Biology subjects

Forbes, K. M.

Publications and source records attributed to Forbes, K. M..

8 recordsLinked to original sources

bioRxiv2026

Egyptian rousette bat humoral immunity to H9 influenza hemagglutinin

In mammals, antibodies are central to antiviral defense, but they can also impose selective pressure that drives viral evolution. The interplay between viral antigenic variation and host antibody diversification constitutes a molecular arms race that influences pathogenicity, transmission, and spillover risk. Bats are reservoirs for zoonotic viruses with pandemic potential yet they appear to tolerate infection without overt disease. Although distinctive features of bat innate immunity have been described, the role of adaptive immunity--particularly antibody-mediated responses--remains largely undefined. Moreover, how antibody evolutionary pressure operates in bats is unknown, in part because tools to interrogate bat B cell responses at the monoclonal level are limited. Here, we developed a yeast surface display library of bat antibodies derived from splenic RNA of wild-caught Egyptian rousette bats to interrogate humoral responses to the bat-derived H9 influenza hemagglutinin. We isolated monoclonal antibodies recognizing the hemagglutinin (HA) antigen and defined their gene usage, somatic hypermutation frequency, binding affinities, and breadth. We then used cryo-EM to structurally characterize three bat antibodies in complex with HA engaging distinct antigenic sites. Together, these data enable direct comparison with human anti-influenza antibodies highlighting similarities in humoral immunity across mammals and provides a tool to examine bat antibody responses to other potential zoonotic viruses.

immunology↗

bioRxiv2026

Bartonella and hemotropic Mycoplasma species in synanthropic bats in Kenya

Identifying and characterizing zoonotic pathogens in wildlife is essential for understanding disease risk to humans. In Sub-Saharan Africa, many people live with bats in their houses and are exposed to their pathogens, yet little is known about the bacterial pathogens in Afrotropical bat species. Globally, Bartonella spp. (bartonellae) and hemotropic Mycoplasma spp. (hemoplasmas) are common bacterial pathogens in bats, and some lineages are known to spill over and cause infections in humans. To evaluate this disease risk, we screened three common synanthropic bat species in Kenya, and their ectoparasites, for hemoplasmas and bartonellae and assessed their relatedness to known human pathogens. Of 767 bats across 21 sites, 17.9% of bats were Bartonella spp. positive and 19.3% were hemoplasma positive. Bat ectoparasites had similar Bartonella prevalence (13.5-25.0%) and, for most bat species, ectoparasite loads were not associated with increased likelihood of Bartonella infection. We found that Bartonella lineages displayed phylogenetic overlap between different bat species and ectoparasites, suggesting pathogen sharing between species, while hemoplasma lineages corresponded strictly to host taxonomy. Finally, we found that 16S rRNA sequences from one heart-nosed bat (Cardioderma cor) were 97.85% similar to a human-associated hemoplasma found previously in Schreibers bats (Miniopterus schreibersii) in Spain. We show that synanthropic bats host bacteria of potential public health concern, highlighting the need to investigate the emerging impacts of these pathogens on human health in Kenya and elsewhere in Sub-Saharan Africa.

ecology↗

bioRxiv2026

Rat hepatitis E virus and novel paramyxoviruses in synanthropic rodents and shrews in Kenya

