Immunogenic potential and protective efficacy of a sptP deletion mutant of Salmonella Enteritidis as a live vaccine for chickens against a lethal challenge.

Salmonella Enteritidis (SE) is a highly adapted pathogen causing severe economic losses in the poultry industry worldwide. Chickens infected by SE are a major source of human food poisoning. Vaccination is an effective approach to control SE infections. This study evaluated the immunogenicity and protective efficacy of a SE sptP deletion mutant (C50336ΔsptP) as a live attenuated vaccine (LAV) candidate in chickens. 14 day-old specific pathogen-free (SPF) chickens were intramuscularly immunized with various doses of C50336ΔsptP. Several groups of chickens were challenged with the virulent wild-type SE strain Z-11 via the same route at 14 days post vaccination. Compared to the control group, the groups vaccinated with 1 × 106, 1 × 107 and 1 × 108 colony-forming units (CFU) of C50336ΔsptP exhibited no clinical symptoms after immunization. Only slight pathological changes occurred in the organs of the 1 × 109 CFU vaccinated group. C50336ΔsptP bacteria were cleared from the organs of immunized chickens within 14 days after vaccination. Lymphocyte proliferation and serum cytokine analyses indicated that significant cellular immune responses were induced after the vaccination of C50336ΔsptP. Compared to the control group, specific IgG antibody levels increased significantly in vaccinated chickens, and the levels increased markedly after the challenge. The 1 × 107, 1 × 108, and 1 × 109 CFU vaccinated chickens groups showed no clinical symptoms or pathological changes, and no death after the lethal challenge. Whereas severe clinical signs of disease and pathological changes were observed in the control group chickens after the challenge. These results suggest that a single dose of C50336ΔsptP could be an effective LAV candidate to against SE infection in chickens.

The Type III Secretion System Effector SptP of Salmonella enterica Serovar Typhi.

Strains of the various Salmonella enterica serovars cause gastroenteritis or typhoid fever in humans, with virulence depending on the action of two type III secretion systems (Salmonella pathogenicity island 1 [SPI-1] and SPI-2). SptP is a Salmonella SPI-1 effector, involved in mediating recovery of the host cytoskeleton postinfection. SptP requires a chaperone, SicP, for stability and secretion. SptP has 94% identity between S. enterica serovar Typhimurium and S Typhi; direct comparison of the protein sequences revealed that S Typhi SptP has numerous amino acid changes within its chaperone-binding domain. Subsequent comparison of ΔsptP S Typhi and S. Typhimurium strains demonstrated that, unlike SptP in S. Typhimurium, SptP in S Typhi was not involved in invasion or cytoskeletal recovery postinfection. Investigation of whether the observed amino acid changes within SptP of S Typhi affected its function revealed that S Typhi SptP was unable to complement S. Typhimurium ΔsptP due to an absence of secretion. We further demonstrated that while S. Typhimurium SptP is stable intracellularly within S Typhi, S Typhi SptP is unstable, although stability could be recovered following replacement of the chaperone-binding domain with that of S. Typhimurium. Direct assessment of the strength of the interaction between SptP and SicP of both serovars via bacterial two-hybrid analysis demonstrated that S Typhi SptP has a significantly weaker interaction with SicP than the equivalent proteins in S. Typhimurium. Taken together, our results suggest that changes within the chaperone-binding domain of SptP in S Typhi hinder binding to its chaperone, resulting in instability, preventing translocation, and therefore restricting the intracellular activity of this effector. IMPORTANCE: Studies investigating Salmonella pathogenesis typically rely on Salmonella Typhimurium, even though Salmonella Typhi causes the more severe disease in humans. As such, an understanding of S. Typhi pathogenesis is lacking. Differences within the type III secretion system effector SptP between typhoidal and nontyphoidal serovars led us to characterize this effector within S Typhi. Our results suggest that SptP is not translocated from typhoidal serovars, even though the loss of sptP results in virulence defects in S. Typhimurium. Although SptP is just one effector, our results exemplify that the behavior of these serovars is significantly different and genes identified to be important for S. Typhimurium virulence may not translate to S Typhi.

