Immunogenicity and safety of the non-typable Haemophilus influenzae-Moraxella catarrhalis (NTHi-Mcat) vaccine administered following the recombinant zoster vaccine versus administration alone: Results from a randomized, phase 2a, non-inferiority trial.

A candidate AS01-adjuvanted vaccine containing four surface proteins from non-typable Haemophilus influenzae and Moraxella catarrhalis (NTHi-Mcat) has been developed to help prevent exacerbations of chronic obstructive pulmonary disease (COPD). Sequential administration of different vaccines containing the same AS01-adjuvant system could lead to immune interference. We compared administration of NTHi-Mcat following AS01-adjuvanted recombinant zoster vaccine (RZV) versus NTHi-Mcat alone. This phase 2a, open-label trial (NCT03894969) randomized healthy current or former smokers (50-80 years) without COPD to administration of NTHi-Mcat at 1, 3 or 6 months after RZV or to NTHi-Mcat alone (2-dose for both vaccines). Primary outcome was non-inferiority of the humoral immune response to NTHi-Mcat administered 1 month after RZV versus NTHi-Mcat alone, evaluated by specific antibody geometric mean concentration (GMC) ratio with 95% confidence intervals (CIs). The per-protocol set included 411 participants. Primary objective was met; lower limit of the 95%CI for the GMC ratio above 0.667 for all four vaccine antigens, 1 month after the second NTHi-Mcat dose. NTHi-Mcat induced similar immune response regardless of whether administered alone or 1, 3 or 6 months following RZV. Safety and reactogenicity profiles were acceptable; adverse event frequency was similar among study groups. Injection site pain was the most common symptom. No new safety concerns were identified. The study demonstrated non-inferiority of the immune response elicited by NTHi-Mcat administered sequentially to RZV versus NTHi-Mcat alone, indicating no immune interference. Starting from 1 month, no specific interval is required between RZV and NTHi-Mcat containing the same AS01-adjuvant system components in different quantities.

Long-term immunogenicity and safety of a non-typeable Haemophilus influenzae-Moraxella catarrhalis vaccine: 4-year follow-up of a phase 1 multicentre trial.

A multicomponent vaccine has been developed to reduce the frequency of acute exacerbations of COPD associated with non-typeable Haemophilus influenzae (NTHi) and Moraxella catarrhalis (Mcat) infections, containing NTHi (PD and PE-PilA) and Mcat (UspA2) surface proteins. In a randomised, observer-blind, placebo-controlled study with two steps (NCT02547974), the investigational vaccine had good immunogenicity and no safety concerns were identified. In step 2, 90 adults aged 50-71 years with smoking history received two doses 60 days apart of one of two AS01E-adjuvanted formulations containing 10 µg of each antigen (10-10-AS01) or 10 µg NTHi antigens and 3.3 µg UspA2 (10-3-AS01), or placebo. Long-term persistence of antigen-specific humoral antibodies was assessed in 81 participants during 3 years of follow-up after the initial 14-month study (NCT03201211). Antigen-specific antibody concentrations were measured in blood samples taken every 6 months. Safety monitoring evaluated serious adverse events (SAEs) and potential immune-mediated disease (pIMD). Immune responses against NTHi antigens persisted up to 4 years post-vaccination. For PD, PE and PilA, at each follow-up time point, adjusted antibody geometric mean concentrations (GMCs) were higher (non-overlapping 95% confidence intervals [CIs]) in the vaccine groups versus placebo and versus pre-vaccination. Antibody GMC point estimates were higher with 10-3-AS01 than with 10-10-AS01. For UspA2, 95% CIs included 1 for GMC ratios of 10-10-AS01 or 10-3-AS01 to placebo at each time point. During follow-up, SAEs were reported in nine (11.1%) participants, one of which was fatal (lung cancer, 607 days after second 10-10-AS01 dose). One non-serious pIMD, trigeminal neuralgia, was reported 771 days after second 10-3-AS01 dose. The SAEs and pIMD were considered not related to vaccination. Immune responses against NTHi antigens persisted for 4 years after two-dose vaccination with the investigational NTHi-Mcat vaccine. There was no persistent response against the Mcat antigen. No safety concerns were identified during the long-term follow-up.

