Biomedical subjects

C W Livingston

Publications and source records attributed to C W Livingston.

At least 19 recordsLinked to original sources

PubMed1991

Cache Valley virus infection in Texas sheep flocks.

Cache Valley virus (CVV), an arbovirus indigenous to the United States, has been implicated as an important teratogenic agent in sheep. The prevalence and distribution of Texas sheep with CVV-specific antibody were investigated. In 1981, 19.1% of 366 sheep located in 22 counties of Texas had antibodies specific for CVV. Of 50 flocks examined in the major sheep-producing counties in Texas, 34 had sheep with antibodies that reacted with CVV, including all sheep tested in 6 flocks that were seropositive. Sera obtained from sheep at the Texas Agricultural Experiment Station at San Angelo between 1986 and 1989 were also examined for CVV-specific antibody because this flock was the subject of the episode of CVV-associated congenital malformations during the 1986 and 1987 lambing season. Approximately 8.6% of 104 sheep in 1986, 63.4% of 164 in 1987, 11.3% of 44 in 1988, and 71.9% of 89 in 1989 from the Texas Agricultural Experiment Station at San Angelo tested were seropositive. The data indicate that CVV infections in sheep were widespread in Texas in 1981 and that the virus is enzootic in sheep at the Texas Agricultural Experiment Station in San Angelo, where the episode of congenital malformations had initially been reported in 1987.

Animals↗

PubMed1991

Isolation and identification of a variant of bluetongue virus serotype 11 from a ram in a bluetongue outbreak in western Texas.

A field strain of bluetongue virus was isolated from a blood sample of a ram during an outbreak of bluetongue in November 1985 in western Texas. In this bluetongue outbreak at least 25 of the 2,000 sheep were infected. Isolation was made by intravenous inoculation of 11-day-old embryonated chicken eggs. The serotype was identified as serotype 11 by serum neutralization tests. The genomic pattern on sodium dodecyl sulfate (SDS)-polyacrylamide gel electrophoresis (PAGE) of the new isolate is similar to that of bluetongue virus prototype 11. Comparisons were also made with proteins labeled in vivo with [3H]leucine and separated by SDS-PAGE. We conclude that this virus belongs to serotype 11, with slight differences in both genome and protein electrophoretic patterns.

Animals↗

PubMed1990

Evidence that Cache Valley virus induces congenital malformations in sheep.

An outbreak of congenital abnormalities occurred in sheep at San Angelo, Texas, between December 1986 and February 1987. Of 360 lambs born, 19.2% had arthrogryposis or other musculo-skeletal problems and hydranencephaly (AGH), and the total neonatal loss was 25.6%. In 1987, all ewes that were tested with AGH lambs had antibody to Cache Valley virus (CVV), whereas 62% of the ewes with normal lambs had CVV-specific antibody. Pre-colostral serum samples from AGH lambs had neutralizing antibody to CVV. An increase in prevalence of CVV-specific antibody, from 5% during the spring of 1986 to 63.4% during the winter of 1987, occurred during a time that included the gestation of these affected lambs, as well as a period of increased rainfall. The isolation of a CVV-related strain from a sentinel sheep in October 1987 confirmed the continued presence of this virus in the pasture where this outbreak occurred and provided a recent field strain for future studies.

Animals↗

PubMed1990

Congenital malformations in sheep resulting from in utero inoculation of Cache Valley virus.

Serologic evidence indicated that an episode of congenital abnormalities in sheep was caused by Cache Valley virus (CVV), a bunyavirus indigenous to the United States. To determine the teratogenic potential of CVV in sheep, fetuses were infected in utero between 27 and 54 days of gestation with an isolate (CK-102) obtained in 1987 from a sentinel sheep in San Angelo, Texas. The dams of these fetuses were euthanatized between 28 and 75 days after inoculation, and the fetuses were examined for malformations. Twenty-eight of 34 fetuses had congenital abnormalities, including arthrogryposis, hydranencephaly, mummification, reabsorption, and oligohydroamnion. Virus was isolated from the allantoic fluid of 11 of 17 fetuses euthanatized at less than 70 days of gestation. The virus-positive fetuses, which were all negative for CVV-neutralizing antibody, had lesions ranging from none to severe arthrogryposis and hydranencephaly. Virus was not recovered from the allantoic fluid of fetuses after 76 days' gestation when CVV-specific antibody could be detected in 5 of 8 fetuses examined. The 2 fetuses infected on days 50 and 54 of gestation appeared normal and 1 had antibody to CVV.

