Global phylogeny of Treponema pallidum lineages reveals recent expansion and spread of contemporary syphilis

Spatial and trend analysis of gestational syphilis cases in Brazil from 2011 to 2020: an ecological study

OBJECTIVES

To analyze the rate of gestational syphilis (GS) based on temporal trends over 11 years, as well as the spatial distribution of GS in Brazil, based on the identification of spatial clusters.

METHODOLOGY

An ecological, using Brazil and its regions as an analysis unit, based on gestational syphilis data reported in the Notifiable Diseases Information System (SINAN), from 2011 to 2020. Thematic maps were built for spatial data analysis, and the Prais-Winsten autoregressive model was used to verify the trend. Spatial analysis identified the distribution of clusters (high-high; low-low; high-low and low-high) of distribution of GS across Brazilian municipalities, using a 5% significance level.

RESULTS

Gestational syphilis experienced a considerable increase in cases during the studied period, with a peak of 37,436 cases in 2018. The spatial distribution of the disease is heterogeneous in the country. A growing trend was observed in all states of Brazil, except for Espírito Santo, where it remained stationary, with a monthly variation of 10.32%.

CONCLUSION

The spatial and temporal trend analysis point to syphilis as an important public health problem. The numbers are alarming and show the urgent need for measures to prevent and control syphilis during pregnancy.

Antimicrobial treatment and resistance in sexually transmitted bacterial infections

Sexually transmitted infections (STIs) have been part of human life since ancient times, and their symptoms affect quality of life, and sequelae are common. Socioeconomic and behavioural trends affect the prevalence of STIs, but the discovery of antimicrobials gave hope for treatment, control of the spread of infection and lower rates of sequelae. This has to some extent been achieved, but increasing antimicrobial resistance and increasing transmission in high-risk sexual networks threaten this progress. For Neisseria gonorrhoeae, the only remaining first-line treatment (with ceftriaxone) is at risk of becoming ineffective, and for Mycoplasma genitalium, for which fewer alternative antimicrobial classes are available, incurable infections have already been reported. For Chlamydia trachomatis, in vitro resistance to first-line tetracyclines and macrolides has never been confirmed despite decades of treatment of this highly prevalent STI. Similarly, Treponema pallidum, the cause of syphilis, has remained susceptible to first-line penicillin.

Serofast status in syphilis: Pathogenesis to therapeutics

Syphilis, a sexually transmitted infection caused by Treponema pallidum, has been experiencing a rise in prevalence in recent years. "Syphilis serofast" describes a unique serological reaction in patients with syphilis whose clinical symptoms have resolved following consistent anti-syphilitic therapy, but the non-Treponema pallidum antigen serologic test is still positive. Syphilis serofast is a risk factor for syphilis recurrence, neurosyphilis, and multisystem involvement. Considering the current lack of comprehensive knowledge about the epidemiological characteristics, pathogenesis, and therapies of syphilis serofast, we conducted an online search of research relating to syphilis serofast over the last twenty years. Previous research has shown that the pathogenesis of syphilis serofast is mainly related to clinical factors, immune factors, syphilis subtypes, and T.pallidum membrane protein repeat gene antigen. There are two distinct viewpoints on the treatment of serofast: no excessive treatment and active treatment. In addition, serofast patients also showed two clinical outcomes: syphilis recurrence and persistent serofast status. This article systematically reviews the related factors, treatment, and clinical outcomes of syphilis serofast, provides a theoretical basis for its research, diagnosis, and treatment, and helps clinicians develop a follow-up treatment management plan for syphilis serofast.

A Rare Case of Widely Disseminated Syphilis

Abstract is missing (Short communication)

Treponema pallidum subsp. pallidum strains DAL-1 and Philadelphia 1 differ in generation times in vitro as well as during experimental rabbit infection

In this work, we determined that Treponema pallidum subsp. pallidum (TPA) DAL-1 (belonging to Nichols-like group of TPA strains) grew 1.53 (± 0.08) times faster compared to TPA Philadelphia 1 (SS14-like group) during in vitro cultivations. In longitudinal individual propagation in rabbit testes (n = 12, each TPA strain), infection with DAL-1 manifested clinical symptoms (induration, swelling, and erythema of testes) sooner than Philadelphia 1 infection, which resulted in a significantly shorter period of the experimental passages for DAL-1 (median = 15.0 and 23.5 days, respectively; p < 0.01). To minimize the confounding conditions during rabbit experiments, the growth characteristics of DAL-1 and Philadelphia 1 strains were determined during TPA co-infection of rabbit testes (n = 20, including controls). During two weeks of intratesticular co-infection, DAL-1 overgrew Philadelphia 1 in all twelve testes, regardless of inoculation ratio and dose (median of relative excess DAL-1 multiplication = 84.85×). Moreover, higher DAL-1 to Philadelphia 1 inoculum ratios appeared to increase differences in growth rates, suggesting direct competition between strains for available nutrients during co-infection. These experiments indicate important physiological differences between the two TPA strains and suggest growth differences between Nichols-like and SS14-like strains that are potentially linked to their virulence and pathogenicity.

Associated factors, incidence, and management of gestational and congenital syphilis in a Brazilian state capital: a cross-sectional study

Maternal and child health remains an enduring global challenge, having occupied a prominent position on international agendas since the dawn of the 21st century. During pregnancy, syphilis emerges as the second most prevalent cause of stillbirth on a global scale, potentially leading to a range of adverse outcomes. This study aimed to describe the clinical and epidemiological profile of cases of gestational and congenital syphilis and the hospital care provided for newborns in Campo Grande municipality, Mato Grosso do Sul State, Brazil, from 2013 to 2018. This is a cross-sectional study based on data from Brazilian Notifiable Diseases Surveillance System (SINAN) and hospital medical records. Chi-square or Fisher's exact test and logistic regression analysis were used to assess the associations and relationships between the child's clinical outcome at birth and the mother's clinical-obstetric and epidemiological characteristics. Cumulative detection rate of gestational syphilis was 174.3 cases per 1,000 live births and cumulative incidence of congenital syphilis was 47.7 cases per 1,000 live births. Alcoholism, prenatal care, number of prenatal visits, maternal treatment regimen, and timing of maternal diagnosis were associated with child's clinical outcome at birth and considered in the regression model. Prenatal visits showed a protective effect against the signs and symptoms of congenital syphilis (odds ratio = 0.37; 95% confidence interval = 0.17-0.77). Medical assistance was considered inadequate in 62.3% of cases. Prenatal consultations should be encouraged among pregnant women. There is a need for better education of health personnel on the treatment and diagnosis of syphilis.

