Evaluation of humoral and cellular immune responses against Vibrio cholerae using oral immunization by multi-epitope-phage-based vaccine.

INTRODUCTION: Cholera is a severe gastrointestinal disease that manifests with rapid onset of diarrhea, vomiting, and high mortality rates. Due to its widespread occurrence in impoverished communities with poor water sanitation, there is an urgent demand for a cost-effective and highly efficient vaccine. Multi-epitope vaccines containing dominant immunological epitopes and adjuvant compounds have demonstrated potential in boosting the immune response. MATERIAL AND METHODS: B and T epitopes of OMPU, OMPW, TCPA, CTXA, and CTXB proteins were predicted using bioinformatics methods. Subsequently, highly antigenic multi-epitopes that are non-allergenic and non-toxic were synthesized. These multi-epitopes were then cloned into the pCOMB phagemid. A plasmid M13KO7ΔpIII containing all helper phage proteins except pIII was created to produce the recombinant phage. Female Balb/c mice were divided into three groups and immunized accordingly. The mice received the helper phage, recombinant phage or PBS via gavage feeding thrice within two weeks. Serum samples were collected before and after immunization for the ELISA test as well as evaluating immune system induction through ELISpot testing of spleen lymphocytes. RESULTS: The titer of the recombinant phage was determined to be 1011 PFU/ml. The presence of the recombinant phage was confirmed through differences in optical density between sample and control groups in the ELISA phage technique, as well as by observing transduction activity, which demonstrated successful production of a recombinant phage displaying the Vibrio multi-epitope on M13 phage pIII. ELISA results revealed significant differences in phage antibodies before and after inoculation, particularly notable in the negative control mice. Mice treated with multi-epitope phages exhibited antibodies against Vibrio cholerae lysate. Additionally, ELISpot results indicated activation of cellular immunity in mice receiving both Vibrio and helper phage. CONCLUSION: This study emphasizes the potential of multi-epitope on phage to enhance both cellular and humoral immunity in mice, demonstrating how phages can be used as adjuvants to stimulate mucosal immunity and act as promising candidates for oral vaccination.

Mortality Associated with Priority Diseases in Flood-Affected Areas Using District Health Information System (DHIS2) During September-December 2022: Pakistan Experience.

OBJECTIVES: To quantify the burden of communicable diseases and characterize the most reported infections during public health emergency of floods in Pakistan. METHODS: The study's design is a descriptive trend analysis. The study utilized the disease data reported to District Health Information System (DHIS2) for the 12 most frequently reported priority diseases under the Integrated Disease Surveillance and Response (IDSR) system in Pakistan. RESULTS: In total, there were 1,532,963 suspected cases during August to December 2022 in flood-affected districts (n = 75) across Pakistan; Sindh Province reported the highest number of cases (n = 692,673) from 23 districts, followed by Khyber Pakhtunkhwa (KP) (n = 568,682) from 17 districts, Balochistan (n = 167,215) from 32 districts, and Punjab (n = 104,393) from 3 districts. High positivity was reported for malaria (79,622/201,901; 39.4%), followed by acute diarrhea (non-cholera) (23/62; 37.1%), hepatitis A and E (47/252; 18.7%), and dengue (603/3245; 18.6%). The crude mortality rate was 11.9 per 10 000 population (1824/1,532,963 [deaths/cases]). CONCLUSION: The study identified acute respiratory infection, acute diarrhea, malaria, and skin diseases as the most prevalent diseases. This suggests that preparedness efforts and interventions targeting these diseases should be prioritized in future flood response plans. The study highlights the importance of strengthening the IDSR as a Disease Early Warning System through the implementation of the DHIS2.

Are young and older children with diarrhea presenting in the same way?