Animals↗

PubMed1990

Immune response to pulmonary injection of Pasteurella haemolytica-impregnated agar beads followed by transthoracic challenge exposure in goats.

A method of inducing Pasteurella haemolytica serotype 1 (Ph1) lung infection in goats, using low numbers of bacteria and without impairing host immunity, was developed. Two trials were conducted. Results of trial 1, using 10 principals (Ph1 agar beads) and 6 controls (agar beads alone), indicated that Ph1 organisms imbedded in agar beads could survive host lung defenses for 32 days. Results of trial 2 indicated that lung immunity in the inoculated goats (principals) was high and they were more protected than controls against a transthoracic challenge of Ph1 (1.18 x 10(7) colony-forming units) injected into a lung of each goat on posttreatment day 35. When comparing challenge-exposed principals with controls, the controls developed rectal temperatures above normal for a longer time, duration of anorexia was longer, and signs of depression were seen. The controls developed large areas of consolidated lung tissue, more Ph1 isolates were recovered from nasal turbinates and lung tissue, and higher Ph1 concentrations were found in the lungs. The serum Ph1 indirect hemagglutination antibody titers in the principals of both trials increased, compared with titers in controls. Principal goats in trial 2 had higher Ph1 indirect hemagglutination antibody titers after injection of Ph1-impregnated agar beads and less severe lung lesions after challenge exposure than did controls. The small pneumonic consolidated lesions in the principals, compared with extensive lesions in controls after Ph1 challenge exposure, indicated a high degree of immunity after exposure to Ph1 organisms imbedded in agar beads.

Animals↗

PubMed1989

Ovine arthrogryposis and central nervous system malformations associated with in utero Cache Valley virus infection: spontaneous disease.

Gross appearance and histologic lesions seen in 15 newborn lambs in an outbreak of congenital arthrogryposis with hydrocephalus or hydranencephaly (CAH) in Texas are described. Severe arthrogryposis with skeletal muscle hypoplasia was seen in limbs of affected lambs. Spinal column deformities were also present. Multiple central nervous system (CNS) malformations were present in CAH lambs including micrencephaly, cerebellar hypoplasia, micromelia, hydrocephalus, hydranencephaly, and porencephaly. Histologic lesions consisted primarily of areas of necrosis and loss of the paraventricular neuropil and motor neurons in the CNS and a resolving myositis with poorly developed myotubular myocytes in skeletal muscle. Seroepidemiologic studies on the flock and serologic data from heart blood taken from the stillborn affected lambs indicated that the outbreak was due to in utero infection with Cache Valley Virus.

Animals↗

PubMed1989

Laboratory investigation of a naturally occurring outbreak of arthrogryposis-hydranencephaly in Texas sheep.

An epizootic of abortions, weak lambs, stillbirths, and congenital arthrogryposis-hydranencephaly occurred in a sheep flock in West Texas. The outbreak began during the first week of January 1987 and continued through the third week of February 1987. Lambs born after February 1987 were not affected. A high incidence of antibodies to Cache Valley virus (Texas 7856 isolate) was demonstrated in the ewes' serum and in precolostral serum from affected lambs. No virus was isolated from tissues and body fluids of the affected lambs. The clinical, pathological, and immunological features of the epizootic were similar to those reported in Akabane virus infection in sheep. Although serological findings strongly suggest Cache Valley virus as the etiological agent of this outbreak, transmission studies are needed.

Animals↗

PubMed1988

Sarcocystis arieticanis and other Sarcocystis species in sheep in the United States.

Histological sections of tongues, esophagi, and diaphragms from 512 adult ewes from the northwest United States and Texas were examined for Sarcocystis spp. Sarcocysts were found in sections of 82.1% of 504 tongues, 44.4% of 478 esophagi, and 51.7% of 89 diaphragms. Sarcocystis tenella was the predominant species and was found in 430 (84.0%) sheep; S. arieticanis was found in 18 (3.5%) sheep. The mean number of S. tenella sarcocysts in tissue sections was approximately 10 times higher than that of S. arieticanis. The identification of S. arieticanis was confirmed by ultrastructural studies and by transmission to dogs. Macroscopic sarcocysts of S. gigantea were also found but were not quantitated in all sheep; sarcocysts of S. medusiformis were not observed.

