College of Natural Sciences, Forestry, and Agriculture_Covid Related Teaching Materials Email

Email thread featuring messages between Jeffrey St. John, Senior Associate Provost for Academic Affairs University of Maine and Pauline Kamath, Assistant Professor of Animal Health Animal and Veterinary Sciences School of Food & Agriculture regarding Professor Kamath\u27s submission of course material to the Provost Office on subjects related to the COVID-19 pandemic

College of Natural Sciences, Forestry, and Agriculture_AVS 249_Laboratory and Companion Animal Science Slides

Lecture slides from Pauline L. Kamath Class, Assistant Professor of Animal Health Animal and Veterinary Sciences School of Food & Agriculture Class AVS 249 Laboratory and Companion Animal Science

Pathogen-Mediated Evolution of Immunogenetic Variation in Plains Zebra (Equus quagga) of Southern Africa

Investigating patterns of variability in functional protein-coding genes is fundamental to identifying the basis for population and species adaptation and ultimately, for predicting evolutionary potential in the face of environmental change. The Major Histocompatibility Complex (MHC), a family of immune genes, has been one of the most emphasized gene systems for studying selection and adaptation in vertebrates due to its significance in pathogen recognition and consequently, in eliciting host immune response. Pathogen evasion of host resistance is thought to be the primary mechanism preserving extreme levels of MHC polymorphism and shaping immunogenetic patterns across host populations and species. In this thesis, I examined the evolution of two equine MHC genes, DRA and DQA, over the history of the genus Equus and across free-ranging plains zebra (E. quagga) populations of southern Africa: Etosha National Park (ENP), Namibia and Kruger National Park (KNP), South Africa. Furthermore, I evaluated the relationships between the DRA locus and parasite intensity in E. quagga of ENP, to elucidate the mechanisms by which parasites have shaped diversity at the MHC. In equids, the full extent of diversity and selection on the MHC in wild populations is unknown. Therefore, in this study, I molecularly characterized MHC diversity and selection across equid species to shed light on its mode of evolution in Equus and to identify specific sites under positive selection. Both the DRA and DQA exhibited a high degree of polymorphism and more intriguingly, greater allelic diversity was observed at the DRA than has previously been shown in any other vertebrate taxon. Global selection analyses of both loci indicated that the majority of codon sites are under purifying selection which may be explained by functional constraints on the protein. However, maximum likelihood based codon models of selection, allowing for heterogeneity in selection across codons, suggested that selective pressures varied across sites. Furthermore, at the DQA locus, all sites predicted to be under positive selection were antigen binding sites, implying that a few selected amino acid residues may play a significant role in equid immune function. Observations of trans-species polymorphisms and elevated genetic diversity were concordant with the hypothesis that balancing selection is acting on these genes. Over the past half century, the role of neutral versus selective processes in shaping genetic diversity has been at the center of an ongoing dialogue among evolutionary biologists. To determine the relative influence of demography versus selection on the DRA and DQA loci, I contrasted diversity patterns of neutral and MHC data across the E. quagga populations of ENP and KNP. Neutrality tests, along with observations of elevated diversity and low differentiation across populations relative to nuclear intron data, provided further evidence for balancing selection at these loci among E. quagga populations. However, at the DRA locus, differentiation was comparable to results at microsatellite loci. Furthermore, zebra in ENP exhibited reduced levels of diversity relative to KNP due to a highly skewed allele frequency distribution that could not be explained by demography. These findings were indicative of spatially heterogeneous selection and suggested directional selection and local adaptation at the DRA locus. There still remains a great deal of discussion over the mechanisms by which pathogens preserve immune gene diversity. The leading hypotheses that have been predominantly considered are: (i) heterozygote advantage (i.e. overdominant selection), (ii) rare allele advantage (i.e. frequency-dependent selection), and (iii) spatiotemporally fluctuating selection. An increasing number of studies have investigated MHC-parasite relationships to reconcile this debate, with conflicting results. To elucidate the mechanism driving the population-level patterns of diversity at the DRA locus, I examined relationships between this locus and both gastrointestinal (GI) and ectoparasite intensity in plains zebra of ENP. I discovered antagonistic pleiotropic effects of particular DRA alleles, with rare alleles predicting increased GI parasitism and common alleles associated with higher tick burdens. These results supported a frequency-dependent process and because maladaptive ‘susceptibility alleles’ were found at reduced frequencies, suggested that GI parasites exert strong selective pressure at this locus. Furthermore, heterozygote advantage also played a role in decreasing GI parasite burden, but only when a common allele was paired with a more divergent allele, implying that frequency-dependent and overdominant selection are acting in synchrony. These results indicated that an immunogenetic tradeoff may modulate resistance/susceptibility to parasites in this system, such that with MHC-based resistance to GI parasitism, a fitness cost is incurred to the host in the form of increased ectoparasite susceptibility. It is also suggested that these selective mechanisms are not mutually exclusive. In conclusion, these results provided species and population-level evidence for selection on the equid MHC, and highlighted the complexity in which selection operates in natural systems. In addition to heterogeneity in selective pressures at the molecular-level (across a gene region), selection likely varies spatiotemporally across populations due to fluctuations in pathogen regimes. Furthermore, pleiotropic effects of multiple pathogens can obscure our ability to understand adaptive processes. Given the level of complexity in which selection operates, I emphasize the necessity of incorporating multiple lines of evidence, using both neutral and adaptive data, to illuminate how selection operates. Finally, I also highlight the importance of considering the selective effects of multiple pathogens on host immunogenetics to better understand MHC function and adaptation

S5E8: How are ticks threatening Maine’s moose?

