1974 Onderstepoort Journal of Veterinary Research, Volume 41, 1974
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Item Subject index(Pretoria : The Government Printer, 1974) Anonymous; Bigalke, R.D.; Cameron, Colin McKenzie; Verster, Anna J.M.; Walker, Jane B.; De Kock, V.E.Item Author index(Pretoria : The Government Printer, 1974) Anonymous; Bigalke, R.D.; Cameron, Colin McKenzie; Verster, Anna J.M.; Walker, Jane B.; De Kock, V.E.Item The elimination of ribonucleic acid interference in the spectrophotometric determination of protein concentration(Pretoria : The Government Printer, 1974) Oellermann, R.A.; Bigalke, R.D.; Cameron, Colin McKenzie; Verster, Anna J.M.; Walker, Jane B.; De Kock, V.E.A simple, sensitive and rapid spectrophotometric method for the determination of protein concentration in the presence of RNA contaminants is described. Only small spectral differences exist between RNAs from different sources and to eliminate their interference, two wavelengths must be selected where absorbance due to RNA is identical. The isoabsorbance wavelengths must lie between 235 nm and 226 nm, the region where with decrease in wavelength the increase in absorbance is linear for most proteins. From data presented wavelengths of 233,0 nm and 226,0 nm were selected as the most suitable. A linear relationship between difference in absorbance (226, 0 nm-233, 0 nm) and protein concentration was observed for pure protein preparations up to 300 µg/ml and for protein: RNA mixtures. Protein concentrations determined by this method were comparable with those determined by the colorimetric method of Lowry. Differences in isoabsorbance wavelengths selected in this study and those reported by other workers are discussed.Item Studies on schistosomiasis. 6. A field outbreak of bilharzia in cattle(Pretoria : The Government Printer, 1974) Van Wyk, Jan Aucamp; Bartsch, R.C.; Van Rensburg, L.J.; Heitmann, L.P.; Goosen, P.J.; Bigalke, R.D.; Cameron, Colin McKenzie; Verster, Anna J.M.; Walker, Jane B.; De Kock, V.E.An outbreak of bilharzia (Schistosoma mattheei) infestation involving about 100 oxen on the farm Otthilie near Tolwe in northern Transvaal is described. Infestation of the cattle appears to have occurred per os from a single drinking trough. The cattle showed clinical signs and pathological lesions of both the reinfestation and the acute syndromes. The worm burdens were the highest recorded hitherto in naturally infested cattle. Severe macroscopic clay pipe stem periportal fibrosis, granulomata of the ureters and severe grey pigmentation of the lungs, are described for the first time in naturally infested cattle. There was more marked liver pigmentation than had been encountered previously in this host. A striking feature in every case was conspicuous congestion and enlargement of the ileo-cecal valve, which was dark red in colour. Treatment of affected animals with injectable trichlorphon controlled the outbreak without causing mass embolism and liver infarcts. At least 11 treatments at a dosage level of 10-12 mg/kg per treatment at 3-5 day intervals are necessary. Faecal examinations for eggs or miracidia cannot be used to assess the worm burden or the clinical state of the animal. Moreover, it is suggested that this disease may be confused with other conditions and this probably accounts for the rarity of reports of outbreaks in ruminants.Item Serum protein fractions as determined by cellulose acetate electrophoresis in Schistosoma mattheei infested sheep(Pretoria : The Government Printer, 1974) Van Zyl, L.C.; Bigalke, R.D.; Cameron, Colin McKenzie; Verster, Anna J.M.; Walker, Jane B.; De Kock, V.E.The serum protein fraction values of Dorper sheep infested with Schistosoma mattheei were determined by cellulose acetate electrophoresis at regular intervals for 15 months. Statistical analyses showed that increases in ƴ globulin and decreases in albumin were significant.Item Studies on the effect of cortisol on the primary immune response to sheep erythrocytes in vivo by mouse spleen cells(Pretoria : The Government Printer, 1974) Waldek, J.F.; Hellig, H.R.; Bigalke, R.D.; Cameron, Colin McKenzie; Verster, Anna J.M.; Walker, Jane B.; De Kock, V.E.Female mice were injected with a suspension of 0, 2 ml of 10 per cent v/v sheep