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[Molecular and immunodiagnostic studies of bovine neosporosis in Switzerland].

Cyst-forming coccidia may cause significant losses in livestock, primarily due to abortion, loss of young animals and neuromuscular diseases. Rather recently, Neospora caninum has been recognized as one of the major protozoal abortion-inducing parasites in cattle. The present study addressed the performance of different diagnostic tools (in vitro-cultivation; histology; immunohistochemistry; serology; PCR) suitable for the direct or indirect detection of N. caninum. By PCR, Neospora-DNA was detected in 24 brains (29%) from 83 bovine abortion, many of these brains were simultaneously characterized by histopathological findings typical for a protozoal, cerebral parasitosis. The diagnostic methods were furthermore assessed using samples of different tissues and body fluids from three experimentally Neospora-infected pregnant cows and their foetuses. The diaplacental passage of N. caninum to the foetus was successful in two of the three cases. In these two cases, PCR was positive for different foetal organs and, additionally, for the abomasal and amniotic fluid. The successfully infected cows developed anti-Neospora serum antibodies between 10 and 17 days post infection, foetuses remained serologically negative in all cases. The results obtained in the present study demonstrated the usefulness of PCR, complemented by serology, for the specific diagnosis of bovine neosporosis. Such tests may prove suitable to perform epidemiological investigations. Taken together, our data indicated that prenatal neosporosis may be an important cause of infectious bovine abortion in Switzerland.

Abortion, Veterinary↗

Disorders of pregnancy.

Ectopic pregnancy, uterine torsion, hypocalcemia, and hypoglycemia are discussed. A diagnostic and therapeutic approach to spontaneous abortion and embryonic death is given. Infectious causes of abortion are emphasized. Discussed are the normal variation in gestation length and its relationship to the diagnosis of dystocia as well as the diagnosis and treatment of dystocia.

Abortion, Spontaneous↗

Nutrient partitioning during pregnancy: adverse gestational outcome in overnourished adolescent dams.

Appropriate nutrient partitioning between the maternal body and gravid uterus is essential for optimum fetal growth and neonatal survival, and in adult sheep nutrient partitioning during pregnancy generally favours the conceptus at the expense of the dam. However, recent studies using an overnourished adolescent sheep model demonstrate that the hierarchy of nutrient partitioning during pregnancy can be dramatically altered in young growing females. Overnourishing the adolescent dams to promote rapid maternal growth throughout pregnancy results in a major restriction in placental mass and leads to a significant decrease in birth weight relative to moderately-fed adolescents of equivalent gynaecological age. High maternal feed intakes are also associated with an increased incidence of non-infectious spontaneous abortion, a reduction in gestation length and colostrum production, and a higher incidence of neonatal mortality. The present paper examines the putative role of a variety of endocrine regulators of nutrient partitioning in this unusual model system, where the dam is overnourished while the stunted placenta restricts nutrient supply to the fetus. The central role of nutritionally-mediated alterations in placental growth and development in setting the subsequent pattern of nutrient partitioning between the maternal body, placenta and fetus is examined, and critical periods of sensitivity to alterations in maternal nutritional status are defined. Finally, the consequences of this form of inappropriate nutrient partitioning on the growth and development of the fetus and neonate are described with particular emphasis on the reproductive axis.

Adolescent↗

Herpes simplex virus products in productive and abortive infection. 3. Differentiation of infectious virus derived from nucleus and cytoplasm with respect to stability and size.

Approximately 67% of infectivity is associated with the nucleus 8 hr after productive infection of HEp-2 cells with herpes simplex virus. Comparison of nuclear and cytoplasmic infectious virus and macromolecular aggregates labeled with (3)H-thymidine or with (3)H-choline revealed the following. (i) Cytoplasmic infectious virus and macromolecular aggregates banded in CsCl at a density corresponding to enveloped nucleocapsids. The virus was relatively stable; there was only 50% loss of infectivity and only 16% of the virions became disaggregated. (ii) Nuclear macromolecular aggregates banded in CsCl solution at a density corresponding to unenveloped nucleocapsids and, moreover, both the infectious virus and aggregates were highly unstable. (iii) In sucrose density gradients, the nuclear macromolecular aggregates and infectivity sedimented as a single band and migrated more slowly than the corresponding cytoplasmic material. (iv) The infectivity of nuclear and cytoplasmic virus is readily inactivated by digestion with phospholipase C and with pronase. We conclude the following. (i) Cytoplasmic virus consists of enveloped nucleocapsids. (ii) Nuclear virus consists of nucleocapsids covered with lipid or partially enveloped. (iii) The molecular integrity of viral lipids is essential for infectivity. (iv) The envelope protects the nucleocapsid and accelerates adsorption to cells; it is not, however, inherently essential for infectivity.

Cell Nucleus↗

CD21-mediated entry and stable infection by Epstein-Barr virus in canine and rat cells.

