Antizyme inhibitor: a defective ornithine decarboxylase or a physiological regulator of polyamine biosynthesis and cellular proliferation

ODC (ornithine decarboxylase) is a central regulator of cellular polyamine synthesis. ODC is a highly regulated enzyme stimulated by a variety of growth-promoting stimuli. ODC overexpression leads to cellular transformation. Cellular ODC levels are determined at transcriptional and translational levels and by regulation of its degradation. Here we review the mechanism of ODC degradation with particular emphasis on AzI (antizyme inhibitor), an ODC homologous protein that appears as a central regulator of ODC stability, cellular polyamine homoeostasis and cellular proliferation.

Overexpression of antizyme-inhibitor in NIH3T3 fibroblasts provides growth advantage through neutralization of antizyme functions

Antizyme inhibitor (AzI) is a homolog of ornithine decarboxylase (ODC), a key enzyme of polyamine synthesis. Antizyme inhibitor retains no enzymatic activity, but exhibits high affinity to antizyme (Az), a negative regulator of polyamine homeostasis. As polyamines are involved in maintaining cellular proliferation, and since AzI may negate Az functions, we have investigated the role of AzI in regulating cell growth. We show here that overexpression of AzI in NIH3T3 cells increased growth rate, enabled growth in low serum, and permitted anchorage-independent growth in soft agar, while reduction of AzI levels by AzI siRNA reduced cellular proliferation. Moreover, AzI overproducing cells gave rise to tumors when injected into nude mice. AzI overexpression resulted in elevation of ODC activity and of polyamine uptake. These effects of AzI are a result of its ability to neutralize Az, as overexpression of an AzI mutant with reduced Az binding failed to alter cellular polyamine metabolism and growth properties. We also demonstrate upregulation of AzI in Ras transformed cells, suggesting its relevance to some naturally occurring transformations. Finally, increased uptake activity rendered AzI overproducing and Ras-transformed cells more sensitive to toxic polyamine analogs. Our results therefore imply that AzI has a central and meaningful role in modulation of polyamine homeostasis, and in regulating cellular proliferation and transformation properties.

The use of skin delayed-type hypersensitivity as an adjunct test to diagnose brucellosis in cattle: a review

Brucellosis, caused by bacteria of the genus Brucella, is a contagious disease that causes economic loss to owners of domestic animals due to loss of progeny and milk yield. Because cattle, sheep, goats, and to a lesser extent pigs are considered to be the source of human brucellosis, serological tests have been used to screen domestic animals for antibodies against Brucella. Although the serological tests helped to eradicate brucellosis in many countries, serological tests are not always adequate to detect latent carriers of Brucella. Therefore, the use of the skin delayed-type hypersensitivity (SDTH) test, which is independent of circulating antibodies, might improve the diagnosis of brucellosis. In the literature, however, there are conflicting reports as to the value of the SDTH test for the diagnosis of brucellosis. Some studies consider the test unreliable, whereas others advocate its use because it detects brucellosis earlier than serological tests. The objectives of this study were therefore to assess the characteristics of the SDTH test, to select a Brucella strain that will yield a suitable brucellin for use in the field, and to determine whether the use of serological tests in combination with the SDTH test improves the detection of brucellosis. The results of this study clearly show that the SDTH test detects latent carriers of Brucella and confirms brucellosis in cattle with ambiguous serological test results. Brucellins prepared from smooth or mucoid strains of Brucella are better suited for use in the field than brucellins prepared from rough strains because they detect brucellosis in cattle with acute as well as chronic infection. The SDTH test is highly specific (99.3% specificity), and repeated testing of naive cattle or cattle infected with microorganisms that serologically cross-react with Brucella does not sensitize cattle to subsequent SDTH tests. However, it is possible that some naive cattle may serologically react to the injection of brucellin. The effect of these serological reactions on the sero-diagnosis of brucellosis is limited, because cattle may only now and then react serologically either with the serum agglutination test (SAT) or the complement fixation test (CFT). Nevertheless, cattle infected with microorganisms that serologically cross-react with Brucella may test seropositive for brucellosis 4 to 7 weeks after injection of brucellin, depending on the cross-reacting microorganism. The value of the SDTH test for the diagnosis of brucellosis was demonstrated after an outbreak of brucellosis. When the SDTH test was used in combination with SAT and CFT at diagnostic threshold > or =2 mm or > or =1 mm (increase in skinfold thickness), respectively, 39/44 (88%) or 42/44 (95%) of the infected cattle were detected compared with only 27/44 (61%) when SAT and CFT were used. When cattle in areas of low prevalence or in areas free from brucellosis are tested with the SDTH test an increase > or =2 mm in skinfold thickness should be considered indicative of infection. When the control and eradication of brucellosis is based on test-and-slaughter, an increase of > or =1 mm in skinfold thickness should be considered indicative of infection. Repeated serological testing complemented with the SDTH test in this programme will shorten the quarantine (movement control) period of a suspect herd, limiting the financial loss incurred during outbreaks of the disease. Consequently, since the SDTH test usually does not interfere with the serological diagnosis and can safely be used to establish the infection status of cattle in a suspect herd, it is opportune to consider adding the SDTH test to the procedure currently used to diagnose brucellosis in individual animals.

