BRAF-Mutated Melanoma Journey in Latin America: Expert Recommendations From Diagnosis to Treatment.

OBJECTIVES: • Gather a panel of Latin American experts in testing and treating BRAF-melanoma. • Describe the current landscape of BRAF-mutated melanoma in Latin America. • Outline the current gaps in testing and recommend improvements for testing and treating BRAF-mutated melanoma in the region. INTRODUCTION: Melanoma prevalence in Latin America is lower than in high- and middle-income countries. However, recent data indicate that the region's incidence and mortality are rising, with more stage IV patients being diagnosed. According to international clinical practice guidelines, conducting BRAF-mutation testing in patients with stage III or stage IV melanoma and high-risk resected disease is imperative. Still, BRAF-mutation testing and targeted therapies are inconsistently available in the region. METHODS: Americas Health Foundation convened a meeting of Latin American experts on BRAF-mutated melanoma to develop guidelines and recommendations for diagnosis through treatment. RESULTS AND CONCLUSIONS: Some recommendations for improving diagnostics through improving access and reducing the cost of BRAF-mutation testing, enhancing efficiency in pathology laboratories, and creating country-specific local guidelines. The panel also gave treatment recommendations for neo-adjuvant therapy, adjuvant therapy, and therapy for patients with metastatic disease in Latin America.

Chronic Kidney Disease in Brazil: Current Status and Recommended Improvements.

Background: Over the last 3 decades, over 700 million individuals worldwide have been diagnosed with chronic kidney disease (CKD). In a 2017 survey in southern Brazil, 11.4% of those surveyed had CKD. Early identification and effective therapy in Brazil may reduce CKD's impact. This panel discusses the early diagnosis and treatment of CKD and the barriers and actions needed to improve the management of CKD in Brazil. A panel of Brazilian nephrologists was provided with relevant questions to address before a multiday conference. During this meeting, each narrative was discussed and edited through several rounds until agreement on the relevant topics and recommendations was achieved. Summary: Panelists highlighted hurdles to early diagnosis and treatment of CKD. These include, but are not limited to, a lack of public and patient education, updated recommendations, multidisciplinary CKD treatment, and a national CKD database. People-centered, physician-centered, and healthcare institution-centered actions can be taken to improve outcomes. Patient empowerment is needed via multiple channels of CKD education and access to health-monitoring wearables and apps. Primary care clinicians and nonspecialists must be trained to screen and manage CKD-causing illnesses, including diabetes and hypertension. The healthcare system may implement a national health data gathering system, more screening tests, automated test result reporting, and telehealth. Key Messages: Increasing access to early diagnosis can provide a path to improving care for patients with CKD. Concerted efforts from all stakeholders are needed to overcome the barriers.

Crossing the Andes: Challenges and opportunities for digital pathology in Latin America.

The most widely accepted and used type of digital pathology (DP) is whole-slide imaging (WSI). The USFDA granted two WSI system approvals for primary diagnosis, the first in 2017. In Latin America, DP has the potential to reshape healthcare by enhancing diagnostic capabilities through artificial intelligence (AI) and standardizing pathology reports. Yet, we must tackle regulatory hurdles, training, resource availability, and unique challenges to the region. Collectively addressing these hurdles can enable the region to harness DP's advantages-enhancing disease diagnosis, medical research, and healthcare accessibility for its population. Americas Health Foundation assembled a panel of Latin American pathologists who are experts in DP to assess the hurdles to implementing it into pathologists' workflows in the region and provide recommendations for overcoming them. Some key steps recommended include creating a Latin American Society of Digital Pathology to provide continuing education, developing AI models trained on the Latin American population, establishing national regulatory frameworks for protecting the data, and standardizing formats for DP images to ensure that pathologists can collaborate and validate specimens across the various DP platforms.

A Salmonella Typhimurium-Typhi genomic chimera: a model to study Vi polysaccharide capsule function in vivo.

