Typhimurium bacteremia in South Africa.75 HIV infection causes loss of CD4+T helper 17 cells in the gastrointestinal mucosa, and therefore reduces local IL-17 levels. traits and host immune responses associated with iNTS infections in sSA, then discusses how this knowledge can guide vaccine development while providing a summary of vaccine candidates in preclinical and early clinical development. KEYWORDS:Ints disease, non-typhoidalSalmonella, invasive, vaccines == 1. Introduction == There is growing awareness that foodborne diarrheal agents, such as non-typhoidalSalmonella(NTS), pose a serious threat to public health in resource-limited settings.1NTS are facultative, anaerobic, intracellularEnterobacteriaceaebelonging to theSalmonella enterica(S. enterica) species.2They are commonly transmitted by the consumption of contaminated food or water and have a broad host-range. Following ingestion, a proportion of the infectiousSalmonellaload survives the acidic pH of the stomach and competition with the gut microbiota.Salmonellacan penetrate the intestinal epithelial barrier by invading non-phagocytic cells, such as enterocytes, or, preferentially, microfold cells (M cells) of Peyers Patches, through the expression of a multiprotein needlelike apparatus (the Type III Secretion System (T3SS) encoded bySalmonellaPathogenicity Island 1 (SPI-1-T3SS)), which is used as a conduit to translocate effector proteins into the host cell cytoplasm. Gut luminalSalmonellacan also be taken up by dendritic cells (DCs) or be phagocytized by CD18+ intestinal macrophages.3VirulentSalmonellaeuse several strategies to elude the immune system and promote bacterial growth, including interference with the DC-mediated antigen presentation process Mianserin hydrochloride or modification of the phagosome environment. 3 Salmonella-containing macrophages and DCs constitute a vehicle for systemic dissemination, as these cells can rapidly migrate3and spread through the bloodstream to extra-intestinal sites, such as the spleen and bone marrow.4However, in otherwise healthy individuals, NTS infections remain localized in the small intestine and colon3and mostly cause a self-limiting enterocolitis, which is commonly associated with secretory diarrhea, vomiting and abdominal pain. Hepatomegaly, splenomegaly or gastrointestinal complications (which may include cholecystitis, pancreatitis and appendicitis) are not frequently observed in NTS patients.5 Recent estimates report thatSalmonellaenterocolitis resulted in 95.1 million cases and 50,771 deaths globally in 2017.6In countries with medium-to-high socio-demographic development, only a small proportion (13 cases per 100,000 person-years) of the population develops an invasiveSalmonellainfection, and this is more likely to occur in children, the elderly and immunocompromised individuals.6By contrast, NTS species are often responsible for life-threatening systemic infections in low-income settings, where poor sanitation, lack of proper diagnostic tools, malnutrition and other comorbidities can further exacerbate the outcome of the disease.7,8 According to current incidence data, invasive non-typhoidalSalmonella(iNTS) infections particularly haunt Africa. Of the estimated 535,000 cases of iNTS disease and 77,500 deaths that occurred globally in 2017, the highest incidence (34.5 cases per 100,000 person-years) was observed in Sub-Saharan Africa (sSA).6An average case-fatality rate of 20.6% was recently reported among iNTS patients in sSA, with peaks up to 72% in people presenting infections caused by the human immunodeficiency virus (HIV).9 The typical clinical presentation of iNTS disease in Africa is a nonspecific febrile systemic illness, which is often accompanied by respiratory symptoms and hepatosplenomegaly. For this reason, iNTS infections can be confused with Mianserin hydrochloride comorbidities Mianserin hydrochloride commonly reported in sSA, such as malaria and pneumonia. African patients with iNTS infections also display the features of other concurrent conditions which are frequently observed in sSA, such as anemia, malnutrition, and advanced HIV illness. Diarrhea is not a predominant Rabbit polyclonal to Caspase 6 symptom of iNTS disease in Africa.5 The most common invasiveS. entericastrains identified in African regions since 1966 belong to theSalmonellaserovar Typhimurium (S. Typhimurium) and theSalmonellaserovar Enteritidis (S. Enteriditis),9although other serovariants, such asSalmonellaDublin (S. Dublin),SalmonellaConcord (S. Concord),SalmonellaStanleyville (S. Stanleyville) andSalmonellaIsangi (S. Isangi) have been reported in sSA.10 During the last 5 decades, several countries of sSA have experienced multiple outbreaks associated with a multidrug-resistant (MDR) iNTS classified asS. Typhimurium sequence type (ST) 313 (ST313).11Whole genome sequencing (WGS) of iNTS isolates from sSA has Mianserin hydrochloride identified two closely related, but genetically distinct, ST313 lineages, which emerged in the 1960 s (lineage 1) and late 1970 s (lineage 2).12It is supposed that around 20 years ago, as a result of the acquisition of chloramphenicol resistance, ST313.