Enzyme-linked immunosorbent assay for the detection of antibodies to bovine viral diarrhea virus in bovine sera

A specific and sensitive enzyme-linked immunosorbent assay (ELISA) was established for the detection of antibodies to bovine viral diarrhea virus (BVDV) in bovine sera. Polyethylene-glycol concentrated, equilibrium density gradient purified BVDV was used as test antigen at an optimal amount of 1 microgram/well, whereas the optimal concentration of conjugate was at 1/2000 dilution. The standardized test encountered no non-specific reaction with test sera at a starting dilution of 1/10. A total of 50 bovine serum samples was assayed for the presence of antibodies against BVDV by ELISA and serum neutralization test (SNT). A positive correlation between the 2 tests was found. However, ELISA could be as much as 500-fold more sensitive than SNT in detecting low levels of BVDV antibodies.     

A protective antigen for Turkeys purified from a type 1 strain of Pasteurella multocida

A protective antigen was purified from a saline extract of a Type 1 strain of Pasteurella multocida by chromatographic methods, and its chemical and immunological ccharacteristics were studied. Three protein peaks were obtained from crude extract by gel filtration with Sephadex G-200. A bacteria-specific antigen was detected only in the first peak fraction, which, after passing through an immunoadsorbent column to remove any components originating from the growth medium, was adsorbed onto DEAE-cellulose followed by elution with a gradient of NaCl. From the first peak fraction of the gel filtration, 4 protein peaks were obtained, the second and third peaks being the major ones. Carbohydrate/protein ratios of the peak fractions varied from 0.06 to 1.0. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis showed that 2 proteins of molecular weights 44 000 and 25 000 were present in all the fractions. The 4 DEAE-cellulose fractions (DP-1 to DP-4) contained a single antigenically identical material, and induced protective immunity in turkeys against challenge exposure. The second peak fraction from DEAE-cellulose (DP-2) protected turkeys when subcutaneously injected as 2 doses of 10 μg protein with a 14-day interval between doses. The DP-2 fraction induced antibodies in rabbits which formed a single precipitin line against the crude extract. The purified antigen (DP-2) from a Type 1 strain was antigenically distinct from a similar antigen purified from a Type 3 strain; there was no significant cross protection in turkeys between the 2 antigens. These results indicate that protective antigens purified from soluble extracts of a Type 1 or Type 3 strain possess similar physicochemical properties, but that they are immunologically distinct from each other.     

Studies on fascioliasis in four selected sites in Ethiopia

The incidence of fascioliasis was studied in Asela, Awasa, Debre Zeit and Debre Berhan by using 153 experimental sheep divided up into 4 groups designated tracer sheep, Controls I, II and III. Fasciola hepatica was encountered in Debre Berhan, Asela and Awasa, but it was not detected at Debre Zeit. In all areas, it was most frequently recovered after heavy rains. Altitude, soil type, salt content and local crowding of animals in watering sites appear to have influenced the varying degrees of incidence and intensity of infection.     

Radioimmunoassay for β-endorphin/β-lipotropin in unextracted plasma from sheep

A double antibody radioimmunoassay (RIA) was developed and validated for the quantification of β-endorphin (EP) in unextracted plasma from sheep. The RIA crossreacted on a molar basis approximately 100% with β-lipotropin (LPH). Almost all of the immunoreactivity in silicic acid extracts of plasma migrated on gel filtration as either EP or LPH. Incubation of radioiodinated EP with unextracted plasma under assay conditions resulted in the formation of a radioiodinated product which could still bind to the anti-EP serum. Basal concentrations of EP/LPH ranged from .1 to .2 ng/ml plasma, but transient peaks of 1.4 to 2.4 ng/ml were sometimes observed.     