The Vi capsular polysaccharide is a virulence-associated factor expressed by Salmonella enterica serotype Typhi but absent from virtually all other Salmonella serotypes. In order to study this determinant in vivo, we characterised a Vi-positive S. Typhimurium (C5.507 Vi(+)), harbouring the Salmonella pathogenicity island (SPI)-7, which encodes the Vi locus. S. Typhimurium C5.507 Vi(+) colonised and persisted in mice at similar levels compared to the parent strain, S. Typhimurium C5. However, the innate immune response to infection with C5.507 Vi(+) and SGB1, an isogenic derivative not expressing Vi, differed markedly. Infection with C5.507 Vi(+) resulted in a significant reduction in cellular trafficking of innate immune cells, including PMN and NK cells, compared to SGB1 Vi(-) infected animals. C5.507 Vi(+) infection stimulated reduced numbers of TNF-α, MIP-2 and perforin producing cells compared to SGB1 Vi(-). The modulating effect associated with Vi was not observed in MyD88(-/-) and was reduced in TLR4(-/-) mice. The presence of the Vi capsule also correlated with induction of the anti-inflammatory cytokine IL-10 in vivo, a factor that impacted on chemotaxis and the activation of immune cells in vitro.

Healthcare Disparities in Atopic Dermatitis in Latin America: A Narrative Review.

INTRODUCTION: Atopic dermatitis (AD) is a chronic, pruritic skin disease caused by a mixture of genetic, immunological, and environmental factors, characterized by periods of inflammation and remission. In Latin America (LA), the prevalence of AD ranges up to 25% in children and 1-3% in adults. The natural history of the disease for most patients is that AD goes into remission in adolescence and adult life. Only 10-30% of patients continue to have symptoms of the disease in adulthood. There are patients (3-4%) who have the onset of AD during adolescence or after adulthood. Those with limited access to healthcare services, such as diagnosis and treatment, have increased difficulties coping with AD. Healthcare disparities are a complex topic that include social, political, racial/ethnic, and geographical factors. Publications about healthcare disparities in AD in LA are scarce. As a result, recognizing and resolving healthcare inequalities is critical to improving the treatment and quality of life (QoL) of individuals with AD. METHODS: A panel of Latin American experts in dermatology and allergies was provided with a series of relevant questions to address before a multiday conference. During this conference, the entire group discussed and edited each narrative through numerous drafts and rounds of discussion until they reached a consensus. RESULTS: This paper examines the barriers to equal access to care and recommends realistic actions to overcome them. Inadequate disease knowledge, cultural and linguistic barriers, stigmatization, maldistribution of resources, absence of local clinical practice guidelines, arduous patient journey, and limited consultation time were identified as causes of health inequality. CONCLUSIONS: Among the suggested solutions are enhanced education for healthcare professionals, patients, and the general public, a focus on underprivileged communities, telemedicine and telementoring, translators, multidisciplinary teams, and local living clinical practice guidelines.

Rarecare: A policy perspective on the burden of rare diseases on caregivers in Latin America.

In Latin America (LA), 40-50 million people live with rare diseases (RDs) that require constant monitoring, care, and attention. Caregivers help them with their basic life activities and medication administration, which they would otherwise be unable to perform. Family caregivers complement healthcare and social security systems; however, their unpaid work is often underappreciated and under-protected. Recognizing the need to address these unrecognized and undervalued women, the Americas Health Foundation (AHF) convened a panel of LA experts on caregiving for people with RDs to provide recommendations to support the undervalued family caregivers. A panel of LA experts in caregiving for RDs were given questions to address the challenges faced by family caregivers of people with RDs in LA. During a 3-day conference, the panelists' responses were discussed and edited until the panel agreed on recommendations to address the challenges. The identified challenges for caregivers included physical, emotional, and economical areas. Caregivers, primarily women, experienced physical pain, and social isolation, and were forced to pay substantial out-of-pocket expenses in their caregiving roles. Brazil and Colombia are at the forefront of policies to protect caregivers and their experiences in attempting to provide for this group are outlined as case studies for what is possible in LA. Finally, recognizing that caregivers must be included in formulating, executing, and evaluating care policies for people living with RDs and that the caregivers themselves require social assurances, the panel suggested policy objectives aimed at protecting caregivers of people living with RDs. The recommendations ranged from recognizing the role of the family caregiver as an essential supplement to the formal healthcare system to providing financial assistance, training, and workplace protection, among others. Finally, monitoring and evaluating the impact of policies is necessary to ensure that LA is moving forward in caring for family caregivers for people with RDs.