The majority of emerging infectious diseases are zoonotic, having their origin in wildlife before spilling over into the human population. While small mammals are recognized as critical reservoirs for these viruses, their viral diversity remains largely uncharacterized across many African countries. We conducted molecular surveillance of synanthropic rodents and shrews in the Kibera informal settlement in Nairobi and the rural Taita Hills region of Kenya to detect and characterize potential zoonotic viruses. Tissue samples from 228 rodents and shrews were screened for six viral families using PCR assays. Rat hepatitis E virus (HEV) (Rocahepevirus ratti), a rodent-associated virus with potential for human spillover, was identified in Mus musculus and Rattus norvegicus from Kibera. NGS was conducted for the HEV positive samples, and we obtained two near-complete HEV genomes from Rattus norvegicus, which clustered within rodent-associated HEV genotypes in the phylogenetic analysis. The two sequences from the Rattus norvegicus cluster together, indicating a close genetic relationship. Paramyxoviruses belonging to the genera Jeilongvirus and Parahenipavirus were detected both from Taita and Kibera in nine different samples from Rattus norvegicus, Mus minutoides, Crocidura sp and Acomys ignitus. One paramyxovirus positive sample (Acomys ignitus) from Taita was selected for further sequencing with NGS, and a complete genome of a new jeilongvirus was assembled. Phylogenetic analysis of the detected viruses confirmed the close relation to previously known rodent-borne jeilongviruses but also revealed potentially novel jeilong- and parahenipavirus species. Our findings highlight the circulation of potentially zoonotic viruses in both urban and rural small mammals in Kenya. It emphasizes the necessity of continued genomic surveillance of zoonotic viruses to mitigate risks of their spillover into human populations. HighlightsO_LISurveillance reveals diverse rodent-borne viruses circulating in Kenya. C_LIO_LIRat-HEV was detected in Rattus norvegicus and Mus musculus from an urban low-income area. C_LIO_LIParamyxoviruses were detected across multiple rodent and shrew species, including novel Acomys ignitus jeilongvirus. C_LI Graphical abstract O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=139 SRC="FIGDIR/small/719784v1_ufig1.gif" ALT="Figure 1"> View larger version (66K): org.highwire.dtl.DTLVardef@86c94aorg.highwire.dtl.DTLVardef@10946adorg.highwire.dtl.DTLVardef@1ff45eforg.highwire.dtl.DTLVardef@4876f1_HPS_FORMAT_FIGEXP M_FIG C_FIG

microbiology↗

bioRxiv2026

Age-dependent effects of infection on survival of a wild rodent reservoir host

Due to long co-evolutionary histories, many zoonotic pathogens are thought to exert little or no negative effects on their wildlife reservoir hosts. However, there remains a lack of rigorous investigations in natural settings. We conducted a 3-year factorial field experiment to investigate how survival of the Puumala hantavirus (PUUV) reservoir, the bank vole, is impacted by PUUV infection, nematode infections, and food availability. We hypothesized that PUUV would not impact survival, but that coinfection with nematodes would negatively impact survival, and that increased food availability would mitigate the negative effects of coinfection. Surprisingly, we demonstrated that PUUV infected voles had substantially reduced survival when compared to uninfected voles, and this strong negative effect manifested in young voles. Nematode removal increased survival of young voles and food supplementation interacted with movement rather than survival. Our results provide empirical evidence in a natural system for infection reducing survival of its reservoir host.

ecology↗

bioRxiv2026

Food Supplementation Reduces Nematode Super-Shedding in a Wild Mammal

Anthropogenic changes to the environment, including altered food resource availability, influence host physiology, behaviour, and population dynamics, which can have strong downstream consequences on wildlife disease dynamics. Additionally, some individuals within a population contribute disproportionately to infection as super-shedders of infection, but the extent to which food availability alters the likelihood of super-shedding and overall parasite infection patterns is poorly understood. We conducted a three-year field experiment in southern Finland to investigate how food supplementation and parasite removal affect nematode infection measures and the relationship between nematode infection and fitness of wild bank voles (Clethrionomys glareolus). Using a factorial design across 12 populations, we manipulated food availability and administered anthelmintic treatments to assess effects on nematode infection status, intensity, and two measures of super-shedding (abundance super-shedding, intensity super-shedding). We also examined parasite impacts on host fitness, including apparent survival probability and reproductive status. Food supplementation did not affect likelihood of infection, intensity or intensity super-shedding, but did reduce the likelihood of abundance super-shedding, suggesting an effect of food availability on infection heterogeneity. We also identified an interaction between nematode infection status and host age on fitness. Notably, infected younger individuals had reduced survival and reproduction, but infected older individuals had greater survival and reproduction compared to their uninfected counterparts. Our study provides novel empirical evidence on how anthropogenic changes in food availability can influence parasite transmission dynamics and the fitness consequences of these sub-lethal parasites in a wildlife system.

ecology↗

bioRxiv2024

Ecological factors alter how spatial overlap predicts viral infection dynamics in wild rodent populations

Spatial overlap between animals in wildlife populations can have important implications for pathogen transmission. Ecological factors and animal demographic traits can influence animal space use and spatial overlap, but it is unclear how these interactions drive pathogen transmission. We experimentally manipulated wild bank vole populations via resource supplementation and anthelmintic treatment. Using network analysis, we investigated the relationship between spatial overlap and infection likelihood of an endemic zoonotic hantavirus, including how vole sex and reproductive status interact with spatial behaviour to affect infection likelihood. Spatial overlap in a previous month drove the likelihood of current hantavirus infection, and food supplementation and anthelmintic treatment altered the effects of spatial overlap on infection likelihood. Vole sex and reproductive status were important factors determining whether spatial overlap increased or decreased the likelihood of hantavirus infection and interacted with resource supplementation and anthelmintic treatment, generating different infection dynamics in each treatment. Our research provides rare empirical evidence linking previous spatial overlap to current infection status in wildlife populations, with implications for understanding disease dynamics and persistence as well as developing effective management efforts. We further highlight the importance of incorporating variation in ecological factors and host demography when studying pathogen transmission in wildlife systems.

