David Lorne Tyrrell

The rapidity and aggressiveness of many group A streptococcal ( Streptococcus pyogenes ) clinical syndromes highlight the urgent need for a vaccine. Two related combination cryptic epitope peptide vaccines, J8-CRM+K4S2-CRM (‘J8-K4S2’) and p*17-CRM+K4S2-CRM (‘p*17-K4S2’), are novel vaccine candidates under investigation. In this single-centred, two-stage, unblinded sentinel safety dosing, then randomized, double-blinded, placebo-controlled trial, 30 volunteers were recruited (NCT04882514). Ten volunteers (Stage 1) were given test doses of J8-K4S2 and then p*17-K4S2 in a staggered, unblinded fashion at weeks 0, 3 and 6 to confirm immediate safety of the products. This was followed by twenty volunteers (Stage 2) who were randomized to receive either of the trial vaccines, J8-K4S2 or p*17-K4S2, or comparator (RabAvert) vaccine following the same vaccination schedule. The primary outcome was vaccine safety; the secondary outcome was immunogenicity. Both vaccine candidates were well tolerated and elicited robust immune responses. The most common adverse events noted were transient injection site pain, injection site erythema, fatigue and headache. These were similar for those receiving either the novel vaccines or the rabies vaccine comparator. There were no high-grade attributable adverse events and no severe adverse events overall. Immunogenicity assessment by ELISA demonstrated that both vaccine candidates consistently induced strong and sustained antibody responses against their respective target antigens, J8 and p*17, with lower responses to K4S2 commensurate with the lower dose of K4S2 present in the vaccines. Both vaccines induced antibody responses to the surface of different strains of live S. pyogenes . All 20 participants who received the candidate vaccines achieved at least a 4-fold rise in J8- or p*17-specific antibody titers from baseline, demonstrating 100% seroconversion, while 90% also seroconverted to K4S2. Notably, these elevated antibody responses persisted for at least six months post-vaccination, remaining significantly above pre-immunisation levels, highlighting the durability of the immune response induced by both vaccines. The safety and immunogenicity profiles for J8-K4S2 and p*17-K4S2 were favourable and support ongoing development of these promising vaccine candidates.

A major challenge in hepatitis C virus (HCV) research is the lack of an in vivo model that supports robust infection, antiviral testing, and vaccine development. The humanized liver chimeric mouse models support high-level viremia from various HCV sources, although they lack an immune system. Here, we used Fah ^−/− /Rag2 ^−/− /Il2rg ^−/− (FRG) and urokinase-type plasminogen activator–severe combined immunodeficiency ( uPA -SCID) mice engrafted with primary human hepatocytes to investigate HCV infection dynamics and evaluate lipid nanoparticle (LNP)–mediated delivery of full-length HCV RNA. Mice were inoculated with HCV-positive chimpanzee serum or LNP-encapsulated HCV RNA of various genotypes and developed viremia reaching 10 ⁸ copies per milliliter. RNA-LNP–mediated infection mirrored serum-derived infection that was transmissible to naïve mice. Glecaprevir/pibrentasvir cleared viremia, and treated mice could be reinfected. The proportion of antibody-free HCV RNA in human serum correlated with infectivity. These findings demonstrate the utility of this model for studying HCV infection and treatment and highlight LNP-based RNA delivery as a scalable approach for generating standardized challenge inocula.

A sensor capable of quantifying avian influenza A virus (subtype H5) was developed by targeting hemagglutinin (HA) protein. This was accomplished by designing a solution-based sandwich assay that generated orthophosphate (PO₄ ³⁻) in proportion to the concentration of HA protein (and hence virus particles) present in a sample. Virus particles were captured and concentrated using an H5-specific primary antibody conjugated to magnetic microparticles. Following magnetic separation, an alkaline phosphatase (AP)-conjugated secondary antibody was introduced to bind to the captured virus. The resulting assembly was exposed to p-nitrophenyl phosphate (PNPP), producing PO₄ ³⁻ in proportion to the amount of virus present. The generated phosphate was subsequently converted to glucose through the addition of maltose and maltose phosphorylase, and the resulting glucose was quantified amperometrically using an off-the-shelf commercial glucose test strip interfaced with a mini-potentiostat. Using this approach, limits of detection of 7.78 × 10⁵ RNA copies per mL in binding buffer, 1.46 × 10⁶ RNA copies per mL in artificial saliva, and 1.26 × 10⁶ RNA copies per mL in tap water were obtained. Selectivity was demonstrated against respiratory pathogen pools, representative Gram-positive and Gram-negative bacteria, and severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). This work presents a modular immunoassay-based strategy that leverages widely available glucose test strips for quantitative viral detection in a laboratory proof-of-concept format and may be adaptable to other targets through substitution of capture and detection antibodies.

