Serologic survey for selected microbial agents in mammals from Alberta, 1976

Blood samples were taken from humans and several species of free-ranging wild mammals from five different geographic areas of Alberta, Canada. Sera were tested for antibody to eastern equine encephalitis (EEE) virus, western equine encephalitis (WEE) virus, St. Louis encephalitis (SLE) virus, Powassan (POW) virus, the snowshoe hare (SSH) strain of the California group (CAL) of viruses, Northway (NOR) virus, Klamath (KLA) virus, infectious bovine rhinotracheitis (IBR) virus, and two bacteria, Brucella abortus and Francisella tularensis. CAL antibody was found in 63% of 11 snowshoe hares (Lepus americanus), 33% of 167 black bears (Ursus americanus), and 19% of 55 humans (Homo sapiens). NOR antibody was found in 0.4% of 258 hares, 11% of 9 bighorn sheep (Ovis canadensis), 20% of 44 moose (Alces alces), 4% of 56 bears, 14% of 22 woodland caribou (Rangifer tarandus), and 2% of 50 humans. IBR antibody was detected in 14% of 14 moose. B. abortus antibody was found in 1% of 283 bears. F. tularensis antibody was detected in 2% of 52 humans. These findings represent extension of: (1) the natural host range of IBR, CAL, and NOR; (2) the geographical distribution of NOR infection in North America; and (3) the geographical distribution of CAL infection within Alberta.     

Prevalence of neutralizing antibody to Jamestown Canyon virus (California group) in populations of elk and moose in northern Michigan and Ontario, Canada

Blood samples were collected from free-ranging elk (Cervus elaphus) harvested in Michigan's northern Lower Peninsula, from moose (Alces alces) relocated from Ontario's Algonquin Provincial Park to Michigan's Upper Peninsula, and from moose from Michigan's Isle Royale National Park. Sera were tested by serum dilution neutralization tests in Vero cell culture for neutralizing antibody to California serogroup viruses, in particular Jamestown Canyon (JC), La Crosse/snowshoe hare (LAC/SSH), and trivittatus (TVT) viruses. Specific neutralizing antibody to JC virus was detected in 71% of 31 and 65% of 20 moose from Algonquin and Isle Royale, respectively. An additional six moose from Algonquin and five from Isle Royale showed evidence of multiple infection. One juvenile moose from Isle Royale had specific neutralizing antibody to TVT virus. Specific neutralizing antibody to JC virus was detected also in 54% of 50 elk from Michigan; 20 of the 50 elk showed evidence of multiple infection. While no single serum sample showed specific neutralizing antibody only to LAC/SSH virus, its presence in sera from some animals may have been masked by the high prevalence of antibody to JC virus.     

Serologic survey for selected microbial pathogens in Alaskan wildlife

Antibodies to Brucella spp. were detected in sera of seven of 67 (10%) caribou (Rangifer tarandus), one of 39 (3%) moose (Alces alces), and six of 122 (5%) grizzly bears (Ursus arctos). Antibodies to Leptospira spp. were found in sera of one of 61 (2%) caribou, one of 37 (3%) moose, six of 122 (5%) grizzly bears, and one of 28 (4%) black bears (Ursus americanus). Antibodies to contagious ecthyma virus were detected in sera of seven of 17 (41%) Dall sheep (Ovis dalli) and five of 53 (10%) caribou. Antibodies to epizootic hemorrhagic disease virus were found in sera of eight of 17 (47%) Dall sheep and two of 39 (6%) moose. Infectious bovine rhinotracheitis virus antibodies were detected in sera of six of 67 (9%) caribou. Bovine viral diarrhea virus antibodies were found in sera of two of 67 (3%) caribou. Parainfluenza 3 virus antibodies were detected in sera of 14 of 21 (67%) bison (Bison bison). Antibodies to Q fever rickettsia were found in sera of 12 of 15 (80%) Dall sheep. No evidence of prior exposure to bluetongue virus was found in Dall sheep, caribou, moose, or bison sera.     