Growth hormone secretion in chicks during dietary calcium deficiency

The role of calcium in the secretion of growth hormone (GH) has been examined in vivo in immature domestic fowl. Chicks reared on a low calcium (0.16% calcium in the feed) diet showed a reduced growth rate, compared with those on a normal (0.86%) calcium diet and had lower basal levels of plasma GH 1, 5, 10 and 15 d after calcium deprivation, but not after 20, 25, 30 or 35 d of calcium deficiency. No consistent changes in the concentration of immunoreactive somatomedin C were observed during calcium restriction. In both the control and low calcium fed birds the plasma concentrations of GH were elevated by the intravenous administration of human pancreatic GH releasing factor (hpGRF) and by thyrotropin releasing hormone (TRH). The GH responses to these provocative stimuli were not reduced in magnitude by calcium deficiency. It is suggested, therefore, that the effect of calcium deprivation on the secretion of GH is mediated via the reduced release of stimulatory hypophysiotrophic factors from the hypothalamus.

Pharmacological alterations in calcium status also suggest that calcium deprivation inhibits GH secretion. Plasma concentrations of GH were acutely depressed in young chicks following the administration of a calcium chelator (ethylene diaminotetraacetic acid) a calcium channel blocker (verapamil) and after calmodulin inhibition (by chlordiazapine and trifluorpenazine administration). These data therefore demonstrate the importance of calcium in the stimulation of GH secretion in the domestic fowl.     

Swine trichinosis in mid-atlantic slaughterhouses: Possible relationship to hog marketing systems

Digests of diaphragms from 33 482 hogs slaughtered in the mid-atlantic states were examined for the presence of Trichinella spiralis larvae. The samples were obtained from 7 slaughterhouses, ranging in slaughter capacity from less than 50 per day to more than 4000 per day. The sources of the hogs varied from “backyard” operations, raising hogs for home use, to commercial farms. The means by which hogs were brought to the slaughterhouse also differed; the larger slaughterhouses often purchased directly from the producer while the smaller slaughterhouses (1000 hogs per day or less) usually purchased through dealers or brokers. Infected hogs were detected more frequently than was expected from previously-published prevalence studies; overall, 0.58% of samples examined contained T. spiralis larvae. All of the infected hogs were marketed through the smaller slaughterhouses (less than 1000 per day) and nearly all were marketed through brokers. The mean number of larvae per gram of diaphragm, determined by slaugterhouses type, ranged from 0.5 to 74.6; most infections were light although 5 had counts of 1000–2480.Most of the positive samples were obtained from one slaughterhouse, the data from which exhibited marked differences in the frequency of infection by day of the week; 128 positive samples of the total of 190 found were obtained on Fridays, although only 10% of all samples were obtained on that day. Analysis of the geographic origin of shipments containing infected hogs revealed that most originated in New Jersey and Pennsylvania, although the hogs shipped from the latter state might originated in New England or Maryland. Attempts to trace back infected hogs for further epidemiological investigation were largely futile, owing to the absence of an identification system.     

Half-life,clearance and production rate for oxytocin in cattle during lactation and mammary involution I

Basal concentration, production rate, metabolic clearance rate and $\text{T}{}_{\mathrm{<mtext>1</mtext><mtext>2</mtext>}}$ for oxytocin were measured in Holstein cows at three lactational stages and during mammary involution. At each lactational stage, oxytocin was given intravenously at .5 IU/min or 1.0 IU/min for 60 min. Infusions were preceded by priming. During involution, the high dose was used. Mean basal concentrations of oxytocin ranged from 8.7 to 21.4 uU/ml. Mean basal values at early, middle, late lactation and involution were 17.57, 12.33, 15.15, 21.13 uU/ml, respectively and differed significantly. The mean “rapid” $\text{T}{}_{\mathrm{<mtext>1</mtext><mtext>2</mtext>}}$ was 3.87 ± .1 min. Early, middle, late lactation and involution $\text{T}\text{1}\text{2}\text{s}$ were 4.2, 3.7, 4.0 and 3.5 min, respectively. The rapid $\text{T}{}_{\mathrm{<mtext>1</mtext><mtext>2</mtext>}}$ was not affected by lactational stage. The mean “slow” $\text{T}{}_{\mathrm{<mtext>1</mtext><mtext>2</mtext>}}$ was 25.53 ± 1 min. Early lactation and dry period means differed significantly. The overall mean oxytocin clearance rate was 8.41 ± .1 ml/kg^·min. Clearance rate declined through lactation and into the dry period. Mean values of 9.3, 8.8, 7.8 and 7.1 ml/kg^·min were obtained at early, middle, late lactation and involution, respectively. Clearance rates at late lactation and involution differed significantly from one another and from the early and middle stages. Mean entry rates for oxytocin at early, middle, late lactation and involution were 168.79, 106.03, 111.1 and 146.8 uU/kg^·min, respectively. Measurements at early lactation and involution were greater than values for middle and late lactation. To summarize, basal oxytocin concentrations can be measured in cows that are lactating or undergoing mammary involution and changes in concentrations during lactation are related to hormone production (entry rate) and metabolic clearance rates.     