Immunogenicity and protective efficacy of a Salmonella Enteritidis sptP mutant as a live attenuated vaccine candidate.

BACKGROUND: Salmonella enterica serovar Enteritidis (S. Enteritidis) is a highly adaptive pathogen in both humans and animals. As a Salmonella Type III secretion system (T3SS) effector, Salmonella protein tyrosine phosphatase (SptP) is critical for virulence in this genus. To investigate the feasibility of using C50336ΔsptP as a live attenuated oral vaccine in mice, we generated the sptP gene deletion mutant C50336ΔsptP in S. Enteritidis strain C50336 by λ-Red mediated recombination and evaluated the protective ability of the S. Enteritidis sptP mutant strain C50336ΔsptP against mice salmonellosis. RESULTS: We found that C50336ΔsptP was a highly immunogenic, effective, and safe vaccine in mice. Compared to wild-type C50336, C50336ΔsptP showed reduced virulence as confirmed by the 50% lethal dose (LD50) in orally infected mice. C50336ΔsptP also showed decreased bacterial colonization both in vivo and in vitro. Immunization with C50336ΔsptP had no significant effect on body weight and did not result in obvious clinical symptoms relative to control animals treated with phosphate-buffered saline (PBS), but induced humoral and cellular immune responses at 12 and 26 days post inoculation. Immunization with 1 × 108 colony-forming units (CFU) C50336ΔsptP per mouse provided 100% protection against subsequent challenge with the wild-type C50336 strain, and immunized mice showed mild and temporary clinical symptoms as compared to those of control group. CONCLUSIONS: These results demonstrate that C50336ΔsptP can be a live attenuated oral vaccine for salmonellosis.

[The clinical characteristics surgical procedures and prognosis of solid pseudopapillary tumor of the pancreas].

Objective: To explore the clinical characteristics, surgical procedures and prognosis of solid pseudopapillary tumor of the pancreas(SPTP). Methods: The clinical and follow-up data of 55 cases with SPTP in Henan Tumor Hospital from June 2005 to April 2015 were retrospectively analyzed. Results: There were 55 SPTP cases, including 7 males and 48 females. The age ranged from 16 to 76 (median, 33). Clinical presentations of SPTP were not specific. The mean size of the tumor was 7.6 cm (range from 2 to 25cm). Pancreatic head and tail were the most common locations of SPTP. All the patients received surgical resection with a definitive pathological diagnosis. Some immunohistochemical markers were mostly positive, including ß-catenin, Vim, Syn, CD10, CD56, PR, etc. With a median follow-up of 53 months, the 1-year, 2-year and 5-year survival rate were 98.1%, 96.1% and 94.0%, respectively. Conclusions: SPTP is an uncommon exocrine pancreatic neoplasm with low malignant potential, which frequently occurs in young women. Preoperative imaging can provide evidence for the selection of treatment modalities among which surgical resection ispreferred. Diagnosis still relies on pathology and immunohistochemistry.

Characterization and protective efficacy of a sptP mutant of Salmonella Paratyphi A.