Serologic survey for Toxoplasma gondii in selected wildlife species from Alaska

Blood was collected from selected wildlife species in specific areas of Alaska (USA) during 1976-96. A modified agglutination test was used to test sera for evidence of exposure to Toxoplasma gondii. Serum antibody prevalence was 43% (62 positive of 143 tested) for black bears (Ursus americanus), 9% (11/125) for wolves (Canis lupus), 7% (22/319) for Dall sheep (Ovis dalli), 6% (14/241) for caribou (Rangifer tarandus), 1% (3/240) for moose (Alces alces), and 1% (2/241) for bison (Bison bison). A predictive model was developed to determine the effect of sex, age, location, and year of collection on antibody prevalence for each species. Prevalence was higher in older black bears, caribou, and wolves. For black bears, prevalence was highest in the southeast region of the state. For caribou, prevalence was lowest on the Alaska Peninsula.     

Activity of California encephalitis group viruses in Entrelacs (province of Quebec, Canada)

During the summer of 1979, indicator rabbits were placed in three sites in Entrelacs (Laurentian area, province of Quebec) and mosquitoes were collected in order to monitor arbovirus activity in the area. Eight seroconversions to California encephalitis (CE) group viruses were detected in rabbits during June, July, and August. Twenty-five strains identified as members of the CE group were isolated: 3 were obtained from viremic rabbit sera, 1 from adult Aedes communis reared in the laboratory from field-collected larvae, and 21 from mosquito pools. Twenty-two of these were typed as snowshoe hare (SSH) virus. No evidence of La Crosse (LAC) virus was detected but three strains belonging to the CE group showed antigenic properties different from reference SSH, LAC, or Jamestown Canyon (JC) viruses. One isolate identified as Flanders virus was obtained from Culex pipiens. Three mosquito species (A. communis, A. punctor, and A. excrucians) were involved in the transmission cycle of SSH virus in Entrelacs. This is the first report, in the province of Quebec, of SSH isolation from animal sera and the first demonstration of its transovarial transmission.     

Serum antibody prevalence of malignant catarrhal fever viruses in seven wildlife species from Alaska

Blood samples were collected from seven species of free-ranging ungulates in Alaska. Sera were tested for evidence of exposure to malignant catarrhal fever viruses (MCFV) by means of a competitive enzyme-linked immunosorbent assay. Antibody prevalences were as follows: muskox (Ovibos moschatus) 100 positive samples of 104 tested (96%); Dall sheep (Ovis dalli) 212 of 222 (95%); elk (Cervus elaphus) 14 of 51 (27%); bison (Bison bison) 34 of 197 (17%); caribou (Rangifer tarandus) nine of 232 (4%); Sitka black-tailed deer (Odocoileus hemionus sitkensis) one of 49 (2%); and moose (Alces alces) three of 219 (1%). Antibody prevalence in a bison population from the Interior was stable over a 5 yr period. These results indicate that at least one virus in the MCF group is enzootic in Dall sheep and muskox in Alaska. Lower antibody prevalences in the other species in this survey suggest that MCFV are latent or subclinical in these free-ranging ruminants. Whole blood samples were collected from 14 Dall sheep and subjected to a polymerase chain reaction assay. Fragments of ovine herpesvirus-2 DNA were detected in six of the samples. The significance of these findings for the health of free-ranging ungulates in Alaska is unknown.     

Coyote prey selection and community stability during a decline in food supply

The foraging behavior of predators can have a large influence on community dynamics and has been shown to increase stability in some cases and decrease stability in others. I studied the foraging behavior of coyotes ( Canis latrans ) in the Alaska Range during the peak and decline of a snowshoe hare ( Lepus americanus ) population cycle (1999–2002). Coyote diet was compared with prey availability to test for changes in prey selection and to examine the effect of coyote predation on the vertebrate prey community. Coyotes responded to the hare decline by increasing selection for hares and porcupines, whereas selection for voles, ground squirrels and Dall sheep did not change. Although the study area was characterized by considerable habitat heterogeneity, coyotes utilized the area as a fine-grained environment. Coyote foraging behavior was driven primarily by changes in snowshoe hare abundance, and their sensitivity to change in alternative prey density was low. Predation by coyotes may therefore decrease the stability of alternative prey populations rather than dampening fluctuations. In order for predation to enhance the stability of prey populations, I hypothesize that prey profitability must be determined primarily by abundance.     