Genomic Epidemiology of Treponema pallidum and Circulation of Strains With Diminished tprK Antigen Variation Capability in Seattle, 2021-2022

BACKGROUND

The incidence of syphilis continues to increase in the United States, yet little is known about Treponema pallidum genomic epidemiology within American metropolitan areas.

METHODS

We performed whole-genome sequencing and tprK deep sequencing of 28 T. pallidum-containing specimens, collected mostly from remnant Aptima swab specimens from 24 individuals from Seattle Sexual Health Clinic during 2021-2022.

RESULTS

All 12 individuals infected with Nichols-lineage strains were men who have sex with men, while a specific SS14 cluster (mean, 0.33 single-nucleotide variant) included 1 man who has sex with women and 5 women. All T. pallidum strains sequenced were azithromycin resistant via 23S ribosomal RNA A2058G mutation. Identical T. pallidum genomic sequences were found in pharyngeal and rectal swab specimens taken concurrently from the same individuals. The tprK sequences were less variable between patient-matched specimens and between epidemiologically linked clusters. We detected a 528-base pair deletion in the tprK donor site locus, eliminating 9 donor sites, in T. pallidum genomes of 3 individuals with secondary syphilis, associated with diminution of TprK diversity.

CONCLUSIONS

We developed an end-to-end workflow for public health genomic surveillance of T. pallidum from remnant Aptima swab specimens. tprK sequencing may assist in linking cases beyond routine T. pallidum genome sequencing. T. pallidum strains with deletions in tprK donor sites currently circulate and are associated with diminished TprK antigenic diversity.

Redefining the treponemal history through pre-Columbian genomes from Brazil

The origins of treponemal diseases have long remained unknown, especially considering the sudden onset of the first syphilis epidemic in the late 15th century in Europe and its hypothesized arrival from the Americas with Columbus' expeditions1,2. Recently, ancient DNA evidence has revealed various treponemal infections circulating in early modern Europe and colonial-era Mexico3-6. However, there has been to our knowledge no genomic evidence of treponematosis recovered from either the Americas or the Old World that can be reliably dated to the time before the first trans-Atlantic contacts. Here, we present treponemal genomes from nearly 2,000-year-old human remains from Brazil. We reconstruct four ancient genomes of a prehistoric treponemal pathogen, most closely related to the bejel-causing agent Treponema pallidum endemicum. Contradicting the modern day geographical niche of bejel in the arid regions of the world, the results call into question the previous palaeopathological characterization of treponeme subspecies and showcase their adaptive potential. A high-coverage genome is used to improve molecular clock date estimations, placing the divergence of modern T. pallidum subspecies firmly in pre-Columbian times. Overall, our study demonstrates the opportunities within archaeogenetics to uncover key events in pathogen evolution and emergence, paving the way to new hypotheses on the origin and spread of treponematoses.

Endothelial dysfunction of syphilis: Pathogenesis

Treponema pallidum is the causative factor of syphilis, a sexually transmitted disease (STD) characterized by perivascular infiltration of inflammatory cells, vascular leakage, swelling and proliferation of endothelial cells (ECs). The endothelium lining blood and lymphatic vessels is a key barrier separating body fluids from host tissues and is a major target of T. pallidum. In this review, we focus on how T. pallidum establish intimate interactions with ECs, triggering endothelial dysfunction such as endothelial inflammation, abnormal repairment and damage of ECs. In addition, we summarize that migration and invasion of T. pallidum across vascular ECs may occur through two pathways. These two mechanisms of transendothelial migration are paracellular and cholesterol-dependent, respectively. Herein, clarifying the relationship between T. pallidum and endothelial dysfunction is of great significance to provide novel strategies for diagnosis and prevention of syphilis, and has a great potential prospect of clinical application.

Bioactive Compounds from Plant Origin as Natural Antimicrobial Agents for the Treatment of Wound Infections

The rising prevalence of drug-resistant bacteria underscores the need to search for innovative and nature-based solutions. One of the approaches may be the use of plants that constitute a rich source of miscellaneous compounds with a wide range of biological properties. This review explores the antimicrobial activity of seven bioactives and their possible molecular mechanisms of action. Special attention was focused on the antibacterial properties of berberine, catechin, chelerythrine, cinnamaldehyde, ellagic acid, proanthocyanidin, and sanguinarine against Staphylococcus aureus, Enterococcus spp., Klebsiella pneumoniae, Acinetobacter baumannii, Escherichia coli, Serratia marcescens and Pseudomonas aeruginosa. The growing interest in novel therapeutic strategies based on new plant-derived formulations was confirmed by the growing number of articles. Natural products are one of the most promising and intensively examined agents to combat the consequences of the overuse and misuse of classical antibiotics.

Evaluation of whole-genome enrichment and sequencing of T. pallidum from FFPE samples after 75 years

The recent developments in genomic sequencing have permitted the publication of many new complete genome sequences of Treponema pallidum pallidum, the bacterium responsible for syphilis, which has led to a new understanding of its phylogeny and diversity. However, few archived samples are available, because of the degradability of the bacterium and the difficulties in preservation. We present a complete genome obtained from a Formalin-Fixed Paraffin-Embedded (FFPE) organ sample from 1947, kept at the Strasbourg Faculty of Medicine. This is the preliminary, proof-of concept study of this collection/biobank of more than 1.5 million FFPE samples and the evaluation of the feasibility of genomic analyses. We demonstrate here that even degraded DNA from fragile bacteria can be recovered from 75-year-old FFPE samples and therefore propose that such collections as this one can function as sources of biological material for genetic studies of pathogens, cancer, or even the historical human population itself.

High prevalence and genetic diversity of Treponema paraluisleporidarum isolates in European lagomorphs

IMPORTANCE

Syphilis is an ancient disease of humans and lagomorphs caused by two distinct but genetically closely related bacteria (>98% sequence identity based on the whole genome) of the genus Treponema. While human syphilis is well studied, little is known about the disease in the lagomorph host. Yet, comparative studies are needed to understand mechanisms in host-pathogen coevolution in treponematoses. Importantly, Treponema paraluisleporidarum-infected hare populations provide ample opportunity to study the syphilis-causing pathogen in a naturally infected model population without antibiotic treatment, data that cannot be obtained from syphilis infection in humans. We provide data on genetic diversity and are able to highlight various types of repetitions in one of the two hypervariable regions at the tp0548 locus that have not been described in the human syphilis-causing sister bacterium Treponema pallidum subsp. pallidum.