The landscape of vitiligo in Latin America: a call to action.

Vitiligo is a chronic pigmentary condition and severely impacts patient quality of life (QoL). It is an underrecognized burden for patients, healthcare systems, and society in Latin America (LA). This paper examines the journey of a vitiligo patient in LA and assesses the disease landscape. Americas Health Foundation (AHF) assembled a panel of six Argentine, Brazilian, Colombian, and Mexican vitiligo experts. On 10-12 May 2022, they met in a virtual meeting. Each panelist wrote a short paper on barriers to vitiligo diagnosis and treatment in LA before the meeting. AHF staff moderated as the panel reviewed and modified each paper over three days. The panel approved the recommendations based on research, professional opinion, and personal experience. The panel agreed that lack of disease awareness and research, social ostracization, and limited therapeutic options hinder patients in their quest for diagnosis and treatment. In addition to the medical and psychological difficulties associated with vitiligo, problems connected to the Latin American healthcare system may negatively impact diagnosis, prognosis, and treatment. Access to timely diagnosis and treatment is crucial for improving outcomes. Governments, medical societies, academics, patient organizations, industry, and the public must unite to eliminate these challenges.

Alopecia Areata in Latin America: Where are We and Where are We Going?

Alopecia areata (AA) represents an underrecognized burden in Latin America (LA), severely impacting quality of life (QoL). This impact is exacerbated by limited access to specialized dermatologic care and therapies for AA within and among nations. Many of the unmet needs for AA globally also exist in LA. The region has geographic, ethnic, cultural, and economic conditions. With new AA medicines targeting immunologic pathways on the horizon, LA must prepare regarding regulatory issues, reimbursement, awareness, and education to give adequate and timely treatment for patients with AA. To address these issues, the Americas Health Foundation convened a panel of six dermatologists from Argentina, Brazil, Colombia, and Mexico who are experts in AA and its comorbidities for a 3-day virtual meeting to discuss AA diagnosis and treatment in LA and create a manuscript offering recommendations to address discussed barriers. This publication examines unmet AA needs in LA, treatment, and innovative therapies and recommends improving AA care. Access constraints to conventional and novel medicines hinder appropriate treatments for patients. Therapy initiation delays can affect QoL, mental health, and disease progression. People with AA face stigmas, discrimination, and misconceptions owing to a lack of disease awareness. With promising new treatments for AA on the horizon, all stakeholders must coordinate efforts to enhance LA's AA management landscape and improve patient outcomes.

Expert Recommendations for the Diagnosis, Treatment, and Management of Adult B-Cell Acute Lymphoblastic Leukemia in Latin America.

PURPOSE: Despite strong induction chemotherapy response rates, only 30%-40% of patients with adult B-cell acute lymphoblastic leukemia (ALL) attain long-term remission. This study analyzes ALL in Latin America (LA) and recommends diagnosis, treatment, and management protocols. METHODS: The Americas Health Foundation organized a panel of hematologists from Argentina, Brazil, Chile, Colombia, and Mexico to examine ALL diagnosis and therapy and produce recommendations. RESULTS: Lack of regional data, unequal access to diagnosis and therapy, inadequate treatment response, and uneven health care distribution complicate adult ALL management. The panel recommended diagnosis, first-line and refractory treatment, and post-transplantation maintenance. Targeted treatments, including rituximab, blinatumomab, and inotuzumab ozogamicin, are becoming available in LA and must be equitably accessed. CONCLUSION: This review adapts global information on treating ALL to LA. Governments, the medical community, society, academia, industry, and patient advocates must work together to improve policies.

