Vaccines against gastroenteritis, current progress and challenges

Abstract

Enteric viral and bacterial infections continue to be a leading cause of mortality and morbidity in young children in low-income and middle-income countries, the elderly, and immunocompromised individuals. Vaccines are considered an effective and practical preventive approach against the predominantly fecal-to-oral transmitted gastroenteritis particularly in the resource-limited countries or regions where implementation of sanitation systems and supply of safe drinking water are not quickly achievable. While vaccines are available for a few enteric pathogens including rotavirus and cholera, there are no vaccines licensed for many other enteric viral and bacterial pathogens. Challenges in enteric vaccine development include immunological heterogeneity among pathogen strains or isolates, a lack of animal challenge models to evaluate vaccine candidacy, undefined host immune correlates to protection, and a low protective efficacy among young children in endemic regions. In this article, we briefly updated the progress and challenges in vaccines and vaccine development for the leading enteric viral and bacterial pathogens including rotavirus, human calicivirus, Shigella, enterotoxigenic Escherichia coli (ETEC), cholera, nontyphoidal Salmonella, and Campylobacter, and introduced a novel epitope-and structurebased vaccinology platform known as MEFA (multiepitope fusion antigen) and the application of MEFA for developing broadly protective multivalent vaccines against heterogenous pathogens.

L-DBF Elicits Cross Protection Against Different Serotypes of Shigella spp

“…Additionally, L-DBF provides the much-desired crossprotection that is lacking with traditional LPS based vaccines including whole killed, live-attenuated and O-antigen based vaccines that are considered serotype specific. In contrast, the T3SS proteins IpaB and IpaD are conserved among all serotypes and have been considered attractive target antigens in subunit vaccine development (30,31). Early studies showed that DBF with dmLT administered IN protected mice against S. flexneri, S. sonnei and S. dysenteriae.…”

Antibody in Lymphocyte Supernatant (ALS) responses after oral vaccination with live Shigella sonnei vaccine candidates WRSs2 and WRSs3 and correlation with serum antibodies, ASCs, fecal IgA and shedding

“…An additional concern limiting treatment options is the evolution of multidrug-resistant Shigella strains. Thus, control measures have primarily focused on development of vaccines that include whole -cells killed, live attenuated and various subunit-based Shigella vaccines [4][5][6][7]. Following vaccination or infection the ability to measure the immune response, using reproducible and technologically simple methods is critical, particularly if evaluating a vaccine candidate in a resource limited region.…”

Norovirus Vaccines: Current Clinical Development and Challenges

“…Despite these drawbacks, advancements have been achieved, with four candidate vaccines having reached the stage of clinical development. While several review papers were published recently, giving systematic overviews on the preclinical developments of various norovirus vaccine candidates [12][13][14][15][16][17], this short article focuses on the current advances in clinical evaluations of four vaccine candidates.…”