Hantaviruses are a newly emerging group of rodent-borne viruses that have significant zoonotic potential. Human infection by hantaviruses can result in profound morbidity and mortality, with death rates as high as 50%, and potentially long-term cardiovascular consequences. Hantaviruses are carried by peridomestic and wild rodents worldwide and have occasionally been linked to infections in laboratory rodents. Because these viruses have been associated with significant human disease, they have become the subject of intense scientific investigation. In this review the reader is introduced to the hantaviruses, including hantavirus diseases and their pathogenesis. A review of the biology, morphology, and molecular biology of the hantaviruses with a brief overview of the ecology and biology of hantavirus-rodent pairs is also included. The risks of occupational exposure to hantaviruses, diagnosis of hantavirus infections, and methods for handling potentially infected rodents and tissues are discussed as well.

Reverse transcriptase-polymerase chain reaction (RT-PCR) assays have proved useful for the detection of mouse hepatitis virus (MHV) and rat coronavirus (RCV) in acutely infected animals and contaminated biomaterials. Fluorogenic nuclease RT-PCR assays combine RT-PCR with an internal fluorogenic hybridization probe, thereby eliminating post-PCR processing and potentially enhancing specificity. Consequently, a fluorogenic nuclease RT-PCR assay specific for rodent coronaviruses was developed. Primer and probe sequences were selected from the viral genome segment that encodes the membrane (M) protein that is highly conserved among rodent coronaviruses. Use of the fluorogenic nuclease RT-PCR detected all strains of MHV and RCV that were evaluated, but did not detect other RNA viruses that naturally infect rodents. Use of the assay detected as little as two femtograms of in vitro transcribed RNA generated from cloned amplicon, and when compared directly with mouse antibody production tests, had similar sensitivity at detecting MHV-A59 in infected cell culture lysates. Finally, use of the assay detected coronavirus RNA in tissues, cage swipes, and feces obtained from mice experimentally infected with MHV, and in tissues and cage swipes obtained from rats naturally infected with RCV. These results indicate that the fluorogenic nuclease RT-PCR assay should provide a potentially high-throughput, PCR-based method to detect rodent coronaviruses in infected rodents and contaminated biological materials.

Purpose: Swine models have been used to study cardiovascular disease, cardiac physiology, and transplantation, and have been associated with problems, such as friability of certain organs, anesthesia difficulties, ventricular fibrillation, and edema. We describe a stable model of extended cardiopulmonary bypass (up to 22 h) in swine weighing > 80 kg to be used as a research model.Methods: Swine (n = 5, 88 ± 6 kg) had both femoral arteries cannulated and after open sternotomy, a two-stage venous catheter was placed in the right atrium/caudal vena cava. The circuit was primed with four parts blood and one part 0.9% NaCl.Results: Cardiopulmonary bypass was maintained for 10 to 22 h, with the following parameters measured at beginning/middle/end: heart rate, 108 to 134 beats per minute; hematocrit, 30 to 38%; glucose concentration, 4 to 11 mmol/L; lactate concentration 6 to 7 mmol/L; pH 7.4 to 7.5; pCO₂, 35 to 38 mmHg; pO₂, 197-228 mmHg; HCO⁻₃, 21 to 25 mmol/L; base excess, −3 to +2; and total urine output, 425 to 1,600 ml.Conclusions: Factors responsible for the success of this model include a higher oxygen concentration on initiation of cardiopulmonary bypass (567 ± 54 mmHg), maintenance of appropriate hematocrit, and use of non-citrated blood-crystalloid prime. The results indicate a stable model of normothermic long-term cardiopulmonary bypass in swine that allows researchers a longer opportunity for further exploration of relevant research issues.

The ability to manipulate mouse pre-implantation embryos in vitro has become a valuable tool in many scientific disciplines. However, fewer embryos maintain viability following in vitro manipulation compared with embryos in vivo. It has been suggested that use of dynamic medium environments may improve viability by simulating in utero environment. The objective of the study reported here was to compare a microdrop in vitro culture system with a microdevice in vitro culture system containing a static and two dynamic medium environments (0.1 and 0.5 μl/h) for culturing of mouse pre-implantation embryos. Results indicated that the static medium environment, in silicon-glass microdevices, was not significantly different from the microdrop control environment in proportion of embryos developing from the two-cell to the blastocyst stage. However, the static microdevice environment produced significantly (P < 0.05) more morulas than did that of the control group. Both of these treatment groups, under the presented conditions, consistently had significantly higher proportions of blastocysts (P < 0.05) and morulas (P < 0.05) and lower proportions of abnormal (P < 0.05) and eight-cell embryos (P < 0.05), compared with those of the high flow rate dynamic environment microdevice treatment groups. Studies exploring slower or pulsatile rates of medium delivery in a dynamic medium environment are indicated.

