In recent years, listeriosis has become a prevalent health problem in Spain, with the number of cases per year increasing by 232% between 2012 and 2016 according to the European Union (EU) health authorities. Despite the disease being included in the Spanish National Network of Epidemiological Surveillance since 2015, data are still based on estimations, and therefore, the national incidence rate cannot be correctly calculated.
The study of listeriosis outbreaks occurring in Spain has provided important information about the epidemiology of the causative agent, Listeria monocytogenes. At least four outbreaks of listeriosis have occurred within the last 10 years, all located in the north of Spain. Both the elderly (>70 years old) and pregnant women present a higher incidence of listeriosis. The development of novel genotyping techniques, such as multilocus sequence typing (MLST), compared to traditional serotyping, combined with the existence of strain databases, has made the process of tracing of L. monocytogenes hypervirulent strains easier.
Our laboratory has focused on listeriosis and the virulence factors of this pathogen for several years. We have performed a clinical study in collaboration with health institutions from two regions in northern Spain, Cantabria and Gipuzkoa. Consequently, biomarkers of listeriosis have been identified that may be effectively used to study disease evolution and trace the susceptibility to infection of specific high-risk groups, such as cancer or autoimmune patients, the elderly populations and pregnant women.
Based on the collective information obtained, we have also designed vaccines against experimental listeriosis that may provide useful tools to prepare human vaccines. The vaccines developed are based on dendritic cells or nanomaterials loaded with epitopes of virulence factors of L. monocytogenes, the latter formulated with specific adjuvants. Vaccines based on L. monocytogenes show considerable efficiency in several animal models of the main groups at risk of listeriosis and potentiate innate immune responses by recruiting and activating dendritic cells, implementing Th1-type cytokines, such as IL-12 and IFN-g, and eliciting robust L. monocytogenes-specific CD4 and CD8 T-cell responses. Moreover, strong protection abilities against adult systemic and neonatal listeriosis were reported, because both the vector and L. monocytogenes antigen used in the vaccine design are determinants of protection.
|Title of host publication||Listeriosis Outbreaks: Symptoms, Risk Factors and Treatment|
|Editors||Christopher J. Horan|
|Place of Publication||New York (USA)|
|Number of pages||39|
|Publication status||Published - Apr 2019|
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