Biology subjects

Gomes-Solecki, M.

Publications and source records attributed to Gomes-Solecki, M..

13 recordsLinked to original sources

bioRxiv2026

A double-blinded, placebo-controlled field trial of an OspA-based oral reservoir targeted vaccine against Borrelia burgdorferi

Lyme disease, caused by Borrelia burgdorferi and transmitted by Ixodes scapularis ticks, remains a significant vector-borne illness in the United States. Small mammal reservoirs, particularly Peromyscus leucopus, play a critical role in B. burgdorferi maintenance. Here we conducted a five-year, randomized, double-blinded, placebo-controlled field trial deploying an oral OspA-based reservoir targeted vaccine (RTV) across seven Maryland sites. Bayesian modeling provided estimates of vaccine impact on mouse anti-OspA antibody levels, nymphal tick infection prevalence (NIP), mouse infection rates, and seroconversion to B. burgdorferi in hunting dogs. RTV sites exhibited an estimated 10.5% proportional increase in protective murine anti-OspA antibody levels and a 15.4% reduction in NIP by year five. We also found a lower infection prevalence in mouse blood fed nymphal ticks (9.8%). RTV sites exhibited modest decreases in mouse infection prevalence and dog seroconversion rates were similar between groups. Our results indicate that anti-OspA antibody in vaccinated-infected P. leucopus reduced B. burgdorferi summertime larval infection prevalence, measured as NIP reductions the following spring. This suggests that OspA-based oral RTV reduces B. burgdorferi transstadial transmission within tick populations. Our findings advance development of reservoir targeted solutions for Lyme disease prevention. Further evaluation of impacts on incidental hosts is needed.

microbiology↗

bioRxiv2026

Homologous and Heterologous Immunization with a PIV5-Based Modified OspA Vaccine Confers Equivalent Protection Against Tick-Transmitted Borrelia burgdorferi

Vaccines targeting outer surface protein A (OspA) of Borrelia burgdorferi protect against Lyme disease by eliciting antibodies that neutralize spirochetes in the Ixodes scapularis tick midgut during engorgement before transmission occurs. We evaluated whether different delivery vehicles and administration routes for a modified OspA construct (OspABPBPk) differed in protective efficacy. Four groups of nine C3H-HeN mice were immunized with OspABPBPk delivered intranasally by live parainfluenza virus 5 (PIV5-OspABPBPk) or by subcutaneous administration of recombinant protein adjuvanted with aluminum hydroxide (rOspABPBPk) using three prime-boost regimens and a vector/adjuvant control: homologous intranasal PIV5-OspABPBPk (IN/IN), homologous subcutaneous rOspABPBPk (SC/SC), and heterologous intranasal PIV5-OspABPBPk prime/subcutaneous rOspABPBPk boost (IN/SC). Mice were challenged on day 90, approximately 2 months after the boost, with nymphal ticks infected with 19 strains of B. burgdorferi. All OspABPBPk-containing vaccines elicited high antigen-specific IgG antibody titers (geometric mean titers of 10^4-10^6, approximately 4 log10 higher than the control group), reduced B. burgdorferi loads in engorged nymphal ticks by 1.7-2 log10, neutralized B. burgdorferi motility in multi-strain cultures, and prevented recovery of viable spirochetes from tissues after tick challenge. While one mouse (1/9, 11%) in the heterologous IN/SC vaccinated group had detectable flaB DNA in tissues and seroreactivity to B. burgdorferi PepVF, culture of spirochetes from heart and bladder showed no evidence of active infection. Although homologous immunization produced the most consistent results in mice, different delivery vehicles and routes of immunization with OspABPBPk vaccines did not affect overall efficacy as assessed by recovery of viable B. burgdorferi from tissues.

microbiology↗

bioRxiv2025

Complement C3 Deficiency Enhances Renal Leptospiral Load and Inflammation While Impairing T Cell Differentiation During Chronic Leptospira interrogans Infection