Resurgence of congenital syphilis: new strategies against an old foe

Congenital syphilis is a major global cause of fetal loss, stillbirth, neonatal death, and congenital infection. In 2020, the global rate of congenital syphilis was 425 cases per 100 000 livebirths-substantially higher than WHO's elimination target of 50 cases per 100 000 livebirths. Case rates are rising in many high-income countries, but remain low compared with those in low-income and middle-income settings. This Review aims to summarise the current epidemiology and knowledge on transmission and treatment of syphilis in pregnancy, and proposes measures to reduce the rising incidence seen worldwide. We also describe emerging diagnostic and treatment tools to prevent vertical transmission and improve management of congenital syphilis. Finally, we outline a programme of public health priorities, which include research, clinical, and preventive strategies.

A Rare Case of Neurosyphilis with Calvaria Osteitis Presenting in Pregnancy

Background

The incidence of syphilis throughout the world is increasing. Rates in pregnancy are similarly rising, presenting risks of an untreated syphilis infection that can be detrimental to the mother and fetus. Although routine screening for syphilis infections is recommended at the initial prenatal visit, there is a lack of universal agreement on rescreening pregnant people and approximately 50% of syphilis cases are asymptomatic in the general population. Furthermore, some symptoms of syphilis can overlap with nonspecific pregnancy-related symptoms. Meanwhile, Treponema pallidum can spread to various maternal and fetoplacental tissues quickly after infection and occur at any stage of syphilis.

Case

A 26-year-old gravida 5 para 2 presented with a new onset headache and visual and auditory changes at 23 weeks of gestation. A computerized tomography scan revealed numerous ill-defined lytic lesions throughout the calvarium, suspicious for syphilitic osteitis. She tested positive for syphilis antibodies with a rapid plasma reagin (RPR) titer of 1 : 32. Cerebrospinal fluid evaluation from a lumbar puncture resulted in reactive fluorescent treponemal antibody (FTA) testing. She was diagnosed with secondary syphilis with osteitis and neuro and otic components. She completed 14 days of intravenous aqueous crystalline penicillin G with additional benzathine penicillin G 2.4 million units intramuscular weekly for two weeks. There was no evidence of congenital syphilis on neonatal examination.

Conclusion

Syphilitic osteitis and neuro, otic, or ocular syphilis infections occur rarely in the nonpregnant population, and therefore, little data in pregnancy is available to inform outcomes in these specific disease states. It is of paramount importance to complete appropriate syphilis screening, recognize symptoms, and consider utilizing rescreen protocols to ensure prompt infection identification and treatment. For neuro, otic, and ocular syphilis, aqueous crystalline penicillin G (as opposed to benzathine penicillin G) is required to achieve treponemicidal concentrations in those physiologic compartments. There is no agreement as to the appropriate treatment regimen for the rare finding of syphilitic osteitis.

Insight into the invasion process and immune-protective evaluation of Tp0971, a membrane lipoprotein from Treponema pallidum

IMPORTANCE

The past two decades have seen a worldwide resurgence in infections caused by Treponema pallidum (T. pallidum) subsp. pallidum, the syphilis spirochete. The well-recognized capacity of the syphilis spirochete for early dissemination and immune evasion has earned it the designation "the stealth pathogen." There are many hurdles to studying syphilis pathogenesis, most notably the difficulty of culturing and genetically manipulating T. pallidum, as well as the absence of an effective vaccine for T. pallidum prevention. T. pallidum infection in humans is a complex and lengthy process. In this study, we investigated the invasion process and the function of the infection-dependent antigen Tp0971 as an immunogen to inhibit the dissemination of T. pallidum in an animal infection model. This enables a better understanding of the specific pathogenic mechanism of this pathogen, syphilis pathogenesis, and vaccine research.

Epidemiology and determinants of reemerging bacterial sexually transmitted infections (STIs) and emerging STIs in Europe

In this scoping review, we offer a comprehensive understanding of the current and recent epidemiology, challenges, and emerging issues related to bacterial sexually transmitted infections (STIs) in the WHO European Region. We endeavour in collating data from both EU/EEA and non- EU/EEA countries, thereby giving a complete picture of the region which highlights the higher notification rates in Northern and Western countries than other regions, likely due to differences in testing, access to testing, and surveillance capacity. We provide an up-to-date review on the current knowledge of determinants and persistent inequities in key populations as well as the use of molecular epidemiology for identifying transmission networks in gonorrhoea and syphilis, and detecting chlamydia mutations that evade molecular diagnosis. Finally, we explore the emerging STIs in the region and the evolving transmission routes of food and waterborne diseases into sexual transmission. Our findings call for harmonized STI surveillance systems, proactive strategies, and policies to address social factors, and staying vigilant for emerging STIs.

Immunisation with the glycolytic enzyme enolase inhibits dissemination of Treponema pallidum in C57BL/6 mice

Treponema pallidum (T. pallidum), an obligate extracellular bacterium, is the causative agent of sexually transmitted bacterial diseases. In this study, the glycolytic enzyme enolase (Tp Eno) of T. pallidum were injected intramuscularly into C57BL/6 mice, resulting in higher levels of specific anti-Tp Eno antibodies and Tp Eno-specific splenocyte proliferation than those in the mice immunized with recombinant protein Tp Eno. Cytokine (IL-4, IL-6, IL-10, IFN-γ, and TNF-α) analysis of splenocytes showed that the Tp Eno could slightly trigger the Th1-biased immune response. Furthermore, immunization of mice with Tp Eno elicited a significant production of IFN-γ by CD4+ T-cells in the spleen. Subsequently, mice were inoculated intradermally (between the scapulae), intraperitoneally, intrarectally and via the corpora cavernosa with 2.5 × 106 organisms per site (1 × 107 total organisms). The bacterial organ burden detected in the blood, spleen, liver, testes or brain of immunized mice suggested that Tp Eno enhances protective immunity to inhibit T. pallidum colonization in distal tissues. Therefore, Tp Eno vaccination enhances Tp Eno-specific immunogenicity and provides protection against T. pallidum dissemination.

Early syphilis in Guangzhou, China: presentation, molecular detection of Treponema pallidum , and genomic sequences in clinical specimens and isolates obtained by rabbit infectivity testing

Background

The global resurgence of syphilis requires novel prevention strategies. Whole genome sequencing (WGS) of Treponema pallidum ( TPA ) using different specimen types is essential for vaccine development.

