Bordetella bronchiseptica has long been associated with respiratory tract infections in laboratory research, foodproducing, companion, and wildlife animal species. Its range of distribution also may include humans and contaminated inanimate environmental sources. Natural diseases due to B. bronchiseptica infections in laboratory rats and mice were described before many of the major pathogens of these hosts were discovered. To our knowledge, there are no recent reports of natural disease due to B. bronchiseptica in these species; as a result, some have questioned its role as a natural pathogen in murine hosts. We reviewed occurrence of natural B. bronchiseptica infections and present information gained from recent experimental infection studies in murine hosts. We also discuss the potential impact of natural B. bronchiseptica infections on research and methods of control.

Experiments were designed to detect and determine differences between nitrite/nitrate concentration ([NO_x]) in plasma across 15 species selected from seven classes of vertebrates. Blood collected in syringes was placed immediately into ethylenediaminetetraacetic acid (EDTA)-containing tubes and was centrifuged. Plasma [NO_x] was determined by measurement of chemiluminescence. Across classes of vertebrates, baseline plasma [NO_x] ranged from 0.6 to 171.3 nmol/ml. Mean ± SD plasma [NO_x] was highest in a fresh-water, jawless fish (lamprey, 95.5 ± 9.1 nmol/ml) and lowest in a saltwater cartilaginous fish (skates, 1.1 ± 0.4 nmol/ml). Both amphibians tested had a wide range in plasma [NO_x], which was explained partly by temporal changes during the year. Within the mammalian class, plasma [NO_x] ranged from 3.8 to 43.2 nmol/ml. Results of this study indicate that NO_x is detectable in plasma of all classes of vertebrates and that baseline concentration varies among species.

Rodent models of neuropathic pain require extensive tissue manipulation to induce the lesion of interest which results in inflammation and postoperative pain that is unrelated to nerve injury per se. We sought to determine whether acute postoperative pain management affects the development of hallmark signs of neuropathic pain. Analgesic regimens (q 24 h × 3 days) were buprenorphine (0.05 and 0.1 mg/kg of body weight, s.c.), flunixin meglumine (1.1 and 2.5 mg/kg, s.c.), and fentanyl citrate (0.01 and 0.1 mg/kg, i.p.). The spared nerve injury model of neuropathic pain was used, and mechanical and cold allodynia as well as body weight gain were measured for 28 days. Buprenorphine and fentanyl alleviated mechanical sensitivity and prevented weight loss associated with the surgery (0 to 3 days), but opioid-related adverse effects were observed. Flunixin reduced wound inflammation and improved weight gain, but had no effect on nociceptive thresholds. Cold allodynia was unaltered by any treatment. By postoperative day 7, control and treatment groups did not differ with respect to weight gain or nociceptive thresholds. Our findings suggest that postsurgical inflammation and pain behavior can be ameliorated without substantially altering the long-term development of neuropathic pain, provided that the selection of agent(s) and treatment regimen(s) is appropriate and the neuropathic pain of interest is evaluated seven days after surgery.

The zebrafish (Danio rerio) has proven an excellent model for study of vertebrate development and genetics. Mutagenesis studies have produced many blood mutants with defects ranging from hematopoiesis to coagulation. The overwhelming majority of zebrafish studies have focused on development and mutational effects in embryos, whereas effects in mature zebrafish have gone largely unexplored. We believe that zebrafish will prove a valuable model for study of aging and age-related diseases, and we have sought to characterize some of the basic features of mature zebrafish. Accordingly, blood was collected from adult zebrafish and was analyzed to determine reference hematologic and biochemical parameters. White blood cell differential counts indicated predominantly lymphocytes, with mean proportion of 82.95%. Total red blood cell counts averaged 3.02×10⁶ cells/μl. Except for increases in alanine transaminase (ALT), amylase, and phosphorus values, serum biochemical analytes were within the range of reported values for mammals and other species of fish. Accurate analysis of the many zebrafish mutants generated requires determination of normal characteristics of zebrafish. We believe results such as these will help define normal adult zebrafish, which have a tremendous potential for use in the study of human disease and aging.