BACKGROUND: Diarrhoea is a global health problem. More than a quarter of diarrhoeal deaths occur among children less than five years. Different literatures analyzed presentation and outcomes of less than five diarrhoeal children. The world has made remarkable progress in reducing child mortality. So, older children are growing in number. Our aim was to identify clinical differentials and variations of pathogens among younger (less than five) and older (five to nine years) diarrhoeal children. METHOD: Data were extracted from the diarrhoeal disease surveillance system (DDSS) of Dhaka Hospital (urban site) and Matlab Hospital (rural site) of the International Centre for Diarrhoeal Disease Research, Bangladesh for the period of January 2012 to December 2021. Out of 28,781 and 12,499 surveillance patients in Dhaka and Matlab Hospital, 614 (2.13%) and 278 (2.22%) children were five to nine-years of age, respectively. Among under five children, 2456 from Dhaka hospital and 1112 from Matlab hospital were selected randomly for analysis (four times of five to nine years age children, 1:4). RESULTS: Vomiting, abdominal pain, and dehydrating diarrhoea were significantly higher in older children in comparison to children of less than five years age (p-value <0.05) after adjusting study site, gender, antibiotic use before hospitalization, diarrhoeal duration < 24 hours, intake of oral rehydration fluid at home, parental education, WASH practice and history of cough. Vibrio. cholerae, Salmonella, and Shigella were the common fecal pathogen observed among older children compared to under five after adjusting for age, gender and study site. CONCLUSION: Although percentage of admitted diarrhoeal children with five to nine years is less than under five years children but they presented with critical illness with different diarrhoeal pathogens. These observations may help clinicians to formulate better case management strategies for children of five to nine years that may reduce morbidity.

Estimated global and regional causes of deaths from diarrhoea in children younger than 5 years during 2000-21: a systematic review and Bayesian multinomial analysis.

BACKGROUND: Information on the causes of deaths from diarrhoea in children younger than 5 years is needed to design improved preventive and therapeutic approaches. We aimed to conduct a systematic analysis of studies to report estimates of the causes of deaths from diarrhoea in children younger than 5 years at global and regional levels during 2000-21. METHODS: For this systematic review and Bayesian multinomial analysis, we included 12 pathogens with the highest attributable incidence in the Global Enteric Multicenter Study. We searched PubMed, Scopus, Embase, Web of Science, Global Health Index Medicus, Global Health OVID, IndMed, Health Information Platform for the Americas (PLISA), Africa-Wide Information, and Cochrane Collaboration for articles published between Jan 1, 2000, and Dec 31, 2020, using the search terms "child", "hospital", "diarrhea", "diarrhoea", "dysentery", "rotavirus", "Escherichia coli", "salmonella", "shigella", "campylobacter", "Vibrio cholerae", "cryptosporidium", "norovirus", "astrovirus", "sapovirus", and "adenovirus". To be included, studies had to have a patient population of children younger than 5 years who were hospitalised for diarrhoea (at least 90% of study participants), at least a 12-month duration, reported prevalence in diarrhoeal stools of at least two of the 12 pathogens, all patients with diarrhoea being included at the study site or a systematic sample, at least 100 patients with diarrhoea, laboratory tests done on rectal swabs or stool samples, and standard laboratory methods (ie, quantitative PCR [qPCR] or non-qPCR). Studies published in any language were included. Studies were excluded if they were limited to nosocomial, chronic, antibiotic-associated, or outbreak diarrhoea or to a specific population (eg, only children with HIV or AIDS). Each article was independently reviewed by two researchers; a third arbitrated in case of disagreement. If both reviewers identified an exclusion criterion, the study was excluded. Data sought were summary estimates. Data on causes from published studies were adjusted when necessary to account for the poor sensitivity of non-qPCR methods and for attributable fraction based on quantification of pathogens in children who are ill or non-ill. The causes of deaths from diarrhoea were modelled on the causes of hospitalisations for diarrhoea. We separately modelled studies reporting causes of diarrhoea in children who were hospitalised in low-income and middle-income countries (LMICs) and in high-income countries (HICs). FINDINGS: Of 74 282 papers identified in the initial database search, we included 138 studies (91 included data from LMICs and 47 included data from HICs) from 73 countries. We modelled estimates for 194 WHO member states (hereafter referred to as countries), including 42 HICs and 152 LMICs. We could attribute a cause to 1 003 448 (83·8%) of the estimated 1 197 044 global deaths from diarrhoea in children younger than 5 years in 2000 and 360 730 (81·3%) of the estimated 443 833 global deaths from diarrhoea in children younger than 5 years in 2021. The cause with the largest estimated global attribution was rotavirus; in LMICs, the proportion of deaths from diarrhoea due to rotavirus in children younger than 5 years appeared lower in 2021 (108 322 [24·4%] of 443 342, 95% uncertainty interval 21·6-29·5) than in 2000 (316 382 [26·5%] of 1 196 134, 25·7-28·5), but the 95% CIs overlapped. In 2000, the second largest estimated attribution was norovirus GII (95 817 [8·0%] of 1 196 134 in LMICs and 225 [24·7%] of 910 in HICs); in 2021, Shigella sp had the second largest estimated attribution in LMICs (36 082 [8·1%] of 443 342), but norovirus remained with the second largest estimated attribution in HICs (84 [17·1%] of 490). INTERPRETATION: Our results indicate progress in the reduction of deaths from diarrhoea caused by 12 pathogens in children younger than 5 years in the past two decades. There is a need to increase efforts for prevention, including with rotavirus vaccine, and treatment to eliminate further deaths. FUNDING: Bill & Melinda Gates Foundation via Johns Hopkins University and the University of Virginia.

