Oral Immunization of Mice With Vaccine of Attenuated Salmonella typhimurium Expressing Helicobacter pylori Urease B Subunit

Objective To prepare the live recombinant vaccine of attenuated Salmonella typhimurium SL3261 expressing Helicobacterpylori （H. pylori） B subunit （UreB） and to determine whether it could be used as an oral vaccine against H. pylori infection. Methods Using genomic DNA of H. pylori Sydney strain （SS1） as template, the H. pylori UreB gene fragment was amplified by PCR and subcloned into the expression vector pTC01. The recombinant plasmid pTC01-UreB was then transferred into LBS000 to obtain modified forms, and further conversed into the attenuated Salmonella typhimurium SL3261 to obtain recombinant SL3261/pCT01-UreB as an oral immunization reagent, which was then used to orally immunize Balb/c mice twice at a three-week interval. Twelve weeks later, anti-UreB IgA antibodies in intestinal fluid and IgG antibodies in sera were determined by ELISA. The relating data in control groups （including body weight, gastric inflammation, etc.） were also collected. Results The sequencing analysis showed that the UreB gene fragment amplified by PCR was consistent with the sequence of the H. pylori UreB gene. The restriction enzyme digestion revealed that the correct pTC01-UreB was obtained. SDS-PAGE and Western blot showed that a 61KD protein was expressed in SL3261/pTC01-UreB, which could be recognized by anti-H, pylori UreB antiserum and was absent in the control containing only Salmonella typhimurium SL3261 strain. The multiple oral immunization with SL3261/pTC01-UreB could significantly induce H. pylori specific mucosal IgA response as well as serum IgG responses. IFN-T and IL-10 levels were significantly increased in SL3261/pTC01-UreB group, and no obvious side effect and change in gastric inflammation were observed. Conclusion The attenuated vaccine of Salmonella typhimurium expressing H. pylori UreB can be used as an oral vaccine against H. pylori infection.

Mucosal COVID-19 vaccines:Risks,benefits and control of the pandemic

Based on mucosal immunization to promote both mucosal and systemic immune responses,next-generation coronavirus disease 2019(COVID-19)vaccines would be administered intranasally or orally.The goal of severe acute respiratory syndrome coronavirus 2(SARS-CoV-2)vaccines is to provide adequate immune protection and avoid severe disease and death.Mucosal vaccine candidates for COVID-19 including vector vaccines,recombinant subunit vaccines and live attenuated vaccines are under development.Furthermore,subunit protein vaccines and virus-vectored vaccines have made substantial progress in preclinical and clinical settings,resulting in SARS-CoV-2 intranasal vaccines based on the previously successfully used nasal vaccines.Additional to their ability to trigger stable,protective immune responses at the sites of pathogenic infection,the development of‘specific’mucosal vaccines targeting coronavirus antigens could be an excellent option for preventing future pandemics.However,their efficacy and safety should be confirmed.

Pediatric case with vaccine-related poliovirus infection: A case report

BACKGROUND As long as oral poliovirus vaccine(OPV)is used,the potential risk for the emergence of vaccine-related polioviruses remains.CASE SUMMARY We report a case of Sabin-like type 1 poliovirus infection in an immunocompetent 17-mo-old child after receiving four scheduled doses of OPV.Somehow,the four doses did not confer full protection,possibly because of interference created by other enteroviruses.CONCLUSION The surveillance of vaccine-related polioviruses has important implications for improving health policies and vaccination strategies.Missed cases of vaccinerelated poliovirus infection might pose a potential risk to global poliovirus eradication.Therefore,the global withdrawal of OPV and a shift to the inclusion of only inactivated poliovirus vaccine in the vaccination schedule is the main objective of the polio eradication program.

Autophagy is involved in oral rAAV/Aβ vaccine-induced Aβ clearance in APP/PS1 transgenic mice

The imbalance between β-amyloid （Aβ） generation and clearance plays a fundamental role in the pathogenesis of Alzheimer＇s disease （AD）. The sporadic form of AD is characterized by an overall impairment in Aβ clearance. Immunotherapy targeting Aβ clearance is believed to be a promising approach and is under active clinical investigation. Autophagy is a conserved pathway for degrading abnormal protein aggregates and is crucial for Aβ clearance. We previously reported that oral vaccination with a recombinant AAV/Aβ vaccine increased the clearance of Aβ from the brain and improved cognitive ability in AD animal models, while the underlying mechanisms were not well understood. In this study, we first demonstrated that oral vaccination with rAAV/Aβ decreased the p62 level and up-regulated the LC3B- II/LC3B-I ratio in APP/PS1 mouse brain, suggesting enhanced autophagy. Further, inhibition of the Akt/mTOR pathway may account for autophagy enhancement. We also found increased anti-Aβ antibodies in the sera of APP/PS1 mice with oral vaccination, accompanied by elevation of complement factors C1q and C3 levels in the brain. Our results indicate that autophagy is closely involved in oral vaccination-induced Aβ clearance, and modulating the autophagy pathway may be an important strategy for AD prevention and intervention.

Assessment of risk factors associated with oral polio vaccine refusal in Rahim Yar Khan District,Pakistan(2017)

Objective:This study aimed to determine the risk factors associated with oral polio vaccine(OPV)refusal.Methodology:A case-control study was conducted in Rahim Yar Khan(RYK)District,Pakistan.A case was defined as‘‘any child aged<5 years who was enrolled in the microplans of RYK District as part of the National Immunization Days program in January 2017 and whose parents or guardians refused to receive OPV for these eligible children.”The age-and sex-matched controls(1:1)were obtained from the same locality.Ratios were calculated,and odds ratios(ORs)were determined at 95%confidence interval(CI)and p<0.05.Results:Among the 110 children,64(58%)were male(male to female ratio,1.4:1).The mean age was 29.5 months(range,0.26–60 months).Seventy-four(67.2%)children were living in urban areas and 29(26.3%)children were living in peri-urban and rural areas,while seven(6.3%)were considered nomads.A total of 72(65.2%)children were Punjabi speaking,33(30%)were Saraiki speaking,2(3.7%)were Urdu speaking,and 2(1.82%)were Balochi speaking.Repeated campaigns(n=91,82.7%)was the major reason for OPV refusal.Living at a distance>1 km from a healthcare facility was significantly associated(OR,2.5;95%CI,1.4–4.4;p<0.05)with OPV refusal,while prior visits by healthcare workers(OR,0.11;95%CI,0.06–0.22;p<0.05)and mother’education above primary level(OR,0.42;95%CI,0.24–0.73;p<0.05)were inversely associated with OPV refusal.Conclusion:On the basis of our recommendations,door-to-door social mobilization visits by healthcare workers to alleviate fear,misconception,and fatigue of repeated campaigns and strict accountability mechanism were developed by district government at pre-and intra-campaign levels.