Biology subjects

Lopez, J. E.

Publications and source records attributed to Lopez, J. E..

7 recordsLinked to original sources

bioRxiv2026

Defining strain variation in the maintenance of Borrelia turicatae during hyperparasitism and transovarial transmission in Ornithodoros turicata

Tick-borne relapsing fever (TBRF) spirochetes are maintained in nature through vector-associated transmission routes primarily in argasid ticks. However, the extent to which strain-level differences influence the maintenance of TBRF spirochetes remains unclear. We evaluated two Borrelia turicatae strains, Bt-SSK1 and Bt-FCB, in Ornithodoros turicata. Both strains were acquired by female ticks, and after mating we unexpectedly observed that they were hyperparasitized by uninfected and unfed male O. turicata. Bt- SSK1 was maintained in males while Bt-FCB was not. Transovarial transmission (TOT) of Bt-SSK1 and Bt-FCB was also evaluated and striking differences were observed between strains. Bt-SSK1 was vertically maintained in F1 progeny but we failed to detect TOT of Bt-FCB. TOT of Bt-SSK1 occurred inefficiently in early ovipositions but increasing in later or delayed reproductive events, indicating a timing-dependent barrier. Using a gfp-expressing Bt-FCB strain, we show that failure of vertical transmission is associated with a lack of persistent oocyte colonization despite dissemination to ovarian tissues. These findings demonstrate strain-dependent differences in oocyte colonization and represent a critical bottleneck governing vertical transmission and persistence of relapsing fever spirochetes in tick populations. ImportanceVector-borne pathogens rely on diverse transmission strategies to persist in nature, yet the biological factors that govern these processes remain poorly understood. In this study, we demonstrated that strains of Borrelia turicatae differ markedly in their ability to persist within Ornithodoros turicata ticks. We also discovered that male ticks frequently hyperparasitized engorged females, creating an unrecognized transmission route in which previously uninfected ticks can acquire, maintain, and transmitted the B. turicatae. We further showed phenotypic differences in vertical transmission and that it is temporally regulated and linked to successful colonization of developing oocytes, identifying a critical bottleneck in pathogen maintenance. Together, these findings revealed that strain-specific traits influence both horizontal maintenance within tick populations and vertical transmission to progeny. This work provides insight into the ecological and evolutionary processes that enable relapsing fever spirochetes to persist in nature.

microbiology↗

bioRxiv2025

Human exposure to spirochete-infected Ornithodoros turicata collected from the home of an individual in the Austin, Texas Metropolitan Area

A Central Texas resident found an engorging Ornithodoros turicata tick attached to their leg while at home. The tick was submitted for testing, which confirmed that it was infected with a Borrelia species. Spirochetes were successfully cultured and whole genome sequencing confirmed that the species was Borrelia turicatae. The tick submitter reported being hospitalized and was recovering from Bells Palsy. Searching the Texas National Electronic Disease Surveillance System indicated that the individual had an undiagnosed febrile illness that spanned three weeks prior to finding the tick attached on them. These findings indicated possible recurrent tick exposure in a domestic environment.

microbiology↗

bioRxiv2023

Isolation and genomic characterization of the tick-borne relapsing fever spirochete, Borrelia turicatae, from ticks collected in a peridomestic setting of Camayeca, Mexico

Surveillance studies were implemented in Sinaloa, Mexico to determine the circulation of tick-borne relapsing fever spirochetes. Argasid ticks were collected from a human dwelling in the village of Camayeca and spirochetes were isolated. Genomic analysis indicated that Borrelia turicatae is a threat to those living in resource limited settings. Article Summary LineWe report the collection of argasid ticks from a peridomestic setting in Mexico and the isolation of Borrelia turicatae; increased surveillance efforts are needed on this overlooked vector-borne pathogen.

ecology↗

bioRxiv2023

Vertical transmission of Borrelia turicatae (Spirochaetales: Borreliaceae) by autogenously reproducing Ornithodoros turicata (Ixodida: Argasidae) female naturally infected with the spirochetes

Ornithodoros turicata is a vector of relapsing fever (RF) spirochetes in North America and transmits Borrelia turicatae to a variety of vertebrate hosts. The remarkably long lifespan of O. turicata and its ability to maintain spirochetes horizontally (between life stages) and vertically to progeny promotes the perpetuation of B. turicatae in nature. Nevertheless, the reproductive biology of O. turicata is poorly understood. In this report, we collected ticks from a park within a neighborhood of Austin, Texas. They were reared to adulthood and male ticks were individually housed with females. We observed autogenous reproduction by the ticks and further investigated vertical transmission of B. turicatae by quantifying filial infection rates in a cohort of progeny ticks. These results indicate that O. turicata transovarially transmits B. turicatae during autogenous reproduction and further signify the tick as a natural reservoir of the spirochetes. ImportancePrevious research has implicated Ornithodoros ticks, including Ornithodoros turicata, as long-term reservoirs of relapsing fever (RF) spirochetes. Considering the ticks long lifespan and their efficiency in maintaining and transferring spirochetes within the population, the infection could persist in a given enzootic focus for decades. However, little is known about the relative importance of horizontal and vertical transmission routes in the persistence and evolution of RF Borrelia. Our observations on the reproductive biology of O. turicata in the absence of vertebrate hosts indicate an additional mechanism by which B. turicata can be maintained in the environment. This work establishes the foundation for studying O. turicata reproduction and spirochete-vector interactions, which will aid in devising control measures for Ornithodoros ticks and RF spirochetes.