Leptospirosis is a neglected zoonotic disease caused by pathogenic Leptospira spp., affecting an estimated of one million people annually and resulting in approximately 60,000 fatalities. The disease can lead to hepatic, renal, and pulmonary dysfunctions and may contribute to the development of chronic kidney disease. The Complement System plays a crucial role in eliminating bacteria by generating opsonins, anaphylotoxins, that degranulate mastocytes and basophils, and attract immune cells to the infection site, among other important functions. This study aimed to investigate the role of C3, the central protein of the Complement System, in vivo during chronic infection of L interrogans serovar Copenhageni strain FIOCRUZ L1-130 (LIC). C57BL/6 wild-type (WT) and C3 knockout (C3KO) mice were infected with 108 LIC and monitored at 15, 30, 60, 90 and 180 days post-infection (d.p.i.). LIC-infected C3KO mice exhibited a significantly higher leptospiral load in the kidneys compared to WT counterparts. Both groups showed local inflammation at 15 and 30 d.p.i., but only C3KO LIC-infected mice had a higher number of Leptospira DNA copies at 30 d.p.i. At the same time point, C3KO LIC-infected mice developed a larger fibrotic area than WT mice. Interestingly, independent of C3, mice pre-treated with a nephrotoxic drug increased the renal inflammatory response; however, this pretreatment did not affect the local leptospiral load in infected mice. Additionally, levels of specific IgG2b and IgG3 antibodies were significantly higher in LIC-infected C3KO mice compared to WT mice. Proteomic analysis showed lower levels of C5/C5a in WT and C3KO LIC-infected mice, as well as in C3KO control mice. M-CSF and SDF-1 cytokine levels were reduced in both LIC-infected groups. Furthermore, naive T lymphocytes count (both CD4+ and CD8+) were higher in LIC-infected C3KO mice, whereas effector CD8+ T lymphocyte numbers declined during LIC infection - a phenomenon more pronounced in C3KO mice. Overall, this study demonstrates that during LIC infection, the absence of C3 does not affect mouse survival but leads to increased renal leptospiral load and fibrosis. Additionally, it highlights the crucial role of C3 in supporting the maturation and differentiation of T lymphocytes into pre-effector cells, underscoring its importance as a key link between the innate and adaptive immune responses in leptospirosis. Author SummaryLeptospirosis is an infectious disease with approximately one million new cases annually and is responsible for about 5% of deaths, particularly in underdeveloped countries. Our objective is to understand the immune response in leptospirosis, specifically the role of the Complement C3 protein. In this study, we observed that C3 deficiency is associated with a higher renal leptospiral load and an increased incidence of renal fibrosis after one month of chronic infection. Notably, C3 also influences the differentiation of helper and cytotoxic T lymphocytes into effector cells, potentially contributing to the increased severity of chronic leptospirosis observed in C3-deficient animals.

immunology↗

bioRxiv2025

Maternal Transfer of Vaccine-Induced Anti-OspA Antibodies in Peromyscus spp Protects Pups from Tick-Transmitted Borrelia burgdorferi

The efficacy and duration of passive immunity protection depends on maternal antibody levels and transfer efficiency. We investigated whether oral vaccination of Peromyscus leucopus dams with recombinant OspA-expressing E. coli could induce maternal transfer of anti-OspA antibodies and protect pups from Borrelia burgdorferi challenge. Dams were vaccinated until breeding pairs were created (i), until parturition (ii), and until pups were 2 weeks old (iii). Pups were challenged with nymphal I. scapularis-transmitted B. burgdorferi at [~] 4 weeks of age. Anti-OspA IgG were quantified in dams and pups, and anti-B. burgdorferi IgG were quantified in pups. B. burgdorferi burden was assessed by flaB qPCR in pups tissues [~] 4 weeks after tick challenge and viability of B. burgdorferi was assessed by culture of heart tissue. P. leucopus pups born to dams vaccinated until breeding had low serologic anti-OspA antibody and were not protected from tick transmitted B. burgdorferi infection. However, when dams vaccination extended until parturition and until pups were two weeks old, significant anti-OspA antibody transfer and protection from B. burgdorferi infection occurred. This was evidenced by absence of antibody to B. burgdorferi PepVF, absence of B. burgdorferi flaB DNA in heart and bladder tissues, and absence of flaB in culture from heart tissues from pups euthanized >9 weeks after birth. We show that transfer of anti-OspA antibodies from vaccinated P. leucopus dams to offspring prevents tick transmission and infection dynamics of B. burgdorferi in the major reservoir host of this spirochete in the United States. ImportanceThis study contributes to our understanding of how interventions based in reservoir targeted OspA vaccines designed to block transmission of B. burgdorferi from infected I. scapularis ticks may disrupt the enzootic cycle of this spirochete and reduce incidence of Lyme disease.