Early use of oral cholera vaccines as a prime control measure during outbreaks: Necessary but not sufficient.

INTRODUCTION: Despite being a preventable and treatable disease, cholera remains a public health problem in Sudan. The objective of the outbreak investigation was to identify associated risk factors that would help institute appropriate control measures. MATERIAL AND METHODS: A case control study design was chosen to identify the risk factors for cholera in Gadarif State. RESULTS: Multi-variate analysis of identified two risk factors and three preventive factors for cholera in Gadarif City. RISK FACTORS: Buying foods or drinks from street vendors (OR = 71.36), 95 % CI: 16.58-307.14), living in an urban setting (Gadarif City) (OR = 5.38), 95 % CI: 2.10-13.81); and the preventive factors were: Washing hands with water after defecation but without soap (OR = 0.16), 95 % CI: 0.04-0.63) or with soap (OR = 0.01), 95 % CI: 0.00-0.03), washing hands before eating (OR = 0.15), 95 % CI: 0.05-0.51) and taking Oral Cholera Vaccine (OCV) (OR = 0.19, 95 % CI: 0.08-0.44). The effectiveness of OCV (VE) was (Unadjusted VE: 80 %, 95 % CI: 69 %-87 %) or (Adjusted VE = 81.0 %, 95 % CI: 56.0 %-92.0 %). DISCUSSION: Cholera outbreaks, especially in the setting of a complex humanitarian crises, can spread rapidly, resulting in many deaths, and quickly become a public health crisis. Implementation of a community-wide vaccination campaign using OCV as early as possible during the outbreak while implementing other control measures to target hotspots and at-risk populations would expedite halting outbreaks of cholera and save lives.

Comparison of analysis methods to classify cholera hotspots in Ethiopia from 2015 to 2021.

Cholera continues to represent a major public health concern in Ethiopia. The country has developed a Multi-sectoral National Cholera Elimination Plan in 2022, which targets prevention and control interventions in cholera hotspots. Multiple methods to classify cholera hotspots have been used in several countries. Since 2014, a classification method developed by United Nations Children's Fund has been applied to guide water, sanitation and hygiene interventions throughout Sub-Saharan Africa based on three outbreak parameters: frequency, duration and standardized attack rate. In 2019, the Global Task Force on Cholera Control (GTFCC) proposed a method based on two parameters: average annual cholera incidence and persistence. In 2023, an updated GTFCC method for multisectoral interventions considers three epidemiological indicators (cumulative incidence, cumulative mortality and persistence,) and a cholera-case confirmation indicator. The current study aimed to classify cholera hotspots in Ethiopia at the woreda level (equivalent to district level) applying the three methods and comparing the results to optimize the hotspot targeting strategy. From 2015 to 2021, cholera hotspots were located along major routes between Addis Ababa and woredas adjacent to the Kenya and Somalia borders, throughout Tigray Region, around Lake Tana, and in Afar Region. The multi-method comparison enables decision makers to prioritize interventions according to a sub-classification of the highest-priority areas.