red blood cells (SRBC) and sacrificed on the 5th day for recording of spleen mass and assay of plaque-forming cells (PFCs) in the spleens. All PFCs from a pool of five spleens and the individual spleen masses were subjected to rigid statistical analysis to verify whether differences from the control groups were significant (P < 0, 05). Three doses of 4 mg cortisol administered at 24-hourly intervals were given at various times relative to the time of immunization to determine the optimum stage at which to inhibit the formation of PFCs. The greatest inhibitory effect was obtained when the first dose was given at -6 h, with a lesser though still significant depression of PFCs with the -30 h dose regimen. Earlier and later injections had relatively little effect. An attempt was made to determine the response to different dosage levels by injecting doubling doses of steroid starting at the -6 h period. A maximal effect was attained using either 1 to 2 mg cortisol suspension or 0, 5 mg of the soluble pharmaceutical preparations, Efcortolan* and Betsolan*. Inhibition of PFCs appeared to be a more sensitive indicator of steroid action than loss of mass. In addition, spleen mass was determined after injection of either 4 mg cortisol three times or SRBC. During steroid treatment the spleen mass decreased, but the masses started to increase again almost immediately this treatment was discontinued; the maximum antigenic response, as evinced by attainment of maximal mass, occurred at + 4 days, when the PFC production reached its peak.Item The transmission of Babesia bovis using frozen infective material obtained from Boophilus microplus larvae(Pretoria : The Government Printer, 1974) Van Vuuren, A.S.; Potgieter, F.T.; Bigalke, R.D.; Cameron, Colin McKenzie; Verster, Anna J.M.; Walker, Jane B.; De Kock, V.E.Boophilus microplus larvae infected with Babesia bovis were removed from a susceptible ox approximately 72 hours after attachment, triturated and stored in liquid nitrogen refrigerator with dimethyl sulphoxide as cryoproctectant. When inoculated into splenectomised cattle the suspension was infective in the 2 animals into which it was injected intravenously but not in the 3rd, which was only injected subcutaneously. The prepatent period in the infected cattle was 10 and 11 days respectively.Item The golden hamster as a definitive host of Taenia solium and Taenia saginata(Pretoria : The Government Printer, 1974) Verster, Anna J.M.; Bigalke, R.D.; Cameron, Colin McKenzie; Verster, Anna J.M.; Walker, Jane B.; De Kock, V.E.The susceptibility of golden hamsters to infestation with Taenia solium is increased by treatment with antilymphocytic scrum (ALS) or whole body irradiation or chemical immunosuppressants, viz. methylprednisolone acetate and betamethazone disodium phosphate. Although the worms develop to sexual maturity they do not produce eggs. Such treatment is less effective in increasing their susceptibility to T. saginata. When young hamsters were exposed to whole body irradiation and subsequently treated with ALS, 60 per cent of them became infested with T. saginata. As young animals do not survive immunosuppression for any length of time the further development of this tapeworm was not investigated.Item Sedimentation of bacteria with polyethylene glycol(Pretoria : The Government Printer, 1974) Cameron, Colin McKenzie; Weiss, K.E.; Bigalke, R.D.; Cameron, Colin McKenzie; Verster, Anna J.M.; Walker, Jane B.; De Kock, V.E.Experiments are reported which show that the addition of 4,0% polyethylene glycol (6 000 MW) to liquid cultures of Clostridium welchii Type D , Pasteurella and Vibrio fetus (venerialis) will effectively sediment the bacteria. Live Brucella abortus S19, a smooth S. gallinarum Strain 28 600 and a formalin inactiviated suspension of V. fetus (intestinalis) Strain 661 were, however, not sedimented. When effective the method has appreciable application in the production of vaccines and other processes requiring the easy collection of large volumes of cells, and the separation of bacteria from their soluble exotoxins.Item The effect of immunosuppression on the development of immunity to fowl typhoid(Pretoria : The Government Printer, 1974) Brett, O.L.; Fuls, W.J.P.; Cameron, Colin McKenzie; Verster, Anna J.M.; Walker, Jane