Animals↗

PubMed1987

Analysis of mixed infection of sheep with bluetongue virus serotypes 10 and 17: evidence for genetic reassortment in the vertebrate host.

Two seronegative sheep were infected intravenously with 10(9) PFU each of bluetongue virus (BTV) serotype 10 and BTV serotype 17. One animal experienced a mild bluetongue-like disease, and both experienced a short-duration viremia and developed neutralizing immune responses to both virus serotypes. Progeny virus was isolated from venous blood from each animal by using conditions in which reassortment could not have occurred during isolation. Electropherotypes were determined for the progeny viruses from the infected sheep, yielding strikingly similar results for the two animals. In both sheep, serotype 10 dominated among the progeny, accounting for 92% of the progeny. Serotype 17 was rarely isolated and accounted for 3% of the progeny analyzed. The remaining 5% of the progeny clones were reassortant and derived genome segments from both serotypes 10 and 17. Analysis of the parental origin of genome segments in the small number of reassortant progeny analyzed suggested that selection of specific genome segments may have occurred in the infected sheep. These data indicate that reassortment of genome segments occurs, at low frequency, in sheep mixedly infected with BTV.

Animals↗

PubMed1987

Kleingrass (Panicum coloratum L.) poisoning in sheep.

Twenty-four lambs grazing pastures of Panicum coloratum developed photosensitization secondary to hepatic dysfunction. Lesions were necrosis of scattered hepatocytes, obstruction of small bile ducts and bile canaliculi by small aggregates of birefringent crystals, and accumulation of birefringent crystals in phagocytes within sinusoids. The number of crystals in livers of affected sheep varied, depending on the amount of time of exposure to toxic plants and severity of hepatic abnormalities. Crystals in the liver were soluble in acidified ethyl alcohol, acetic acid, pyridine, chloral hydrate, and methanol, but not in xylene, petroleum ether, diethyl ether, acetone, water, or cold ethyl alcohol. Crystals were not stained by oil red O. There was necrosis of epithelial cells in renal distal convoluted tubules, papillary muscles of the heart, and the adrenal cortex. Lesions of Panicum coloratum-associated disease are similar to those associated with photosensitization induced by Tribulus terrestris, Agave lecheguilla, and Nolina texana.

Adrenal Glands↗

PubMed1986

A live Pasteurella haemolytica vaccine efficacy trial.

A live Pasteurella haemolytica serotype 1 vaccine was used in an efficacy trial conducted on 100 lightweight feeder calves purchased from a Florida ranch. Forty-one calves were inoculated with the vaccine intradermally in the neck. Fifty-nine calves served as nonvaccinated controls. Fourteen days later, the calves were shipped to an order buyer in eastern Tennessee, where the calves were mixed with 60 local calves in a community sale barn for 72 hours. After 3 additional days, the calves were shipped to a research feedlot in Bushland, Tex. They remained in the feedlot for 56 days, and the test was concluded 76 days after vaccination. The P haemolytica vaccine had no significant effect on performance, morbidity, or mortality. There was no significant difference between the vaccinated and nonvaccinated calves in the number of times Pasteurella was isolated. The calves became seropositive to bovine viral diarrhea virus, respiratory syncytial virus, and infectious bovine rhinotracheitis (IBR) virus during the 76-day experiment. All calves initially were seropositive to parainfluenza-3 virus. A virulent outbreak of IBR occurred 30 days after the calves arrived at the feedlot. Before the onset of IBR, the isolation of P haemolytica serotype 1 from nasal turbinates was rare (2 of 500 nasal swabs). After the IBR outbreak, P haemolytica serotype 1 was isolated from 40 of 92 calves.

Animals↗

PubMed1986

Sarcocystis capracanis and Toxoplasma gondii infections in range goats from Texas.

