Production and Composition of Group B Streptococcal Membrane Vesicles Vary Across Diverse Lineages

Although the neonatal and fetal pathogen Group B Streptococcus (GBS) asymptomatically colonizes the vaginal tract of ∼30% of pregnant women, only a fraction of their offspring develops invasive disease. We and others have postulated that these dimorphic clinical phenotypes are driven by strain variability; however, the bacterial factors that promote these divergent clinical phenotypes remain unclear. It was previously shown that GBS produces membrane vesicles (MVs) that contain active virulence factors capable of inducing adverse pregnancy outcomes. Because the relationship between strain variation and vesicle composition or production is unknown, we sought to quantify MV production and examine the protein composition, using label-free proteomics on MVs produced by diverse clinical GBS strains representing three phylogenetically distinct lineages. We found that MV production varied across strains, with certain strains displaying nearly twofold increases in production relative to others. Hierarchical clustering and principal component analysis of the proteomes revealed that MV composition is lineage-dependent but independent of clinical phenotype. Multiple proteins that contribute to virulence or immunomodulation, including hyaluronidase, C5a peptidase, and sialidases, were differentially abundant in MVs, and were partially responsible for this divergence. Together, these data indicate that production and composition of GBS MVs vary in a strain-dependent manner, suggesting that MVs have lineage-specific functions relating to virulence. Such differences may contribute to variation in clinical phenotypes observed among individuals infected with GBS strains representing distinct lineages.

263 Characterizing Vaginal Bacterial Community Composition in Brangus Heifers

The role of the reproductive tract microbiota is an emerging field receiving considerable attention in human research, whereby the vaginal microbiota has been characterized in relation to fertility, conception, pregnancy, and parturition. However, the acidic, Lactobaccillus dominated vaginal microbiota in humans contrasts the neutral, dynamic microbial environment characterized in cattle. Over the past few years, many postpartum studies in dairy cattle described a mechanism recently proposed in humans, the ascension of the vaginal microbiota into the uterine body at the onset of labor. Although bovine fetal sterility prior to parturition is under debate, the vaginal microbiota is an early contact for the neonate with microorganisms and inoculates the uterus during parturition. Thus, any changes occurring in the vaginal microbiota could have implications in dam and calf health; this, combined with ease of access, led to the current research focusing on the bovine vaginal microbiota. Characterization studies during the estrous cycle, gestation, and postpartum period have been performed, concluding the bovine vaginal microbiota is dynamic. However, due to the low abundance in the vaginal microbiota, the seemingly small taxonomic changes reported in these studies could be of great importance. Secondly, researchers have begun to evaluate the effect of exogenous and endogenous hormone concentrations on the vaginal microbiota. Little to no differences have been found except with exogenous melatonin supplementation. In pregnant heifers, exogenous melatonin altered the beta diversity of the vaginal tract by increasing aerobic bacteria present. Moreover, a study evaluating the effects of nutrient restriction on the vaginal microbiota found no taxonomic or structure differences. These findings have allowed researchers to target paucities, improve methodology, and realize the importance of the reproductive tract microbiota. In short, based on these studies, future research examining the role of the reproductive tract microbiota could uncover mechanisms vital to increasing reproductive performance.

Lactobacillus rhamnosus reduces the cytotoxic effects of Group B Streptococcus on HeLa cells

Group B Streptococcus (GBS) is an opportunistic pathogen found in the vaginal tract and is a leading cause of preterm birth and neonatal illness. Aside from GBS, the vaginal tract is predominantly colonized by commensal Lactobacillus species that are thought to protect the vaginal tract from pathogens, including GBS. Studies that examined if, and how Lactobacilli modulate GBS pathogenicity remain limited. This study sought to investigate the potential protective role of Lactobacillus rhamnosus against GBS, using an in vitro model system. Immunofluorescence microscopy and Scanning Electron Microscopy (SEM) captured images of infected HeLa cells and were analyzed using the image analysis program ImageJ. Results indicate that GBS causes HeLa cell detachment unless L. rhamnosus is present. SEM images show that GBS reduces length and number of microvilli on HeLa cell surface, as well as size of secreted vesicles. L. rhamnosus partially inhibits GBS-dependent microvilli and vesicle disruption. GBS also disrupts HeLa cell F-actin fibers unless L. rhamnosus is present. These results reveal effects of GBS infection on the host cell cytoskeleton and implies a protective role of L. rhamnosus against GBS colonization.