A task force for diagnosis and treatment of people with Alzheimer's disease in Latin America.

Alzheimer's disease (AD) represents a substantial burden to patients, their caregivers, health systems, and society in Latin America and the Caribbean (LAC). This impact is exacerbated by limited access to diagnosis, specialized care, and therapies for AD within and among nations. The region has varied geographic, ethnic, cultural, and economic conditions, which create unique challenges to AD diagnosis and management. To address these issues, the Americas Health Foundation convened a panel of eight neurologists, geriatricians, and psychiatrists from Argentina, Brazil, Colombia, Ecuador, Guatemala, Mexico, and Peru who are experts in AD for a three-day virtual meeting to discuss best practices for AD diagnosis and treatment in LAC and create a manuscript offering recommendations to address identified barriers. In LAC, several barriers hamper diagnosing and treating people with dementia. These barriers include access to healthcare, fragmented healthcare systems, limited research funding, unstandardized diagnosis and treatment, genetic heterogeneity, and varying social determinants of health. Additional training for physicians and other healthcare workers at the primary care level, region-specific or adequately adapted cognitive tests, increased public healthcare insurance coverage of testing and treatment, and dedicated search strategies to detect populations with gene variants associated with AD are among the recommendations to improve the landscape of AD.

Community based sociotherapy for depressive symptomatology of Congolese refugees in Rwanda and Uganda (CoSTAR): a protocol for a cluster randomised controlled trial.

Background: Conflict in the Democratic Republic of Congo has led to large numbers of refugees fleeing to Uganda and Rwanda. Refugees experience elevated levels of adverse events and daily stressors, which are associated with common mental health difficulties such as depression. The current cluster randomised controlled trial aims to investigate whether an adapted form of Community-based Sociotherapy (aCBS) is effective and cost-effective in reducing depressive symptomatology experienced by Congolese refugees in Uganda and Rwanda.Methods: A two-arm, single-blind cluster randomised controlled trial (cRCT) will be conducted in Kyangwali settlement, Uganda and Gihembe camp, Rwanda. Sixty-four clusters will be recruited and randomly assigned to either aCBS or Enhanced Care As Usual (ECAU). aCBS, a 15-session group-based intervention, will be facilitated by two people drawn from the refugee communities. The primary outcome measure will be self-reported levels of depressive symptomatology (PHQ-9) at 18-weeks post-randomisation. Secondary outcomes will include levels of mental health difficulties, subjective wellbeing, post-displacement stress, perceived social support, social capital, quality of life, and PTSD symptoms at 18-week and 32-week post-randomisation. Cost effectiveness of aCBS will be measured in terms of health care costs (cost per Disability Adjusted Life Year, DALY) compared to ECAU. A process evaluation will be undertaken to investigate the implementation of aCBS.Conclusion: This cRCT will be the first investigating aCBS for mental health difficulties experienced by refugees and will contribute to knowledge about the use of psychosocial interventions for refugees at a time when levels of forced migration are at a record high.Trial registration: ISRCTN.org identifier: ISRCTN20474555.

There is a need to evaluate community-based psychosocial interventions for refugees.Community-based sociotherapy has been used to support communities in post-conflict situations but has not been evaluated in a randomised controlled trial.This protocol outlines a proposed randomised controlled trial of community-based sociotherapy adapted for Congolese refugees in Uganda and Rwanda.

Evaluating the impact of Community-Based Sociotherapy on social dignity in post-genocide Rwanda: study protocol for a cluster randomized controlled trial.