The efficacy of the skin delayed-type hypersensitivity using a Brucellin prepared from a mucoid strain of Brucella abortus to detect brucellosis

Eight-hundred-and-ninety-six cattle belonging to herds officially designated Brucella-free, and 190 cattle belonging to infected herds were tested with the skin delayed-type hypersensitivity (SDTH) test, using brucellin (273) prepared from a mucoid strain of Brucella abortus. An increase in skinfold thickness > or = 2 mm was considered a positive SDTH test. The serum agglutination test, complement fixation test and bacteriological examination were used to confirm SDTH test results. Results show that 6 of the 896 uninfected cattle tested positive in the SDTH test, indicating a 99.3% specificity. Of the 44 cattle that tested serologically or bacteriologically positive, 33 tested positive in the SDTH test, indicating a 75% sensitivity. The value of the SDTH test was demonstrated by its ability to detect infection earlier than serological tests, and by confirming infection in cattle with ambiguous serological test results. An increase in skinfold thickness > or = 1 mm in cattle in suspected herds should not be ignored, as it may indicate specific sensitization. We recommend the use of the SDTH test in combination with serological tests for early diagnosis of brucellosis in cattle.

Estimation of the biological activity (potency) of batches of brucellin prepared from a mucoid strain of Brucella abortus

A study was conducted to determine the repeatability of a procedure used to prepare brucellin from a mucoid strain of Brucella abortus, and to determine the biological activity of those brucellins. The brucellins were standardized to contain 1 mg protein/ml, and their potency was estimated according to the European pharmacopoeia norm for tuberculin. Estimation of the potency was done in cattle that have been sensitized with living or killed brucellae. A brucellin that effectively detected acute and chronic brucellosis in cattle with experimentally induced brucellosis was used as reference brucellin. Results show that five of the nine batches of brucellin equalled the potency of the reference brucellin. Three brucellins had 79-88% potency of the reference brucellin and one had only 59%. Since the potency of various brucellins may vary it is suggested to estimate the potency of the brucellins according to the European pharmacopoeia norm for tuberculin.

Maintenance of Brucella abortus-free herds: a review with emphasis on the epidemiology and the problems in diagnosing brucellosis in areas of low prevalence

This review covers some epidemiological aspects that allow Brucella to survive, spread, and maintain itself in the environment. Because the success of maintaining Brucella-free herds is determined by the efficiency of the serological tests to detect a single infected animal the limitations of the traditional serological tests are emphasized. Serological tests cannot differentiate between cattle infected with Brucella and cattle infected with microorganisms that serologically cross-react with B. abortus antigen. These cattle and cattle with 'natural' antibodies jeopardize the Brucella-free status of a herd. Likewise, infected cattle with serologically inconclusive test results or which elude detection are also a hazard to Brucella-free herds. Since cattle that elude detection with serological tests and the presence of non-specific serum antibodies in healthy cattle have long been recognized as problems, it is opportune to reconsider the procedures currently used to diagnose brucellosis in individual animals. Use of the skin delayed-type hypersensitivity test in addition to serological tests will significantly improve the diagnosis of brucellosis. This will limit the financial loss incurred by outbreaks of brucellosis.

The sensitizing effect of a Brucella abortus antigen in cattle after repeated intradermal inoculations

An antigen prepared from a mucoid strain of B. abortus was repeatedly injected intradermally into cattle to determine whether it sensitizes cattle so that they test false positive with the skin delayed-type hypersensitivity (SDTH) test. Cattle (n = 14) that were experimentally inoculated. with microorganisms that serologically cross-react with B. abortus, and uninfected cattle (n = 15) were tested with the antigen 2 to 5 times over a period of 16 to 17 weeks. An increase in skinfold thickness of > or = 2.0 mm on the injection site was considered a reaction elicited by the antigen. The sera from the cattle were tested with the serum agglutination test, complement fixation test, and an enzyme-linked immunosorbent assay for antibodies against B. abortus. Results showed that none of the animals had an increase in skinfold thickness of > or = 2.0 mm on the injection site of the antigen, which is considered a positive reaction. However, cattle experimentally inoculated with microorganisms other than B. abortus tested seropositive for brucellosis after one SDHT test only. We conclude that the B. abortus antigen inoculated intradermally does not sensitize cattle after repeated inculations, and therefore does not interfere with the subsequent use of the SDTH test in the diagnosis of brucellosis.

