The emergence of antimicrobial resistance (AMR) is a principal global health crisis projected to cause 10 million deaths annually worldwide by 2050. While the Gram-negative bacteria Escherichia coli is commonly found as a commensal microbe in the human gut, some strains are dangerously pathogenic, contributing to the highest AMR-associated mortality. Strains of E. coli that can translocate from the gastrointestinal tract to distal sites, called extraintestinal E. coli (ExPEC), are particularly problematic and predominantly afflict women, the elderly, and immunocompromised populations. Despite nearly 40 years of clinical trials, there is still no vaccine against ExPEC. One reason for this is the remarkable diversity in the ExPEC pangenome across pathotypes, clades, and strains, with hundreds of genes associated with pathogenesis including toxins, adhesins, and nutrient acquisition systems. Further, ExPEC is intimately associated with human mucosal surfaces and has evolved creative strategies to avoid the immune system. This review summarizes previous and ongoing preclinical and clinical ExPEC vaccine research efforts to help identify key gaps in knowledge and remaining challenges.

The various strains of influenza virus cause respiratory symptoms in humans every year and annual vaccinations are recommended. Due to its RNA-type genes and segmented state, it belongs to a virus that mutates frequently with antigenic drift and shift, giving rise to various strains. Each year, the World Health Organization identifies the epidemic strains and operates a global surveillance system to suggest the viral composition for the influenza vaccine. Influenza viruses, which have multiple viral strains, are produced in the format of multivalent vaccine. However, the multivalent vaccine has a possibility of causing immune interference by introducing multiple strain-specific antigens in a single injection. Therefore, evaluating immune interference phenomena is essential when assessing multivalent vaccines. In this study, the protective ability and immunogenicity of multivalent and monovalent vaccines were evaluated in mice to assess immune interference in the multivalent vaccine. Monovalent and multivalent vaccines were manufactured using the latest strain of the 2022-2023 seasonal influenza virus selected by the World Health Organization. The protective abilities of both types of vaccines were tested through hemagglutination inhibition test. The immunogenicity of multivalent and monovalent vaccines were tested through enzyme-linked immunosorbent assay to measure the cellular and humoral immunity expression rates. As a result of the protective ability and immunogenicity test, higher level of virus neutralizing ability and greater amount of antibodies in both IgG1 and IgG2 were confirmed in the multivalent vaccine. No immune interference was found to affect the protective capacity and immune responses of the multivalent vaccines.

Since the emergence of the ancestral severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) virus and the successful rollout of protective vaccines based on this original strain, SARS-CoV-2 has evolved into several variants, in a classical virus-host arms race typical of RNA viruses, to progressively evade the host immune response. Next-generation bivalent vaccines have been developed with broader protection against emerging variants than the ancestral vaccine. Nonetheless, even these vaccines show lower protection against the latest Omicron variants. Immune printing describes how an immune response to an immunogen is impacted by earlier exposures to a related immunogen. Several lessons about the effect of immune imprinting on responses to SARS-CoV-2 infection and vaccination, including age-associated impacts, can be learned from influenza. Understanding the mechanisms of imprinting of SARS-CoV-2 will be important to inform the design of vaccines that produce broader and more durable protective immune responses to emerging variants.

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In 2017, the World Health Organization (WHO) published an updated document aimed at facilitating the understanding of the immunological basis of pertussis vaccines and their use. The document \"The Immunological Basis for Immunization Series: Pertussis Vaccines\" is freely available on the WHO website. The main purpose of the module is to provide national immunization managers and vaccination professionals with an overview of the scientific basis of vaccination against pertussis and the immunological basis for the WHO position on pertussis vaccines. The Immunological Basis for Immunization Series was initially developed in 1993. Since then the series was regularly updated and extended. They reflect the biological differences in immune responses to the individual pathogens and the differing strategies employed to create the best possible level of protection that can be provided by vaccination. We invite the immunization community to use these references, and we hope the updated pertussis vaccine module will be a valuable resource.

In 2017, the World Health Organization (WHO) published a document aimed at facilitating influenza vaccine introduction and use in low- and middle-income countries. The document \"The Immunological Basis for Immunization Series: Influenza Vaccines\" is freely available on the WHO website. The main purpose of this document is to give immunization managers and vaccination professionals an authoritative but easily-understood overview of the scientific basis of influenza vaccination and the immunological basis for the WHO position on influenza vaccines. The influenza vaccine document comprises one module of the WHO Immunological Basis for Immunization series. We invite the immunization community to use these references, and we hope the influenza vaccine module will be a valuable resource for persons who manage and monitor influenza vaccine programs, particularly in low- and middle-income countries.

Adenovirus vaccine vectors generated from new viral serotypes are routinely screened in pre-clinical laboratory animal models to identify the most immunogenic and efficacious candidates for further evaluation in clinical human and veterinary settings. Here, we show that studies in a laboratory species do not necessarily predict the hierarchy of vector performance in other mammals. In mice, after intramuscular immunization, HAdV-5 (Human adenovirus C) based vectors elicited cellular and humoral adaptive responses of higher magnitudes compared to the chimpanzee adenovirus vectors ChAdOx1 and AdC68 from species Human adenovirus E. After HAdV-5 vaccination, transgene specific IFN-γ(+) CD8(+) T cell responses reached peak magnitude later than after ChAdOx1 and AdC68 vaccination, and exhibited a slower contraction to a memory phenotype. In cattle, cellular and humoral immune responses were at least equivalent, if not higher, in magnitude after ChAdOx1 vaccination compared to HAdV-5. Though we have not tested protective efficacy in a disease model, these findings have important implications for the selection of candidate vectors for further evaluation. We propose that vaccines based on ChAdOx1 or other Human adenovirus E serotypes could be at least as immunogenic as current licensed bovine vaccines based on HAdV-5.

Vaccines have had a profound influence on human health with no other health intervention rivaling their impact on the morbidity and mortality associated with infectious disease. However, the magnitude and persistence of vaccine immunity varies considerably between individuals, a phenomenon that is not well understood. Recent studies have used contemporary technologies to correlate variation in the genome and transcriptome to immunological measures of vaccine responsiveness. These approaches have provided fresh insight into the intrinsic factors determining the potency and duration of vaccine-induced immunity. The fundamental challenge will be to translate these findings into innovative and pragmatic strategies to develop new and more effective vaccines.