Genetic interaction mapping reveals functional relationships between peptidoglycan endopeptidases and carboxypeptidases.

Peptidoglycan (PG) is the main component of the bacterial cell wall; it maintains cell shape while protecting the cell from internal osmotic pressure and external environmental challenges. PG synthesis is essential for bacterial growth and survival, and a series of PG modifications are required to allow expansion of the sacculus. Endopeptidases (EPs), for example, cleave the crosslinks between adjacent PG strands to allow the incorporation of newly synthesized PG. EPs are collectively essential for bacterial growth and must likely be carefully regulated to prevent sacculus degradation and cell death. However, EP regulation mechanisms are poorly understood. Here, we used TnSeq to uncover novel EP regulators in Vibrio cholerae. This screen revealed that the carboxypeptidase DacA1 (PBP5) alleviates EP toxicity. dacA1 is essential for viability on LB medium, and this essentiality was suppressed by EP overexpression, revealing that EP toxicity both mitigates, and is mitigated by, a defect in dacA1. A subsequent suppressor screen to restore viability of ΔdacA1 in LB medium identified hypomorphic mutants in the PG synthesis pathway, as well as mutations that promote EP activation. Our data thus reveal a more complex role of DacA1 in maintaining PG homeostasis than previously assumed.

Application of machine learning with large-scale data for an effective vaccination against classical swine fever for wild boar in Japan.

Classical swine fever has been spreading across the country since its re-emergence in Japan in 2018. Gifu Prefecture has been working diligently to control the disease through the oral vaccine dissemination targeting wild boars. Although vaccines were sprayed at 14,000 locations between 2019 and 2020, vaccine ingestion by wild boars was only confirmed at 30% of the locations. Here, we predicted the vaccine ingestion rate at each point by Random Forest modeling based on vaccine dissemination data and created prediction surfaces for the probability of vaccine ingestion by wild boar using spatial interpolation techniques. Consequently, the distance from the vaccination point to the water source was the most important variable, followed by elevation, season, road density, and slope. The area under the curve, model accuracy, sensitivity, and specificity for model evaluation were 0.760, 0.678, 0.661, and 0.685, respectively. Areas with high probability of wild boar vaccination were predicted in northern, eastern, and western part of Gifu. Leave-One-Out Cross Validation results showed that Kriging approach was more accurate than the Inverse distance weighting method. We emphasize that effective vaccination strategies based on epidemiological data are essential for disease control and that our proposed tool is also applicable for other wildlife diseases.

Facility capacity and provider knowledge for cholera surveillance and diarrhoea case management in cholera hotspots in the Democratic Republic of Congo - a mixed-methods study.

BACKGROUND: Wider healthcare-strengthening interventions are recommended in cholera hotspots and could benefit other types of diarrhoeal diseases which contribute to greater mortality than cholera. OBJECTIVE: Describe facility capacity and provider knowledge for case management of diarrhoea and cholera surveillance in cholera hotspots in the Democratic Republic of Congo (DRC) among health facilities, drug shops, and traditional health practitioners. METHODS: We conducted a sequential exploratory mixed-method study, using focus group discussions, facility audits, and provider knowledge questionnaires during September and October 2022 in North Kivu and Tanganyika provinces, Eastern DRC. Content analysis was used for qualitative data. Quantitative data were summarised by facility level and healthcare provider type. Audit and knowledge scores (range 0-100) were generated. Multivariable linear regression estimated association between scores and explanatory factors. Qualitative and quantitative data were triangulated during interpretation. RESULTS: Overall, 244 facilities and 308 providers were included. The mean audit score for health facilities was 51/100 (SD: 17). Private facilities had an -11.6 (95% CI, -16.7 to -6.6) lower adjusted mean score compared to public. Mean knowledge score was 59/100 (95% CI, 57 to 60) for health facility personnel, 46/100 (95% CI, 43 to 48) for drug shop vendors and 37/100 (95% CI, 34 to 39) for traditional health practitioners. Providers had particularly low knowledge concerning when to check for low blood sugar, use of nasogastric tubes, and dosing schedules. Knowledge about case definitions for cholera was similar between groups (range 41-58%) except for traditional health practitioners for the definition during an outbreak 15/73 (21%). CONCLUSIONS: Increasing awareness of cholera case definitions in this context could help improve cholera surveillance and control. Increased support and supervision, especially for private providers, could help ensure facilities are equipped to provide safe care. More nuanced aspects of case management should be emphasised in provider training.

