Ontogeny of immunity and leukocytes in the ovine fetus and elevation of immunoglobulins related to congenital infection

Certain humoral and cellular aspects of the immune response were observed during gestation in the ovine fetus. Emergence and development of leukocytes in peripheral blood were observed. Morphologically mature lymphocytes were consistently present at 32 days of gestation, but mature neutrophils were not neutrophils were not consistently present until gestational day 123. Monocytes were first observed at 63 days and eosinophils at 112 days of gestational age. Numbers of each class of leukocyte increased from the time of their appearance until just prior to birth when they declined. Production of immunoglobulin G (IgG) and immunoglobulin M (IgM) was monitored from the time of their appearance at 56 and 77 days, respectively, until birth. In contrast to consistently low base-line values of IgG and IgM (below 0.22 mg/ml and 0.21 mg/ml, respectively) found in clinically normal, unstimulated fetuses, the immunoglobulin values in experimentally infected animals increased with the age of the fetus. This finding can be utilized in diagnosis of several congenital infections and anomalies.     

Ontogeny of T cells in the pig fetus

Mononuclear cells isolated from thymus, spleen and cord blood of pig fetuses ranging in age from 48 to 112 days were examined for the presence of sheep red blood cell rosette-forming cells (SRBC-RFC). After an initial increase from 77 % (mean) at 48 days of gestation to 88 % at 60 days, the proportion of SRBC-RFC in thymus remained constant throughout the gestational period. In spleen and cord blood, the proportion of SRBC-RFC increased with age, from occasional rosette-forming cells at 48 days of gestation to 21 % and 30 %, respectively, at 112 days. The demonstrated development of SRBC-RFC in the thymus, spleen and cord blood is considered to reflect the ontogeny of T cells in these fetal pig tissues.     

Effect of maternal ketoacidosis on the ovine fetus

Ketoacidosis during pregnancy carries significant risk of intrauterine fetal demise, but little is known about the impact of ketoacids on the ovine fetus. We report a case series of maternal ketoacidosis in ewes. Maternal ketoacidosis may result in biochemical and acid-base fetal abnormalities associated with changes in feto-placental unit perfusion.     

Serology of Campylobacter fetus fetus strains from four outbreaks of ovine abortion

As a result of a Ministry of Agriculture & Fisheries survey on ovine abortions, 76 isolates of Campylobacterfetus fetus were obtained. These isolates were from four farms in the southern Hawkes Bay, with an abortion incidence of 2.8% to 9.1%. Antisera to eight different strains of C. fetus fetus were made in rabbits. Strains were then examined using whole cell tube agglutination tests and sensitised Staphylococcal Protein A slide agglutination tests. Heat labile antigens were examined by absorbing antisera with heat-treated bacteria. Two broad serogroups were found, but within-group variation was demonstrated by cross-absorbing antisera. The isolates from one farm were all of a single broad serogroup. Both serogroups were found on the remaining three farms. Evidence for the presence of two major serogroups was also obtained by immobilisation tests and antigen analysis by gel diffusion.     

Histological development of the small intestinal mucosa in the ovine fetus.

Histological changes in the small intestine of 85 ovine fetuses were studied, with particular reference to the mucosa. In 24-day-old fetuses the endoderm of the intestine consisted of a single layer of epithelium. By the 26th day the epithelium was flattened and stratified. The first evidence of rudimentary villus formation was noted in 39-day-old fetuses. Intestinal glands were first observed at 56 days. Other mucosal structures were present by 101 days. At birth the intestinal mucosa was fully mature.     

Arthritis associated with ovine progressive pneumonia

Chronic nonsuppurative arthritis developed in carpal and tarsal joints of border Leicester sheep that were naturally or experimentally infected with ovine progressive pneumonia (OPP) virus. Clinical signs of arthritis began at 1 to 6.2 years of age (1 to 5.7 years after inoculation of OPP virus) and slowly progressed in severity until the sheep died or were killed. The joint lesions were characterized by edema, hyperemia, hyperplasia, and necrosis of the synovial membrane; by necrosis and erosion of articular bone; by necrosis and fibrosis of subchondral bone; and by extensive periarticular fibrosis. The OPP virus alone was isolated from arthritic joints. In 7 of 14 sheep, the arthritis was associated with interstitial pneumonitis induced by the virus. Therefore, it was concluded that OPP virus was the cause of arthritis in this group of sheep.     