Safety and immunogenicity of non-typeable Haemophilus influenzae-Moraxella catarrhalis vaccine.

Non-typeable Haemophilus influenzae (NTHi) and Moraxella catarrhalis (Mcat) are frequent pathogens in acute exacerbations of COPD. We assessed the safety, reactogenicity and immunogenicity of different investigational vaccine formulations containing surface proteins of NTHi (PD and PE-PilA) and Mcat (UspA2) in adults with smoking history ≥10 pack-years, to immunologically represent the COPD population. Participants received two doses 60 days apart in a randomised, observer-blind, placebo-controlled study (NCT02547974). In step 1, 30 healthy adults aged 18-40 years were randomised (1:1) to receive a non-adjuvanted formulation (10-10-PLAIN) or placebo. In step 2, 90 smokers/ex-smokers aged 50-70 years randomly (1:1:1) received an AS01-adjuvanted formulation containing either 10 µg of each antigen (10-10-AS01) or 10 µg of each NTHi antigen and 3.3 µg of Mcat antigen (10-3-AS01), or placebo. Incidences of solicited local adverse events (AEs) tended to be highest in the AS01-adjuvanted vaccine groups. Most solicited AEs had mild/moderate intensity. No vaccine-related serious AEs were reported. The 10-3-AS01 formulation induced the best humoral immune response against the NTHi antigens. Responses against the Mcat antigen were similar across groups, with waning immunogenicity after 30 days post-dose 2. The investigational NTHi-Mcat vaccine had an acceptable safety and reactogenicity profile and good immunogenicity in older adults with a smoking history.

Functional characterization of the incomplete phosphotransferase system (PTS) of the intracellular pathogen Brucella melitensis.

BACKGROUND: In many bacteria, the phosphotransferase system (PTS) is a key player in the regulation of the assimilation of alternative carbon sources notably through catabolic repression. The intracellular pathogens Brucella spp. possess four PTS proteins (EINtr, NPr, EIIANtr and an EIIA of the mannose family) but no PTS permease suggesting that this PTS might serve only regulatory functions. METHODOLOGY/PRINCIPAL FINDINGS: In vitro biochemical analyses and in vivo detection of two forms of EIIANtr (phosphorylated or not) established that the four PTS proteins of Brucella melitensis form a functional phosphorelay. Moreover, in vitro the protein kinase HprK/P phosphorylates NPr on a conserved serine residue, providing an additional level of regulation to the B. melitensis PTS. This kinase activity was inhibited by inorganic phosphate and stimulated by fructose-1,6 bisphosphate. The genes encoding HprK/P, an EIIAMan-like protein and NPr are clustered in a locus conserved among α-proteobacteria and also contain the genes for the crucial two-component system BvrR-BvrS. RT-PCR revealed a transcriptional link between these genes suggesting an interaction between PTS and BvrR-BvrS. Mutations leading to the inactivation of EINtr or NPr significantly lowered the synthesis of VirB proteins, which form a type IV secretion system. These two mutants also exhibit a small colony phenotype on solid media. Finally, interaction partners of PTS proteins were identified using a yeast two hybrid screen against the whole B. melitensis ORFeome. Both NPr and HprK/P were shown to interact with an inorganic pyrophosphatase and the EIIAMan-like protein with the E1 component (SucA) of 2-oxoglutarate dehydrogenase. CONCLUSIONS/SIGNIFICANCE: The B. melitensis can transfer the phosphoryl group from PEP to the EIIAs and a link between the PTS and the virulence of this organism could be established. Based on the protein interaction data a preliminary model is proposed in which this regulatory PTS coordinates also C and N metabolism.

Correlations between carbon metabolism and virulence in bacteria.