B.; Bigalke, R.D.; Cameron, Colin McKenzie; De Kock, V.E.Chickens which were given cyclophosphamide during the first three to five days of life showed a marked depression in their humoral antibody response to sheep erythrocytes and Brucella antigen. Their ability to develop tuberculin sensitivity and their immune response to live Salmonella gallinarum vaccine was, however, unimpaired. The administration of methylprednisoline acetate, hydrocortisone acetate, azathioprim and 6-mercaptopurine to either six or 10 to 12-week-old chickens neither selectively depressed the humoral or cellular immune response nor affected the immune response to live S. gallinarum vaccine. Similarly, the immune response could not be depressed by thymectomy or antilymphocyte globulin. These results indicate that immunity to S. gallinarum after administration of a live avirulent vaccine is not dependent on a humoral immune mechanism but probably primarily on cellular immunity, although this could not be proven.Item The diagnosis of subclinical mastitis in lactating cows : a comparison of cytological methods and a monovalent radial immunodiffusion test(Pretoria : The Government Printer, 1974) Giesecke, W.H.; Viljoen, M.H.; Bigalke, R.D.; Cameron, Colin McKenzie; Verster, Anna J.M.; Walker, Jane B.; De Kock, V.E.The diagnostic accuracy of conventional methods for the diagnosis of subclinical mastitis, such as the direct microscopic count (DMC) and electronic cell count (ECC) either used alone or in combination with bacteriological examinations, according to international standards, were compared with DNA determinations and a radial immunodiffusion test (MMT). The latter is based on single radial immunodiffusion of bovine serum albumin (BSA) in agarose containing anti-BSA serum. This investigation was conducted on 1 008 foremilk samples, collected via the teat canal from 179 dairy cows, plus 56 samples obtained from 14 of them by means of cisternal puncture. It is concluded that BSA concentrations in milk causing an MMT diameter ≥ 8mm are diagnostic for mastitis in lactating cows under the conditions existing in this experiment. The coefficient of variation of the MMT (14, 67%) is significantly smaller than that of the DMC (87, 78%), ECC (72,25%) and DNA content (37, 19%) respectively and lies within the 15% limit recommended for diagnostic methods. Diagnoses made by MMT, DMC and ECC over 3 successive days varied by 4,1%; 14,5% or 28,4% respectively. The reduced repeatability of the MMT resulted from genuine changes in udder health whereas 10,1% and 24,3% of variance observed for the DMC and ECC respectively were due to other factors. In comparison to the MMT, mastitis diagnosis based on international standards resulted in 43,13 ± 20, 8% false positives. These are mainly due to teat canal infections simulating mastitis. When both the MMT and international mastitis standards were used it was possible to distinguish between quarters with irrelevant and relevant teat canal infections, non-specific cellular reactions and septic or aseptic mastitis without having to resort to cisternal puncture. Staphylococcal beta toxin inoculated into the teat canal, facilitated studies on the sequence of events leading to elevated BSA levels and cellular counts in the udder. A pre-inflammatory leucocytosis, resulting from passage of small amounts of toxin into the teat cistern was shown to occur in this investigation. The diagnosis of subclinical mastitis in dry cows and within the first week post parium is as inaccurate by means of the MMT as by conventional methods.Item Immunization against bovine besnoitiosis with a live vaccine prepared from a blue wildebeest strain of Besnoitia besnoiti grown in cell cultures. 