BACKGROUND: Salmonella Paratyphi A causes paratyphoid A, a severe systemic disease of people and remains a major public health problem in many parts of the world. In the interest of researching the roles of sptP on Salmonella Paratyphi A and developing a live-attenuated vaccine candidate, an sptP mutant of Salmonella Paratyphi A SPA017 (SPA017ΔsptP) was constructed, and then its characterization, immunogenicity, and protective ability were evaluated. RESULTS: The deletion of sptP had no effect on growth and biochemical properties. Adhesion and invasion assays showed that the lack of sptP did not affect the adhesion of Salmonella Paratyphi A, but the invasive ability of the mutant strain was significantly decreased, the half-lethal dose (LD50 ) of the mutant strain was 1.43 × 104 times of the parent strain in intraperitoneally injected mice. Single intraperitoneal vaccination with SPA017ΔsptP (1 × 105 CFU) in mice did not affect the body weight or elicit clinical symptoms relative to the control group, SPA017ΔsptP bacteria were isolated from livers and spleens of vaccinated mice at 14 days postvaccination. Notably, specific humoral and cellular immune responses were significantly induced. The protective assessment showed that the mutant strain could provide high-level protection against subsequent challenge with the wild-type SPA017 strain. CONCLUSIONS: These results demonstrated that SptP plays an essential role in the pathogenicity of Salmonella Paratyphi A, and Salmonella Paratyphi A lacking sptP is immunogenic and protective in mice.

Diagnosis and prognosis of solid pseudopapillary tumor of pancreas: an analysis of 68 patients / 中华肝胆外科杂志

Objective To study the diagnosis,treatment and prognosis of patients with solid-pseudopapillary tumor of the pancreas (SPTP).Methods The clinical and follow-up data of 68 patients with SPTP treated in the Affiliated Tumor Hospital of Zhengzhou University from January 2008 to March 2017 were retrospectively analyzed.Results There were 6 males and 62 females,with an average age +/-S.D.of (32.0 ± 12.0) years.The mean tumor size was (4.4 ±2.3) cm.The primary symptom was abdominal pain,and a pancreatic mass was subsequently detected.All the patients underwent surgical resection which included pancreaticoduodenectomy,duodenal preserving pancreatic head resection,distal pancreatectomy,middle pancreatectomy,local excision,resection of pancreatic tail plus splenectomy and distal pancreaticosplenectomy.Postoperative histopathological examination confirmed solid pseudopapillary tumor of the pancreas in all these patients.Twenty-one patients (30.9％) developed postoperative complications,which included pancreatic fistula in 12 patients (17.7％),hemorrhage in 2 patients (2.9％),pleural effusion in 2 patients (2.9％),incision infection in 3 patients (4.4％),and gastric emptying disorder in 2 patients (2.9％).There was no in-hospital mortality.The average length of hospital stay was (26.0 ± 10.0) days.Of the 57 patients (83.8％) who were followed-up (mean 38 months,range 3 to 114 months),11 patients developed postoperative indigestion and 2 patients diabetes.No patient developed tumor recurrence,metastasis and death.Conclusions SPTP is a low grade malignant tumor,which is found primarily in young women.The clinical characteristics are non-specific,and preoperative diagnosis is difficult.Excellent prognosis can be achieved with surgical resection which is the preferred treatment for SPTP.

The clinical characteristics surgical procedures and prognosis of solid pseudopapillary tumor of the pancreas / 中华肿瘤杂志

Objective@#To explore the clinical characteristics, surgical procedures and prognosis of solid pseudopapillary tumor of the pancreas(SPTP).@*Methods@#The clinical and follow-up data of 55 cases with SPTP in Henan Tumor Hospital from June 2005 to April 2015 were retrospectively analyzed.@*Results@#There were 55 SPTP cases, including 7 males and 48 females. The age ranged from 16 to 76 (median, 33). Clinical presentations of SPTP were not specific. The mean size of the tumor was 7.6 cm (range from 2 to 25cm). Pancreatic head and tail were the most common locations of SPTP. All the patients received surgical resection with a definitive pathological diagnosis. Some immunohistochemical markers were mostly positive, including β-catenin, Vim, Syn, CD10, CD56, PR, etc. With a median follow-up of 53 months, the 1-year, 2-year and 5-year survival rate were 98.1%, 96.1% and 94.0%, respectively.@*Conclusions@#SPTP is an uncommon exocrine pancreatic neoplasm with low malignant potential, which frequently occurs in young women. Preoperative imaging can provide evidence for the selection of treatment modalities among which surgical resection ispreferred. Diagnosis still relies on pathology and immunohistochemistry.