Colonisation of the respiratory tract of lambs by strains of Mycoplasma ovipneumoniae

The age and time of year when colonisation of the nasal cavity of lambs by Mycoplasma ovipneumoniae occurs; the persistence of the organism, and its prevalence in the lungs at slaughter were examined in 2 flocks of sheep in New Zealand. No colonisation had occurred at the time of weaning at 6–7 weeks, but M. ovipneumoniae was recovered from most lambs on at least one occasion before they were slaughtered when about 8 months old. In most cases, colonisation of the nasal cavity by M. ovipneumoniae was a transient phenomenon. At slaughter M. ovipneumoniae was recovered from the lungs of 89% of the lambs of one flock and 80% of the other flock.

Bacterial restriction endonuclease DNA analysis (BRENDA) of 34 nasal isolates from one flock showed that it was possible to identify 7 “groups” each with markedly different BRENDA patterns. Lambs initially colonised by one strain, often lost that strain, and if recolonisation occurred it was with a different strain.

M. ovipneumoniae was recovered at slaughter from the lungs of most lambs, both normal and pneumonic. The isolates from one flock were examined by BRENDA, and approximately 90% of them gave similar or identical patterns. The predominant strain isolated from the lungs had been recovered from the nasal cavity of many of the lambs about 3 weeks earlier. This suggests that the nasal and lung isolates do not represent independent populations. However, nasal strains may differ in their ability to colonise the lungs.     

Analysis and in vivo assay of B. abortus agglutinating and non-agglutinating antibodies

Studies were made of physicochemical and immunochemical characteristics of Brucella abortus agglutinating and non-agglutinating antibodies in the sera of cattle repeatedly injected with living B. abortus (Strain 1119). Both agglutinating and non-agglutinating antibody were shown to be IgG1, and by immunodiffusion against rabbit anti-cattle gamma-globulin, agglutinating antibody gave a precipitation line of identity with that given by non-agglutinating antibody. Whilst agglutinating antibody increased clearance of antigen from the blood of passively protected mice, non-agglutinating antibody did not enhance clearance. Determination of the spleen infection index in mice pre-treated with agglutinating and non-agglutinating antibody showed that in animals passively immunized with non-agglutinating antibody the number of living (infecting) bacteria was approximately 4 times higher than in the case of agglutinating antibody. The possible potentiation of chronic B. abortus infection by non-agglutinating antibody is discussed.     

Epidemiology of theilerioses in the Trans-Mara division, Kenya: Husbandry and disease background and preliminary investigations on theilerioses in calves