microbiology↗

bioRxiv2025

C3H-HeN as a TLR4 competent mouse model of sublethal leptospirosis

AbstractMice are slowly being accepted as alternative models for investigation of leptospiral infection. The strain most used to analyse sublethal disease (C3H-HeJ) expresses a tlr4 gene in its immune cells that is hyporesponsive to leptospiral LPS and thus the model is deemed immunocompromised. To help resolve this valid scientific concern we did a study in which we compared infection with Leptospira interrogans serovar Copenhageni Fiocruz in mice expressing fully competent tlr4 (C3H-HeN, C57BL6) versus tlr4 hyporesponsive mice (C3H- HeJ) over a period of two weeks. We found that the C3H-HeJ mouse was the only strain that sustained lethal infection, thus confirming the association between tlr4 function and acute disease. We found that the two mouse strains with a fully functional tlr4 gene (C3H-HeN and C57BL/6) also developed clinical and molecular signs of sublethal leptospirosis nearly on par with C3H-HeJ, as quantified by weight loss, survival curves, presence of Leptospira 16S rRNA in blood and urine, and burden of viable spirochetes in kidney. Regarding kidney markers of inflammation and fibrosis, C3H-HeN and C57BL/6 produced less IL-1 beta, iNOS and ColA1 than C3H-HeJ, which is consistent with increased resilience to infection expected of the tlr4 competent strains. Regarding Leptospira-specific antibody, all mouse strains produced IgM and T-cell independent IgG3. Interestingly, in contrast to C57BL/6, both C3H strains produced circulating IgG1 but only C3H-HeN produced IgG2a to L. interrogans two weeks post infection. Thus, TLR4-competent C3H-HeN and C57BL/6 may be more appropriate mouse models of sublethal leptospirosis, whereas C3H-HeJ can be used to further establish a mouse model of lethal leptospirosis. Our data strongly suggests that TLR4 function is important but not sufficient to cause susceptibility to leptospirosis. Author summaryPrevious studies by different laboratories have shown C3H-HeJ to be a susceptible mouse strain to sublethal and lethal leptospirosis. The goal of our study was to evaluate if low tlr4 responsiveness to leptospiral LPS in C3H-HeJ mice is the factor that drives susceptibility to infection with pathogenic Leptospira. We did a comparative study using mouse strains immunocompetent and hyporesponsive to tlr4. The data shows that although tlr4 does affect the virulence of leptospirosis (only C3H-HeJ succumbed to infection), the tlr4 competent strains (C3H-HeN and C57BL/6) also developed measurable sublethal leptospirosis. Thus, competent recognition of leptospiral-LPS by murine TLR4 plays a role but it is not sufficient to determine susceptibility to leptospirosis. Furthermore, the data suggests that T-cell dependent responses could be involved in susceptibility to leptospirosis in the C3H models of infection.

microbiology↗

bioRxiv2024

Exposure to live saprophytic Leptospira before challenge with a pathogenic serovar prevents severe leptospirosis and promotes kidney homeostasis

Previous studies demonstrated that Leptospira biflexa, a saprophytic species, triggers innate immune responses in the host during early infection. This raised the question of whether these responses could suppress a subsequent challenge with pathogenic Leptospira. We inoculated C3H/HeJ mice with a single or a double dose of L. biflexa before challenge with a pathogenic serovar, L. interrogans serovar Copenhageni FioCruz (LIC). Pre-challenge exposure to L. biflexa did not prevent LIC dissemination and colonization of the kidney. However, it rescued weight loss and mouse survival thereby mitigating disease severity. Unexpectedly, there was correlation between rescue of overall health (weight gain, higher survival, lower kidney fibrosis marker ColA1) and higher shedding of LIC in urine. This stood in contrast to the L. biflexa unexposed LIC challenged control. Immune responses were dominated by increased frequency of effector T helper (CD4+) cells in spleen, as well as significant increases in serologic IgG2a. Our findings suggest that exposure to live saprophytic Leptospira primes the host to develop Th1 biased immune responses that prevent severe disease induced by a subsequent challenge with a pathogenic species. Thus, mice exposed to live saprophytic Leptospira before facing a pathogenic serovar may withstand infection with far better outcomes. Furthermore, a status of homeostasis may have been reached after kidney colonization that helps LIC complete its enzootic cycle. SignificancePrevious evidence of host innate immunity induced by live saprophytic Leptospira in mice led us to posit that these responses might mitigate leptospirosis severity upon a subsequent challenge with a pathogenic serovar. In this study, we validated our hypothesis. This is important for development of novel strategies to control leptospirosis and for understanding the epidemiologic risk factors of this and other infectious diseases transmitted by direct contact between pathogen and host. Unexpectedly, these studies also show that there is a correlation between kidney health after L. interrogans infection (less fibrosis marker ColA1) and higher shedding of this spirochete in urine. This suggests that a status of homeostasis may be reached after kidney colonization by L. interrogans that helps the spirochete fulfill its enzootic cycle.