Exploring different health care providers´ perceptions on the management of diarrhoea in cholera hotspots in the Democratic Republic of Congo: A qualitative content analysis.

Global cholera guidelines support wider healthcare system strengthening interventions, alongside vertical outbreak responses, to end cholera. Well-trained healthcare providers are essential for a resilient health system and can create synergies with childhood diarrhoea, which has higher mortality. We explored how the main provider groups for diarrhoea in cholera hotspots interact, decide on treatment, and reflect on possible limiting factors and opportunities to improve prevention and treatment. We conducted focus group discussions in September 2022 with different healthcare provider types in two urban and two rural cholera hotspots in the North Kivu and Tanganyika provinces in the Eastern Democratic Republic of Congo. Content analysis was used with the same coding applied to all providers. In total 15 focus group discussions with medical doctors (n = 3), nurses (n = 4), drug shop vendors (n = 4), and traditional health practitioners (n = 4) were performed. Four categories were derived from the analysis. (i) Provider dynamics: scepticism between all cadres was prominent, whilst also acknowledging the important role all provider groups have in current case management. (ii) Choice of treatment: affordability and strong caregiver demands shaped by cultural beliefs strongly affected choice. (iii) Financial consideration on access: empathy was strong, with providers finding innovative ways to create access to treatment. Concurrently, financial incentives were important, and providers asked for this to be considered when subsiding treatment. (iv) How to improve: the current cholera outbreak response approach was appreciated however there was a strong wish for broader long-term interventions targeting root causes, particularly community access to potable water. Drug shops and traditional health practitioners should be considered for inclusion in health policies for cholera and other diarrhoeal diseases. Financial incentives for the provider to improve access to low-cost treatment and investment in access to potable water should furthermore be considered.

Oral Fluids for the Early Detection of Classical Swine Fever in Commercial Level Pig Pens.

The early detection of classical swine fever (CSF) remains a key challenge, especially when outbreaks are caused by moderate and low-virulent CSF virus (CSFV) strains. Oral fluid is a reliable and cost-effective sample type that is regularly surveilled for endemic diseases in commercial pig herds in North America. Here, we explored the possibility of utilizing oral fluids for the early detection of CSFV incursions in commercial-size pig pens using two independent experiments. In the first experiment, a seeder pig infected with the moderately-virulent CSFV Pinillos strain was used, and in the second experiment, a seeder pig infected with the highly-virulent CSFV Koslov strain was used. Pen-based oral fluid samples were collected daily and individual samples (whole blood, swabs) every other day. All samples were tested by a CSFV-specific real-time RT-PCR assay. CSFV genomic material was detected in oral fluids on the seventh and fourth day post-introduction of the seeder pig into the pen, in the first and second experiments, respectively. In both experiments, oral fluids tested positive before the contact pigs developed viremia, and with no apparent sick pigs in the pen. These results indicate that pen-based oral fluids are a reliable and convenient sample type for the early detection of CSF, and therefore, can be used to supplement the ongoing CSF surveillance activities in North America.

Enhanced cholera surveillance to improve vaccination campaign efficiency.