Sequential sterile autolysis in the ovine fetus: macroscopic changes.

Sterile intrauterine autolysis was experimentally produced in 28 ovine fetuses in the last 3rd of gestation by umbilical artery ligation. The fetuses were retrieved by cesarean section after periods of sterile intrauterine autolysis ranging from 0.5 to 168 hours. The following autolytic changes, frequently reported as significant lesions in infectious abortions in cattle and sheep, were observed: subcutaneous blood-tinged gelatinous edema, blood-tinged fluid in the serous cavities, renal cortical softening, uniform reddish brown tissues, hepatic friability and mottling, and cloudy yellow to cloudy red abomasal contents. The appearance of these and other autolytic changes corresponded to sterile sequential autolytic changes reported in the rabbit fetus and used to determine duration of retention of stillborn infants and are of comparative biomedical significance. The sequential autolytic changes may be used as an index to duration of retention after death of a ruminant fetus and provide a basis for reappraising various infective abortifacients common to ruminants by allowing separation of specific lesions from strictly autolytic changes.     

Serogroups of Campylobacter fetus and Campylobacter jejuni isolated in cases of ovine abortion

Of 38 aborted ovine fetuses from 23 sheep flocks 29 C. fetus subsp. fetus and 22 C. jejuni were isolated and examined biochemically and serologically for heat-stable antigens. Serologic examinations were carried out by passive haemagglutination test. In case of C. fetus subsp. fetus strains alkaline antigen extraction was used. Antisera to two serogroups of C. fetus and to Penner serotype reference strains 1 to 60 were produced in rabbits. Abortion was caused in 18 (78.3%) flocks by C. fetus subsp. fetus and in 5 (21.7%) flocks by C. jejuni. Six C. fetus subsp. fetus strains grew well at both 43 and 25 degrees C. With one exception all C. fetus subsp. fetus were resistant, whereas all 29 C. fetus subsp. venerealis strains were sensitive to 30 micrograms/ml cefoxitin and cefamandole. These two cephalosporins can be used to differentiate the two subspecies of C. fetus. Passive haemagglutination test using alkaline antigen extraction is a proper method for the examination of heat-stable antigens of both C. fetus subspecies. Out of 24 C. fetus subsp. fetus strains 13 belonged to serogroup A(01), and 11 to serogroup B(02). C. jejuni strains examined belonged to Penner serogroup 1 (6 strains), to serogroup 5 (4 strains) and to serogroup 8 (4 strains).     

Immunohistochemical identification of Campylobacter fetus in natural cases of bovine and ovine abortions

An immunohistochemistry (IHC) procedure for the detection of Campylobacter fetus antigens using an avidin-biotin complex technique was performed on formalin fixed bovine and ovine fetal tissues from 26 natural cases of Campylobacter spp. abortion (four ovine and 22 bovine). The species of Campylobacter isolated included C. fetus ssp. venerealis from 13 bovine fetuses, C. fetus ssp. fetus from two ovine and one bovine fetus, Campylobacter jejuni from seven bovine fetuses, Campylobacter lari from two ovine fetuses and an unspeciated Campylobacter species in one bovine fetus. Histologic lesions identified in the aborted fetuses included placentitis, serositis, pneumonia, gastroenteritis, hepatitis and encephalitis. Campylobacter fetus antigens were identified by IHC in 13 of 13 bovine fetuses from which C. fetus ssp. venerealis was isolated and in two of two ovine fetuses from which C. fetus ssp. fetus was isolated. The IHC stains were negative in tissues from seven bovine fetuses from which C. jejuni was isolated, one bovine fetus infected with C. fetus ssp. fetus, one bovine fetus infected with the unspeciated Campylobacter and two ovine fetuses infected with C. lari. In positive cases, the IHC stain most frequently identified bacteria in the lung and gastrointestinal tract. The C. fetus IHC procedure performed on formalin fixed tissues is a practical tool for the diagnosis of natural cases of ovine and bovine abortion caused by C. fetus.     