A comparison of the potency of several Brucella allergens used to detect brucellosis in cattle

The potency of Brucella allergens prepared from a smooth Brucella abortus strain S-99, mucoid strain Leewarden, rough strain 45/20, and rough Brucella melitensis strain B-115 was assessed. The potency of these allergens was compared with that of a standard allergen prepared from smooth Brucella abortus S-99 that efficiently detected bovine brucellosis in other studies. Eight cattle experimentally inoculated with Brucella abortus 544 were tested with the allergens 4 and 10 weeks after infection, and again 8 months after infection. All the allergens effectively detected infection but there was a clear distinction in the mean skin reactions 48 and 72 h after injection of the allergens. The skin reactions provoked by the allergens prepared from smooth or mucoid strains of Brucella were most pronounced 48 h after injection. Skin reactions provoked by allergens prepared from rough strains of Brucella were strongest 72 h after injection. Allergens prepared from smooth or mucoid Brucella strains were more potent in detecting brucellosis than those prepared from rough strains of Brucella.

Serological response of cattle to Brucella allergen after repeated intradermal applications of this allergen

A study was conducted to determine whether an allergen that has been prepared from a mucoid strain of Brucella abortus triggers a serum antibody response that interferes with the interpretation of serologic tests results. Fifteen cattle seronegative for Brucella antigen were tested with the SDTH test several times. Blood samples were collected weekly and tested with the serum agglutination test and complement fixation test. Results show that some cattle tested seronegative after each of the SDTH tests while other cattle tested weakly positive with the serum agglutination test or the complement fixation test. All seropositive cattle tested seronegative 4-7 weeks after the last SDTH test indicating an antibody response of a transient nature. We conclude that serologic tests results indicating infection are reliable when recorded four weeks after a single SDTH test. If cattle are tested with the SDTH test several times an interval of seven weeks should be observed after the last test to ensure a reliable interpretation of the serologic test results.

Production of Brucella allergens and evaluation of their biological activity in a guinea-pig bio-assay

A study was conducted to evaluate the biological activity of Brucella allergens extracted with hydrochloride or trichloroacetic acid. Smooth and mucoid Brucella abortus cells and the medium in which brucellae were propagated were used to prepare the allergens. The biological activity of the allergens was estimated in guinea-pigs sensitized with Brucella abortus strain 544. The guinea-pigs were intradermally injected with several allergen dilutions. The dilutions were coded and randomized for site of injection so that none of the dilution was injected twice on the same site. Variance analysis using incomplete Latin square was used for the statistical calculation of the results. The calculated biological activity of the allergens was compared with the biological activity of a 'standard' allergen that has proved effective in detecting cattle brucellosis. The skin erythema diameter was best when recorded 32 h after allergen injection. Statistical analysis of the skin erythema diameters showed a great variation in biological activity (12-105%) between the allergens. Only the allergen extracted from the medium in which a mucoid Brucella strain was propagated was as potent as the standard. The use of the incomplete Latin square for variance analysis resulted in the estimation of the biological activity of nine batches of allergen in only 27 guinea-pigs.

A unified pathway for the degradation of ornithine decarboxylase in reticulocyte lysate requires interaction with the polyamine-induced protein, ornithine decarboxylase antizyme

Recent studies have provided convincing evidence to add to a number of earlier observations suggesting that the rapid intracellular degradation of mammalian ornithine decarboxylase (ODC) is further accelerated by the action of ornithine decarboxylase antizyme (ODC-Az), a polyamine-induced protein. However, the mechanism whereby ODC-Az exerts its effect in this proteolytic process is mostly unknown. Here, by using reticulocyte-lysate-based synthesis and degradation systems, we demonstrate that interaction of ODC-Az with ODC results in two related outcomes: (a) ODC is inactivated as a result of its monomerization, and (b) ODC degradation is dramatically accelerated. While ODC inactivation requires the integrity of the ODC-Az binding site of ODC and the ODC binding site of ODC-Az, acceleration in ODC degradation also requires the previously characterized carboxyl-terminal destabilizing segment of ODC and a specific segment of ODC-Az that may be functionally distinct from that required for ODC binding. Interestingly, an active ODC variant with a mutant ODC-Az binding site is stable under basal degradation conditions. This, together with the ability of anti-(ODC-Az) antibody to specifically inhibit the basal degradation of ODC in the lysate, suggests that ODC-Az is an essential general mediator of ODC degradation. Based on these observations, we propose a model for the degradation of ODC which always require interaction with antizyme.