The moose has become so synonymous with Maine that it serves as the state animal. Residents and tourists alike scout the forests and mountains to catch at least a glimpse of this majestic mammal, and their odds aren’t too slim. Maine has the highest wild moose population in the lower 48 states, with 60,000–80,000 roaming the woods. Their population is considered stable, but it faces a tiny, yet lethal, threat: winter ticks. Moose populations along the southern edge of their range in the U.S. have been declining due to winter ticks, or moose ticks, and other parasites. Some moose carry as many as 70,000 ticks. Calves are especially at risk, as those with heavy tick loads often die in their first winter. Pauline Kamath, an assistant professor of animal health, is studying the impact of ticks on moose survival. On this episode of “The Maine Question,” she speaks with host Ron Lisnet about winter ticks and how they threaten the viability of Maine’s state animal

Movement ecology and sex are linked to barn owl microbial community composition.

The behavioural ecology of host species is likely to affect their microbial communities, because host sex, diet, physiology, and movement behaviour could all potentially influence their microbiota. We studied a wild population of barn owls (Tyto alba) and collected data on their microbiota, movement, diet, size, coloration, and reproduction. The composition of bacterial species differed by the sex of the host and female owls had more diverse bacterial communities than their male counterparts. The abundance of two families of bacteria, Actinomycetaceae and Lactobacillaceae, also varied between the sexes, potentially as a result of sex differences in hormones and immunological function, as has previously been found with Lactobacillaceae in the microbiota of mice. Male and female owls did not differ in the prey they brought to the nest, which suggests that dietary differences are unlikely to underlie the differences in their microbiota. The movement behaviour of the owls was associated with the host microbiota in both males and females because owls that moved further from their nest each day had more diverse bacterial communities than owls that stayed closer to their nests. This novel result suggests that the movement ecology of hosts can impact their microbiota, potentially on the basis of their differential encounters with new bacterial species as the hosts move and forage across the landscape. Overall, we found that many aspects of the microbial community are correlated with the behavioural ecology of the host and that data on the microbiota can aid in generating new hypotheses about host behaviour

Genomics reveals historic and contemporary transmission dynamics of a bacterial disease among wildlife and livestock

Whole-genome sequencing has provided fundamental insights into infectious disease epidemiology, but has rarely been used for examining transmission dynamics of a bacterial pathogen in wildlife. In the Greater Yellowstone Ecosystem (GYE), outbreaks of brucellosis have increased in cattle along with rising seroprevalence in elk. Here we use a genomic approach to examine Brucella abortus evolution, cross-species transmission and spatial spread in the GYE. We find that brucellosis was introduced into wildlife in this region at least five times. The diffusion rate varies among Brucella lineages (∼3 to 8 km per year) and over time. We also estimate 12 host transitions from bison to elk, and 5 from elk to bison. Our results support the notion that free-ranging elk are currently a self-sustaining brucellosis reservoir and the source of livestock infections, and that control measures in bison are unlikely to affect the dynamics of unrelated strains circulating in nearby elk populations

Development of conjugated secondary antibodies for wildlife disease surveillance

Disease monitoring in free-ranging wildlife is a challenge and often relies on passive surveillance. Alternatively, proactive surveillance that relies on the detection of specific antibodies could give more reliable and timely insight into disease presence and prevalence in a population, especially if the evidence of disease occurs below detection thresholds for passive surveillance. Primary binding assays, like the indirect ELISA for antibody detection in wildlife, are hampered by a lack of species-specific conjugates. In this study, we developed anti-kudu (Tragelaphus strepsiceros) and anti-impala (Aepyceros melampus) immunoglobulin-specific conjugates in chickens and compared them to the binding of commercially available protein-G and protein-AG conjugates, using an ELISA-based avidity index. The conjugates were evaluated for cross-reaction with sera from other wild herbivores to assess future use in ELISAs. The developed conjugates had a high avidity of >70% against kudu and impala sera. The commercial conjugates (protein-G and protein-AG) had significantly low relative avidity (<20%) against these species. Eighteen other wildlife species demonstrated cross-reactivity with a mean relative avidity of >50% with the impala and kudu conjugates and <40% with the commercial conjugates. These results demonstrate that species-specific conjugates are important tools for the development and validation of immunoassays in wildlife and for the surveillance of zoonotic agents along the livestock-wildlife-human interface

Genomics of Brucellosis in Wildlife and Livestock of the Greater Yellowstone Ecosystem