Methods

Patients with primary (PS) and secondary (SS) syphilis were recruited in Guangzhou, China. We collected ulcer exudates and blood from PS participants, and skin biopsies and blood from SS participants for TPA polA polymerase chain reaction (PCR); ulcer exudates and blood were also used to isolate TPA strains by rabbit infectivity testing (RIT). TPA WGS was performed on 52 ulcer exudates and biopsy specimens and 25 matched rabbit isolates.

Results

We enrolled 18 PS and 51 SS participants from December 2019 to March 2022. Among PS participants, TPA DNA was detected in 16 (89%) ulcer exudates and three (17%) blood specimens. Among SS participants, TPA DNA was detected in 50 (98%) skin biopsies and 27 (53%) blood specimens. TP A was isolated from 48 rabbits, with a 71% (12/17) success rate from ulcer exudates and 69% (36/52) from SS bloods. Twenty-three matched SS14 clade genomes were virtually identical, while two Nichols clade pairs had discordant tprK sequences. Forty-two of 52 unique TPA genomes clustered in an SS14 East Asia subgroup, while ten fell into two East Asian Nichols subgroups.

Conclusions

Our TPA detection rate was high from PS ulcer exudates and SS skin biopsies and over 50% from SS whole blood, with RIT isolation in over two-thirds of samples. Our results support the use of WGS from rabbit isolates to inform vaccine development.

Summary

We performed Treponema pallidum molecular detection and genome sequencing from multiple specimens collected from early syphilis patients and isolates obtained by rabbit inoculation. Our results support the use of whole genome sequencing from rabbit isolates to inform syphilis vaccine development.

Genomic epidemiology of syphilis in England: a population-based study

BACKGROUND

Syphilis is a sexually transmitted bacterial infection caused by Treponema pallidum subspecies pallidum. Since 2012, syphilis rates have risen dramatically in many high-income countries, including England. Although this increase in syphilis prevalence is known to be associated with high-risk sexual activity in gay, bisexual, and other men who have sex with men (GBMSM), cases are rising in heterosexual men and women. The transmission dynamics within and between sexual networks of GBMSM and heterosexual people are not well understood. We aimed to investigate if whole genome sequencing could be used to supplement or enhance epidemiological insights around syphilis transmission.

METHODS

We linked national patient demographic, geospatial, and behavioural metadata to whole T pallidum genome sequences previously generated from patient samples collected from across England between Jan 1, 2012, and Oct 31, 2018, and performed detailed phylogenomic analyses.

FINDINGS

Of 497 English samples submitted for sequencing, we recovered 240 genomes (198 from the UK Health Security Agency reference laboratory and 42 from other laboratories). Three duplicate samples (same patient and collection date) were included in the main phylogenies, but removed from further analyses of English populations, leaving 237 genomes. 220 (92·8%) of 237 samples were from men, nine (3·8%) were from women, and eight (3·4%) were of unknown gender. Samples were mostly from London (n=118 [49·8%]), followed by southeast England (n=29 [12·2%]), northeast England (n=24 [10·1%]), and southwest England (n=15 [6·3%]). 180 (76·0%) of 237 genomes came from GBMSM, compared with 25 (10·5%) from those identifying as men who have sex with women, 15 (6·3%) from men with unrecorded sexual orientation, nine (3·8%) from those identifying as women who have sex with men, and eight (3·4%) from people of unknown gender and sexual orientation. Phylogenomic analysis and clustering revealed two dominant T pallidum sublineages in England. Sublineage 1 was found throughout England and across all patient groups, whereas sublineage 14 occurred predominantly in GBMSM older than 34 years and was absent from samples sequenced from the north of England. These different spatiotemporal trends, linked to demography or behaviour in the dominant sublineages, suggest they represent different sexual networks. By focusing on different regions of England we were able to distinguish a local heterosexual transmission cluster from a background of transmission in GBMSM.

INTERPRETATION

These findings show that, despite extremely close genetic relationships between T pallidum genomes globally, genomics can still be used to identify putative transmission clusters for epidemiological follow-up. This could be of value for deconvoluting putative outbreaks and for informing public health interventions.

FUNDING

Wellcome funding to the Sanger Institute, UK Research and Innovation, National Institute for Health and Care Research, European and Developing Countries Clinical Trials Partnership, and UK Health Security Agency.

Insights into the protective immune response by immunization with full-length recombinant TprK protein: cellular and humoral responses

Syphilis has resurged in many countries, which has called attention to vaccine development. Based on the immunization-based rabbit model of infection with the Nichols strain, this study explored the protective immune response of a controversial syphilis vaccine candidate, TprK, and found that immunization with full-length rTprK was effective in attenuating lesion development and accelerating lesion resolution, which could reduce the probability of the pathogen spreading to distant tissue sites to prevent the progression of the disease to some extent. Furthermore, the results revealed that immunization with rTprK not only rapidly induced a strong Th1-like cellular response but also elicited a humoral immune response to produce opsonic antibodies to enhance macrophage-mediated opsonophagocytosis. Although complete protection against infection was not achieved, the study provided a comprehensive and in-depth exploration of the immunogenicity of TprK and highlighted the importance of TprK as a promising syphilis vaccine component.

Sexually transmitted infections and associated risk factors among the transgender population of Pakistan

BACKGROUND

Transgender (TG) people are key drivers for sexually transmitted infections (STIs) all over the world. There is substantial evidence that STIs are associated with an increased likelihood of risky sexual behavior however little is known about the prevalence of STIs (HIV, HBV, HCV, and Syphilis) among HIV infected transgender population in Pakistan.

METHODS

The current study investigated the seroprevalence of four STIs and associated socio-demographic risk factors among TGs of Punjab, Pakistan from July 2019 to June 2021. The samples were tested serologically and final confirmation was done through PCR for HIV, HBV, and HCV.

RESULTS

A total of 1,562 transgenders cross-sectional descriptive records of the Punjab AIDS Control Program (PACP) were reviewed during the period from July 2019 to June 2021. The serological results evidenced that 533 (34.1%) had one pathogen, 309 (19.8%) had two or more (multiple) infections. The most predominant mono-infection among the transgender population was Syphilis 324 (20.7%) followed by HCV 114 (7.3%), HIV 69 (4.4%), and HBV 26 (1.7%). The highest proportions of Infections were found in TG residing in urban areas (68.6%) as compared to rural areas (31.4%). The seropositivity of all STIs was predominantly increased in Sex worker TGs i-e 55%, 46.5%, 38.5%, and 41.8% in HIV, HBV, HCV, and Syphilis respectively. Among 280 HIV-infected Transgender, 177 (63.2%) had Syphilis co-infections. While 87 (31%) and 47 (16.8%) HIV-infected individuals had HC and HBV co-infection respectively.