Specificity of the skin delayed-type hypersensitivity test in brucellosis free cattle tested with a Brucella allergen

A study was conducted to determine possible nonspecific skin delayed-type hypersensitivity (SDTH) test reactions in cattle tested with a Brucella allergen. Cattle (n = 14) experimentally inoculated with microorganisms known serologically to cross-react with Brucella and cattle (n = 549) from Brucella free herds were tested serologically and with the SDTH test. The increase in skinfold thickness at the injection site of the allergen was measured to the nearest mm with calipers 48 hours after injection. The results show that none of the SDTH test reactions in cattle experimentally inoculated with microorganisms other than Brucella exceeded 2.0 mm. This indicates that an increase in skinfold thickness > or = 2.0 mm can be considered a positive SDTH test reaction. When this norm was applied to cattle in Brucella free herds 11/549 (2%) cattle showed an increase > or = 2.0. It is concluded that infections with microorganisms other than Brucella are unlikely to cause sensitization that interferes with the SDTH test when used to detect brucellosis. Therefore, the SDTH test can be used to verify positive serologic tests results that might have been caused by microorganisms that serologically cross-react with Brucella.

Involvement of the 20S proteasome in the degradation of ornithine decarboxylase

Eukaryotic cells have been shown to contain two high-molecular-mass proteases of 700 kDa and 1400 kDa (20S and 26S proteases, respectively). It has been suggested that the 20S protease, also known as proteasome, may constitute the catalytic core of the 26S protease. While the role of the free 20S protease in intracellular protein degradation is unclear, the 26S protease is implicated in the degradation of ubiquinated proteins. We have recently demonstrated, that ornithine decarboxylase (ODC), one of the most labile proteins in mammalian cells, is degraded via an ATP-dependent but ubiquitin-independent proteolytic pathway. Here we extend these observations by demonstrating that in reticulocyte lysate ODC degradation is inhibited by antibodies raised against the C9 subunit of rat proteasome. Partial fractionation of the lysate demonstrated preferential degradation of ODC in the fraction of the lysate proteins that are precipitated by 38% ammonium sulfate. Since it was demonstrated that the 26S protease precipitates at this concentration of ammonium sulfate while the 20S proteasome remains soluble, our results suggest that the 26S protease is the one degrading ODC.

cis-recognition and degradation of ornithine decarboxylase subunits in reticulocyte lysate

One of the most interesting characteristics of ornithine decarboxylase (ODC) is its extremely short half-life. In a recent study we have demonstrated that deletion of a C-terminal segment converts ODC into a stable protein. In the present study we have extended this observation by testing the degradation of an ODC heterodimer composed of one rapidly degraded wild-type subunit and one stable mutant subunit. Our study was motivated by the possibility of trans-recognition of stable subunits due to their association with labile subunits. Our results demonstrate that such an association did not confer lability upon the stable subunits, not did it stabilize the short-lived subunits.

Characterization of sequences involved in mediating degradation of ornithine decarboxylase in cells and in reticulocyte lysate

Mouse ornithine decarboxylase is a 461-amino-acid protein that is extremely labile. A set of contiguous in-frame deletions were introduced into its C-terminal hydrophilic region. The resulting mutant proteins were expressed in cos monkey cells using an expression vector based on simian virus 40 (SV40) or by in vitro translation in reticulocyte lysate. The degradation of wild-type and mutant proteins was determined in transfected cos cells and in a degradation system based on reticulocyte lysate. Deletion mutants lacking segments of the C-terminus (amino acids 423-461, 423-435, 436-449 and 449-461) were converted into stable proteins in both experimental systems. The mutant lacking amino acids 295-309 was significantly stabilized in transfected cos cells, but was rapidly degraded in reticulocyte-lysate-based degradation mix. Our results suggest that the carboxyl-terminal region encompassing amino acids 423-461 and perhaps also amino acids 295-309 may constitute a signal recognized by the proteolytic machinery that degrades ornithine decarboxylase.