Production and composition of group B streptococcal membrane vesicles varies across diverse lineages

Although the neonatal and fetal pathogen Group B Streptococcus (GBS) asymptomatically colonizes the vaginal tract of ~30% of pregnant women, only a fraction of their offspring develops invasive disease. We and others have postulated that these dimorphic clinical phenotypes are driven by strain variability; however, the bacterial factors that promote these divergent clinical phenotypes remain unclear. It was previously shown that GBS produces membrane vesicles (MVs) that contain active virulence factors capable of inducing adverse pregnancy outcomes. Because the relationship between strain variation and vesicle composition or production is unknown, we sought to quantify MV production and examine the protein composition, using label-free proteomics on MVs produced by diverse clinical GBS strains representing three phylogenetically distinct lineages. We found that MV production varied across strains, with certain strains displaying nearly two-fold increases in production relative to others. Hierarchical clustering and principal component analysis of the proteomes revealed that MV composition is lineage-dependent but independent of clinical phenotype. Multiple proteins that contribute to virulence or immunomodulation, including hyaluronidase, C5a peptidase, and sialidases, were differentially abundant in MVs, and were partially responsible for this divergence. Together, these data indicate that production and composition of GBS MVs vary in a strain-dependent manner, suggesting that MVs have lineage-specific functions relating to virulence. Such differences may contribute to variation in clinical phenotypes observed among individuals infected with GBS strains representing distinct lineages.

To understand the reproductive tract microbiome associated with infertility through metagenomics analysis

Background Knowledge of the microbiome is in its infancy in health and human illness, especially concerning human reproduction. We will be better able to treat dysbiosis of the reproductive tract clinically if it is better explained and understood. It has been shown that altered vaginal microbiota affects parturition, and its function is uncertain in assisted reproductive technologies. However, the effects of recognized microbes such as Mycoplasma tuberculosis, Chlamydia trachomatis, and Neisseria gonorrhoeae are well established, resulting in subclinical changes which are considered to be risk factors for infertility and poor reproductive outcomes. Main body Recent studies indicate that the vaginal tract comprises several different organisms of the microbiome. Some microbiota can play an important role not only in the reproductive tract but also in overall health. The microbiome of the female reproductive tract has been identified mainly based on studies that examine vaginal samples across many reproductive technologies, using a metagenomics approach. Conclusion Alteration of reproductive tract microbiota or presence of certain microbiota irrespective of the level of pathogenicity may interfere with fertilization, implantation, and subsequent embryo development. This may lead to failed fertility treatments and reduced live birth rate (LBR).

Corynebacterium phoceense, resident member of the urogenital microbiota?

Corynebacterium phoceense is a Gram-positive species previously isolated from human urine. Although other species from the same genus have been associated with urinary tract infections, C. phoceense is currently believed to be a non-pathogenic member of the urogenital microbiota. Prior to our study, only two isolates were described in the literature, and very little is known about the species. Here, we describe C. phoceense UFMG-H7, the first strain of this species isolated from the urine of healthy cattle. The genome for this isolate was produced and compared to the two other publicly available C. phoceense as well as other Corynebacterium genome assemblies. Our in-depth genomic analysis identified four additional publicly available genome assemblies that are representatives of the species, also isolated from the human urogenital tract. Although none of the strains have been associated with symptoms or disease, numerous genes associated with virulence factors are encoded. In contrast to related Corynebacterium species and Corynebacterium species from the bovine vaginal tract, all C. phoceense strains examined code for the SpaD-type pili suggesting adherence is essential for its persistence within the urinary tract. As the other C. phoceense strains analysed were isolated from the human urogenital tract, our results suggest that this species may be specific to this niche.

The mobile genetic element RD2 affects colonization potential of different GAS serotypes

M-type 28 Streptococcus pyogenes (Group A Strep, GAS) strains are highly associated with life-threatening puerperal infections. Genome sequencing has revealed a large mobile genetic element, RD2, present in most M28 GAS isolates but not found widely in other serotypes. Previous studies have linked RD2 to the ability of M28 GAS to colonize the vaginal tract. A new study by Roshika and colleagues use gain-of-function mutants in three different GAS serotypes to help determine why RD2 appears to have a serotype preference and what that could mean for GAS mucosal colonization and pathogenesis.