BACKGROUND: Community-Based Sociotherapy (CBS) is an approach that was introduced in Rwanda in 2005, with the aim of improving psychosocial well-being among its participants and facilitating reconciliation processes. Over the years, CBS has been adapted contextually and the effectiveness of the approach has been measured in different ways, using qualitative and quantitative study designs. This study specifically assesses the effectiveness of CBS in terms of fostering the social dignity of participants as the primary outcome. METHODS/DESIGN: A cluster randomized controlled trial design with person-level outcomes whereas the CBS treatment is delivered at the cluster level. A total of 1200 eligible participants will be randomly assigned to two groups in a 1:1 ratio. Participants in the intervention group will receive the CBS intervention, while the control group will be waitlisted. The primary outcome measure is a self-designed and psychometrically validated Social Dignity Scale. The secondary outcome measures will be the WHO (Five) Well-Being Index (WHO-5), the Multidimensional Scale of Perceived Social Support (MSPSS), the Posttraumatic Stress Disorder Checklist for DSM-5 (PCL-5), the Self-reporting Questionnaire (SRQ-20), and the perceived parental self-efficacy scale. The primary analysis will be performed following an intention to treat analysis, using generalized estimating equation modeling. DISCUSSION: We expect this cluster randomized controlled trial to provide insight into the effectiveness of CBS on social dignity and secondary psychosocial outcomes among its group participants, who have different socio-historical backgrounds including genocide survivors, perpetrators, bystanders and their descendants, people in conflicts (family/community), and local leaders. This study will inform CBS implementers, policymakers, practitioners, and other stakeholders on the role of social dignity in interventions that focus on psychosocial healing. TRIAL REGISTRATION: ISRCTN ISRCTN11199072. It was registered on 2 April 2022.

BRAF Testing in Melanoma and Colorectal Cancer in Latin America: Challenges and Opportunities.

The incidence of colorectal cancer in Argentina and Brazil has reached levels comparable to those in higher-income countries. Similarly, the incidence of melanoma in Latin America has increased during the past decades. BRAFmutation is seen frequently in melanomas and colorectal cancer. Discovering the expression of this specific biomarker in both cancers has unleashed the potential for targeted molecular therapies.In patients with BRAF-mutated melanoma, adopting a combined targeted treatment approach has shown a dramatic increase in overall survival. However, several barriers impede the development of early BRAF testing in Latin America, jeopardizing the potential for personalized therapies and care. To address this, the Americas Health Foundation convened a virtual meeting of Latin American oncologists to address the barriers to BRAF testing in melanoma and colorectal cancer. During a three-day conference, expert oncologists used literature reviews and personal experience to detail the barriers to early BRAF testing in their region. They proposed actionable steps to overcome the barriers identified, which included deficiencies in knowledge, treatment options, equitable distribution, timely results, and local data on BRAF mutations. Oncologists proposed several actions to overcome barriers, including raising public and healthcare awareness about the importance of BRAF testing, expanding treatment options in clinics across the region, developing centers in underserved areas, and increasing affordable treatment options for patients who test positive for BRAF mutations.

Correction: BRAF Testing in Melanoma and Colorectal Cancer in Latin America: Challenges and Opportunities.

[This corrects the article DOI: 10.7759/cureus.31972.].

From Child to Genocide Perpetrator: Narrative Identity Analysis Among Genocide Prisoners Incarcerated in Muhanga Prison, Rwanda.

