B-Cell Epitope Mapping of TprC and TprD Variants of Treponema pallidum Subspecies Informs Vaccine Development for Human Treponematoses

Syphilis vaccine development: Aligning vaccine design with manufacturing requirements

Syphilis, caused by Treponema pallidum subsp. pallidum, is a global health concern with increasing rates worldwide. Current prevention strategies, including screen-and-treat approaches, are not sufficient to resolve rising infection rates, emphasizing the need for a vaccine. Developing a syphilis vaccine necessitates a range of cross-disciplinary considerations, including essential disease-specific protection, technical requirements, economic feasibility, manufacturing constraints, public acceptance, equitable vaccine access, alignment with global public vaccination programs, and identification of essential populations to be vaccinated to achieve herd immunity. Central to syphilis vaccine development is prioritization of global vaccine availability, including access in low- to middle-income settings. Various vaccine platforms, including subunit, virus-like particle (VLP), mRNA, and outer membrane vesicle (OMV) vaccines, present both advantages and challenges. The proactive consideration of both manufacturing feasibility and efficacy throughout the pre-clinical research and development stages is essential for producing an efficacious, inexpensive, and scalable syphilis vaccine to address the growing global health burden caused by this disease.

A novel pan-proteome array for high-throughput profiling of the humoral response to Treponema pallidum

Given the resurgence of syphilis, research endeavors to improve current assays for serological diagnosis and management of this disease are a priority. A proteome-scale platform for high-throughput profiling of the humoral response to Treponema pallidum (T. pallidum) proteins during infection could identify antigens suitable to ameliorate the performance and capabilities of treponemal tests for syphilis. Additionally, because infection-induced immunity is partially protective, profiling the response to T. pallidum outer membrane proteins (OMPs) could help select vaccine candidates. Therefore, we developed a pan-proteome array (PPA) based on the Nichols and SS14 strain complete proteomes and used it to define the immunoglobulin M (IgM) and IgG humoral response to T. pallidum proteins in sera collected longitudinally from long-term infected rabbits and from rabbits that were infected, treated, and re-infected. We identified antigens that could facilitate early diagnosis and immunity to a core set of OMP that could explain protection upon reinfection.

Update on syphilis in pregnancy: marrying basic science advances and clinical perseverance to solve an ancient public health problem

PURPOSE OF REVIEW

While the clinical disease of syphilis, its consequences in pregnancy, and its sensitivity to penicillin treatment have remained relatively unchanged for a century or more, new technologies and basic discoveries in syphilis research have translated into tangible advances in clinical diagnosis, treatment, and prevention. The purpose of this review is to help the reader understand some of the recent relevant scientific publications on syphilis and its causative organism in a clinical obstetric context.

RECENT FINDINGS

Rates of adult and congenital syphilis have risen dramatically in the last decade despite public health efforts. Penicillin shortages and lack of screening or adequate treatment have all contributed to global disease burden. Advances in genomic and microbiological characterization of this spirochete have led to new developments in serologic and molecular diagnosis as well as evaluation of potential vaccine candidates. Until a syphilis vaccine is available, substance use disorders and lack of screening in pregnancy are associated with increased congenital syphilis, and these challenges will require novel solutions to fully address this public health crisis.

SUMMARY

Addressing the burden of congenital syphilis demands that obstetricians stay well informed of new tools and resources for diagnosis, treatment, and prevention of syphilis now and in the future.

Evaluation of a minimal array of Treponema pallidum antigens as biomarkers for syphilis diagnosis, infection staging, and response to treatment

IMPORTANCE

This manuscript explores the host humoral response to selected antigens of the syphilis agent during infection to evaluate their potential use as diagnostic tests and markers for treatment.

Comprehensive Overview of Treponema pallidum Outer Membrane Proteins

Treponema pallidum, the causative agent of syphilis, is a sexually transmitted microorganism that exhibits remarkable motility capabilities, allowing it to affect various systems. Despite its structural resemblance to gram-negative bacteria due to its dual-membrane, T. pallidum possesses a lower abundance of outer membrane proteins (OMPs), which enables it to effectively conceal itself. This review presents a comprehensive analysis of the clinical diagnostic potential associated with the OMPs of T. pallidum. Furthermore, the known OMPs in T. pallidum that are responsible for mediating host interactions have been progressively elucidated. This review aims to shed light on the pathogenesis of syphilis, encompassing aspects such as vascular inflammation, chancre self-healing, neuroinvasion, and reinfection. Additionally, this review offers a detailed overview of the current state and prospects of development in the field of syphilis vaccines, with the ultimate goal of establishing a foundation for understanding the pathogenesis and implementing effective prevention strategies against syphilis.