We identified minimal conserved epitopes on the M-protein (J8, P*17) and the anti-neutrophil chemoattractant virulence factor, SpyCEP (K4S2), of Streptococcus pyogenes (‘Strep A’) as targets of protective antibodies

The high antigenic diversity of Streptococcus pyogenes (StrepA) presents extensive challenges to vaccine development; however, cryptic epitopes—conserved across emm types—offer an alternative approach

Group A streptococci (Strep A) orStreptococcus pyogenes is a major human pathogen causing an estimated 500,000 deaths worldwide each year. Disease can range from mild pharyngitis to more severe infections, such as necrotizing fasciitis, septicemia, and toxic shock syndrome. Untreated, Strep A infection can lead to the serious post streptococcal pathologies of rheumatic fever/rheumatic heart disease and post-streptococcal glomerulonephritis. An effective vaccine against Strep A would have great benefits worldwide. Here, we test two products, J8 and p*17—both peptide derivatives of a highly conserved region in the M protein, in combination with the protein subunit K4S2 of SpyCEP, an IL-8 protease associated with neutrophil chemoattraction. Each peptide is individually conjugated to cross reacting material (CRM197), and the conjugated peptide vaccines are abbreviated as J8-K4S2 or p*17-K4S2. This single-site phase I, two-stage clinical trial in Edmonton, Alberta, Canada, aims to recruit a total of 30 healthy volunteers, aged 18–45 years, without any evidence of pre-existing valvular heart disease. The trial is divided into the initial unblinded safety test dose stage (stage 1) and the randomized, double-blinded, controlled trial stage (stage 2). Stage 1 will recruit 10 volunteers—5 each to receive either J8-K4S2 or p*17-K4S2 in an unblinded, staggered fashion, whereby volunteers are dosed with intentional spacing of at least 2 days in between doses to monitor for any immediate side effects before dosing the next. Once all 5 volunteers have received 3 doses of the first test vaccine, a similar process will follow for the second test vaccine. Once safety is established in stage 1, we will proceed to stage 2, which will recruit 20 volunteers to our 3-arm randomized controlled trial (RCT), receiving either of the trial vaccines, J8-K4S2 or p*17-K4S2, or comparator (rabies) vaccine. All product dosing will be at 0, 3, and 6 weeks. The primary outcome is vaccine safety; the secondary outcome is immunogenicity and comparative analyses of the different vaccine regimens. This Strep A vaccine clinical trial aims to investigate safety and immunogenicity of two novel conjugated peptide-based vaccines, J8-KS42 and p*17-K4S2. If one or both vaccine products demonstrate favorable primary and secondary outcomes, the product(s) will move into phase II and III studies. ClinicalTrials.gov Identifier: NCT04882514. Registered on 2021–05-12, https://clinicaltrials.gov/study/NCT04882514 .

Interferon regulatory factors (IRFs) are key elements of antiviral innate responses that regulate the transcription of interferons (IFNs) and IFN-stimulated genes (ISGs). While the sensitivity of human coronaviruses to IFNs has been characterized, antiviral roles of IRFs during human coronavirus infection are not fully understood. Type I or II IFN treatment protected MRC5 cells from human coronavirus 229E infection, but not OC43. Cells infected with 229E or OC43 upregulated ISGs, indicating that antiviral transcription is not suppressed. Antiviral IRFs, IRF1, IRF3 and IRF7, were activated in cells infected with 229E, OC43 or severe acute respiratory syndrome-associated coronavirus 2 (SARS-CoV-2). RNAi knockdown and overexpression of IRFs demonstrated that IRF1 and IRF3 have antiviral properties against OC43, while IRF3 and IRF7 are effective in restricting 229E infection. IRF3 activation effectively promotes transcription of antiviral genes during OC43 or 229E infection. Our study suggests that IRFs may be effective antiviral regulators against human coronavirus infection.

Interferons induced early after SARS-CoV-2 infection are crucial for shaping immunity and preventing severe COVID-19. We previously demonstrated that injection of pegylated interferon-lambda accelerated viral clearance in COVID-19 patients (NCT04354259). To determine if the viral decline is mediated by enhanced immunity, we assess in vivo responses to interferon-lambda by single cell RNA sequencing and measure SARS-CoV-2-specific T cell and antibody responses between placebo and interferon-lambda-treated patients. Here we show that interferon-lambda treatment induces interferon stimulated genes in peripheral immune cells expressing IFNLR1, including plasmacytoid dendritic cells and B cells. Interferon-lambda does not affect SARS-CoV-2-specific antibody levels or the magnitude of virus-specific T cells. However, we identify delayed T cell responses in older adults, suggesting that interferon-lambda can overcome delays in adaptive immunity to accelerate viral clearance in high-risk patients. Altogether, interferon-lambda offers an early COVID-19 treatment option for outpatients to boost innate antiviral defenses without dampening peripheral adaptive immunity.

The SARS-CoV-2 pandemic is an ongoing threat to global health, and wide-scale vaccination is an efficient method to reduce morbidity and mortality. We designed and evaluated two DNA plasmid vaccines, based on the pIDV-II system, expressing the SARS-CoV-2 spike gene, with or without an immunogenic peptide, in mice, and in a Syrian hamster model of infection. Both vaccines demonstrated robust immunogenicity in BALB/c and C57BL/6 mice. Additionally, the shedding of infectious virus and the viral burden in the lungs was reduced in immunized hamsters. Moreover, high-titers of neutralizing antibodies with activity against multiple SARS-CoV-2 variants were generated in immunized animals. Vaccination also protected animals from weight loss during infection. Additionally, both vaccines were effective at reducing both pulmonary and extrapulmonary pathology in vaccinated animals. These data show the potential of a DNA vaccine for SARS-CoV-2 and suggest further investigation in large animal and human studies could be pursued.