CONCLUSION

Transgender is neglected population group in society. All STIs were predominantly common among sex worker transgenders, Illiterate educational groups, and TGs residing in urban areas. There is a need to spread awareness about STIs, preventive strategies, and facilitation to health care programs in this high-risk population group.

Clinical and genomic diversity of Treponema pallidum subsp. pallidum: A global, multi-center study of early syphilis to inform vaccine research

Background

The continuing increase in syphilis rates worldwide necessitates development of a vaccine with global efficacy. We conducted a multi-center, observational study to explore Treponema pallidum subsp. pallidum ( TPA ) molecular epidemiology essential for vaccine research by analyzing clinical data and specimens from early syphilis patients using whole-genome sequencing (WGS) and publicly available WGS data.

Methods

We enrolled patients with primary (PS), secondary (SS) or early latent (ELS) syphilis from clinics in China, Colombia, Malawi and the United States between November 2019 - May 2022. Inclusion criteria included age ≥18 years, and syphilis confirmation by direct detection methods and/or serological testing. TPA detection and WGS were conducted on lesion swabs, skin biopsies/scrapings, whole blood, and/or rabbit-passaged isolates. We compared our WGS data to publicly available genomes, and analysed TPA populations to identify mutations associated with lineage and geography.

Findings

We screened 2,820 patients and enrolled 233 participants - 77 (33%) with PS, 154 (66%) with SS, and two (1%) with ELS. Median age of participants was 28; 66% were cis -gender male, of which 43% reported identifying as "gay", "bisexual", or "other sexuality". Among all participants, 56 (24%) had HIV co-infection. WGS data from 113 participants demonstrated a predominance of SS14-lineage strains with geographic clustering. Phylogenomic analysis confirmed that Nichols-lineage strains are more genetically diverse than SS14-lineage strains and cluster into more distinct subclades. Differences in single nucleotide variants (SNVs) were evident by TPA lineage and geography. Mapping of highly differentiated SNVs to three-dimensional protein models demonstrated population-specific substitutions, some in outer membrane proteins (OMPs) of interest.

Interpretation

Our study involving participants from four countries substantiates the global diversity of TPA strains. Additional analyses to explore TPA OMP variability within strains will be vital for vaccine development and improved understanding of syphilis pathogenesis on a population level.

Funding

National Institutes of Health, Bill and Melinda Gates Foundation.

Molecular Evolution of Human Parainfluenza Virus Type 2 Based on Hemagglutinin-Neuraminidase Gene

To understand the molecular evolution of human parainfluenza virus type 2 (HPIV2), 21 Hemagglutinin-Neuraminidase (HN) gene sequences covering seven Chinese provinces in 2011 and 2017 to 2021 were combined with 90 published HN sequences worldwide for phylogenetic analysis. The result showed that global HPIV2 could be classified into two distinct clusters (I and II), five lineages (IA to IIE), and four sublineages (IB1 and 2, and IIE1 and 2). The minimum genetic distances between different clusters and lineages were 0.049 and 0.014, respectively. In the last decade, one lineage (IID) and three sublineages (IB1, IB2, and IIE1) have been cocirculating in China, with the sublineages IB2 and IIE1 dominating, while sublineages IB1 and IIE1 are dominant globally. In addition, the spread of HPIV2 had relative spatial clustering, and sublineage IB2 has only been detected in China thus far. The overall evolution rate of HPIV2 was relatively low, on the order of 10-4 substitutions/site/year, except for sublineage IB2 at 10-3 substitutions/site/year. Furthermore, human-animal transmission was observed, suggesting that the HPIV2 might have jumped out of animal reservoirs in approximately 1922, the predicted time of a common ancestor. The entire HN protein was under purifying/negative selection, and the specific amino acid changes and two novel N-glycosylation sites (N316 and N517) in sublineages IB1, IB2, and IIE1 were mostly located in the globular head region of the HN protein. In this study, preliminary evolutionary characteristics of HPIV2 based on the HN gene were obtained, increasing the recognition of the evolution and adaptation of HPIV2. IMPORTANCE The phylogenetic analysis showed that global HPIV2 could be classified into two distinct clusters (I and II) and five lineages (IA to IIE) with at least 0.049 and 0.014 genetic distances between clusters and lineages, respectively. Furthermore, lineages IB and IIE could be further divided into two sublineages (IB1-2 and IIE1-2). All China sequences belong to one lineage and three sublineages (IB1, IB2, IID, and IIE1), among which sublineages IB2 and IIE1 are predominant and cocirculating in China, while sublineages IB1 and IIE1 are dominant globally. The overall evolution rate of HPIV2 is on the order of 10-4 substitutions/site/year, with the highest rate of 2.18 × 10-3 for sublineage IB2. The entire HN protein is under purifying/negative selection, and the specific amino acid substitutions and two novel N-glycosylation sites (N316 and N517) in sublineages IB1, IB2, and IIE1 are mostly located in the globular head region of the HN protein.

Treponema pallidum Strains Among Women and Men Who Have Sex With Women in Amsterdam, the Netherlands and Antwerp, Belgium Between 2014 and 2020

ABSTRACT

The Treponema pallidum strain distribution among men who have sex with women were similar to the strain distribution men who have sex with men. The most prevalent strains and percentage of strains belonging to the Nichols lineage are similar to previous studies in Amsterdam focusing on men who have sex with men.

Patterns of within-host spread of Chlamydia trachomatis between vagina, endocervix and rectum revealed by comparative genomic analysis

Introduction

Chlamydia trachomatis, a gram-negative obligate intracellular bacterium, commonly causes sexually transmitted infections (STIs). Little is known about C. trachomatis transmission within the host, which is important for understanding disease epidemiology and progression.

Methods

We used RNA-bait enrichment and whole-genome sequencing to compare rectal, vaginal and endocervical samples collected at the same time from 26 study participants who attended Fijian Ministry of Health and Medical Services clinics and tested positive for C. trachomatis at each anatomic site.

Results

The 78 C. trachomatis genomes from participants resolved into two major clades of the C. trachomatis phylogeny (the "prevalent urogenital and anorectal" clade and "non-prevalent urogenital and anorectal" clade). For 21 participants, genome sequences were almost identical in each anatomic site. For the other five participants, two distinct C. trachomatis strains were present in different sites; in two cases, the vaginal sample was a mixture of strains.

Discussion

The absence of large numbers of fixed SNPs between C. trachomatis genomes within many of the participants could indicate recent acquisition of infection prior to the clinic visit without sufficient time to accumulate significant genetic variation in different body sites. This model suggests that many C. trachomatis infections may be resolved relatively quickly in the Fijian population, possibly reflecting common prescription or over-the-counter antibiotics usage.