We developed an adenovirus vector for transduction of the human CD21 gene (Adv-CD21), the Epstein-Barr virus (EBV)-specific receptor on human B lymphocytes, to overcome the initial barrier of EBV infection in nonprimate mammalian cells. Inoculation of Adv-CD21 followed by exposure to recombinant EBV carrying a selectable marker resulted in the successful entry of EBV into three of seven nonprimate mammalian cell lines as evidenced by expression of EBV-determined nuclear antigen (EBNA). The EBV-susceptible cell lines included rat glioma-derived 9L, rat mammary carcinoma-derived c-SST-2, and canine kidney-derived MDCK. Subsequent selection culture with G418 yielded drug-resistant cell clones. In these cell clones, EBV existed as an episomal form, as evidenced through the Gardella gel technique. Among the known EBV latency-associated gene products, EBV-encoded small RNAs, EBNA1 and transcripts from the BamHI-A rightward reading frame (BARF0), and latent membrane protein 2A were expressed in all EBV-infected cell clones. The viral lytic events could be induced in these cell clones by simultaneous treatment with 12-O-tetradecanoylphorbol-13-acetate and n-butyric acid, but they were abortive, and infectious virus was not produced. These results indicate that once the initial barrier for attachment is overcome artificially, EBV can establish a stable infection in some nonprimate mammalian cells, and they raise the possibility that transgenic animals with the human CD21 gene could provide an animal model for EBV infection.

Adenoviridae↗

Nutrient partitioning and fetal growth in rapidly growing adolescent ewes.

A highly controlled model to investigate nutrient partitioning and the control of fetal growth in the rapidly growing adolescent sheep is described. Embryos recovered from superovulated adult ewes inseminated by a single sire were transferred in singleton to the uterus of prepubertal adolescent recipients induced to ovulate at 21 weeks of age (liveweight 44.4 +/- 0.38 kg). After embryo transfer, the adolescent recipients were individually offered a high (n = 28) or low (n = 20) quantity of a complete diet calculated to achieve rapid (RMG) or normal (NMG) maternal growth rates. After day 100 of gestation the feed intake of the NMG group was adjusted weekly to meet the increasing nutrient demands of the gravid uterus. The proportion of adolescent recipients initially conceiving was significantly (P < 0.01) influenced by maternal nutrient intake and was lower in the RMG (0.57) than in the NMG (0.85) group. For adolescent dams that maintained their pregnancies, liveweight gain during the first 95 days of gestation was significantly (P < 0.001) higher in the RMG compared with the NMG group (234 +/- 9.5 and 75 +/- 5.0 g day-1, respectively). Rapid maternal growth rates were associated with a significant reduction in both fetal and placental weights as determined when the animals were killed on day 95 of gestation (n = 3 per group) or at term. For the RMG (n = 8) and NMG (n = 11) groups, respectively, mean lamb birthweights at term were 2.74 +/- 0.25 and 4.34 +/- 0.27 kg (P < 0.001), while term placental weights were 263 +/- 16.8 and 438 +/- 44.6 g (P < 0.002). The number of fetal cotyledons per placenta and mean fetal cotyledon weight were significantly lower in RMG compared with NMG ewes (P < 0.05). Irrespective of treatment group, lamb birthweight was highly positively correlated with placental weight and both parameters were negatively correlated with maternal liveweight gain during the first 100 days of gestation. The incidence of non-infectious spontaneous abortion at 125 +/- 1.3 days of gestation was higher (P < 0.001) in the RMG (4 of 12) than in the NMG (1 of 12) group. Similarly, duration of gestation for those ewes delivering live young was shorter (P < 0.01) in the RMG compared with the NMG group (140 +/- 0.94 versus 143 +/- 0.28 days). Colostrum yield at parturition was positively related to placental weight and significantly lower (P < 0.001) in the RMG than in the NMG group (35 +/- 12.1 and 247 +/- 36.2 g, respectively). Neonatal survival rates at 72 h after parturition were reduced (P < 0.05) in the RMG (38%) compared with the NMG group (91%). These data suggest that in rapidly growing adolescent ewes, the established anabolic drive to maternal tissue synthesis is maintained at the expense of the gradually evolving nutrient requirements of the gravid uterus. This results in a major restriction in placental growth and a highly significant decrease in birthweight.

Animal Nutritional Physiological Phenomena↗

Effects of monensin on the reproduction, health, and milk production of dairy cows.

A randomized clinical trial including 1109 cows from 12 Australian dairy herds was used to evaluate the effects of monensin on the health (n = > 686 cows), production (n = 915 cows), and reproduction (n = > 908 cows) of dairy cows. Cows were allocated to a treatment group receiving a slow-release intraruminal bolus containing 32 g of sodium monensin that was administered 40 d before and 50 d following the anticipated calving date or to a control group. Treatment did not significantly alter any reproductive outcome; 54.5% of cows treated with monensin and 58.2% of control cows were pregnant at first service, and days to conception were lower for cows treated with monensin. The hazard rate (0.95) was not significant for these cows. The percentage of cows pregnant was 83.8 for control cows, and days to first estrus (hazard rate = 1.04) and first service (hazard rate = 1.04) were not significantly higher for treated cows. Treatment with monensin did not significantly alter the risk of any disease. The incidence of retained fetal membranes, pyometra, lameness, abortion, and infectious diseases was not significantly lower for cows in the treatment group, and the incidence of mastitis was not significantly higher for cows in the treatment group. Monensin significantly increased milk production by 0.75 L/d per cow and tended to increase milk fat and protein yields but had no significant effect on milk fat or milk protein percentages. Changes in the production of milk and milk constituents were consistent throughout lactation.

Animals↗