Resurgence of syphilis: focusing on emerging clinical strategies and preclinical models

Syphilis, a sexually transmitted disease (STD) caused by Treponema pallidum (T. pallidum), has had a worldwide resurgence in recent years and remains a public health threat. As such, there has been a great deal of research into clinical strategies for the disease, including diagnostic biomarkers and possible strategies for treatment and prevention. Although serological testing remains the predominant laboratory diagnostic method for syphilis, it is worth noting that investigations pertaining to the DNA of T. pallidum, non-coding RNAs (ncRNAs), chemokines, and metabolites in peripheral blood, cerebrospinal fluid, and other bodily fluids have the potential to offer novel perspectives on the diagnosis of syphilis. In addition, the global spread of antibiotic resistance, such as macrolides and tetracyclines, has posed significant challenges for the treatment of syphilis. Fortunately, there is still no evidence of penicillin resistance. Hence, penicillin is the recommended course of treatment for syphilis, whereas doxycycline, tetracycline, ceftriaxone, and amoxicillin are viable alternative options. In recent years, efforts to discover a vaccine for syphilis have been reignited with better knowledge of the repertoire of T. pallidum outer membrane proteins (OMPs), which are the most probable syphilis vaccine candidates. However, research on therapeutic interventions and vaccine development for human subjects is limited due to practical and ethical considerations. Thus, the preclinical model is ideal for conducting research, and it plays an important role in clinical transformation. Different preclinical models have recently emerged, such as in vitro culture and mouse models, which will lay a solid foundation for clinical treatment and prevention of syphilis. This review aims to provide a comprehensive summary of the most recent syphilis tactics, including detection, drug resistance treatments, vaccine development, and preclinical models in clinical practice.

AlphaFold2 and its applications in the fields of biology and medicine

AlphaFold2 (AF2) is an artificial intelligence (AI) system developed by DeepMind that can predict three-dimensional (3D) structures of proteins from amino acid sequences with atomic-level accuracy. Protein structure prediction is one of the most challenging problems in computational biology and chemistry, and has puzzled scientists for 50 years. The advent of AF2 presents an unprecedented progress in protein structure prediction and has attracted much attention. Subsequent release of structures of more than 200 million proteins predicted by AF2 further aroused great enthusiasm in the science community, especially in the fields of biology and medicine. AF2 is thought to have a significant impact on structural biology and research areas that need protein structure information, such as drug discovery, protein design, prediction of protein function, et al. Though the time is not long since AF2 was developed, there are already quite a few application studies of AF2 in the fields of biology and medicine, with many of them having preliminarily proved the potential of AF2. To better understand AF2 and promote its applications, we will in this article summarize the principle and system architecture of AF2 as well as the recipe of its success, and particularly focus on reviewing its applications in the fields of biology and medicine. Limitations of current AF2 prediction will also be discussed.

Notes on syphilis vaccine development

The quest for a syphilis vaccine to provide protection from infection or disease began not long after the isolation of the first Treponema pallidum subspecies pallidum (T. pallidum) strain in 1912. Yet, a practical and effective vaccine formulation continues to elude scientists. Over the last few years, however, efforts toward developing a syphilis vaccine have increased thanks to an improved understanding of the repertoire of T. pallidum outer membrane proteins (OMPs), which are the most likely syphilis vaccine candidates. More has been also learned about the molecular mechanisms behind pathogen persistence and immune evasion. Published vaccine formulations based on a subset of the pathogen's OMPs have conferred only partial protection upon challenge of immunized laboratory animals, primarily rabbits. Nonetheless, those experiments have improved our approach to the choice of immunization regimens, adjuvants, and vaccine target selection, although significant knowledge gaps remain. Herein, we provide a brief overview on current technologies and approaches employed in syphilis vaccinology, and possible future directions to develop a vaccine that could be pivotal to future syphilis control and elimination initiatives.