Clonal isolates of Treponema pallidum subsp. pallidum Nichols provide evidence for the occurrence of microevolution during experimental rabbit infection and in vitro culture

The recent development of a system for long-term in vitro culture of the syphilis spirochete, Treponema pallidum subsp. pallidum, has introduced the possibility of detailed genetic analysis of this bacterium. In this study, the in vitro culture system was used to isolate and characterize clonal populations of T. pallidum subsp. pallidum Nichols, the most widely studied strain. In limiting dilutions experiments, it was possible to establish cultures with inocula as low as 0.5 T. pallidum per well despite the long generation time (~35 to 40 hours) of this organism. Six Nichols strain clones isolated by limiting dilution were characterized in detail. All clones exhibited indistinguishable morphology and motility, highly similar in vitro multiplication rates, and comparable infectivity in the rabbit model (ID50 ≤ 100 bacteria). Genomic sequencing revealed sequence heterogeneity in the form of insertions or deletions at 5 sites, single nucleotide variations at 20 sites, and polynucleotide (polyG/C) tract length differences at 22 locations. Genomic sequences of the uncloned Nichols strain preparations propagated in rabbits or in vitro cultures exhibited substantial heterogeneity at these locations, indicating coexistence of many varied 'clonotypes' within these populations. Nearly all genetic variations were specific for the Nichols strain and were not detected in the >280 T. pallidum genomic sequences that are currently available. We hypothesize that these Nichols strain-specific sequence variations arose independently either during human infection or within the 110 years since the strain's initial isolation, and thus represent examples of microevolution and divergence.

Patterns of within-host spread of Chlamydia trachomatis between vagina, endocervix and rectum revealed by comparative genomic analysis

Chlamydia trachomatis , a gram-negative obligate intracellular bacterium, commonly causes sexually transmitted infections (STIs). Little is known about C. trachomatis transmission within the host, which is important for understanding disease epidemiology and progression. We used RNA-bait enrichment and whole-genome sequencing to compare rectal, vaginal and endocervical samples collected at the same time from 26 study participants who attended Fijian Ministry of Health and Medical Services clinics and tested positive for C. trachomatis at each anatomic site. The 78 C. trachomatis genomes from participants were from two major clades of the C. trachomatis phylogeny (the "prevalent urogenital and anorecta"l clade and "non-prevalent urogenital and anorectal" clade). For 21 participants, genome sequences were almost identical in each anatomic site. For the other five participants, two distinct C. trachomatis strains were present in different sites; in two cases, the vaginal sample was a mixture of strains. The absence of large numbers of fixed SNPs between C. trachomatis strains within many of the participants could indicate recent acquisition of infection prior to the clinic visit without sufficient time to accumulate significant variation in the different body sites. This model suggests that many C. trachomatis infections may be resolved relatively quickly in the Fijian population, possibly reflecting common prescription or over-the-counter antibiotics usage.

Importance

Chlamydia trachomatis is a bacterial pathogen that causes millions of sexually transmitted infections (STIs) annually across the globe. Because C. trachomatis lives inside human cells, it has historically been hard to study. We know little about how the bacterium spreads between body sites. Here, samples from 26 study participants who had simultaneous infections in their vagina, rectum and endocervix were genetically analyzed using an improved method to extract C. trachomatis DNA directly from clinical samples for genome sequencing. By analyzing patterns of mutations in the genomes, we found that 21 participants shared very similar C. trachomatis strains in all three anatomic sites, suggesting recent infection and spread. For five participants two C. trachomatis strains were evident, indicating multiple infections. This study is significant in that improved enrichment methods for genome sequencing provides robust data to genetically trace patterns of C. trachomatis infection and transmission within an individual for epidemiologic and pathogenesis interrogations.

Mathematical modelling Treponema infection in free-ranging Olive baboons (Papio anubis) in Tanzania

Yaws is a chronic infection caused by the bacterium Treponema pallidum susp. pertenue (TPE) that was thought to be an exclusive human pathogen but was recently found and confirmed in nonhuman primates. In this paper, we develop the first compartmental ODE model for TPE infection with treatment of wild olive baboons. We solve for disease-free and endemic equilibria and give conditions on local and global stability of the disease-free equilibrium. We calibrate the model based on the data from Lake Manyara National Park in Tanzania. We use the model to help the park managers devise an effective strategy for treatment. We show that an increasing treatment rate yields a decrease in disease prevalence. This indicates that TPE can be eliminated through intense management in closed population. Specifically, we show that if the whole population is treated at least once every 5-6 years, a disease-free equilibrium can be reached. Furthermore, we demonstrate that to see a substantial decrease of TPE infection to near-elimination levels within 15 years, the whole population needs to be treated every 2-3 years.

Teaching computational genomics and bioinformatics on a high performance computing cluster-a primer

The burgeoning field of genomics as applied to personalized medicine, epidemiology, conservation, agriculture, forensics, drug development, and other fields comes with large computational and bioinformatics costs, which are often inaccessible to student trainees in classroom settings at universities. However, with increased availability of resources such as NSF XSEDE, Google Cloud, Amazon AWS, and other high-performance computing (HPC) clouds and clusters for educational purposes, a growing community of academicians are working on teaching the utility of HPC resources in genomics and big data analyses. Here, I describe the successful implementation of a semester-long (16 week) upper division undergraduate/graduate level course in Computational Genomics and Bioinformatics taught at San Diego State University in Spring 2022. Students were trained in the theory, algorithms and hands-on applications of genomic data quality control, assembly, annotation, multiple sequence alignment, variant calling, phylogenomic analyses, population genomics, genome-wide association studies, and differential gene expression analyses using RNAseq data on their own dedicated 6-CPU NSF XSEDE Jetstream virtual machines. All lesson plans, activities, examinations, tutorials, code, lectures, and notes are publicly available at https://github.com/arunsethuraman/biomi609spring2022.

Intrathecal immunoglobin synthesis and its role in patients with neurosyphilis

Background

Intrathecal protein synthesis (ITS) occurs in various central nervous system disorders, but few quantitative studies have focused on ITS for neurosyphilis (NS) in southwestern China. We made a study to quantitatively assess the ITS in patients with NS and to investigate the association between ITS and the stages of NS.