The role of maternal triglycerides in the supply of lipids to the ovine fetus.

Maternal and fetal blood samples were obtained for up to 20 min after the injection of an emulsion of 14C-labelled glycerol tripalmitate into the circulation of pregnant ewes. No evidence was obtained for the direct transfer of intact triglycerides across the placenta. Results obtained suggest that there was a very rapid uptake of the triglyceride from the maternal circulation followed by hydrolysis and release of free fatty acids back into the maternal circulation.     

Farmer reported prevalence and factors associated with contagious ovine digital dermatitis in Wales: A questionnaire of 511 sheep farmers

In 2012, 2000 questionnaires were sent to a random sample of Welsh sheep farmers. The questionnaire investigated farmers’ knowledge and views on contagious ovine digital dermatitis (CODD) – an emerging disease of sheep responsible for causing severe lameness, welfare and production problems. The overall response rate was 28.3% with a usable response rate of 25.6%. The between farm prevalence of CODD was 35.0% and the median farmer estimated prevalence of CODD was 2.0%. The disease now appears endemic and widespread in Wales. Furthermore, there has been a rapid increase in reports of CODD arriving on farms since the year 2000. Risk factors for CODD identified in this study include the presence of bovine digital dermatitis (BDD) in cattle on the farm and larger flocks. Farmers also consider concurrent footrot/interdigital dermatitis, buying in sheep, adult sheep, time of year and housing to be associated with CODD. Further experimental research is necessary to establish whether these observations are true associations.     

Proteomic analysis of ovine muscle hypertrophy

Two-dimensional electrophoresis was used to investigate the effects of a QTL for muscle hypertrophy on sarcoplasmic protein expression in ovine muscles. In the Belgian Texel breed, the QTL for muscle hypertrophy is localized in the myostatin-encoding gene. Based on microsatellite markers flanking the myostatin gene, we compared the hypertrophied genotype with the normal genotype. The average age of the sheep was 3 mo. Among the 4 muscles studied, in the hypertrophied genotype only the vastus medialis was normal, whereas the semimembranosus, tensor fasciae latae, and LM were hypertrophied. In the hypertrophied genotype, these muscles showed upregulation of enzymes involved in glycolytic metabolism together with oxidative metabolism in LM. Certain chaperone proteins, including glutathione S-transferase-Pi, heat shock protein-27, and heat shock cognate-70, were also more highly expressed, probably due to increased use of energetic pathways. Expression of the iron transport protein transferrin was increased. Alpha-1-antitrypsin was the only protein showing a similar pattern of expression (i.e., less expressed) in all 4 muscles of the hypertrophied genotype. It is suggested that transferrin and alpha-1-antitrypsin may interact to reinforce myogenic proliferative signaling.     

Vasculitis associated with ovine progressive pneumonia virus infection in sheep

Vasculitis, involving small muscular arteries and arterioles, was found in 5 of 18 sheep naturally infected with ovine progressive pneumonia (OPP) virus and in 5 of 11 sheep experimentally infected with OPP virus. In order of frequency, arterial lesions were seen in carpal joint capsules, kidneys, meninges, brains, lungs, and tracheas. The lesions were intramural edema and hemorrhage, mononuclear cell infiltration, fibrinoid necrosis of media, and thrombosis. The vascular lesions were frequently associated with interstitial pneumonitis, arthritis, and encephalitis also induced by OPP virus.     

Mastitis associated with ovine progressive pneumonia virus infection in sheep

Eighteen ewes were experimentally infected with ovine progressive pneumonia virus and their mammary glands were examined for lesions and virus at 2.5 to 10 years postinoculation. Lesions were seen in 14 of 18 sheep; virus was isolated from 4 of 8 sheep. Lesion consisted of an interstitial accumulation of lymphocytes with periductal lymphoid nodules, and epithelial vacuolation and necrosis at the site of the lymphoid nodules.