Biology subjects

Yabsley, M. J.

Publications and source records attributed to Yabsley, M. J..

5 recordsLinked to original sources

bioRxiv2025

Comparative transcriptome profiles of first-stage larvae and adult female Dracunculus medinensis (Guinea worm)

Dracunculus medinensis, also called the Guinea worm, is a nematode that causes dracunculiasis, a debilitating neglected tropical disease in humans. The parasite is currently targeted by the global Guinea Worm Eradication Program (GWEP). Historically, GWEP in endemic countries have focused on interrupting transmission of the disease through intervention such as isolation and management of patients, health education, provision of improved water sources and promotion of filtering drinking water to avoid ingestion of the copepod intermediate host (IH) that may contain infectious third-stage larvae. The recent shift of Guinea worm infections in animals - particularly domestic dogs - has introduced an additional challenge to the eradication program, underscoring the urgent need for diagnostics and therapeutics. Understanding the parasite biology and survival strategies in the mammalian host, the copepod IH, and fresh water is pivotal to identifying new control measures. Comparative transcriptomic analysis provides a powerful tool to uncover the molecular mechanisms underlying parasite survival and adaptations. Here, we compared the transcriptome of adult gravid female and first-stage larvae (L1), the stage infective for the copepod IH. Comparative transcriptomic analysis of two adult females and their L1 revealed an upregulation of genes involved in translation, transcription, and DNA repair in L1, likely reflecting adaptations essential for survival in freshwater and subsequent infection of copepods. Additionally, genes involved in cuticle formation were upregulated in adult females highlighting the role of cuticle integrity in retaining millions of L1 until the gravid female worm emerges. We identified highly expressed genes in the adult female that may represent promising candidates for diagnostic markers. This study provides novel insights into the biology of the Guinea worm by examining the transcriptome of L1 and adult female stages. These findings could support the development of novel diagnostics and therapeutics to advance the ongoing eradication effort. Authors summaryGuinea worm disease is caused by the nematode Dracunculus medinensis, a parasitic worm responsible for a debilitating neglected tropical disease in humans and targeted for global eradication. Infection occurs through the consumption of contaminated drinking water with the infective larval stage harbored within fresh water crustacean copepods - the intermediate host of the parasite. The high number of Guinea worm infections in animals specially dogs poses a significant challenge to eradication, as infected animals act as reservoirs, contributing to the parasites persistence in the environment. Furthermore, the absence of early diagnostic tools and effective therapeutics complicates disease control. In this study, we performed a comparative transcriptome analysis of adult female Guinea worms and their first-stage larvae. We identified highly expressed genes in the adult female that may represent promising candidates for diagnostic markers. Additionally, we found genes and pathways upregulated in first-stage larvae which are likely essential for survival in freshwater and subsequent infection of copepods. Our study provides insight into the molecular mechanisms underlying Guinea worm survival across life stages and environments. These findings aim to support the development of novel diagnostics and therapeutics to advance ongoing eradication efforts of this neglected tropical disease.

genomics↗

bioRxiv2024

Duplex PCR assay to determine sex and mating status of Ixodes scapularis (Acari: Ixodidae), vector of the Lyme disease pathogen

Ticks are a major health threat to humans and other animals, through direct damage, toxicoses, and transmission of pathogens. An estimated half a million people are treated annually in the United States of America for Lyme disease, a disease caused by the bite of a black-legged tick (Ixodes scapularis Say) infected with the bacterial pathogen Borrelia burgdorferi. This tick species also transmits another six human-disease causing pathogens, for which vaccines are currently unavailable. While I. scapularis are sexually dimorphic at the adult life stage, the DNA sequence differences between male and female I. scapularis that could be used as a sex-specific marker have not yet been established. We determine the sex-specific DNA sequences for I. scapularis (male heterogametic system with XY), using whole-genome resequencing and restriction site-associated DNA sequencing. Then we identify a male-specific marker that we use as the foundation of a molecular sex identification method (duplex PCR) to differentiate the sex of an I. scapularis tick. In addition, we provide evidence that this molecular sexing method can establish the mating status of adult females that have been mated and inseminated with male-determining sperm. Our molecular tool allows the characterization of mating and sex-specific biology across development for I. scapularis, a major pathogen vector, which is crucial for a better understanding of their biology and controlling tick populations.