Specimens of tongues, esophagi, diaphragms, or abdominal muscles of 115 range goats from San Angelo, Tex, were examined for Sarcocystis and Toxoplasma gondii infections. Sarcocystis spp zoites were found microscopically in pepsin digests of muscles of 60.8% goats and sarcocysts of S capracanis were found in histologic sections of 27.8% goats. Sarcocysts were more common in sections of tongue (19.1%) than in those of other muscles (9.9% to 10.7%). A dog fed Sarcocystis-infected tissues shed sporocysts in feces, whereas 2 cats fed the same tissues did not shed sporocysts. Toxoplasma gondii was neither seen in histologic sections of goat tissues nor found by bioassays in mice or cats. Mice inoculated with pepsin digests of muscles did not develop T gondii infection and 2 cats fed goat tissues did not shed oocysts. Also, antibody to T gondii was not found in serum samples from goats. The low prevalence of T gondii infection in range goats may be because of the relative absence of domestic cats on Texas ranges.

Animals↗

PubMed1986

Pasteurella haemolytica leukotoxin: chemiluminescent responses of peripheral blood leukocytes from several different mammalian species to leukotoxin- and opsonin-treated living and killed Pasteurella haemolytica and Staphylococcus aureus.

A luminol-dependent chemiluminescence (LDCL) assay was used to assess the response of polymorphonuclear leukocyte (PMN) preparations from 4 species of ruminants (ie, cattle, sheep, goats, and antelopes) and 6 species of nonruminants (ie, swine, dogs, cats, rabbits, horses, and persons) to both opsonized and nonopsonized preparations of living and heat-killed Pasteurella haemolytica and Staphylococcus aureus and to opsonized and nonopsonized heat-killed strains of each bacterium in the presence of sterile culture supernatant (leukotoxin) from P haemolytica. The LDCL responses of PMN preparations from each of the species studied were greater for living than for heat-killed S aureus. The most efficient LDCL emission was observed with reaction mixtures containing opsonized living S aureus. Regardless whether they contained killed or living bacteria, the opsonized S aureus preparations elicited LDCL emissions more efficiently than did the corresponding nonopsonized preparations. Living P haemolytica cells and their sterile culture supernatant inhibited the LDCL emissions of phagocytically stimulated PMN preparations from ruminants, but not those from nonruminants. The LDCL response of ruminant PMN to nonopsonized living P haemolytica was characterized by the development of a peak response at 10 minutes of incubation followed by a precipitous decrease and a subsequent complete cessation of chemiluminescence. The peak LDCL response was higher for opsonized living P haemolytica than for nonopsonized living bacteria, and the increased response lasted longer. However, opsonization of living P haemolytica with the serum samples tested only temporarily spared the ruminant PMN preparations from the detrimental effects of leukotoxin.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗

PubMed1985

Use of a quadrivalent modified-live bluetongue virus vaccine in wildlife species.

Three hundred and twenty-seven animals comprised of deer, mouflon sheep and bighorn sheep were vaccinated with an experimental quadrivalent, modified-live, bluetongue virus (BTV) vaccine. No untoward effects due to the vaccine were noted nor were abortions observed in vaccinated pregnant mouflon sheep. Precipitating antibodies to BTV and epizootic hemorrhagic disease (EHD) virus were identified in the serum of several animals prior to vaccination. Virus neutralizing antibodies to 3 of the 5 serotypes of BTV which exist in the US were identified in the serum of 2 peninsular bighorn sheep.

Animals↗

PubMed1985

Corynebacterium pseudotuberculosis exotoxin: fatal hemolytic anemia induced in gnotobiotic neonatal small ruminants by parenteral administration of preparations containing exotoxin.