1. Studies on rabbits(Pretoria : The Government Printer, 1974) Bigalke, R.D.; Schoeman, J.H.; McCully, R.M.; Bigalke, R.D.; Cameron, Colin McKenzie; Verster, Anna J.M.; Walker, Jane B.; De Kock, V.E.The immunizing potency of a live vaccine prepared from a strain of Besnoitia besnoiti isolated from blue wildebeest and stored frozen as a low passage stabilate was studied in adult male rabbits. The vaccine consisted of parasites that were grown in primary lamb kidney or an established line of green monkey kidney cell (Vero) cultures and suspended in serum-free Hanks' or Eagle's medium respectively. Freshly prepared doses containing from 1 x 10 to 2 x 10⁵ parasites of the 14th to 34th culture passages were injected subcutaneously. The blue wildebeest strain was pathogenic in rabbits at all the dosage levels tested and 24, 6 per cent died as result of vaccination. The survivors were challenged one to six months after vaccination by subcutaneous inoculation with a bovine strain of B. besnoiti grown in lamb or Vero cells from a low passage level frozen stabilate. Immunized rabbits were protected against challenge doses that were 10 to 100 000 times greater than those of the vaccine. Immunized rabbits did not show any evidence of infection, whereas all the controls developed typical reactions (patent parasitaemia, scrotal oedema, orchitis) and 58 per cent died. It was therefore not possible to calculate an ID₅₀ for vaccinated and control rabbits in this investigation, but one experiment revealed that more than 5 logs of protection had been induced by the vaccine. Rabbits injected with Vero cells only were not protectedItem Stimulation of the immune response in vivo by different nucleic acids(Pretoria : The Government Printer, 1974) Oellermann, R.A.; Bigalke, R.D.; Cameron, Colin McKenzie; Verster, Anna J.M.; Walker, Jane B.; De Kock, V.E.The number of haemolytic plaque forming cells (PFCs) in the spleens of normal mice could not be increased by the injection of nucleic acids. However, when nucleic acids were injected into mice simultaneously with a priming dose of 3 x 10⁶ sheep erythrocytes (SRBCs) an appreciable stimulatory effect was observed. The same dose of SRBCs did not result in an increase in PFCs when injected alone. Nucleic acids at a concentration of approximately 1.5 mg per mouse resulted in an optimal stimulation of the immune response. Treatment of the nucleic acids by ribonuclease and deoxyribonuclase essentially eliminated the stimulatory effect of the RNA and DNA respectively whereas incubation with trypsin did not. Administration of pure single stranded RNAs from the livers and spleens of both normal and immunized mice resulted in a greater increase in the number of PFCs than nucleic acids from other sources. The stimulation of PFCs by RNAs from immunized mice was slightly greater than by RNAs from non-immunized mice. The immune response was also activated if the nucleic acids and the priming dose of antigen were not injected simultaneously.Item Studies on Haemonchus contortus. I. The influence of previous exposure to Trichostrongylus axei on infestation with H. contortus(Pretoria : The Government Printer, 1974) Reinecke, R.K.; Bigalke, R.D.; Cameron, Colin McKenzie; Verster, Anna J.M.; Walker, Jane B.; De Kock, V.E.A group of Merino sheep, aged 6-7 months was infested orally with 50 000 infective larvae of Trichostrongylus axei. This group and a control group were challenged 90-92 days later with 50 000 infective larvae of Haemonchus contorus. Previous infestation with T. axei caused a reduction of more than 80% in the worm burdens of H. contorus in more than 80% of the sheep.Item The diagnosis of bovine mastitis with particular reference to subclinical mastitis : a critical review of relevant literature(Pretoria : The Government Printer, 1974) Giesecke, W.H.; Van den Heever, Louwrens Wepener; Bigalke, R.D.; Cameron, Colin McKenzie; Verster, Anna J.M.; Walker, Jane B.; De Kock, V.E.From a review of literature on bovine mastitis published between 1833 and 1973 it is concluded that although herd control has caused a shift of emphasis from the clinical to the subclinical forms, diagnostic criteria have remained basically unaltered. Concurrent with this shift, improved bacteriological and cytological techniques are more sensitive than those available at the turn of this century. The sensitivity of these methods apparently has led to great confidence in their use in the diagnosis of mastitis. This culminated recently in a definition of mastitis as well as standardization of diagnostic criteria by the International Dairy Federation (IDF) which stressed the significance of potentially pathogenic bacteria and eleva1ed somatic cell counts (threshold 5 x 10⁵ cells/ml) in aseptically sampled foremilk. The validity of these widely accepted diagnostic