Antibodies to arboviruses in an Alaskan population at occupational risk of infection

A total of 435 United States Geological Survey and United States Forest Service workers in Alaska were studied for serologic evidence of past infections with four arboviruses known or suspected to be human pathogens. Of the personnel tested, 36 (8.3%) had the neutralizing antibody to Jamestown Canyon but not snowshoe hare virus, 6 (1.4%) had the antibody to snowshoe hare but not Jamestown Canyon virus, 53 (12.2%) had the antibody to both viruses, 17 (3.9%) had the antibody to Northway virus, and 15 (3.4%) had the antibody to Klamath virus. The indices most significantly correlated with presence of the Jamestown Canyon and snowshoe hare antibodies were the amount of fieldwork (p less than 0.001 for both antibodies) and the duration of employment by the agencies (p less than 0.0001 for Jamestown Canyon and 0.004 for snowshoe hare). The antibody to the four arboviruses also correlated strongly with a history of travel in certain remote or wilderness areas in Alaska (p values ranged from less than 0.001 to 0.086).     

California serogroup and Powassan virus infection of cats

One hundred and seventy five sera from cats in Ontario, Canada, were tested for hemagglutination inhibition (HI) antibodies to three arboviruses; namely, Powassan (POW) of the Flavivirus serogroup, and Snowshoe hare (SSH) and Jamestown Canyon (JC) viruses of the California (CAL) serogroup. All sera were negative for antibodies to POW virus. Twelve cats possessed CAL serogroup antibodies including 3 with antibodies to SSH alone, 6 with antibodies to JC alone, and 3 with antibodies to both SSH and JC antigens. POW virus was inoculated into seven cats, one intracerebrally and six intravenously. Neurologic signs were not detected in any of the cats. Histologic lesions of a nonsuppurative encephalitis and encephalomyelitis were observed in the intracerebrally inoculated cat and in one of the intravenously inoculated cats, respectively. POW virus was not isolated from the brain or spinal cord of either of these two cats. HI antibodies were detected in the sera of all inoculated animals. HI antibodies were not detected in the CSF of any animal.     

Serologic and experimental investigations of contagious ecthyma in Alaska

Serologic evidence of contagious ecthyma (CE) was found in domestic sheep (Ovis aries), domestic goats (Capra hircus), Dall sheep (Ovis dalli), and musk-ox (Ovibos moschatus) in Alaska. A moose (Alces alces) calf and a caribou (Rangifer tarandus) fawn were susceptible to experimental infection and both developed antibody titers as a result. CE virus was isolated from lesions of Dall sheep which were involved in a natural outbreak of the disease.     

Formation of recombinants between snowshoe hare and La Crosse bunyaviruses.

Wild-type recombinants were obtained at high frequency from coinfections of BHK cells involving temperature-sensitive, conditional-lethal mutants of snowshoe hare (SSH) and La Crosse (LAC) bunyaviruses. Analyses of two of the recombinants indicated that they have the genome compositions SSH/LAC/SSH and SSH/LAC/LAC for their respective L, M, and S virion RNA species. This evidence, together with that for the genetic stability of the recombinants, indicates that they were derived by segment reassortment of the competent genome pieces of the parental viruses. The SSH/LAC/SSH recombinant appears, from polypeptide analysis, to have the SSH type of nucleocapsid protein (N), whereas the SSH/LAC/LAC recombinant has the LAC nucleocapsid protein, suggesting that the viral S RNA codes for the N protein.     

