Vaccination against Bacterial Infections: Challenges, Progress, and New Approaches with a Focus on Intracellular Bacteria

Abstract

Many bacterial infections are major health problems worldwide, and treatment of many of these infectious diseases is becoming increasingly difficult due to the development of antibiotic resistance, which is a major threat. Prophylactic vaccines against these bacterial pathogens are urgently needed. This is also true for bacterial infections that are still neglected, even though they affect a large part of the world’s population, especially under poor hygienic conditions. One example is typhus, a life-threatening disease also known as “war plague” caused by Rickettsia prowazekii, which could potentially come back in a war situation such as the one in Ukraine. However, vaccination against bacterial infections is a challenge. In general, bacteria are much more complex organisms than viruses and as such are more difficult targets. Unlike comparatively simple viruses, bacteria possess a variety of antigens whose immunogenic potential is often unknown, and it is unclear which antigen can elicit a protective and long-lasting immune response. Several vaccines against extracellular bacteria have been developed in the past and are still used successfully today, e.g., vaccines against tetanus, pertussis, and diphtheria. However, while induction of antibody production is usually sufficient for protection against extracellular bacteria, vaccination against intracellular bacteria is much more difficult because effective defense against these pathogens requires T cell-mediated responses, particularly the activation of cytotoxic CD8+ T cells. These responses are usually not efficiently elicited by immunization with non-living whole cell antigens or subunit vaccines, so that other antigen delivery strategies are required. This review provides an overview of existing antibacterial vaccines and novel approaches to vaccination with a focus on immunization against intracellular bacteria.

Efficacy and Immune Correlates of OMP-1B and VirB2-4 Vaccines for Protection of Dogs from Tick Transmission of Ehrlichia chaffeensis

“…In this study, two animal models were used: mouse-intraperitoneal inoculation and dog-tick transmission models. Although the mouse infection model is unnatural, most vaccine studies on vector-borne obligatory intracellular bacteria have been carried out in mice challenged by needle inoculation ( 54 ) and almost all Ehrlichia pathogenesis and immunologic research used this model to derive immunologic or other signatures of responses ( 55 – 58 ). Dog-tick transmission is the natural mode of transmission.…”

A Comprehensive Review on Bacterial Vaccines Combating Antimicrobial Resistance in Poultry

“…Another major scientific challenge is the need to develop bacterial vaccines that are effective against a wide range of bacterial pathogens. This requires a deep understanding of the biology and genetics of bacterial pathogens, as well as the ability to design and synthesize vaccines that are effective against multiple bacterial pathogens [ 116 , 117 ]. This is particularly important in the context of poultry production, as poultry are commonly exposed to a wide range of bacterial pathogens, including E. coli , Salmonella , and Campylobacter .…”

Nanobiotics against antimicrobial resistance: harnessing the power of nanoscale materials and technologies

“…Immunization by vaccine remains the most effective method to provide protection against infectious diseases [197]. However, clinical applicability of many new potential vaccine candidates is limited due to low immunogenicity and inability to stimulate an effective long-lasting immunity [198,199]. In particular, subunit vaccines are less immunogenic and often fail to evoke desirable immune reactions.…”