Depot medroxyprogesterone acetate (DMPA) enhances susceptibility and increases the window of vulnerability to HIV-1 in humanized mice

The progestin-based hormonal contraceptive Depot Medroxyprogesterone Acetate (DMPA) is widely used in sub-Saharan Africa, where HIV-1 is endemic. Meta-analyses have shown that women using DMPA are 40% more likely than women not using hormonal contraceptives to acquire Human Immunodeficiency Virus (HIV-1). Therefore understanding how DMPA increases susceptibility to HIV-1 is an important public health issue. Using C57BL/6 mice and our previously optimized humanized mouse model (NOD-Rag1tm1Mom Il2rgtm1Wjl transplanted with hCD34-enriched hematopoietic stem cells; Hu-mice) where peripheral blood and tissues are reconstituted by human immune cells, we assessed how DMPA affected mucosal barrier function, HIV-1 susceptibility, viral titres, and target cells compared to mice in the diestrus phase of the estrous cycle, when endogenous progesterone is highest. We found that DMPA enhanced FITC-dextran dye leakage from the vaginal tract into the systemic circulation, enhanced target cells (hCD68+ macrophages, hCD4+ T cells) in the vaginal tract and peripheral blood (hCD45+hCD3+hCD4+hCCR5+ T cells), increased the rate of intravaginal HIV-1 infection, extended the window of vulnerability, and lowered vaginal viral titres following infection. These findings suggest DMPA may enhance susceptibility to HIV-1 in Hu-mice by impairing the vaginal epithelial barrier, increasing vaginal target cells (including macrophages), and extending the period of time during which Hu-mice are susceptible to infection; mechanisms that might also affect HIV-1 susceptibility in women.

Comparative Genome Analyses of Lactobacillus crispatus Isolates from Different Ecological Niches Reveal an Adaptation of This Species to the Human Vaginal Environment

ABSTRACT The vaginal microbiota is defined as the community of bacteria residing in the human vaginal tract. Recent studies have demonstrated that the vaginal microbiota is dominated by members of the Lactobacillus genus, whose relative abundance and microbial taxon composition are dependent on the healthy status of this human body site. Particularly, among members of this genus, the high prevalence of Lactobacillus crispatus is commonly associated with a healthy vaginal environment. In the current study, we assessed the microbial composition of 94 healthy vaginal microbiome samples through shotgun metagenomics analyses. Based on our results, we observed that L. crispatus was the most representative species and correlated negatively with bacteria involved in vaginal infections. Therefore, we isolated 15 L. crispatus strains from different environments in which this species abounds, ranging from vaginal swabs of healthy women to chicken fecal samples. The genomes of these strains were decoded and their genetic content was analyzed and correlated with their physiological features. An extensive comparative genomic analysis encompassing all publicly available genome sequences of L. crispatus and combined with those decoded in this study revealed a genetic adaptation of strains to their respective ecological niche. In addition, in vitro growth experiments involving all isolated L. crispatus strains, together with a synthetic vaginal microbiota, reveal how this species is able to modulate the composition of the vaginal microbial consortia at the strain level. Overall, our findings suggest that L. crispatus plays an important ecological role in reducing the complexity of the vaginal microbiota by depleting pathogenic bacteria. IMPORTANCE The vaginal microbiota is defined as the community of bacteria residing in the human vaginal tract. Recent studies have demonstrated that the high prevalence of Lactobacillus crispatus strains is commonly associated with a healthy vaginal environment. In the current study, we assessed the microbial composition of 94 public healthy vaginal samples through shotgun metagenomics analyses. Results showed that L. crispatus was the most representative species and correlated negatively with bacteria involved in vaginal infections. Moreover, we isolated and sequenced the genomes of new L. crispatus strains from different environments, and the comparative genomics analysis revealed a genetic adaptation of strains to their ecological niche. In addition, in vitro growth experiments display the capability of this species to modulate the composition of the vaginal microbial consortia. Overall, our findings suggest an ecological role exploited by L. crispatus in reducing the complexity of the vaginal microbiota toward a depletion of pathogenic bacteria.

Role of Lactobacillus in Female Infertility Via Modulating Sperm Agglutination and Immobilization

Infertility has become a common problem in recent decades. The pathogenesis of infertility is variable, but microbiological factors account for a large proportion of it. Dysbiosis of vaginal microbiota is reportedly associated with female infertility, but the influence of normal vaginal microbiota on infertility is unclear. In this review, we summarize the physiological characteristics of the vaginal tract and vaginal microbiota communities. We mainly focus on the bacterial adherence of vaginal Lactobacillus species. Given that the adherent effect plays a crucial role in the colonization of bacteria, we hypothesize that the adherent effect of vaginal Lactobacillus may also influence the fertility of the host. We also analyze the agglutination and immobilization effects of other bacteria, especially Escherichia coli, on ejaculated spermatozoa, and speculate on the possible effects of normal vaginal microbiota on female fertility.