Systematic testing for Vibrio cholerae O1 is rare, which means that the world's limited supply of oral cholera vaccines (OCVs) may not be delivered to areas with the highest true cholera burden. Here we used a phenomenological model with subnational geographic targeting and fine-scale vaccine effects to model how expanding V. cholerae testing affected impact and cost-effectiveness for preventive vaccination campaigns across different bacteriological confirmation and vaccine targeting assumptions in 35 African countries. Systematic testing followed by OCV targeting based on confirmed cholera yielded higher efficiency and cost-effectiveness and slightly fewer averted cases than status quo scenarios targeting suspected cholera. Targeting vaccine to populations with an annual incidence rate greater than 10 per 10,000, the testing scenario averted 10.8 (95% prediction interval (PI) 9.4-12.6) cases per 1,000 fully vaccinated persons while the status quo scenario averted 6.9 (95% PI 6.0-7.8) cases per 1,000 fully vaccinated persons. In the testing scenario, testing costs increased by US$31 (95% PI 25-39) while vaccination costs reduced by US$248 (95% PI 176-326) per averted case compared to the status quo. Introduction of systematic testing into cholera surveillance could improve efficiency and reach of global OCV supply for preventive vaccination.

Analysis of environmental factors influencing endemic cholera risks in sub-Saharan Africa.

The recurring cholera outbreaks in sub-Saharan Africa are of growing concern, especially considering the potential acceleration in the global trend of larger and more lethal cholera outbreaks due to the impacts of climate change. However, there is a scarcity of evidence-based research addressing the environmental and infrastructure factors that sustain cholera recurrence in Africa. This study adopts a statistical approach to investigate over two decades of endemic cholera outbreaks and their relationship with five environmental factors: water provision, sanitation provision, raising temperatures, increased rainfall and GDP. The analysis covers thirteen of the forty-two countries in the mainland sub-Saharan region, collectively representing one-third of the region's territory and half of its population. This breadth enables the findings to be generalised at a regional level. Results from all analyses consistently associate water provision with cholera reduction. The stratified model links increased water provision with a reduction in cholera risk that ranged from 4.2 % to 84.1 % among eight countries (out of 13 countries) as well as a reduction of such risk that ranged from 9.8 % to 68.9 % when there is increased sanitation provision, which was observed in nine countries (out of 13). These results indicate that the population's limited access to water and sanitation, as well as the rise in temperatures, are critical infrastructure and environmental factors contributing to endemic cholera and the heightened risk of outbreaks across the sub-Saharan region. Therefore, these are key areas for targeted interventions and cross-border collaboration to enhance resilience to outbreaks and lead to the end of endemic cholera in the region. However, it is important to interpret the results of this study with caution; hence, further investigation is recommended to conduct a more detailed analysis of the impact of infrastructure and environmental factors on reducing cholera risk.

Cell-lysis sensing drives biofilm formation in Vibrio cholerae.

Matrix-encapsulated communities of bacteria, called biofilms, are ubiquitous in the environment and are notoriously difficult to eliminate in clinical and industrial settings. Biofilm formation likely evolved as a mechanism to protect resident cells from environmental challenges, yet how bacteria undergo threat assessment to inform biofilm development remains unclear. Here we find that population-level cell lysis events induce the formation of biofilms by surviving Vibrio cholerae cells. Survivors detect threats by sensing a cellular component released through cell lysis, which we identify as norspermidine. Lysis sensing occurs via the MbaA receptor with genus-level specificity, and responsive biofilm cells are shielded from phage infection and attacks from other bacteria. Thus, our work uncovers a connection between bacterial lysis and biofilm formation that may be broadly conserved among microorganisms.

World's cholera vaccine stash is empty-but relief is on its way.

A dramatic shortage of the oral vaccine may ease in the years ahead as more companies enter the market.

Methods for the estimation of direct and indirect vaccination effects by combining data from individual- and cluster-randomized trials.