A weakness of many animal models of diabetes mellitus is the failure to use insulin therapy, which typically results in severe body wasting. Data collected from such studies must be interpreted cautiously to separate the effects of hyperglycemia from those of starvation. We provide several algorithms that were used by us in two longterm (20-week) experiments in which hyperglycemia (300 to 400 mg/dl), dyslipidemia (cholesterol [280 to 405 mg/dl] and triglycerides [55 to 106 mg/dl] concentrations), and positive energy balance were maintained in swine. Yucatan miniature swine groups included control, alloxan-induced diabetes mellitus, diabetes mellitus plus diet-induced dyslipidemia, and exercise-trained diabetic dyslipidemic pigs. The algorithms were developed for the porcine model because of several similarities to humans, including: cardiac anatomy and physiology, propensity for sedentary behavior, and metabolism of dietary carbohydrates and lipids. Acute toxic effects of alloxan (hypoglycemia, hyperglycemia, nephrotoxicosis) were minimized by preventive fluid loading and by use of algorithms in which insulin, food, and fluid therapy were administered. Long-term insulin and food maintenance algorithms elicited normal body weight gain in all three diabetic groups (lean experiment) and threefold greater body weight gain in pigs of an obesity experiment. Exercise-trained pigs of both experiments manifested significantly increased work performance and did not experience medical complications. We conclude that these algorithms can be used in swine, or similar algorithms can be developed for other animal species to maintain hyperglycemia and/or dyslipidemia, while avoiding diabetes-induced wasting. Importantly, animal models of diabetes mellitus that maintain positive energy balance and poor glycemic control provide a marked improvement over other models by more closely mimicking the human presentation of diabetes mellitus.

Hyperglycemia, dyslipidemia, and associated insulin resistance are hallmarks of diabetes mellitus. Purposes of the study reported here were to develop practical methods for assessment of in vivo insulin sensitivity and determine contributions of hyperglycemia and dyslipidemia to insulin resistance in the porcine model of alloxan-induced diabetes mellitus and dyslipidemia. Male Yucatan swine groups were treated for 20 weeks: control (C), high fat-fed (2% cholesterol) hyperlipidemic (H), alloxan-induced diabetic normolipidemic (D), diabetic high fat-fed (diabetic dyslipidemic, DD), and diabetic dyslipidemic treated with the lipid-lowering agent atorvastatin (DDA). Plasma cholesterol concentration increased sixfold in animals of groups H, DD, and DDA, whereas triglyceride concentration increased threefold in animals of group DD only. Diabetics had decreases in glucose tolerance and pancreatic immunostaining for insulin. Use of the gold standard hyperinsulinemic euglycemic clamp procedure indicated that maximal insulin-stimulated glucose uptake was similar to that in humans, but this method was not practical for use in pigs. Instead, a more convenient and valid insulin sensitivity test involving suppression of insulin secretion with somatostatin and a single insulin injection was used. Insulin sensitivity was greatly impaired by anesthesia with isoflurane, but was not affected by use of the anxiolytic agent diazepam. Insulin sensitivity decreased by 75% in diabetics (groups D, DD, DDA), compared with animals of groups C and H, and was inversely related to fasting blood glucose concentration (r = –0.72). Insulin treatment to restore blood glucose values of diabetics (>250 mg/dl) to near control values (<100 mg/dl) promptly restored insulin sensitivity to control values. We conclude that hyperglycemia is a major cause of insulin resistance in the porcine model of alloxan-induced diabetes mellitus and dyslipidemia.

Lymphocytic choriomeningitis virus (LCMV) induces persistent infections in laboratory mice; is a known contaminant of biological materials, such as transplantable tumor cell lines; and is of great concern in animal facilities due to its zoonotic potential. Fluorogenic nuclease reverse transcriptase-polymerase chain reaction (fnRT-PCR) assays combine RT-PCR with an internal fluorogenic hybridization probe, thereby potentially enhancing specificity and eliminating post-PCR processing. An fnRT-PCR assay specific for LCMV was, therefore, developed by targeting primer and probe sequences to a unique region of the LCMV nucleocapsid (NP) gene. The LCMV fnRT-PCR assay detected only LCMV and did not detect other RNA viruses that naturally infect rodents. The fnRT-PCR assay detected as little as one picogram of LCMV RNA, but was 100-fold less sensitive when directly compared with the mouse antibody production test. The fnRT-PCR assay was also able to detect viral RNA in numerous tissues and in feces and cage swipe specimens collected from experimentally inoculated BALB/c mice, but did not detect any viral RNA in similar samples collected from age- and strain-matched mock-infected mice. In conclusion, the LCMV fnRT-PCR assay offers a potentially high-throughput diagnostic assay to detect LCMV in mice and contaminated biological materials.

