on a Drosophila melanogaster S2 stable cell line system). Following development of a high-producing monoclonal S2 cell line, a master cell bank was produced prior to the cGMP campaign. Culture supernatants were processed using C-tag affinity chromatography followed by size exclusion chromatography and virus-reduction filtration. The overall process yielded >400 mg highly pure RH5.1 protein. QC testing showed the MCB and the RH5.1 product met all specified acceptance criteria including those for sterility, purity, and identity. The RH5.1 vaccine product was stored at -80 °C and is stable for over 18 months. Characterization of the protein following formulation in the adjuvant system AS01B showed that RH5.1 is stable in the timeframe needed for clinical vaccine administration, and that there was no discernible impact on the liposomal formulation of AS01B following addition of RH5.1. Subsequent immunization of mice confirmed the RH5.1/AS01B vaccine was immunogenic and could induce functional growth inhibitory antibodies against blood-stage P. falciparum in vitro. The RH5.1/AS01B was judged suitable for use in humans and has since progressed to phase I/IIa clinical trial. Our data support the future use of the Drosophila S2 cell and C-tag platform technologies to enable cGMP-compliant biomanufacture of other novel and “difficult-to-express” recombinant protein-based vaccines.

1

Annual seasonal influenza vaccination is recommended for high-risk populations and often occupational groups such as healthcare workers (HCWs). Repeated annual vaccination has been reported to either have no impact or reduce antibody responses or protection. However, whether repeated vaccination influences T-cell responses has not been sufficiently studied, despite the increasing evidence of the protective roles of T-cell immunity. Here, we explored the impact of repeated annual vaccination with the same vaccine strain (H1N1pdm09) over multiple seasons in the post-2009 pandemic era and showed that repeated vaccination increased both T-cell and humoral responses. Using the T-cell FluroSpot and intracellular cytokine-staining, the hemagglutination inhibition (HI), and the memory B-cell (MBC) ELISpot assays, we investigated pre- and postvaccination T cells, antibodies, and MBCs in a cohort of HCWs repeatedly vaccinated with H1N1pdm09 for 5 years (pandemic vaccination in 2009 and subsequently annual seasonal vaccination containing H1N1pdm09 during 2010-2013). We found that the prevaccination H1N1pdm09-specific T cells, antibodies, and MBCs were significantly increased after 3-4 repeated vaccinations and maintained at high levels throughout seasons 2012 and 2013. The cross-reactive IFN-γ-secreting CD4+ cells recognizing conserved viral external or internal epitopes were also maintained throughout 2012 and 2013. Repeated vaccination improved the multifunctional memory CD4+ responses. Particularly, the IFN-γ+TNF-α+CD4+ T cells were boosted following each vaccination. HI antibodies were significantly induced after each vaccination over 5 years. Our findings indicate a broad impact of repeated annual vaccination, even with the same vaccine component, on the influenza-specific T-cell and humoral immunity and support the continuing recommendation of annual influenza vaccination. Despite the widespread implementation of annual influenza vaccination, the effect of repeated vaccinations on the immune response in subsequent seasons is poorly understood. A team led by Rebecca Jane Cox at the University of Bergen examined the humoral and T-cell response elicited by 2009’s H1N1pdm09 seasonal vaccine. Since the H1N1pdm09 strain continued to circulate in subsequent years it was included in later vaccine formulations and the authors could therefore examine the effects of repeated annual vaccination over multiple seasons. They observed that H1N1pdm09-specific polyfunctional T-cell responses and antibodies were enhanced by multiple annual vaccinations. In particular, T cells showed progressive skewing to IFN-γ+TNF+ double producers, but the magnitude of the T-cell response tended to plateau after 3-4 repeated vaccinations. The findings suggest that including the same component in subsequent annual vaccines can significantly impact the influenza immune response.

1

Over 50 million women are exposed to the risk of malaria during pregnancy every year. Malaria during pregnancy is a leading global cause of maternal morbidity and adverse pregnancy outcomes. Adhesion of Plasmodium falciparum-infected erythrocytes to placental chondroitin-4-sulfate (CSA) has been linked to the severe disease outcome of placental malaria. Accumulated evidence strongly supports VAR2CSA as the leading placental malaria vaccine candidate. Recombinant proteins encompassing the VAR2CSA high affinity CSA binding site have been generated, and their activity as immunogens that elicit functional (inhibitory) and cross-reactive antibodies against CSA-binding parasites assessed. The expression of His-tagged proteins was compared in four different expression systems and their capacity to bind specifically to CSA was analyzed. CHO cells and E. coli SHuffle cells were the two expression systems able to express some of the recombinant proteins in reasonable amounts. Larger analytical scale production of DBL1x-2× (3D7) and DBL3x-4ε (FCR3) best expressed in CHO and E. coli SHuffle cells were performed. Purified proteins were administered to rats either alone or adjuvanted with human approved adjuvants. Analysis of the functionality and cross-reactivity of the induced antibodies allowed us to down-select the DBL1x-2(3D7) expressed in E. coli SHuffle cells as the best antigen to be transitioned to further clinical development in order to protect future pregnant women living in malaria endemic areas against the severe clinical outcomes of placental malaria.