Serological evidence of California serogroup virus activity in Oregon

We wished to demonstrate evidence of the presence of California serogroup viruses in Oregon and to test for the presence of certain other arboviruses in large ungulates. Blood samples from black-tailed deer (Odocoileus hemionus columbianus), mule deer (O. hemionus hemionus), and Roosevelt elk (Cervus elaphus roosevelti) from nine counties in Oregon were tested by serum-dilution plaque reduction neutralization for antibody to California serogroup viruses, including snowshoe hare, California encephalitis, and Jamestown Canyon, as well as to Cache Valley (Bunyamwera serogroup) and Klamath, an ungrouped rhabdovirus. Of 132 samples tested, 60 (46%) were found to be seropositive at a dilution of greater than or equal to 1:10 for at least one of the five different arboviruses. Forty (30%) samples contained antibody to more than one arbovirus, and 15 samples (11%) contained antibody to all five. Of these 15, 14 were from 75 black-tailed deer sera collected in Lincoln County, Oregon. Seropositivity rates for black-tailed deer ranged from 23% to 35%, with all five arboviruses represented. Positive reactions for all five arboviruses were represented among mule deer sera at rates from 5% to 29%. Elk sera were found to be positive for four of the viruses (none for Klamath virus). Although Cache Valley and Klamath viruses have been reported from Oregon, these data represent the first evidence of a California serogroup virus in the state.     

Relationship Between Fecal Pellet Counts and Snowshoe Hare Density in Western Wyoming

ABSTRACT Snowshoe hares (Lepus americanus) are an important prey species for Canada lynx (Lynx canadensis) and are considered critical for lynx population persistence. Determination of snowshoe hare distribution and abundance is needed by land management agencies for lynx conservation. An accepted approach for estimating snowshoe hare abundance is the use of fecal-pellet plot counts. Locally derived regression equations are preferred for accurate calibration of pellet counts to snowshoe hare density due to local differences in pellet deposition and decomposition. We used linear regression to examine correlations between snowshoe hare density, as determined by mark–recapture estimates, and pellet plot counts on both uncleared plots and annually cleared plots on the Bridger-Teton National Forest, western Wyoming, USA. We found significant correlations between snowshoe hare density estimates and fecal pellet counts for both uncleared and annually cleared pellet counts; however, the relationship was stronger (higher r) when using pellet counts from annually cleared plots. In addition, we found that adjusting the buffer size by omitting hard habitat edges (not used by hares) around trapping grids improved correlations between snowshoe hare density and fecal pellet counts for both uncleared plots and annually cleared plots. Though precision is sacrificed when using uncleared plots, they may be useful as a coarse index of habitat use by snowshoe hares. Our derived regression equations may be useful to identify important foraging habitat for Canada lynx in western Wyoming. Land managers responsible for conserving snowshoe hare habitat in western Wyoming may use these equations to monitor changes in hare populations among habitats and during prescribed management actions.     

Epizootiologic and ecologic investigations of European brown hares (Lepus europaeus) in selected populations from Schleswig-Holstein, Germany

From 1997-99 European brown hare (Lepus europaeus) population densities were estimated by spotlight surveys within different areas in Schleswig-Holstein, Germany. These areas showed a wide variation in local hare population densities. In addition, red fox (Vulpes vulpes) densities were estimated in 1997 by surveys of fox dens and litters. Sera of 321 hares (shot between 1998-2000) from four study areas were examined for antibodies against European brown hare syndrome virus (EBHSV) by enzyme linked immunosorbent assay (ELISA), Yersinia spp. (n = 299) and Francisella tularensis (n = 299) by western blotting, Brucella spp. by Rose Bengal test, and Toxoplasma gondii by Sabin-Feldman test (n = 318). Tissue samples comprising lung, liver, spleen, kidney, heart, and adrenal glands were collected for histopathology. Liver (n = 201) and spleen (n = 201) samples were processed for the detection of T. gondii-antigen in tissue sections and 321 liver and spleen samples were investigated for EBHSV-antigen by ELISA. Furthermore, 116 hares were examined macro- and microscopically for lungworms. Significant negative correlations between hare and fox densities were found in spring and autumn 1997. Antibodies against EBHSV were detected in 92 of 321 (29%), against Yersinia spp. in 163 of 299 (55%), and against T. gondii in 147 of 318 (46%) hares. We evaluated the potential influence of origin and hunting season on exposure rates of hares using logistic regression analysis. A strong association between hare densities and exposure rates was observed for various agents. One hundred and eight of 201 (57%) hares were positive for T. gondii-antigen. All sera were negative for antibodies against Brucella spp. and F. tularensis and all lung samples were negative for lungworms. In conclusion, variation in red fox densities may have an impact on the hare populations examined and the infectious diseases we studied seem to play a subordinate role in the dynamics of European brown hare populations from Schleswig-Holstein.     