BACKGROUND: This article focuses on the narrative identity of eight convicted genocide perpetrators in Rwanda, who participated in the 1994 genocide against the Tutsi. Narrative identity is the internalised and evolving story of the self that a person constructs to make sense and meaning out of his life. This study focused on the key autobiographical memories, present day experiences and the anticipated future of genocide perpetrators by exploring the self-perception of genocide perpetrators, in the context of their psychosocial rehabilitation. METHODS: The Biographic Narrative Interpretive Methods (BNIM) were used for the collection and analysis of life stories of the eight genocide prisoners in Muhanga Prison. RESULTS: The narratives of the respondents converged into five main themes: (a) the childhood experience of abandonment, (b) the process of ethnic self-discovery and positioning, (c) the perpetrator narrative, (d) the imprisoned self and (e) the imagined future self. Two main feelings from their narratives were outlined. Those feelings were the feeling of the abandoned and the feeling of the abandoner in the context of making sense and meaning out of their lives. Results revealed that the positioning of genocide perpetrators through their narratives can influence positively or negatively their rehabilitation. What is important in this article is the exploration of the account of the self-perception of the convicted genocide perpetrators throughout pre- and post-genocide Rwanda and the way they project their future self. Two main feelings from their narratives were outlined: the feeling of the abandoned and the feeling of the abandoner in the context of making sense and meaning out of their lives. Results revealed that positioning of genocide perpetrators through their narratives can influence positively or negatively their rehabilitation. CONCLUSION: Genocide perpetrators in the context of Rwanda continuously work on ways to acknowledge, rationalise or justify those acts as part of their biography. Interventions enabling their self-discovery can have a positive impact on their self as prisoners, their families and the community at large in post-genocide Rwanda.

Differential gene expression of pathogens inside infected hosts.

DNA microarray is a useful technology for studying differential gene expression in the context of microbe-host interactions. This review concentrates on recent findings of the survival strategies of three intracellular pathogens: Shigella flexneri, Salmonella enterica serovar Typhimurium and Mycobacterium tuberculosis.

The "treatment gap" in global mental health reconsidered: sociotherapy for collective trauma in Rwanda.

BACKGROUND: The "treatment gap" (TG) for mental disorders refers to the difference that exists between the number of people who need care and those who receive care. The concept is strongly promoted by the World Health Organization and widely used in the context of low- and middle-income countries. Although accepting the many demonstrable benefits that flow from this approach, it is important to critically reflect on the limitations of the concept of the TG and its implications for building capacity for mental health services in Rwanda. OBJECTIVE: The article highlights concerns that the evidence base for mental health interventions is not globally valid, and problematizes the preponderance of psychiatric approaches in international guidelines for mental health. Specifically, the risk of medicalization of social problems and the limited way in which "community" has been conceptualized in global mental health discourses are addressed. Rather than being used as a method for increasing economic efficiency (i.e., reducing healthcare costs), "community" should be promoted as a means of harnessing collective strengths and resources to help promote mental well-being. This may be particularly beneficial for contexts, like Rwanda, where community life has been disrupted by collective violence, and the resulting social isolation constitutes an important determinant of mental distress. CONCLUSIONS: Moving forward there is a need to consider alternative paradigms where individual distress is understood as a symptom of social distress, which extends beyond the more individually oriented TG paradigm. Sociotherapy, an intervention used in Rwanda over the past 10 years, is presented as an example of how communities of support can be built to promote mental health and psychosocial well-being.

Nonionic contrast media iohexol and iomeprol decrease renal arterial tone: comparative studies on human and porcine isolated vascular segments.

RATIONALE AND OBJECTIVES: The vasoconstriction of the renal arteries is frequently considered as a crucial factor for radiocontrast-induced nephropathy. A direct effect of iodinated radiographic contrast medium (RCM) on vascular smooth muscle is supposed to be one component of the vascular response. We studied the effect of the nonionic RCM iomeprol and iohexol on the tonus of isolated human and porcine renal arteries in vitro. METHODS: In an organ bath renal arterial rings, uncontracted or precontracted by 10 micromol/L phenylephrine were incubated with increasing concentrations (15-103 mg iodine/mL) of iohexol, iomeprol, and mannitol solution isoosmolar to the contrast media. In a part of the preparations the endothelium was destroyed. Human vessels were obtained from tumor nephrectomy specimens of 10 patients. RESULTS: In human experiments iomeprol and iohexol (P < 0.05) relaxed renal arterial rings whereas mannitol produced concentration-dependent contractions. The relaxation by both contrast media was slightly attenuated upon increasing their concentration. The differences between mannitol solutions and RCM were statistically significant (P < 0.001) at concentrations of 57 mg iodine/mL and higher. Precontracted rings were significantly stronger relaxed by the RCM compared with mannitol (P < 0.001). The contrast medium induced relaxation did not depend on the presence of an intact endothelium (P > 0.05). Experiments with renal arterial segments prepared from swine showed similar results, with stronger relaxations than the human preparations. CONCLUSION: Iomeprol and iohexol relaxed isolated renal arterial segments. These observations are in contradiction with the hypothesis that contrast media induce nephropathy by a direct vasoconstrictive effect on vascular smooth muscle. They do not exclude, however, a reduction of renal blood flow by other factors like liberation of hormones.