immunology↗

bioRxiv2022

Infected I. scapularis nymphs maintained in prolonged questing under optimal environmental conditions for one year can transmit B. burgdorferi to uninfected hosts

In recent decades, Lyme disease has been expanding to previous non-endemic areas. We hypothesized that infected I. scapularis nymphs that retain host-seeking behavior under optimal environmental conditions are fit to fulfil their transmission role in the enzootic cycle of B. burgdorferi. To test this hypothesis, we produced nymphal ticks in the laboratory under controlled temperature (22-25{degrees}C), humidity (80-90%) and natural daylight cycle conditions to allow them to retain host-seeking/questing behavior for 1 year. We then analyzed differences in B. burgdorferi infection prevalence in questing and diapause nymphs at 6 weeks post-molting (prime questing) as well as differences in infection prevalence of questing nymphs maintained under prolonged environmental induced questing over 12 months (prolonged questing). Lastly, we analyzed the fitness of nymphal ticks subjected to prolonged questing in transmission of B. burgdorferi to naive mice over the course of the year. Our study shows that B. burgdorferi infected unfed I. scapularis nymphal ticks maintained under optimal environmental conditions in the laboratory not only survived for a year in a developmental state of prolonged questing (host-seeking), as they retained an infection prevalence sufficient to effectively fulfil transmission of B. burgdorferi to uninfected mice after tick challenge. Our study is important for understanding and possibly modeling Lyme disease expansion into former non-endemic regions due to global warming. IMPORTANCELyme disease is rapidly spreading from its usual endemic areas in the Northeast, Midwest and Midatlantic states into neighboring areas which could be due to changing climate patterns. Our study shows that unfed I. scapularis nymphal ticks kept under optimal environmental conditions in the laboratory survived for a year while exhibiting aggressive host-seeking behavior and they maintained a B. burgdorferi infection prevalence which was sufficient to infect naive reservoir hosts after tick challenge. Our study raises important questions regarding prolonged survival of B. burgdorferi infected host-seeking nymphal I. scapularis ticks that can potentially increase the risk of Lyme disease incidence, if conditions of temperature and humidity become amenable to the enzootic cycle of B. burgdorferi in regions currently classified as non-endemic.

microbiology↗

bioRxiv2021

Maternal transfer of neutralizing antibodies to OspA after oral vaccination of the rodent reservoir

Lyme Disease presents unique challenges for public health efforts. We hypothesized that transfer of protective antibodies between mothers and offspring should occur after oral vaccination of C3H-HeN mice with E. coli overexpressing OspA. We present new evidence for maternal transfer of vaccine induced neutralizing anti-OspA IgG antibodies to mouse pups through ingestion of colostrum. Protective levels of OspA antibodies in pups were present from 2-5 weeks after birth and they persisted in some mice until 9 weeks of age. This was corroborated by detection of neutralizing antibodies in the serum of all pups at 2-3 weeks after birth and in some mice at 9 weeks of age. A clear association was found between robust antibody responses in mothers and the length of antibody persistence in the respective pups using a novel longitudinal Bayesian model. These factors are likely to impact the enzootic cycle of B. burgdorferi when reservoir targeted OspA-based vaccination interventions are implemented.

microbiology↗

bioRxiv2020

Maximum Antigen Diversification in a Lyme Bacterial Population and Evolutionary Strategies to Overcome Pathogen Diversity