All the calves born (116) into 3 Maasai cattle herds in the Trans-Mara Division of Kenya, between August 1978 and October 1979, were recruited into a monthly health study which concentrated on theileriosis. Twenty-two of the calves died before they were 6 months of age, but the mortality only increased to 25% by the time the calves reached 18 months of age. The mean birth weight of calves was 17.5 kg while at 190 days post-birth the mean weight was 53.4 kg. The main causes of mortality were starvation (7.8%), neonatal diarrhoea (2.6%), chronic indigestion (2.6%) and theileriosis (2.6%) due to Theileria parva and T. mutans infections. The calves were infected with ticks from birth (mostly Rhipicephalus appendiculatus and Amblyomma spp.) and the first Theileria schizonts were detected on Day 17 post birth and reached a maximum of 18.4% of calves in the 11th week post-birth. Seasonal peaks of macroschizont incidence occurred in February and July. All calves had patent Theileria piroplasm infections by the time they were 5 months old and 44% had shown patent Theileria macroschizont infections by 6–7 months of age. Generally low parasitosis of Theileria piroplasms and schizonts occurred. Serology using the indirect fluorescent antibody test showed a high proportion of calves received antibodies against T. mutans and T. parva from their dams by way of colostrum. The majority of calves also had active antibody responses against T. mutans and T. parva by the time they were 6 months of age. There was a correlation between the pre-patent period of piroplasms and active antibody responses to T. mutans and between the prepatent period of schizonts and an antibody response to T. parva. Eighteen older calves developed T. velifera infections. “Turning sickness” due to Theileria infection in the brain was detected in older cattle. Other blood parasites such as Trypanosoma vivax, T. congolense, Anaplasma marginale and Babesia bigemina occurred at patent levels at a lower incidence than Theileria spp. and did not cause disease problems in the calves. The calf population was highly resistant to theileriosis since they had a 100% morbidity, but only 2.6% mortality. Theileria infections would appear to have an important effect on the growth of calves but this and many aspects of the epidemiology of theileriosis in the area required more intensive sampling.     

Dirofilariasis in wild canids from the Gulf coastal prairies of Texas and Louisiana,U.S.A.

Heartworms, Dirofilaria immitis, were recovered from 17 out of 24 (71%) coyotes, Canis latrans, 38 out of 46 (83%) coyote × red wolf hybrids and all of 8 (100%) red wolves, Canis rufus gregoryi, collected from the Gulf coastal prairies of southeast Texas and southwest Louisiana. Intensities of infection ranged from 1 to 176 ($\text{x}\text{=25}$) worms per host. There was a significantly (P<0.05) higher intensity of infection in red wolves. Prevalence of heartworms increased significantly with increasing age. There were no significant differences between coyotes, hybrids and red wolves or between different host sexes in terms of prevalence. The female to male ratio of heartworms was close to unity (1.2:1) and was not correlated with worm burdens. Nematodes were primarily localized in the right heart, frequently extending into the pulmonary artery and the pulmonary arterial tree in the lungs. In 13 instances, 1–4 adult heartworms were recovered from the venae cavae. Pathological responses in the right heart were variable, depending on the intensity of infection. In severe infections, there were small areas of infarctive necrosis with mild to severe interstitial edema in the myocardium. Lesions in the pulmonary artery and pulmonary arterial trunk varied from mild focal hyperplastic intimal changes to extensive exudative villous endarteritis. The latter was characterized by a hyperplastic collagenous stroma with numerous histiocytes, plasma cells and eosinophils. Lung pathology varied from patchy to extensive areas of congestion, edema, hemorrhage, interstitial pneumonitis and infarction. In cases with heartworms in the venae cavae, hepatic changes were minimal and associated with liver changes such as passive congestion and centrolobular necrosis seen in cases without adult worms in the venae cavae. In heavily infected animals, hemosiderosis of the liver, spleen and kidneys was pronounced. A microfilaremia was noted in 46% of the infected wild canids. Microfilariae were observed in tissue sections of the myocardium, lungs, liver, kidney, spleen, lymph nodes, pancreas and appendix. Wild canids from this area are regarded as natural definitive hosts and primary reservoirs for heartworms and it appears that this infection is an important factor in the morbidity and mortality of these hosts.     

Kinetics of infection with Theileria parva (East Coast fever) in the central lymph of cattle

During the course of a lethal infection with Theileria parva in susceptible cattle, the dissemination of the parasite was examined in central lymph efferent from superficial lymph nodes in the thoracic duct. From the regional node, lymphocytes containing macroschizonts of T. parva were detected in efferent lymph 8 days after challenge where their appearance coincided with a dramatic increase in the output of lymphoblasts. The number of infected cells reached a maximum around Day 14, when 60-65% of efferent lymphocytes were parasitized. A severe reduction in the total cell output occurred after Day 14, at the time when widespread lymphocytosis was observed in the parent lymph node. A similar pattern of cellular kinetics was observed in the thoracic duct and in lymph efferent from lymph nodes distant from the site of challenge, although in the latter, the parasitosis reached only 10% of total cells. There was no selective depletion of parasitized cells from central lymph during the third week of infection, although the comparative parasitosis between lymph and lymph node cells indicated that infected cells entered central lymph less readily during this period. Macroschizonts appeared in cultures of lymphatic lymphocytes sampled between 5-9 days after challenge. These results, together with the failure of ablation of the regional lymph node 2, 3 or 5 days after challenge to delay the onset of the disease, indicated that dissemination of the infection from the site of challenge occurred within the first 2-3 days after the inoculation T. parva.     