Serologic survey for Actinobacillus capsulatus in free-ranging snowshoe hares (Lepus americanus) from Alaska and Alberta

A plate agglutination method was developed to test sera from free-ranging snowshoe hares (Lepus americanus) captured in Alaska (USA) or Alberta (Canada) for antibody against Actinobacillus capsulatus. Antiserum against A. capsulatus was prepared in a domestic rabbit. A concentrated suspension of formalin-killed A. capsulatus was prepared for use as an antigen. Serum antibody prevalence for hares was 98 of 239 (41%) in Alaska and 51 of 111 (46%) in Alberta. Prevalence in Alaska peaked in 1981 corresponding to a peak in hare population density. Seasonal prevalence peaked in May in Alaska. Prevalence at one capture site in Alaska was significantly higher than at four other sites. There was no difference in sex-specific prevalence for either Alaska or Alberta.     

Fox colors in relation to colors in mice and sheep

Color inheritance in foxes is explained in terms of homology between color loci in foxes, mice, and sheep. The hypothesis presented suggests that the loci A (agouti), B (black/chocolate brown pigment) and E (extension of eumelanin vs. phaeomelanin) all occur in foxes, both the red fox, Vulpes vulpes, and the arctic fox, Alopex lagopus. Two alleles are postulated at each locus in each species. At the A locus, the (top) dominant allele in the red fox, Ar, produces red color and the corresponding allele in the arctic fox, Aw, produces the winter-white color. The bottom recessive allele in both species is a, which results in the black color of the silver fox and a rare black color in the Icelandic arctic fox when homozygous. The B alleles are assumed to be similar in both species: B, dominant, producing black eumelanin, and b, recessive, producing chocolate brown eumelanin when homozygous. The recessive E allele at the E locus in homozygous form has no effect on the phenotype determined by alleles at the A locus, while Ed, the dominant allele is epistatic to the A alleles and results in Alaska black in the red fox and the dark phase in the arctic fox. Genetic formulae of various color forms of red and arctic fox and their hybrids are presented.     

Novel wildlife in the Arctic: the influence of changing riparian ecosystems and shrub habitat expansion on snowshoe hares

Warming during the 20th century has changed the arctic landscape, including aspects of the hydrology, vegetation, permafrost, and glaciers, but effects on wildlife have been difficult to detect. The primary aim of this study is to examine the physical and biological processes contributing to the expanded riparian habitat and range of snowshoe hares (Lepus americanus) in northern Alaska. We explore linkages between components of the riparian ecosystem in Arctic Alaska since the 1960s, including seasonality of stream flow, air temperature, floodplain shrub habitat, and snowshoe hare distributions. Our analyses show that the peak discharge during spring snowmelt has occurred on average 3.4 days per decade earlier over the last 30 years and has contributed to a longer growing season in floodplain ecosystems. We use empirical correlations between cumulative summer warmth and riparian shrub height to reconstruct annual changes in shrub height from the 1960s to the present. The effects of longer and warmer growing seasons are estimated to have stimulated a 78% increase in the height of riparian shrubs. Earlier spring discharge and the estimated increase in riparian shrub height are consistent with observed riparian shrub expansion in the region. Our browsing measurements show that snowshoe hares require a mean riparian shrub height of at least 1.24–1.36 m, a threshold which our hindcasting indicates was met between 1964 and 1989. This generally coincides with observational evidence we present suggesting that snowshoe hares became established in 1977 or 1978. Warming and expanded shrub habitat is the most plausible reason for recent snowshoe hare establishment in Arctic Alaska. The establishment of snowshoe hares and other shrub herbivores in the Arctic in response to increasing shrub habitat is a contrasting terrestrial counterpart to the decline in marine mammals reliant on decreasing sea ice.     