ecology↗

bioRxiv2022

Effects of Food Addition and Helminth Removal on Space Use and Spatial Overlap in Wild Rodent Populations

1. Animal space use and spatial overlap can have important consequences for population-level processes such as social interactions and pathogen transmission. Identifying how environmental variability and inter-individual variation affect spatial patterns and in turn influence interactions in animal populations is a priority for the study of animal behavior and disease ecology. Environmental food availability and macroparasite infection are common drivers of variation, but there are few experimental studies investigating how they affect spatial patterns of wildlife. 2. Bank voles (Clethrionomys glareolus) are a tractable study system to investigate spatial patterns of wildlife and are amenable to experimental manipulations. We conducted a replicated, factorial field experiment in which we provided supplementary food and removed helminths in vole populations in natural forest habitat and monitored vole space use and spatial overlap using capture-mark-recapture methods. 3. Using network analysis, we quantified vole space use and spatial overlap. We compared the effects of food supplementation and helminth removal and investigated the impact of season, sex, and reproductive status on space use and spatial overlap. 4. We found that food supplementation decreased vole space use while helminth removal increased space use. Space use also varied by sex, reproductive status, and season. Spatial overlap was similar between treatments despite up to three-fold differences in population size. 5. By quantifying the spatial effects of food availability and macroparasite infection on wildlife populations, we demonstrate the potential for space use and population density to trade off and maintain consistent spatial overlap in wildlife populations. This has important implications for spatial processes in wildlife including pathogen transmission.

ecology↗

bioRxiv2021

Viral competence data improves rodent reservoir predictions for American orthohantaviruses

Identifying reservoir host species is crucial for understanding the risk of pathogen spillover from wildlife to people. Orthohantaviruses are zoonotic pathogens primarily carried by rodents that cause the diseases hemorrhagic fever with renal syndrome (HFRS) and hantavirus cardiopulmonary syndrome (HCPS) in humans. Given their diversity and abundance, many orthohantaviruses are expected to be undiscovered, and several host relationships remain unclear, particularly in the Americas. Despite the increasing use of predictive models for understanding zoonotic reservoirs, explicit comparisons between different evidence types for demonstrating host associations, and relevance to model performance in applied settings, have not been previously made. Using multiple machine learning methods, we identified phylogenetic patterns in and predicted unidentified reservoir hosts of New World orthohantaviruses based on evidence of infection (RT-PCR data) and competence (live virus isolation data). Infection data were driven by phylogeny, unlike competence data, and boosted regression tree (BRT) models using competence data displayed higher accuracy and a narrower list of predicted reservoirs than those using infection data. Eight species were identified by both BRT models as likely orthohantavirus hosts, with a total of 98 species identified by our infection models and 14 species identified by our competence models. Hosts predicted by competence models are concentrated in the northeastern United States (particularly Myodes gapperi and Reithrodontomys megalotis) and northern South America (several members of tribe Oryzomyini) and should be key targets for empirical monitoring. More broadly, these results demonstrate the value of infection competence data for predictive models of zoonotic pathogen hosts, which can be applied across a range of settings and host-pathogen systems. Author SummaryHuman diseases with wildlife origins constitute a significant risk for human health. Orthohantaviruses are viruses found primarily in rodents that cause disease with high rates of mortality and other complications in humans. An important step in disease prevention is to identify which rodent species carry and transmit orthohantaviruses. By incorporating species relatedness and evidence of different levels of host capacity to be infected and transmit virus, we used predictive modeling to determine unidentified rodent hosts of orthohantaviruses. Models using host competence data outperformed models using host infection data, highlighting the importance of stronger data in model optimization. Our results highlighted roughly a dozen key target species to be monitored that are concentrated in two geographic regions--northeastern United States and northern South America. More broadly, the approaches used in this study can be applied to a variety of other host-pathogen systems that threaten public health.

ecology↗