Natural populations of microbes and their hosts are engaged in an arms race in which microbes diversify to escape host immunity while hosts evolve novel immunity. This co-evolutionary process, known as the "Red Queen" hypothesis, poses a fundamental challenge to the development of broadly effective vaccines and diagnostics against a diversifying pathogen. Based on surveys of natural allele frequencies and experimental immunization of mice, we show minimal antigenic cross-reactivity among natural variants of the outer surface protein C (OspC), a dominant antigen of a Lyme Disease-causing bacterium (Borrelia burgdorferi). To overcome the challenge of OspC antigenic diversity to clinical development of preventive measures, we implemented a number of evolution-based strategies to broaden OspC immunological cross-reactivity. In particular, the centroid algorithm - a genetic algorithm to minimize sequence differences with natural variants - generated synthetic OspC analogs with the greatest promise as diagnostic and vaccine candidates against diverse Lyme pathogen strains coexisting in the Northeast United States. Mechanistically, we propose a model of runaway maximum antigen di-versification (MAD) mediated by amino-acid variations distributed across hypervariable regions on the OspC molecule. Under the MAD model, evolutionary centroids display high cross-reactivity by occupying the central void in the antigenic space excavated by diversifying natural variants. In contrast to the vaccine design based on concatenated epitopes, the centroid algorithm generates analogs of native antigens and is automated. The MAD model and evolution-inspired antigen designs have broad implications for combating diversifying pathogens driven by pathogen-host coevolution. ImportanceMicrobial pathogens rely on molecular diversity of cell surface antigens to escape host immunity. Vaccines based on one antigen variant often fail to protect the host against pathogens carrying other variants. Here we show evolution-based designs of synthetic antigens that are broadly reactive to all natural variants. The evolutionary analogs of a major surface antigen of a Lyme disease bacterium (Borrelia burgdorferi) showed promise as vaccine candidates against diverse pathogen strains coexisting in the endemic areas of Lyme disease in Northeast United States. Our evolution-based computational design is automated, generates molecular analogs of natural antigens, and opens a novel path to combating fast-evolving microbial pathogens.

microbiology↗

bioRxiv2020

Humanized TLR4 immunocompetent mice are more susceptible to kidney disease after infection with Leptospira interrogans than wild-type mice

Toll-Like Receptor (TLR) 4, the LPS receptor, plays a central role in the control of leptospirosis and absence of TLR4 results in lethal infection in mice. Because human TLR4 does not sense the atypical leptospiral-LPS, we hypothesized that TLR4/MD-2 humanized transgenic mice (huTLR4) may be more susceptible to leptospirosis than wild-type mice, and thus may constitute a model of acute human leptospirosis. Therefore, we infected huTLR4 mice, which express human TLR4 but not murine TLR4, with a high but sublethal dose of L. interrogans serovar Copenhageni FioCruz (Leptospira) in comparison to C57BL/6J wildtype (WT) and, as a control, a congenic strain in which the tlr4 coding sequences are deleted (muTLR4Lps-del). We show that the huTLR4 gene is fully functional in the murine background. We found that dissemination of Leptospira in blood, shedding in urine, colonization of the kidney and overall kinetics of leptospirosis progression is equivalent between WT and huTLR4 C57BL/6J mice. Furthermore, inflammation of the kidney appeared to be subdued in huTLR4 compared to WT mice in that we observed less infiltrates of mononuclear lymphocytes, less innate immune markers and no relevant differences in fibrosis markers. Contrary to our hypothesis, huTLR4 mice showed less inflammation and kidney pathology, and are not more susceptible to leptospirosis than WT mice. This study is significant as it indicates that one intact TLR4 gene, be it mouse or human, is necessary to control acute leptospirosis. Contribution to the fieldDifferences of recognition exist between mouse and human TLR4, in that the anchor of LPS in the outer membrane of Leptospira (LipidA) activates murine, but not human TLR4. We hypothesized that if human TLR4 does not sense leptospiral-LPS, then transgenic mice in which murine TLR4 was replaced with human TLR4, should be more susceptible to Leptospira dissemination as compared to congenic wild-type mice, which could result in a more robust inflammatory response and pathology in the kidney. However, we found that impaired sensing of leptospiral-LPS in huTLR4 mice did not affect overall infection in comparison to wild-type mice and does not result in increased pathology of the kidney. Our study indicates that rather than leptospiral-LPS sensing, the presence of a fully functional TLR4 receptor is necessary to control acute leptospirosis.