Transplantation of islets of Langerhans is a possible treatment for type-I diabetes mellitus. However, there is a shortage of donors for such transplantations and the pig may be an alternative source of donor organs. The aims of the study reported here were to establish a method for adult porcine islet isolation that was based on enzymatic digestion using Liberase PI in a semiautomatic set-up, and to evaluate the in vitro and in vivo function of isolated islets. After overnight culture, isolated islets, from five of seven batches, had poor insulin response to an in vitro glucose challenge that was only partially increased by additional challenge with arginine. More than 50% of DNA and 90% of the insulin content was lost during a one-week culture period. With some batch-to-batch variation, in 15 of 25 cases, 4,000 to 7,000 porcine islets cured streptozotocin diabetic nude mice within three weeks following transplantation.In conclusion, it is possible to isolate viable islets from adult pigs, using a semiautomatic set-up. With batch-to-batch variation, the islets are able to revert diabetes mellitus when transplanted to diabetic nude mice.

Background and Purpose: Awareness of effects of chemicals on brain and sex organs during organogenesis is increasing. Balance between apoptosis and ornithine decarboxylase (ODC) activity has an essential role for final structure and function of these organs. It is important to localize stages in development where these processes may be particularly vulnerable to chemicals. We describe reference data on apoptosis and ODC activity in brain and testes.Methods: Brain and testes specimens were obtained during gestational days (G) 15 to 21 and on postnatal days (P) 1 to 60, and ODC activity and parameters of apoptosis (DNA laddering and Terminal deoxynucleotidyl transferase mediated dUTP-biotin nick end labeling-staining) were investigated.Results: Brain ODC activity reaches maximum at G19 and thereafter rapidly decreases until P7. Apoptotic DNA laddering occurs in the brain from G17 to P7. Significant apoptotic ladders were not detected between P9 and 60. In the testes, apoptotic laddering was weak from G21 to P15, but increased significantly from P15 to 60. Histologic examination and DNA laddering analyses revealed low-level germ cell apoptosis from G15 to P11. At onset of spermatogenesis at P15, the number of apoptotic germ cells increased markedly.Conclusions: Brain ODC activity and apoptosis from G15 to P7 and at the onset of testes apoptosis at P15 are relevant markers for chemically induced developmental toxicity in these organs.

Bone mineral density (BMD) of the whole body and hind limb of young adult rats, with and without a sham-operated stifle joint was studied, using dual energy x-ray absorptiometry (DEXA) at three time points. Data from the whole body scan were used for analyses of BMD, bone mineral content (BMC), fat, lean, body weight (BW), percentage of BMC (%BMC), percentage of fat (%fat), and percentage of lean (%lean), none of which were significantly different between the groups at any time point. Significant (P < 0.05) differences in BMD, BMC, %BMC, BW, fat, %fat, and %lean were apparent at the second and third scans, compared with the initial scan, within both groups. Changes in whole body BMD, BMC, and %BMC as well as BW were highly correlated with time in both groups. In the hind limb scans, regions of interest (ROIs) were created to obtain values of BMD and BMC from the whole femur, whole tibia including the fibula, distal portion of the femur, and proximal portion of the tibia. Significant differences were not found between the groups for any ROIs. However, significant BMD and BMC increases were evident in all ROIs at the second and third scans, compared with the initial scan. Similar to those in the whole body scan, BMD and BMC obtained from ROIs were highly correlated with time. The positioning technique for the whole body and appendicular scans was analyzed by calculating percentage of the coefficient of variation (%CV) at the beginning of the study. The %CV was low and acceptable in ROIs for the hind limb and for all parameters of the whole body scan, except fat. The results suggest that in vivo DEXA scanning of the rat whole body and appendicular skeleton is highly reproducible and useful to study the whole skeleton, as well as a region of a long bone of the rat. Values for the sham-operated rats were not significantly different from those for the untreated controls, which suggests that soft tissue damage around the stifle joint did not alter BMD in the subchondral bone of the distal portion of the femur and proximal portion of the tibia.