Inoculation of live Corynebacterium pseudotuberculosis, culture supernatant, ammonium sulfate-fractionated crude exotoxin, or chromatographically purified exotoxin preparations into gnotobiotic small ruminants (n = 13) caused death of the ruminants within 48 hours. Characteristic changes observed in animals living greater than or equal to 2 hours after inoculation included hemorrhage and edema at the site of injection, severe hemolytic anemia and hemoglobinuria, dark red fluid in body cavities, lung edema, and icterus. The crude exotoxin preparation caused a syndrome of acute shock in 2 lambs that died within 15 minutes after inoculation. Clinical and pathologic responses of animals inoculated with culture supernatant and purified toxin were similar. Histopathologic evidence indicated that the exotoxin caused necrotic changes in the proximal convoluted tubules of the kidneys. Inoculation with live organisms caused multiple foci of suppurative inflammation in skeletal muscle and adjacent adipose tissue, whereas such changes were not observed in animals administered exotoxin preparations. Although C pseudotuberculosis exotoxin induced a hemolytic anemia in the experimental animals, it did not lead to in vitro lysis of ovine, caprine, or bovine erythrocytes, unless they had been sensitized with Rhodococcus (Corynebacterium) equi filtrate. The toxic sphingomyelin-specific phospholipase D from C pseudotuberculosis had a molecular weight of 31,000 daltons and an isoelectric point of approximately 9.6. The elution profile of exotoxin on a carboxymethyl Sephadex column was studied and the majority of the enzymatic activity was eluted by a NaCl gradient (0.25M to 0.7M) with a maximum at 0.35M NaCl.(ABSTRACT TRUNCATED AT 250 WORDS)

Anemia, Hemolytic↗

PubMed1984

Effect of experimental infection with ovine ureaplasma upon the development of uroliths in feedlot lambs.

Urinary calculi development in grain-fed lambs is a cause of serious economic loss to sheep producers in the USA. Rations containing sorghum grain and cottonseed meal, particularly, are calculogenic especially in those cases in which the calcium and phosphorus ratio is not balanced. The chemical composition of calculi taken from lambs is most often magnesium ammonium phosphate. Ureaplasmas have been isolated from the urinary tract of sheep with urinary calculi. These isolates, as well as certain other isolates of ovine ureaplasma, produce a sediment in aged cultures that is composed primarily of magnesium ammonium phosphate. In order to determine the relationship of ureaplasmal infections to the formation of calculi in the urinary tract, four treatment groups were established, comprising uninoculated-balanced ration, uninoculated-calculogenic ration, inoculated-balanced ration, and inoculated-calculogenic ration. As signs of calculosis developed, the wethers were necropsied and calculi collected and weighed. Also, culture material was obtained from four sites in the urinary tract and urine was collected for examination. A significant difference appeared in the number of lambs developing calculi between the calculogenic and noncalculogenic rations. No significant difference was evident in the total number of cases of urinary calculi in the inoculated compared with the uninoculated group. However, a very large difference in the total weight of calculi (15.4 g) was observed between the inoculated and uninoculated groups. Although the correct formulation of the ration is of prime importance in preventing urinary calculi formation in sheep, it is possible that ureaplasmal infections may influence the total amount of calculi produced and perhaps the physical characteristics of the calculi crystals.

Animals↗

PubMed1983

Immunodiffusion test antigen from bluetongue virus-infected newborn mouse brains.

Three methods of extracting bluetongue virus (BTV)-infected newborn mouse brains to prepare immunodiffusion (ID) test antigen were used. The most readily readable and reproducible results were obtained with fluorocarbon-extracted brains homogenized in 8.5% sucrose. Mouse brain- and reference cell culture-derived antigens gave a line of identity with anti-BTV serum. Extracts of noninfected brains were nonreactive. ID tests on field-collected bovine sera, comparing the two types of antigen, resulted in only 73% agreement due to a greater sensitivity of cell culture-derived antigen. A 70.5% agreement resulted when comparing mouse brain-derived antigen in ID tests with complement fixation tests, the latter being least sensitive. ID test results with sera from experimental sheep gave 95.9% agreement between cell culture- and mouse brain-derived antigens. Between ID, which detects antibody to the BTV common or group antigen, and virus neutralization, which detects type-specific antibody, the agreement was 71.4% with postchallenge sera. Data from pre- and postinjection sera, however, indicate the possible activity in Texas of viruses other than International BTV Types 10, 11, 13, and 17.

Animals↗

PubMed1983

Experimental bluetongue infections in gnotobiotic lambs and kids.

Ten gnotobiotic lambs and 4 gnotobiotic kids inoculated with virulent bluetongue virus (BTV) including BTV international types 10, 11, 13, and 17 did not show clinical signs of bluetongue. Seroconversion was observed in all gnotobiotes and conventional control sheep inoculated with the appropriate challenge BTV. Viremia was detected in 1 BTV-infected gnotobiote. Conventional control sheep inoculated with a given BTV international serotype showed a marked febrile response with hyperemia of the nasal and buccal mucosa.

Animals↗