Bacteria have developed several mechanisms which allow the preferred utilization of the most efficiently metabolizable carbohydrates when these organisms are exposed to a mixture of carbon sources. Interestingly, the same or similar mechanisms are used by some pathogens to control various steps of their infection process. The efficient metabolism of a carbon source might serve as signal for proper fitness. Alternatively, the presence of a specific carbon source might indicate to bacterial cells that they thrive in infection-related organs, tissues or cells and that specific virulence genes should be turned on or switched off. Frequently, virulence gene regulators are affected by changes in carbon source availability. For example, expression of the gene encoding the Streptococcus pyogenes virulence regulator Mga is controlled by the classical carbon catabolite repression (CCR) mechanism operative in Firmicutes. The activity of PrfA, the major virulence regulator in Listeria monocytogenes, seems to be controlled by the phosphorylation state of phosphotransferase system(PTS) components. In Vibrio cholerae synthesis of HapR, which regulates the expression of genes required for motility, is controlled via the Crp/cAMP CCR mechanism, whereas synthesis of Salmonella enterica HilE, which represses genes in a pathogenicity island, is regulated by the carbohydrate-responsive, PTS-controlled Mlc.

The stringent response mediator Rsh is required for Brucella melitensis and Brucella suis virulence, and for expression of the type IV secretion system virB.

Physiological adaptation of intracellular bacteria is critical for timely interaction with eukaryotic host cells. One mechanism of adaptation, the stringent response, is induced by nutrient stress via its effector molecule (p)ppGpp, synthesized by the action of RelA/SpoT homologues. The intracellular pathogen Brucella spp., causative agent of brucellosis, possesses a gene homologous to relA/spoT, named rsh, encoding a (p)ppGpp synthetase as confirmed by heterologous complementation of a relA mutant of Sinorhizobium meliloti. The Rsh deletion mutants in Brucella suis and Brucella melitensis were characterized by altered morphology, and by reduced survival under starvation conditions and in cellular and murine models of infection. Most interestingly, we evidenced that expression of virB, encoding the type IV secretion system, a major virulence factor of Brucella, was Rsh-dependent. All mutant phenotypes, including lack of VirB proteins, were complemented with the rsh gene of Brucella. In addition, RelA of S. meliloti functionally replaced Brucella Rsh, describing the capacity of a gene from a plant symbiont to restore virulence in a mammalian pathogen. We therefore concluded that in the intramacrophagic environment encountered by Brucella, Rsh might participate in the adaptation of the pathogen to low-nutrient environments, and indirectly in the VirB-mediated formation of the final replicative niche.

NnrA is required for full virulence and regulates several Brucella melitensis denitrification genes.

We identified two regulators of denitrification genes in Brucella melitensis 16M: NarR, which regulates the nitrate reductase (nar) operon, and NnrA, which is involved in the expression of the last three reductases of the denitrification pathway (nirK, norB, and nosZ). NnrA is required for virulence in mice and for intracellular resistance to nitric oxide.

Systematic targeted mutagenesis of Brucella melitensis 16M reveals a major role for GntR regulators in the control of virulence.

In order to identify transcriptional regulators involved in virulence gene control in Brucella melitensis, we generated a collection of 88 mutants in the AraC, ArsR, Crp, DeoR, GntR, IclR, LysR, MerR, RpiR, and TetR families of regulators. This collection was named LiMuR (library of mutants for regulators). We developed a method to test several mutants simultaneously in one animal in order to identify those unable to survive. This method, called the plasmid-tagged mutagenesis method, was used to test the residual virulence of mutants after 1 week in a mouse model of infection. Ten attenuated mutants, of which six and three belong to the GntR and LysR families, respectively, were identified and individually confirmed to replicate at lower rates in mice. Among these 10 mutants, only gntR10 and arsR6 are attenuated in cellular models. The LiMuR also allows simple screenings to identify regulators of a particular gene or operon. As a first example, we analyzed the expression of the virB operon in the LiMuR mutants. We carried out Western blottings of whole-cell extracts to analyze the production of VirB proteins using polyclonal antisera against VirB proteins. Four mutants produced small amounts of VirB proteins, and one mutant overexpressed VirB proteins compared to the wild-type strain. In these five mutants, reporter analysis using the virB promoter fused to lacZ showed that three mutants control virB at the transcriptional level. The LiMuR is a resource that will provide straightforward identification of regulators involved in the control of genes of interest.