A serological and biochemical study of new field isolates of foot-and-mouth disease virus type A in Peru, 1975 to 1981

Three foot-and-mouth disease virus type A isolates recovered from field outbreaks in the Department of San Martin, Peru, during the period 1975 to 1981 were compared with each other, and the South American vaccine strains A24 and A27, by complement fixation (CF), virus neutralization (VN) and polyacrylamide gel electrophoresis (PAGE). Complement fixation and VN tests gave comparable results distinguishing the field isolates from each other and from the vaccine strains. Analysis of the structural polypeptides by PAGE also showed clear differences between all the viruses examined. Samples from tissue culture passaged and mouse adapted strains of one of the field isolates gave identical patterns in PAGE, but differences were observed in the polypeptide pattern of the A24/BRA/55 strain and the Peru vaccine strain, which were serologically indistinguishable. Results illustrate a continued antigenic variation in an endemic area where vaccination has been used; however, asymmetric serological reactions between the A24 vaccine strain and the most recent field isolate indicated that a vaccine incorporating A24 should still give adequate protection.     

Normal sexual maturation and reproductive function in domestic hens following unilateral adrenalectomy

The ovulation-inducing properties of adrenal hormones and the anatomical juxtaposition of the left adrenal gland and the ovary suggest that a functional relationship exists between these two endocrine organs. To test this hypothesis, the effect of unilateral adrenalectomy on sexual maturation and reproductive function was examined in left and right adrenalectomized SCWL pullets. Between 9 and 13 weeks of age, 24 and 12 pullets were either left or right adrenalectomized, respectively; 12 birds were sham operated and 7 birds served as unoperated controls. Blood samples were obtained immediately before and after surgery, 48h after surgery and at 14, 19 and 23 weeks of age. All samples were analyzed for plasma corticosterone by radioimmunoassay. At 20 weeks of age all birds were weighed and the photoschedule was changed from 8L:16D to 16L:8D. During the first 52 days following photostimulation the age at first egg and the distribution of ovipositions within the 24h photoschedule were recorded.Mean plasma corticosterone levels of the unilaterally adrenalectomized hens were not significantly different (P > .05) from those of control birds 48h after surgery or at 14, 19 and 23 weeks of age. Unilateral adrenalectomy had no effect on body weight at 20 weeks, average age at first egg, or percent hen-day production. In addition, 95% of the eggs laid in the first 52 days after photostimulation were restricted to a 10 hour period of the day regardless of the surgical treatment. These observations indicate that the removal of either the left or the right adrenal gland does not affect plasma levels of corticosterone, sexual maturation, or the open period for LH release as evidenced by the times of oviposition and fail to support the hypothesis of a localized functional relationship between the left adrenal gland and the ovary.     

Oxytocin concentrations of cattle in response to milking stimuli through lactation and mammary involution II

Patterns of oxytocin release to milking stimuli over a lactation and during mammary involution, were examined in seven Holstein cows used in the previous study. Blood samples were taken before, during and after milking or udder massage. Oxytocin as measured by radioimmunoassay increased within O to 2 min after attachment of the milking unit. Oxytocin levels fluctuated during milking and declined after the initial increase. Oxytocin often dropped below basal levels after milking. Milking-induced oxytocin release decreased as lactation advanced. The maximal increment for oxytocin release was significantly different between early and late lactation. The time taken to reach peak hormone concentrations declined across lactation. Relative amounts of oxytocin released in response to milking stimuli were significantly more in early than during late lactation. Cows released oxytocin during mammary involution with relatively large, rapid increases to udder massage. A distinct peak was observed and return to basal concentrations was rapid. The mean increment of oxytocin concentration above basal was 51.6 ±10.1 uU/ml. Maximal oxytocin levels occurred 1.6 ±.2 min (0 to 2 min) after initial stimulation. The total amount of oxytocin released in response to stimulation was 1.2 ±.1 uU/ml. In summary, a continuous or multiple release of oxytocin occurs during milking. The sensitivity of the neuroendocrine reflex for oxytocin appears dynamic. Changes in maximal concentrations and total amounts of hormone released in response to milking during lactation, and the relationship between these variables and basal concentrations suggest a gradual loss of sensitivity from the early stages of lactation to mammary involution.     