Variability of CAG tandem repeats in exon 1 of the androgen receptor gene is not related with dog intersexuality

Numerous mutations of the human androgen receptor (AR) gene cause an intersexual phenotype, called the androgen insensitivity syndrome. The intersexual phenotype is also quite often diagnosed in dogs. The aim of this study was to conduct a comparative analysis of the entire coding sequence (eight exons) of the AR gene in healthy and four intersex dogs, as well as in three other canids (the red fox, arctic fox and Chinese raccoon dog). The coding sequence of the studied species appeared to be conserved (similarity above 97%) and polymorphism was found in exon 1 only. Altogether, 2 SNPs were identified in healthy dogs, 14 in red foxes, 16 in arctic foxes and 6 were found in Chinese raccoon dogs, respectively. Moreover, a variable number of tandem repeats (CAG and CAA), encoding an array of glutamines, was also observed in this exon. The CAA codon numbers were invariable within species, but the CAG repeats were polymorphic. The highest number of the CAG and CAA repeats was found in dogs (from 40 to 42) and the observed variability was similar in intersex and healthy dogs. In the other canids the variability fell within the following ranges: 29–37 (red fox), 37–39 (arctic fox) and 29–32 (Chinese raccoon dog). In addition, a polymorphic microsatellite marker in intron 2 was found in the dog, red fox and Chinese raccoon dog. It was concluded that the polymorphism level of the AR gene in the dog was lower than in the other canids and none of the detected polymorphisms, including variability of the CAG tandem repeats, could be related with the intersexual phenotype of the studied dogs.     

Predator-Mediated Indirect Effects of Snowshoe Hares on Dall's Sheep in Alaska

ABSTRACT Indirect interactions among species can strongly influence population dynamics and community structure but are often overlooked in management of large mammals. We estimated survival of Dall's sheep (Ovis dalli) in the central Alaska Range, USA, during years of differing snowshoe hare (Lepus americanus) abundance to test whether indirect interactions with a cyclic hare population affect Dall's sheep either negatively, by subsidizing predators (apparent competition), or positively, by diverting predation (apparent commensalism). Annual survival of adult female sheep was consistently high (0.85 for all yr and age classes combined). In contrast, annual estimates of lamb survival ranged from 0.15 to 0.63. The main predators of lambs were coyotes (Canis latrans) and golden eagles (Aquila chrysaetos), which rely on hares as their primary food and prey on lambs secondarily. Coyotes and eagles killed 78% of 65 radiocollared lambs for which cause of death was known. Lamb survival was negatively related to hare abundance during the previous year, and lamb survival rates more than doubled when hare abundance declined, supporting the hypothesis of predator-mediated apparent competition between hares and sheep. However, stage-specific predation and delays in predator responses to changes in hare numbers led to a positive relationship between abundance of adult Dall's sheep and hares. Lacking reliable estimates of survival, a manager might erroneously conclude that hares benefit sheep. Thus, support for different indirect effects can be obtained from different types of data, which demonstrates the need to determine the mechanisms that create indirect interactions. Long-term survey data suggest that predation by coyotes is limiting this sheep population below levels typical when coyotes were rare or absent. Understanding the nature of indirect interactions is necessary to effectively manage complex predator–prey communities.     

Serum antibody prevalence for Herpesvirus sylvilagus, Bacillus piliformis and California serogroup arboviruses in cottontail rabbits from Pennsylvania

A serologic survey of 60 eastern cottontail rabbits (Sylvilagus floridanus) from three counties in Pennsylvania was conducted in March 1983. Serum antibody prevalences for Herpesvirus sylvilagus and La Crosse virus (California serogroup) were less than 4%. There was no evidence of previous exposure to either Jamestown Canyon or snowshoe hare viruses (California serogroup). Antibody to trivittatus virus (California serogroup) was found in 60% of the 20 cottontails from York County. No cottontails had antibodies to Bacillus piliformis, the etiologic agent of Tyzzer's disease.