criteria, particularly in the case of subclinical mastitis, is based on the assumption that an increase in the sensitivity of the methods should lead to an increase in diagnostic accuracy. Consequently, one would expect to find conclusive evidence of the diagnostic significance of the criteria used by the IDF. In contrast, this review attempts to reveal a conspicuous lack of adequately controlled experimental evidence supporting the diagnostic significance of criteria laid down by the IDF. They are of particular importance when dealing with subclinical mastitis, since the demarcation between physiological and pathological changes is considerably less distinct than in acute clinical mastitis. Thus no reference to pathological alteration of the udder epithelium, the primary symptom of mastitis, could be found in the literature assessed in terms of examination of milk. Similarly, the misleading influence of teat canal infections or lesions on the diagnostic accuracy of bacteriological and/or cytological examination of milk samples, obtained by "aseptic'' withdrawal via the teat canal, is disregarded. The physiological significance of Selye’s General Adaptation Syndrome or Schalm's Leucocytic Udder Barrier as non-inflammatory causes of elevated epithelial or leucocytes counts in milk appear to have been overlooked by workers who regard the presence of somatic cells in general or leucocytes in particular as synonymous to pus in milk. Due to absence of appropriately controlled experimental data, there is also no conclusive evidence to support the diagnostic significance of the IDF criteria referring to latent udder infections. Likewise it is not possible to distinguish between clinical and subclinical mastitis in udders with chronic indurative tissue changes in the absence of clinical alterations of the milk. The above considerations do not preclude the control of certain types of mastitis by application of IDF standards. However, because such criteria may result in some 43,13 ± 20,8% false positive diagnoses, it is conceivable that losses resulting from procedures based upon inaccurate diagnoses may far outweigh those caused directly by mastitis. The criteria of the IDF could, however, be used to great advantage for the diagnosis and control of mastitis if augmented by a test capable of establishing the physiological and pathological slate of the mammary epithelium. This is possible by means of a radial immunodiffusion test based on diffusion of bovine serum albumin (BSA), present in milk. The combination of BSA and the IDF criteria permits accurate assessment of udder health and teat canal infections.Item A survey of diseases among 100 free-ranging baboons (Papio ursinus) from the Kruger National Park(Pretoria : The Government Printer, 1974) McConnell, E.E.; Basson, P.A.; De Vos, Valerius; Myers, Betty J.; Kuntz, R.E.; Bigalke, R.D.; Cameron, Colin McKenzie; Verster, Anna J.M.; Walker, Jane B.; De Kock, V.E.The pathological and parasitological findings from 100 free-ranging chacma baboons are described. One of the most striking discoveries was a heretofore unknown coccidian parasite, Isospora papionis, and even more important than its presence in the small intestine was its occurrence in skeletal muscles. Serological and histopathological evidence of toxoplasmosis was found in several animals. Other previously unknown parasites encountered included two mites- Rhinophaga elongata, an unusually long mite that produced small granulomas in the nasal mucosae, and Pneumonyssus vocalis, a mite found in the laryngeal ventricles. A new species of filarid, Tetrapetalonema papionis was found in the subcutis and intermuscular fascia. New records for the chacma baboon of known parasites were R. papionis, a mite found only in the maxillary recess, where it stimulated a polyplike growth, and, in the skeletal muscles, cysticerci of Taenia crocutae, a tapeworm of hyenas (Crocuta crocuta and Hyaena brunnea). Apart from the pathological changes associated with the above parasites, another important finding was numerous cases of "capture myopathy", a syndrome that resembles Meyer-Betz disease of man. One of the most severe diseases encountered was pulmonary acariasis (P. mossambicensis), which at times caused large foci of supportive pneumonia and