Search for an antigenic relationship between aeromonads and Brucella abortus

A. hydrophila, A. punctata subsp. vaviae, A. salmonicida, and Plesiomonas shigelloides strains did not serologically react with three strains of Brucella abortus when tested by serum agglutination, immunodiffusion, and immunoelectrophoresis.     

Clinical and serological evidence of bovine babesiosis and anaplasmosis in St. Lucia

One hundred fifty-nine Holstein calves were imported into St. Lucia from the U.S.A. An outbreak of babesiosis occurred 17 days post-arrival, and an outbreak of anaplasmosis occurred 5 months after importation. Sera obtained 3, 6 and 12 months post-importation revealed a high prevalence of IFA titres to Babesia bovis and B. bigemina 3 months after arrival and an increase in titres to Anaplasma marginale 6 months after arrival. Sera obtained arrives from native cattle from several places on the island indicated infection rates of 80, 65 and 64% with A. marginale, B. bigemina and B. bovis, respectively. The rapid card test only indicated a 25% prevalence of infection of native cattle by A. marginale. This low prevalence was probably due to deterioration of serological activity during shipment.     

Morphogenesis of Trichostrongylus rugatus and distribution during development in sheep

Morphogenesis of Trichostrongylus rugatus was examined in 16 sheep experimentally-infected with 120 000 third-stage larvae and killed 2, 4, 6, 8, 10, 12, 16 and 20 days later (DAI). Third stage larvae moulted between Days 4 and 6, and fourth stage larvae moulted on Day 10 after infection. Four sheep first passed eggs in the faeces between Days 16 and 18 after infection. Rate of growth of larvae was constant between 2 and 10 DAI followed by a period of rapid growth from 10 to 16 DAI. Major features of larval development are described. Nematodes were largely restricted to the first 6 m of gut with 71% of worms occurring in the first 3 m.     

Development of villus atrophy in the small intestine of sheep infected with Trichostrongylus rugatus

Pairs of sheep infected with 120 000 larvae of Trichostrongylus rugatus were killed at intervals from 2 to 56 days after infection (DAI). Worms were located in tunnels in the epithelium of villi or upper intestinal crypts at all stages of development. Villus atrophy developed progressively until 16 DAI, when surface microtopography, characterised by subtotal villus atrophy, stabilised. Most severe lesions were in the first 3 m of small intestine where the density of nematodes was highest. Discontinuities in the epithelium and effusion of inflammatory cells and tissue fluids into the lumen were rare. No effects of infection on body-weight gain, appetite or serum total protein and albumin were evident in the first 20 days of infection. However, it was concluded that T. rugatus fundamentally resembled T. colubriformis and T. vitrinus in the response it elicited in the intestine of sheep, and must be considered potentially pathogenic.     

Serum and abomasal antibody response of sheep to infections with Haemonchus contortus

Serum and abomasal IgA, IgG and IgM antibody response against adult worm, L3 and egg antigens of Haemonchus contortus was monitored by the ELISA technique after one or two infections with this nematode. Following the first infection, antibody levels in serum did not change materially. After administration of a challenge dose of infective larvae, antibodies of the three immunoglobulin classes in infected animals rose slightly, but this rise appeared later than the fall in the faecal egg counts. In contrast, in abomasal mucosa, IgA anti-larval antibody levels, which did not increase materially after the primary infection, rose rapidly after a transient inhibition when sheep were challenged. A close temporal relationship was observed between the rise in local anti-worm IgA antibodies and the self-cure reaction, but antibody levels fell rapidly after worm diminution. The local antibody response was thus considered to be related to immunity of sheep to H. contortus.