Brucellosis, a disease caused by the bacterium Brucella abortus, has recently been expanding its distribution in the Greater Yellowstone Ecosystem (GYE), with increased outbreaks in cattle and rising seroprevalence in elk (Cervus elaphus) over the past decade. Genetic studies suggest elk are a primary source of recent transmission to cattle. However, these studies are based on Variable Number Tandem Repeat (VNTR) data, which are limited in assessing and quantifying transmission among species. The goal of this study was to (i) investigate the introduction history of B. abortus in the GYE, (ii) identify B. abortus lineages associated with host species and/or geographic localities, and (iii) quantify transmission across wildlife and livestock host species and populations. We sequenced B. abortus whole genomes (n= 207) derived from isolates collected from three host species (bison, elk, cattle) over the past 30 years, throughout the GYE. We identified genetic variation among isolates, and applied a spatial diffusion phylogeographic modeling approach that incorporated temporal information from sampling. Based on these data, our results suggest four divergent Brucella lineages, with a time to most recent common ancestor of ~130 years ago, possibly representing a minimum of four brucellosis introductions into the GYE. Two Brucella lineages were generally clustered by geography. Evidence for cross-species transmission was detected among all species, though most events occur within species and herds. Understanding transmission dynamics is imperative for implementing effective control measures and may assist in identifying source populations responsible for past and future brucellosis infections in wildlife and outbreaks in livestock

Variation in herbivore space use: comparing two savanna ecosystems with different anthrax outbreak patterns in southern Africa

Abstract Background The distribution of resources can affect animal range sizes, which in turn may alter infectious disease dynamics in heterogenous environments. The risk of pathogen exposure or the spatial extent of outbreaks may vary with host range size. This study examined the range sizes of herbivorous anthrax host species in two ecosystems and relationships between spatial movement behavior and patterns of disease outbreaks for a multi-host environmentally transmitted pathogen. Methods We examined range sizes for seven host species and the spatial extent of anthrax outbreaks in Etosha National Park, Namibia and Kruger National Park, South Africa, where the main host species and outbreak sizes differ. We evaluated host range sizes using the local convex hull method at different temporal scales, within-individual temporal range overlap, and relationships between ranging behavior and species contributions to anthrax cases in each park. We estimated the spatial extent of annual anthrax mortalities and evaluated whether the extent was correlated with case numbers of a given host species. Results Range size differences among species were not linearly related to anthrax case numbers. In Kruger the main host species had small range sizes and high range overlap, which may heighten exposure when outbreaks occur within their ranges. However, different patterns were observed in Etosha, where the main host species had large range sizes and relatively little overlap. The spatial extent of anthrax mortalities was similar between parks but less variable in Etosha than Kruger. In Kruger outbreaks varied from small local clusters to large areas and the spatial extent correlated with case numbers and species affected. Secondary host species contributed relatively few cases to outbreaks; however, for these species with large range sizes, case numbers positively correlated with outbreak extent. Conclusions Our results provide new information on the spatiotemporal structuring of ranging movements of anthrax host species in two ecosystems. The results linking anthrax dynamics to host space use are correlative, yet suggest that, though partial and proximate, host range size and overlap may be contributing factors in outbreak characteristics for environmentally transmitted pathogens

Immunological evidence of variation in exposure and immune response to Bacillus anthracis in herbivores of Kruger and Etosha national parks

Exposure and immunity to generalist pathogens differ among host species and vary across spatial scales. Anthrax, caused by a multi-host bacterial pathogen, Bacillus anthracis, is enzootic in Kruger National Park (KNP), South Africa and Etosha National Park (ENP), Namibia. These parks share many of the same potential host species, yet the main anthrax host in one (greater kudu (Tragelaphus strepsiceros) in KNP and plains zebra (Equus quagga) in ENP) is only a minor host in the other. We investigated species and spatial patterns in anthrax mortalities, B. anthracis exposure, and the ability to neutralize the anthrax lethal toxin to determine if observed host mortality differences between locations could be attributed to population-level variation in pathogen exposure and/or immune response. Using serum collected from zebra and kudu in high and low incidence areas of each park (18- 20 samples/species/area), we estimated pathogen exposure from anti-protective antigen (PA) antibody response using enzyme-linked immunosorbent assay (ELISA) and lethal toxin neutralization with a toxin neutralization assay (TNA). Serological evidence of pathogen exposure followed mortality patterns within each system (kudus: 95% positive in KNP versus 40% in ENP; zebras: 83% positive in ENP versus 63% in KNP). Animals in the high-incidence area of KNP had higher anti-PA responses than those in the low-incidence area, but there were no significant differences in exposure by area within ENP. Toxin neutralizing ability was higher for host populations with lower exposure prevalence, i.e., higher in ENP kudus and KNP zebras than their conspecifics in the other park. These results indicate that host species differ in their exposure to and adaptive immunity against B. anthracis in the two parks. These patterns may be due to environmental differences such as vegetation, rainfall patterns, landscape or forage availability between these systems and their interplay with host behavior (foraging or other risky behaviors), resulting in differences in exposure frequency and dose, and hence immune response.NSF Division of Environmental Biology.https://www.frontiersin.org/journals/immunologydm2022Veterinary Tropical Disease