Methods

CSF-serum specimen pairs from 142 patients (66 NS and 76 non-NS/syphilis) were collected for routine CSF and serum tests. The NS group was divided into slight and severe subgroups according to the NS stages. Three formulas for the quantitative determination of the intrathecal synthesis were calculated to characterize the specimens, including the Ig index (Q_Ig/Q_alb), Ig extended index (Ig_EI), and intrathecally synthesized fraction (IgIF) using the hyperbolic function. The role of QTPPA/QIgG as an antibody index (AI = Q specific Ig/QIgG) was also explored.

Results

Sero_TRUST titres (1:16, 1:1-1:256), sero_TPPA titres (1:163840, 1:1280-1:1310720), total protein (MTP), and CSF_Igs (p < 0.05) were found to be significantly elevated in the NS group. Intrathecal Ig synthesis can be identified using all three formulas in the NS group. The pattern of Ig intrathecal synthesis was IgIF-G (48.62%) > IgIF-A = IgIF-M (p < 0.05), with the dominant intrathecal fraction being IgG (median, 48.62%), which was also verified by Q_IgG> Q_alb> Q_IgM = Q_IgA. In the slight NS group, the intrathecal fractions of IgM (>0 in 4 out of 20 cases) and IgG (>0 in 16 out of 20) were lower than the intrathecal fractions of IgM (>0 in 19 out of 35 cases) and IgG (>0 in 33 out of 38) in the severe group (p < 0.05). The area under the curve (AUC) of the CSF_TPPA antibody index was 0.867 (0.792, 0.922), with an optimal cutoff point of 0.81, providing a sensitivity of 88.91% and specificity of 84.62%.

Conclusion

Although the intrathecal synthesis pattern is IgG dominant in patients with NS, brain-derived IgM and IgA can also be found. Moreover, intrathecal IgM and IgG were associated with a parenchymatous type of neurosyphilis. Syphilis-specific antibodies are a new potential tool for NS diagnosis.

High frequency of Nichols-like strains and increased levels of macrolide resistance in Treponema pallidum in clinical samples from Buenos Aires, Argentina

Globally, 94% of Treponema pallidum subsp. pallidum (TPA) clinical strains belong to the SS14-like group and 6% to the Nichols-like group, with a prevalence of macrolide resistance of 90%. Our goal was to determine whether local TPA strain distribution and macrolide resistance frequency have changed significantly since our last report, which revealed that Buenos Aires had a high frequency of Nichols-like strains (27%) and low levels of macrolide resistance (14%). Swab samples from patients with suspected syphilis were collected during 2015–2019 and loci TP0136, TP0548, TP0705 were sequenced in order to perform multilocus sequence typing. Strains were classified as Nichols-like or SS14-like. The presence of macrolide resistance-associated mutations was determined by examination of the 23S rDNA gene sequence. Of 46 typeable samples, 37% were classified as Nichols-like and 63% as SS14-like. Macrolide resistance prevalence was 45.7%. Seven allelic profiles were found, five were SS14-like and two were Nichols-like. The frequency of Nichols-like strains increased between studies (26.8% vs. 37%, p = 0.36). A dramatic increase was found in the frequency of macrolide resistant strains between studies (14.3% vs. 45.7%, p = 0.005). Our results are in agreement with international trends and underscore the need to pursue further TPA molecular typing studies in South America.

High-throughput nanopore sequencing of Treponema pallidum tandem repeat genes arp and tp0470 reveals clade-specific patterns and recapitulates global whole genome phylogeny

Sequencing of most Treponema pallidum genomes excludes repeat regions in tp0470 and the tp0433 gene, encoding the acidic repeat protein (arp). As a first step to understanding the evolution and function of these genes and the proteins they encode, we developed a protocol to nanopore sequence tp0470 and arp genes from 212 clinical samples collected from ten countries on six continents. Both tp0470 and arp repeat structures recapitulate the whole genome phylogeny, with subclade-specific patterns emerging. The number of tp0470 repeats is on average appears to be higher in Nichols-like clade strains than in SS14-like clade strains. Consistent with previous studies, we found that 14-repeat arp sequences predominate across both major clades, but the combination and order of repeat type varies among subclades, with many arp sequence variants limited to a single subclade. Although strains that were closely related by whole genome sequencing frequently had the same arp repeat length, this was not always the case. Structural modeling of TP0470 suggested that the eight residue repeats form an extended α-helix, predicted to be periplasmic. Modeling of the ARP revealed a C-terminal sporulation-related repeat (SPOR) domain, predicted to bind denuded peptidoglycan, with repeat regions possibly incorporated into a highly charged β-sheet. Outside of the repeats, all TP0470 and ARP amino acid sequences were identical. Together, our data, along with functional considerations, suggests that both TP0470 and ARP proteins may be involved in T. pallidum cell envelope remodeling and homeostasis, with their highly plastic repeat regions playing as-yet-undetermined roles.

Extracellular Loops of the Treponema pallidum FadL Orthologs TP0856 and TP0858 Elicit IgG Antibodies and IgG+-Specific B-Cells in the Rabbit Model of Experimental Syphilis

The resurgence of syphilis in the new millennium has called attention to the importance of a vaccine for global containment strategies. Studies with immune rabbit serum (IRS) indicate that a syphilis vaccine should elicit antibodies (Abs) that promote opsonophagocytosis of treponemes by activated macrophages. The availability of three-dimensional models for Treponema pallidum's (Tp) repertoire of outer membrane proteins (OMPs) provides an architectural framework for identification of candidate vaccinogens with extracellular loops (ECLs) as the targets for protective Abs. Herein, we used Pyrococcus furiosus thioredoxin (PfTrx) as a scaffold to display Tp OMP ECLs to interrogate sera and peripheral blood mononuclear cells (PBMCs) from immune rabbits for ECL-specific Abs and B cells. We validated this approach using a PfTrx scaffold presenting ECL4 from BamA, a known opsonic target. Using scaffolds displaying ECLs of the FadL orthologs TP0856 and TP0858, we determined that ECL2 and ECL4 of both proteins are strongly antigenic. Comparison of ELISA and immunoblot results suggested that the PfTrx scaffolds present conformational and linear epitopes. We then used the FadL ECL2 and ECL4 PfTrx constructs as "hooks" to confirm the presence of ECL-specific B cells in PBMCs from immune rabbits. Our results pinpoint immunogenic ECLs of two newly discovered OMPs, while advancing the utility of the rabbit model for circumventing bottlenecks in vaccine development associated with large-scale production of folded OMPs. They also lay the groundwork for production of rabbit monoclonal Abs (MAbs) to characterize potentially protective ECL epitopes at the atomic level. IMPORTANCE Recent identification and structural modeling of Treponema pallidum's (Tp) repertoire of outer membrane proteins (OMPs) represent a critical breakthrough in the decades long quest for a syphilis vaccine. However, little is known about the antigenic nature of these β-barrel-forming OMPs and, more specifically, their surface exposed regions, the extracellular loops (ECLs). In this study, using Pyrococcus furiosus thioredoxin (PfTrx) as a scaffold to display Tp OMP ECLs, we interrogated immune rabbit sera and peripheral blood mononuclear cells for the presence of antibodies (Abs) and circulating rare antigen-specific B cells. Our results pinpoint immunogenic ECLs of two newly discovered OMPs, while advancing the utility of the rabbit model for surveying the entire Tp OMPeome for promising OMP vaccinogens. This work represents a major advancement toward characterizing potentially protective OMP ECLs and future vaccine studies. Additionally, this strategy could be applied to OMPs of nonspirochetal bacterial pathogens.