ecology↗

bioRxiv2023

Comparative genomics analysis of three conserved plasmid families in the Western Hemisphere soft tick-borne relapsing fever borreliae provides insight into variation in genome structure and antigenic variation systems

Borrelia spirochetes, causative agents of Lyme disease and relapsing fever (RF), have a uniquely complex genome consisting of a linear chromosome and circular and linear plasmids. The plasmids harbor genes important for the vector-host life cycle of these tick-borne bacteria. The role of Lyme disease causing Borrelia plasmids is more refined compared to RF spirochetes because of limited plasmid-resolved genomes for RF spirochetes. We recently addressed this limitation and found that three linear plasmid families (F6, F27, and F28) were syntenic across all species. Given this conservation, we further investigated the three plasmid families. The F6 family, also known as the megaplasmid, contained regions of repetitive DNA. The F27 was the smallest, encoding genes with unknown function. The F28 family encoded the expression locus for antigenic variation in all species except Borrelia hermsii and Borrelia anserina. Taken together, this work provides a foundation for future investigations to identify essential plasmid-localized genes that drive the vector-host life cycle of RF Borrelia. IMPORTANCEBorrelia spp. spirochetes are arthropod-borne bacteria found globally and infect humans and other vertebrates. RF borreliae are understudied and misdiagnosed pathogens because of the vague clinical presentation of disease and the elusive feeding behavior of argasid ticks. Consequently, genomics resources for RF spirochetes have been limited. Analyses of Borrelia plasmids have been challenging because they are often highly fragmented and unassembled. By utilizing Oxford Nanopore Technologies, we recently generated plasmid-resolved genomes for seven Borrelia spp. found in the Western Hemisphere. This current study is a more in-depth investigation into the linear plasmids that were conserved and syntenic across species. This analysis determined differences in genome structure and, importantly, in antigenic variation systems between species. This work is an important step in identifying crucial plasmid-borne genetic elements essential for the life cycle of RF spirochetes.

microbiology↗

bioRxiv2022

Development and validation of PainFace, a software platform that simplifies and standardizes mouse grimace analyses

Facial grimaces are now commonly used to quantify spontaneous pain in mice and other mammalian species, but scoring remains subjective and relies on humans with very different levels of proficiency. Here, we developed a Mouse Grimace Scale (MGS) for black-coated (C57BL/6) mice consisting of four facial action units (orbitals, nose, ears, whiskers). We used this scale to generate ground truth data from over 70,000 images of black mice in different settings. With this large data set, we developed a deep neural network and cloud-based software platform called PainFace (http://painface.net) that accurately scores facial grimaces of black mice on a 0-8 scale. PainFace generates over two orders of magnitude more MGS data than humans can realistically achieve, and at superhuman speed. By analyzing the frequency distribution of grimace scores, we found that mice spent >7x more time in a high grimace state following laparotomy surgery relative to sham surgery controls. The analgesic carprofen reduced the amount of time animals spent in this high grimace state after surgery. Specific facial action unit score combinations were overrepresented following laparotomy surgery, suggesting that characteristic facial expressions are associated with a high grimace state. We performed validation experiments in two labs located in different countries to demonstrate reproducibility of the PainFace platform. To further enhance rigor and reproducibility, we will invite pain researchers to beta test PainFace and then incorporate their feedback into the software and manuscript prior to peer review. While this study is focused on mice, PainFace was designed to simplify, standardize, and scale up grimace analyses with many other mammalian species, including humans.

neuroscience↗

bioRxiv2018

Immunological responses to the relapsing fever spirochete Borrelia turicatae in infected Rhesus macaques: implications for pathogenesis and diagnosis.

The global public health impact of relapsing fever (RF) spirochetosis is significant, as the pathogens exist on five of seven continents. The hallmark sign of infection is episodic fever and the greatest threat is to the unborn. With the goal of better understanding the specificity of B cell responses and the role of immune responses in pathogenicity, we infected Rhesus macaques with Borrelia turicatae (a new world RF spirochete species) by tick bite and monitored the immune responses generated in response to the pathogen. Specifically, we evaluated inflammatory mediator induction by the pathogen, host antibody responses to specific antigens, and peripheral lymphocyte population dynamics. Our results indicate that B. turicatae elicits from peripheral blood cells key inflammatory response mediators (IL-1{beta} and TNF-) which are associated with pre-term abortion. Moreover, a global decline in peripheral B cell populations was observed in all animals at 14 days post-infection. Serological responses were also evaluated to assess the antigenicity of three surface proteins, BipA, BrpA and Bta112. Interestingly, a distinction was observed between antibodies generated in non-human primates (NHPs) and mice. Our results provide support for the nonhuman primate model not only in studies of prenatal pathogenesis, but for diagnostic and vaccine antigen identification and testing.

immunology↗