genomics↗

bioRxiv2024

One Health in practice: Multi-season survey of ixodid tick species collected from domestic dogs in Chad

Ticks are medically important vectors of pathogens, many of which are zoonotic or impact domestic animal and/or wildlife health. Climate change, landscape use, and increasing interactions between domestic animals, wildlife, and humans have resulted in changes in tick-host dynamics and the emergence of novel pathogens worldwide. Therefore, it is crucial to describe the host and geographic ranges of vector species to assess disease risk, particularly in areas where research is lacking. This task necessitates adopting a One Health approach. In sub-Saharan Africa, previous work on ticks has focused primarily on those species most relevant to domestic livestock or humans, highlighting a significant knowledge gap concerning species of ticks that infest peri-domestic animals in rural areas. The objective of this study was to investigate the species diversity of ticks on peri-domestic dogs in rural areas of Chad, Africa. From 2019-2022, we collected 3,412 ixodid ticks from 435 peri-domestic dogs from 23 villages in Chad, Africa during both dry and wet seasons. Ticks were identified to species using morphological techniques and/or molecular analyses of the 16S rRNA, 12S rRNA, and cytochrome oxidase I gene regions. We identified 11 species of ticks from dogs including Amblyomma variegatum, Amblyomma marmoreum, Haemaphysalis leachi, a Haemaphysalis sp., Hyalomma impressum, Hyalomma truncatum, Rhipicephalus decoloratus, Rhipicephalus guilhoni, Rhipicephalus muhsamae, Rhipicephalus linnaei (=R. sanguineus tropical lineage), and a Rhipicephalus sp. Several of these tick species are known vectors for important canine and zoonotic pathogens and some are more commonly associated with cattle hosts. Our results show that sampling ticks from peri-domestic dogs provides an opportunity to examine vectors that may infest domestic animals, agricultural animals, wildlife, and humans as hosts in an understudied area. HighlightsO_LITick-borne diseases are significant concern across sub-Saharan Africa C_LIO_LILimited data on ticks of animals and people in Chad, Africa C_LIO_LIA high diversity of tick species infested domestic dogs in Chad C_LIO_LIMany detected tick species associated with important pathogens C_LI

zoology↗

bioRxiv2021

Experimental susceptibility of North American raccoons (Procyon lotor) and striped skunks (Mephitis mephitis) to SARS-CoV-2

Skunks and raccoons were intranasally inoculated or indirectly exposed to SARS-CoV-2. Both species are susceptible to infection; however, the lack of, and low quantity of infectious virus shed by raccoons and skunks, respectively, and lack of cage mate transmission in both species, suggest that neither species are competent SARS-CoV-2 reservoirs. Article Summary LineExperimental SARS-CoV-2 inoculation of North American raccoons and striped skunks showed susceptibility to infection, but transient, low-level shedding suggests that neither species is likely to be a competent natural reservoir.

microbiology↗

bioRxiv2019

Population genomic evidence that human and animal infections in Africa come from the same populations of Dracunculus medinensis

BackgroundGuinea worm - Dracunculus medinensis - was historically one of the major parasites of humans and has been known since antiquity. Now, Guinea worm is on the brink of eradication, as efforts to interrupt transmission have reduced the annual burden of disease from millions of infections per year in the 1980s to only 30 human cases reported globally last year. Despite the enormous success of eradication efforts to date, one complication has arisen. Over the last few years, hundreds of dogs have been found infected with this previously apparently anthroponotic parasite, almost all in Chad. Moreover, the relative numbers of infections in humans and dogs suggests that dogs may be key in maintaining transmission in that country.\n\nResultsIn an effort to shed light on this peculiar epidemiology of Guinea worm in Chad, we have sequenced and compared the genomes of worms from dog, human and other animal infections. Confirming previous work with other molecular markers, we show that all of these worms are D. medinensis, and that the same population of worms are causing both infections, can confirm the suspected transmission between host species and detect signs of a population bottleneck due to the eradication efforts. The diversity of worms in Chad appears to exclude the possibility that there were no, or very few, worms present in the country during a 10-year absence of reported cases.\n\nConclusionsThis work reinforces the importance of adequate surveillance of both human and dog populations in the Guinea worm eradication campaign and suggests that control programs should stay aware of the possible emergence of unusual epidemiology as they approach elimination.

genomics↗