Both individually and cluster randomized study designs have been used for vaccine trials to assess the effects of vaccine on reducing the risk of disease or infection. The choice between individually and cluster randomized designs is often driven by the target estimand of interest (eg, direct versus total), statistical power, and, importantly, logistic feasibility. To combat emerging infectious disease threats, especially when the number of events from one single trial may not be adequate to obtain vaccine effect estimates with a desired level of precision, it may be necessary to combine information across multiple trials. In this article, we propose a model formulation to estimate the direct, indirect, total, and overall vaccine effects combining data from trials with two types of study designs: individual-randomization and cluster-randomization, based on a Cox proportional hazards model, where the hazard of infection depends on both vaccine status of the individual as well as the vaccine status of the other individuals in the same cluster. We illustrate the use of the proposed model and assess the potential efficiency gain from combining data from multiple trials, compared to using data from each individual trial alone, through two simulation studies, one of which is designed based on a cholera vaccine trial previously carried out in Matlab, Bangladesh.

Visualization of immune pathways that enhance the neutralizing antibody response to vaccines after primary immunization.

We examined the relationship between the association of a vaccine antigen with immune cells in secondary lymphoid organs shortly after immunization and the resulting neutralizing antibody response induced by that antigen using three antigenic forms of anthrax protective antigen (PA) that induce qualitatively different antibody responses. The three PA forms used were wild-type PA, which binds to anthrax toxin receptors and elicits a robust antibody response that includes both neutralizing and non-neutralizing antibodies; a receptor-binding-deficient (RBD) mutant form of PA, which does not bind cellular receptors and elicits only barely detectable antibody responses; and an engineered chimeric form of PA, which binds cholera toxin receptors and elicits a robust total antibody response but a poor neutralizing antibody response. We found that both wild-type PA and the PA chimera associated with immune cells in secondary lymphoid organs after immunization, but the RBD mutant PA exhibited minimal association, revealing a relationship between antigen binding to toxin receptors on immune cells after immunization and subsequent antibody responses. A portion of wild-type PA that bound to immune cells was cell surface-associated and maintained its native conformation. Much lower amounts of conformationally intact PA chimera were associated with immune cells after immunization, correlating with the lower neutralizing antibody response elicited by the PA chimera. Thus, binding of an antigen to receptors on immune cells in secondary lymphoid organs after immunization and maintenance of conformational integrity of the cell-associated antigen help dictate the magnitude of the resulting neutralizing antibody response, but not necessarily the total antibody response.IMPORTANCEMany vaccines protect by the induction of antibodies that neutralize the action of the pathogen. Here, we followed the fate of three antigenic forms of a vaccine antigen in secondary lymphoid organs after immunization to investigate events leading to a robust neutralizing antibody response. We found that the magnitude of the neutralizing antibody response, but not the total antibody response, correlates with the levels of conformationally intact antigen associated with immune cells in secondary lymphoid organs after primary immunization. We believe that these results provide important insights into the genesis of neutralizing antibody responses induced by vaccine antigens and may have implications for vaccine design.

Combatting infectious diarrhea: innovations in treatment and vaccination strategies.

INTRODUCTION: The escalating prevalence of infectious diseases is an important cause of concern in society. Particularly in several developing countries, infectious diarrhea poses a major problem, with a high fatality rate, especially among young children. The condition is divided into four classes, namely, acute diarrhea, invasive diarrhea, acute bloody diarrhea, and chronic diarrhea. Various pathogenic agents, such as bacteria, viruses, protozoans, and helminths, contribute to the onset of this condition. AREAS COVERED: The review discusses the scenario of infectious diarrhea, the prevalent types, as well as approaches to management including preventive, therapeutic, and vaccination strategies. The vaccination techniques are extensively discussed including the available vaccines, their advantages as well as limitations. EXPERT OPINION: There are several approaches available to develop new-improved vaccines. In addition, route of immunization is important and aerosols/nasal sprays, oral route, skin patches, powders, and liquid jets to minimize needles can be used. Plant-based vaccines, such as rice, might save packing and refrigeration costs by being long-lasting, non-refrigerable, and immunogenic. Future research should utilize predetermined PCR testing intervals and symptom monitoring to identify persistent pathogens after therapy and symptom remission.