A suite of PCR-LwCas13a assays for detection and genotyping of Treponema pallidum in clinical samples

The performance of commonly used assays for diagnosis of syphilis varies considerably depending on stage of infection and sample type. In response to the need for improved syphilis diagnostics, we develop assays that pair PCR pre-amplification of the tpp47 gene of Treponema pallidum subsp. pallidum with CRISPR-LwCas13a. The PCR-LwCas13a assay achieves an order of magnitude better analytical sensitivity than real-time PCR with equivalent specificity. When applied to a panel of 216 biological specimens, including 135 clinically confirmed primary and secondary syphilis samples, the PCR-LwCas13a assay demonstrates 93.3% clinical sensitivity and 100% specificity, outperforming tpp47 real-time PCR and rabbit-infectivity testing. We further adapt this approach to distinguish Treponema pallidum subsp. pallidum lineages and identify genetic markers of macrolide resistance. Our study demonstrates the potential of CRISPR-based approaches to improve diagnosis and epidemiological surveillance of syphilis.

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.

Serum Interleukin-26 is a Potential Biomarker for the Differential Diagnosis of Neurosyphilis and Syphilis at Other Stages

Background

Interleukin-26 (IL-26) is an atypical proinflammatory cytokine due to its binding to circulating double-stranded DNA and direct antibacterial activity. Although IL-26 has been confirmed to be involved in the pathophysiology of cancer, chronic inflammatory diseases and infections, the diagnostic and prognostic values of IL-26 levels in syphilis patients are not clear. This study aimed to investigate IL-26 levels in different stages of syphilis progression.

Methods

A total of 30 healthy controls and 166 patients with syphilis at different stages of disease progression were enrolled. Serum IL-26 levels were quantified in accordance with the protocols of RayBio^® Human Interleukin-26 Enzyme Linked Immunosorbent Assay (ELISA) kits. Clinical laboratory diagnostic parameters and blood analysis data were detected and collected according to clinical medical laboratory standards.

Results

The levels of serum IL-26 were significantly higher in neurosyphilis patients than in healthy subjects (6.87 (4.36, 12.14) and 1.67 (0.09, 4.89) pg/μL, respectively; ****p < 0.0001), latent syphilis (1.48 (0.40, 2.05) pg/μL, ****p < 0.0001), seroresistant syphilis (0.81 (0.20, 2.91) pg/μL, ****p < 0.0001) and secondary syphilis (1.66 (0.41, 4.25) pg/μL, ****p < 0.0001) with data presented as the median with interquartile range. The concentration of serum IL-26 was most sensitive to serum low-density lipoprotein concentration (r = -0.438, **p = 0.004) in latent syphilis, urine epithelial cells (r = 0.459, **p = 0.003) in seroresistant syphilis, and serum creatinine levels (r = 0.463, **p = 0.004) and urea creatinine ratio levels (r = 0.500, **p = 0.008) in secondary syphilis patients. There was no significant correlation with the concentration of IL-26 and toluidine red unheated serum test (TRUST) titers in each type of syphilis patient.

Conclusion

Circulating IL-26 in serum displays diagnostic potential in the progression of neurosyphilis and warrants further evaluation in clinical trials.

Tp47 promoted the phagocytosis of HMC3 cells through autophagy induced by endoplasmic reticulum stress

BACKGROUND

Central nervous system damage is an essential clinical feature that occurs in the early or late stages of syphilis infection. The abnormal enhancement of microglial phagocytosis can cause damage to the nervous system. However, the contribution of abnormally enhanced microglial phagocytosis to the pathogenesis of Treponema pallidum subsp. pallidum (T. pallidum) infection remains unknown.

OBJECTIVES

In this study, we sought to determine the role of recombinant T. pallidum Tp47 in promoting microglia phagocytosis and its associated mechanisms.

METHODS

Microglial HMC3 cells were used to investigate the effect of the Tp47 on phagocytosis and the roles of autophagy and endoplasmic reticulum stress in Tp47-induced phagocytosis.

RESULTS

HMC3 cells exhibited obvious phagocytosis when stimulated with Tp47. The levels of P62 degradation, Beclin1 expression and the LC3II/LC3I ratio were significantly elevated, and the fusion of autophagosomes and lysosomes was promoted in Tp47-stimulated HMC3 cells. Treatment with the autophagy inhibitors 3-MA and Baf A1 inhibited Tp47-induced phagocytosis. Meanwhile, the endoplasmic reticulum stress markers PERK, IRE1α, GRP78, ATF4 and XBP1s were upregulated in Tp47-stimulated HMC3 cells. In addition, we found that TUDCA could inhibit Tp47-induced expression of IRE1α but not PERK or ATF4. 4-PBA inhibited TP47-induced PERK and ATF4 protein expression but did not inhibit IRE1α expression. Attenuation of endoplasmic reticulum stress by administration of TUDCA and 4-PBA abrogated Tp47-mediated autophagy.

CONCLUSIONS

These results suggested that Tp47 activated autophagy through two key pathways associated with endoplasmic reticulum stress, PERK/ATF4 and IRE1/XBP1, to promote phagocytosis in HMC3 cells. These findings provided a basis for the understanding of the pathophysiology of neurological disorders that occur during the course of syphilis.

Selective Whole-Genome Amplification as a Tool to Enrich Specimens with Low Treponema pallidum Genomic DNA Copies for Whole-Genome Sequencing

Syphilis is a sexually transmitted, disseminated acute and chronic infection caused by the bacterial pathogen Treponema pallidum subspecies pallidum . Primary syphilis typically presents as single or multiple mucocutaneous lesions and, if left untreated, can progress through multiple stages with various clinical manifestations.