diffuse pleuritis. The mite pigment was also found in draining lymph nodes. The most serious diseases of the liver were cytomegaly, which was similar to that produced by mycotoxins in other animal species, multiple granulomatous foci caused by Hepatocystis simiae and microgranulomas caused by ova of Schistosoma mattheei. Adult schistosomes were also found in the mesenteric vessels. The most important lesion in the central nervous system was an axonal hamartoma, which was found in two cases and involved a large portion of the brain stem. Also of note were a meningioma in the falx cerebelli, a few examples of non-suppurativc encephalitis and several cases in which neurons in the medulla oblongata had been replaced by a globular eosinophilic mass. Other tumours found were a fibroma in the subcutis of the face and a basal cell carcinoma in the skin on the back. Both were of local importance only. Developmental anomalies included an accessory spleen, ectopic pancreatic tissue in the duodenum, thymic tissue embedded in the thyroid and parathyroid and microcysts in the thymus, parathyroid and adenohypophysis. Arteriosclerosis of limited severity was found in the aorta and coronary and renal arteries of many of the older baboons (males and females). Another vascular change related to previous pregnancy was sclerosis of the ovarian and uterine vessels. Degenerative changes were found in the central arteries of germinal follicles in various lymph nodes and the spleen. Other noteworthy findings included the presence of spargana in the skeletal muscles; ranula formation of the ducts of the glands of Ebner; para-ovarian crystals; large intranuclear inclusions in the submandibular salivary gland compatible with those produced by cytomegalovirus and intranuclear inclusions in the epididymis. Various gastro-intestinal parasites were found and their corresponding lesions are described. Selected bacterial studies for shigellae and salmonellae were negative, as were intradermal tests for tuberculosis and serological tests for leptospirosis and brucellosis. The brain, heart, spleen, liver, lungs and kidneys were mass measured and were compared to the body mass. In all age groups the heart varied the least when expressed as percent body mass. The brain was the most variable in this regard but changed the least in total mass.Item The isolation and identification of an antigen for the diagnosis of bovine mastitis by radial immunodiffusion(Pretoria : The Government Printer, 1974) Viljoen, M.H.; Bigalke, R.D.; Cameron, Colin McKenzie; Verster, Anna J.M.; Walker, Jane B.; De Kock, V.E.An antigen associated with the somatic cells obtained from mastitic milk, which is also present in the whey and can be used for the diagnosis of mastitis in a radial immunodiffusion (RID) test, has been purified and identified. It is water soluble, with an approximate pI of 4,4 and S ₂₀w =4,35 S. The antigen was shown to be immunologically identical to bovine serum albumin by means of Ouchterlony and immunodiffusion techniques. The use of monospecific rabbit antiserum facilitates standardization of the test resultsItem A comparative study on the immunogenicity of live and inactivated Salmonella typhimurium vaccines in mice(Pretoria : The Government Printer, 1974) Cameron, Colin McKenzie; Fuls, W.J.P.; Bigalke, R.D.; Cameron, Colin McKenzie; Verster, Anna J.M.; Walker, Jane B.; De Kock, V.E.Mice were very successfully immunized against intraperitoneal infection with virulent Salmonella typhimurium by fluid and lyophilized formalin inactivated vaccines prepared from a smooth strain of the microorganism. A single subcutaneous injection of 0,2 ml containing 0,1% packed cells was sufficient to confer a solid immunity when tested 2 weeks after immunization. Fluid vaccine was fully potent after storage at 50⁰ C for 1 month. A good immunity was also obtained with live vaccines prepared from rough mutants of S. typhimurium. The degree of protection varied with the vaccine strain used. Only those mutants which possessed some degree of residual virulence produced a solid immunity while absolutely avirulent mutants were ineffective unless excessively high doses were employed. Neither inactivated nor live S. typhimurium vaccines conferred protection against S. dublin infection.