microbiology↗

bioRxiv2018

Transdermal, but not oral mucosa exposure, causes sublethal leptospirosis in mice

The goal of this study was to determine the timing of Leptospira dissemination after infection using natural physiologic routes and its correlation with signs and symptoms of leptospirosis. Groups of C3H-HeJ mice were sub-lethally infected through exposure of a dermis wound and the oral mucosa to L. interrogans serovar Copenhageni, and compared to mice infected via standard laboratory practice of intraperitoneal inoculation. We found that transdermal infection leads to delayed bacterial dissemination in blood and urine when compared to intraperitoneal infection using the same infectious dose, and that the overlapping presence of L. interrogans in both fluids was twice as long as the standard intraperitoneal infection. Furthermore, dissemination of L. interrogans and disease did not occur in mice infected with the same dose of L. interrogans via the oral mucosa. Over the course of these studies we also observed that the timing of exit of Leptospira from blood and establishment of colonization of the kidney in the second week of infection correlated well with weight loss, but not with hypothermia. Thus, a non-invasive sign of leptospirosis such as weigh loss can be used to monitor bacterial dissemination and disease stage in mice. Our findings underline the importance of precise determination of windows of pathogen dissemination in biological fluids and how the route of infection affects the progression of disease. These studies could help focus the development of better treatment strategies and new technologies for diagnostic use.

microbiology↗

bioRxiv2018

Lethality of leptospirosis depends on sex: male hamsters succumb to infection with lower doses of pathogenic Leptospira

Leptospirosis is a widespread zoonotic disease caused by pathogenic spirochetes of the genus Leptospira which affect both humans and animals. A somewhat contradictory published body of evidence suggests that sex impacts severity outcomes of human Leptospirosis. In this study, we used an acute animal model of disease to analyze how male and female hamsters infected side-by-side with low but increasing doses of L. interrogans under the same exposure conditions develop Leptospirosis. We found that female hamsters were considerably more resistant to Leptospirosis given that 87.5% survived infection; male hamsters did not gain weight and 93.7% succumbed to infection with the same infectious doses. Analysis of bacterial burden in kidney of male hamsters showed that infection with the lowest dose (103) resulted in a 4Log increase of L. interrogans, whereas females infected with the same dose had a reduction of ~1Log, after 28 days of infection. Non-surviving hamsters had signs of compromised renal function (higher levels of creatinine in blood), as well as increased levels of anti-inflammatory IL-10 and innate response pro-inflammatory CCL3, CxCL10 and TNF- in kidney, as well as ColA1 which is a marker of kidney fibrosis. In endemic areas, humans are more often exposed to the lower infection doses which were lethal to males, than the higher doses which were lethal to males and females. It is possible that the frequency of lower infectious doses in nature and increased biological susceptibility both contribute for aggravated outcomes of leptospirosis in males.

microbiology↗

bioRxiv2018

Diagnosis of Human Leptospirosis: High Resolution Melting Analysis for Direct Detection of Leptospira in the Early Stage of the Disease in a Clinical Setting

Currently, the direct detection of Leptospira infection can be done in clinical laboratories by a conventional nested polymerase chain reaction method (nested PCR), which is labourious and time-consuming. To overcome these drawbacks, we tested a set of paired samples of serum and urine from 202 patients presenting at a hospital located in an area endemic for leptospirosis using high resolution melting (HRM). The results were compared with those obtained by nested PCR for direct detection of the pathogen in both specimens and with the gold standard test used for indirect detection of anti-Leptospira antibodies in serum (the microscopic agglutination test, MAT). The HRM assay results were positive for 46/202 (22.7%) samples, whereas 47/202 (23.3%) samples were positive by nested PCR. As expected in recently infected febrile patients, MAT results were positive in only 3/46 (6.5%) HRM-positive samples. We did a unique comparative analysis using a robust biobank of paired samples of serum and urine from the same patient to validate the HRM assay for molecular diagnosis of human leptospirosis in a clinical setting. This assay fills a void unmet by serologic assays as it can detect the presence of Leptospira in biological samples even before development of antibody takes place.

microbiology↗