From 1979 to 1999, 28 cases of lymphosarcoma were identified in the Cornell University woodchuck colony (prevalence rate: 152/100,000/yr). The prevalence of lymphosarcoma was similar in woodchucks not infected with the woodchuck hepatitis virus (WHV) and in chronic carriers of WHV. Males (13) and females (15) alike were affected (mean ± SD age 4.7 ± 2.92 years; range, 0.5 to 9 years). On the basis of the major organ system involved, woodchuck lymphosarcoma was classified as multicentric (12 cases, 43%), alimentary (5 cases, 18%), cranial mediastinal (5 cases, 18%), and miscellaneous (6 cases, 21%). A cutaneous form was not observed. Morphologic criteria similar to those of the Kiel classification were used for light microscopic classification. All Kiel categories—except the immunoblastic form—were found: 17 cases (61%) were centroblastic, and 6 were lymphocytic (21%). Other categories (centrocytic and plasmacytoid) were recognized less frequently. Immunophenotyping of 27 cases revealed 15 (56%) B cell (CD3⁻/CD79a⁺ or CD3⁻/BLA.36⁺), 7 (26%) T cell (CD3⁺/CD79a⁻/BLA.36⁻), and 5 (18%) non-T non-B cell (CD3⁻/CD79a⁻/BLA.36⁻) lymphosarcomas. Lymphosarcoma in woodchucks develops at a higher rate than that observed in humans or companion animals, and WHV infection has no effect on prevalence. The anatomic and Kiel classification used in domestic species also can be used in woodchucks. Commercially available α-CD3, α-CD79a, and α-BLA.36 antibodies were useful for immunophenotyping woodchuck lymphosarcomas.

Purpose: Parvoviruses are among the most prevalent infectious agents in mouse colonies. Infection in laboratory mice is confirmed by detection of serum antibodies to these agents, and most diagnostic tests cannot distinguish serogroup of the infecting agent. The principal objective of the research reported here was to develop and validate a sensitive, serogroup-specific diagnostic test that will distinguish between mouse parvovirus (MPV) and minute virus of mice (MVM) infection.Methods: The MPV VP2 protein was expressed in bacteria, purified by use of metal-chelation chromatography, and used as antigen in an ELISA. More than 580 sera from uninfected mice and experimentally or naturally infected mice were screened by MPV indirect fluorescent antibody (IFA) test, then were re-tested using the MPV ELISA to define test sensitivity and specificity. An additional 3,700 sera were screened using a variety of tests, including the MPV ELISA and recombinant NS1 ELISA (rNS1 ELISA).Results: Using MPV IFA test results as a benchmark, the MPV ELISA had sensitivity of 92.3% and specificity of 99.8%. In addition, the MPV ELISA detected anti-viral antibodies at a higher dilution of serum than did the IFA test, and confirmed the infecting agent as MPV or MVM. When compared directly in a commercial laboratory, the MPV ELISA had higher sensitivity (90.3% versus 65%) than and similar specificity (98.3% versus 99.6%) to the rNS1 ELISA.Conclusion: The MPV VP2 ELISA provides a sensitive, serogroup-specific alternative for diagnosis and classification of parvovirus infection in laboratory mice.

During exploratory laparotomy, a 10-year-old female rhesus macaque was found to have a 6.0 × 9.5 × 2.0-cm multichambered, yellow, cystic mass cranial to the uterus, from which large amounts of opaque, white fluid were discharged into the abdominal cavity. The animal was euthanized, and the body was submitted for gross and histologic evaluation. Sections of the mass examined microscopically consisted of sheets of polygonal to round cells, with well defined cell borders and moderate amounts of eosinophilic cytoplasm. Scattered throughout these cells were few, variably sized glandular structures composed of columnar to cuboidal epithelium. Glandular epithelial cells were positive for keratin, and the sheets of polygonal cells were positive for vimentin and negative for keratin and CD 68. Gross and histologic appearance, immunohistochemical findings, and history of medroxyprogesterone acetate injections were compatible with a diagnosis of stromal decidualization of endometriosis. Subsequent biopsies of similar lesions in other rhesus macaques in the colony being treated with medroxyprogesterone acetate for endometriosis revealed comparable histologic findings.

An outbreak of paralysis among 16- to 20-week-old CFW Swiss Webster sentinel mice developed in one of our barrier facilities. Two months after arrival and over a period of four weeks, six of 400 mice purchased from an approved vendor, developed progressive hind limb paralysis without other clinical signs of disease. On the basis of the histopathologic changes and negative serologic test results, lymphoblastic lymphoma causing compression of the spinal cord was diagnosed. There were two leading features to this outbreak: its unusual epidemiologic presentation, and the localization of the lesions principally in the lumbar muscles. A presumptive diagnosis of retroviral infection with Abelson's murine leukemia virus (A-MuLV) was established on the basis of histopathologic and immunohistochemical findings. Little is known about retroviral status in many commercial colonies, and few users report presence of spontaneous lymphomas. This report points out complications derived from commercially available animals that carry endogenous retroviruses. It also emphasizes the need of diagnosing and reporting clusters of hind limb paralysis or lymphomas in mice to assess the prevalence and relevance of retroviral infections in commercial colonies.