Genetics plays a substantial role in host resistance in many host-parasite interactions. We examined the prevalence of naturally acquired infection with Syphacia obvelata in a number of mouse strains housed in a non-barrier facility. These mice, which included cross-bred and congenic, inbred strains on various genetic backgrounds, differ in the loci for the immune function genes—major histocompatibility complex class II (MHCII), toll-like receptor 4 (Tlr4), and solute carrier family 11, member 1 (Slc11a1)—which allowed comparisons of the impact of these genes on resistance to pinworm infection. Male and female mice of various ages were sampled over an 18-month period; infection was determined by use of the cellophane tape test. Results indicated that mice that were MHCII^+/+ had a significantly lower prevalence of infection than did mice that were MHCII^-/-. Differences were not seen between male and female mice. Although MHCII^+/+ mice had an age-associated decrease in infection prevalence, such decrease was not seen in MHCII^-/- mice. In contrast, infection prevalence in mice with the normal Tlr4 gene (Tlr4^LPS-n/LPS-n) gene did not differ significantly compared with that in mice that were homozygous for either the point mutation (Tlr4^LPS-d/LPS-d) or deletion (Tlr4^{LPS-del/LPS-del}) of that gene. Likewise, the presence (Slc11a1^r/r) or absence (Slc11a1^s/s) of functional alleles for Slc11a1 had no effect on the prevalence of infection with S. obvelata. In conclusion, presence of MHCII, but not Tlr4 or Slc11a1 significantly influences prevalence of naturally acquired infection with S. obvelata. These data justify further comprehensive analyses of the immune components that are involved in pinworm resistance.

As an incidental finding in a study of mammary tumorigenesis, two lines of genetically engineered mice were observed to develop pigmentation changes of the fur. Mice with targeted mutations of the Rb1 (Rb) and Cdkn1b (p27^kip1) genes were crossed from C57BL/6 (black coat color; eumelanin) and 129Sv (wild-type agouti coat color) backgrounds, respectively, to one with a dominant yellow coat color (phaeomelanin) carrying a transgene for Agouti under a keratinocyte specific promoter. Both Rb^+/- and p27^-/- mice developed pituitary tumors of the pars intermedia that were associated with a switch to black (eumelanic) fur but were not observed in sibling Rb^+/+ and p27^+/+ mice. This phenomenon was observed first in the vibrissae and, subsequently one to two weeks later, as periorbital and dorsal patches, and was associated with pituitary lesions larger than four millimeters in the longest dimension. In Rb^+/- mice, pigmentation change preceded a moribund state attributable to the tumors by two to four weeks, whereas in p27^-/- mice, the pigmentation alteration was earlier, more gradual, and prolonged. The switch from phaeomelanin to eumelanin in the fur is most likely due to out-competition of the agouti gene product by α-melanocyte-stimulating hormone from the pituitary tumors, an effect masked in black or agouti mice.

A 2-year-old emaciated female South African clawed frog (Xenopus laevis) was euthanized because of chronic weight loss. At necropsy, there was no evidence of bacterial, fungal or viral disease; however, the histopathologic findings indicated a proliferative gastritis and the presence of numerous cryptosporidial stages throughout the intestinal tract. Crytosporidial oocysts were present in the water taken from the aquarium housing the infected frog and were likely shed by the sick frog; however, the exact source of the oocysts could not be identified. Water samples from other frog aquaria in the facility did not contain cryptosporidial oocysts. Some Cryptosporidium species are important zoonotic pathogens and, to our knowledge, this is the first report of disease associated with Cryptosporidium infection in a laboratory Xenopus laevis.

Routine testing of bedding sentinels from a barrier room revealed one mouse seropositive to ectromelia virus (EV). Results of hemagglutination-inhibition testing and western blot analysis were confirmatory for orthopoxvirus antibodies. Additional seropositive animals were not identified. Interviews indicated that replication-competent vaccinia virus (VV), Western Reserve strain (VV-WR), recently had been given to mice. Although VV-WR was not expected to spread by contact or via fomites, the case evidence suggested transmission of vaccinia via soiled bedding. In a follow-up experiment, 15 index mice were inoculated with 10 7 plaque-forming units of VV by either subcutaneous or intrarectal instillation. A dedicated contact sentinel and a bedding sentinel were provided for each index mouse. All 15 index mice were positive for antibodies when tested 22 days after inoculation. One mouse, inoculated by the subcutaneous route, appeared ill and developed lesions on the proximal portion of the tail. The contact sentinel mouse housed with this index mouse was the only sentinel to seroconvert. We conclude that VV-WR can spread to contact sentinels and potentially to bedding sentinels. The ability of other VV strains to be transmitted horizontally and the susceptibility of different mouse strains to infection merit further investigation. The use of VV in animal facilities must be managed carefully since the available serologic tests do not distinguish between VV and EV, an exotic agent of major concern to laboratory animal facilities.