A Phase I, dose-escalation trial in adults of three recombinant attenuated Salmonella Typhi vaccine vectors producing Streptococcus pneumoniae surface protein antigen PspA.

BACKGROUND: Live, attenuated, orally-administered Salmonella strains are excellent vectors for vaccine antigens and are attractive as vaccines based on previous use of S. Typhimurium in animals. A Phase I dose escalation trial was conducted to evaluate the safety and immunogenicity of three newly constructed recombinant attenuated Salmonella enterica serovar Typhi vaccine (RASV) vectors synthesizing Streptococcus pneumoniae surface protein A (PspA). METHODS: The 3 S. Typhi strains used as vectors to deliver PspA were S. Typhi ISP1820; S. Typhi Ty2 RpoS(-); and S. Typhi Ty2 RpoS(+). Sixty healthy adults (median age 25.2 years) were enrolled into 4 Arms (total 15 subjects per Arm); within each Arm, subjects were randomized 1:1:1 into 3 Groups of 5. All subjects in the same Group received the same vaccine vector, and all subjects in the same Arm received the same titer of vaccine (10(7), 10(8), 10(9) or 10(10)CFU). Adverse events, safety, shedding, and IgG and IgA titers against Salmonella outer membrane proteins (OMPs), lipopolysaccharide (LPS) and PspA were evaluated. RESULTS: In the highest dose group, no subject experienced severe reactions or serious adverse events. Most adverse events were mild; one subject had a positive blood culture. No subject shed vaccine in stool. No statistically significant differences for post vaccination ELISA or ELISPOT results between Groups were detected. However, a limited number of ≥ 4 fold increases from baseline for IgA anti-OMPs, IgA and IgG anti-LPS, and IgA anti-PspA occurred for a few individuals as measured by ELISA, and IgA anti-OMPs as measured by ELISPOT assay. CONCLUSIONS: All three S. Typhi vectored pneumococcal vaccines were safe and well-tolerated. Immunogenicity was limited possibly due to pre-existing high antibody titers prior to vaccination. Increases in IgA were most often observed.

Regulated delayed expression of rfc enhances the immunogenicity and protective efficacy of a heterologous antigen delivered by live attenuated Salmonella enterica vaccines.

The Salmonella rfc gene encodes the O-antigen polymerase. We constructed three strains in which we replaced the native rfc promoter with the arabinose-dependent araC P(BAD) promoter so that rfc expression was dependent on exogenously supplied arabinose provided during in vitro growth. The three mutant strains were designed to synthesize different amounts of Rfc by altering the ribosome-binding sequence and start codon. We examined these strains for a number of in vitro characteristics compared to an isogenic Deltarfc mutant and the wild-type parent strain. One promoter-replacement mutation, DeltaP(rfc174), yielded an optimal profile, exhibiting wild-type characteristics when grown with arabinose, and Deltarfc characteristics when grown without arabinose. In addition, when administered orally, the DeltaP(rfc174) strain was completely attenuated in for virulence in mice. The DeltaP(rfc174) mutation was introduced into attenuated Salmonella vaccine strain chi9241 (DeltapabA DeltapabB DeltaasdA) followed by introduction of an Asd(+) balanced-lethal plasmid to designed for expression of the pneumococcal surface protein PspA. Mice immunized with either chi9241 or its DeltaP(rfc174) derivative expressing pspA were protected against S. pneumoniae challenge.