Enzyme immunoassay using mouse monoclonal anti-bovine antibodies for the detection of Brucella abortus antibodies in cow milk

Individual milk samples and artificially constructed tank milk samples from cows with naturally occurring brucellosis were examined by the enzyme-linked immunosorbent assay (ELISA) using sonicated B. abortus S-99 antigen, and mouse monoclonal anti-bovine IgM, IgA, and IgG1 conjugates. ELISA results were compared with the results of the milk ring test using either 1 ml milk (MRT-1) or 8 ml milk (MRT-8). The ELISA using mouse monoclonal anti-bovine IgG1 conjugate was sensitive and specific. In testing individual milk samples and constructed tank milk samples containing milk with low titers in the MRT-1 the ELISA was superior to the MRT-1, and MRT-8. In testing other milk samples, the ELISA was as sensitive or slightly less sensitive than the MRT-8. From a total of 5,910 milk samples collected from cows free from brucellosis, only 24 (0.4%) samples tested positive in the ELISA. All 500 tank milk samples collected from farms negative for brucellosis tested negative in the ELISA. We concluded that the ELISA is a good substitute for the MRT-1 to detect antibodies against Brucella in milk from individual cows. When tank milk is tested for antibodies against Brucella, however, both the MRT-8 and the ELISA should be used.

Use of delayed-type hypersensitivity test to diagnose brucellosis in calves born to infected dams

Calves (n = 2) born to dams with experimentally induced brucellosis, and calves (n = 4) born to dams with naturally occurring infection were examined by the delayed-type hypersensitivity (DTH) test for possible B. abortus infection. The results were compared with the serum agglutination test, complement fixation test, and Coombs test. Five calves were nursed by their dams for 8-10 weeks after birth. One calf was separated from its dam and fed artificial milk. Three to five months after birth, four calves tested seropositive in the serologic tests. Antibodies were detected in one calf as early as 1 week after birth. The calf fed on artificial milk was seronegative 4-5 weeks after birth. All calves reacted to the DTH test antigen from week 12 until the end of the experiment, even though serologic tests were negative. We conclude that the DTH test is a valuable technique for diagnosing Brucella in calves born to infected dams.

An evaluation of the delayed-type hypersensitivity test for diagnosing brucellosis in individual cattle: a field study

A field study was conducted to evaluate the delayed-type hypersensitivity (DTH) test in diagnosing brucellosis in cattle, in particular the diagnosis of infection in individual cows. A total of 93 cows that were negative, suspect, or positive to the serum agglutination test (SAT), complement fixation test (CFT), or the milk ring test (MRT) were subjected to the DTH test. The cows were then slaughtered and the supramammary lymph nodes were collected for bacteriologic examination. In 989 cows the DTH test, MRT and serologic tests were negative. When the DTH test results were compared with bacteriologic results, 12 of the 93 cows with CFT titres greater than 1:200 tested negative in the DTH test while bacteriologic results were positive. The sensitivity of the DTH test (calculated on the remaining 81 cows) was 100%; the specificity was 83%. The sensitivity of the DTH test (calculated on 93 cows) was 81%; the specificity was 83%. The sensitivity and specificity of the DTH test correlated well with those of the CFT (86-83%). We conclude that the DTH test is very sensitive, and specific enough to diagnose brucellosis in individual cows. The DTH test should be used in combination with serologic tests in the diagnosis of brucellosis.

Evaluation of an ELISA for the diagnosis of experimentally induced and naturally occurring Leptospira hardjo infections in cattle

An enzyme-linked immunosorbent assay (ELISA) for the diagnosis of Leptospira interrogans serovar hardjo (hardjo) infection in cattle was compared with the microscopic agglutination test (MAT). Glutardialdehyde was used in the ELISA to couple sonicated hardjo antigen to the microtiter plate. Mouse monoclonal anti-bovine IgG1 coupled to peroxidase was used as conjugate. Sera from calves experimentally inoculated with hardjo reacted positively in the MAT as early as 10 days after inoculation; these sera did not react positively in the ELISA until 25 days after the first inoculation. Positive and negative field sera from 704 adult cattle on 90 farms were examined by the MAT and the ELISA; a 90% correlation between the two tests was demonstrated. Eighty-six sera from calves inoculated with four Leptospira serogroups other than hardjo and 227 field sera from adult cattle with naturally occurring leptospirosis other than hardjo were examined by the ELISA. Fewer than 1% of these heterologous sera reacted with hardjo antigen in the ELISA. We concluded that the ELISA described in this report is an advantageous alternative to the MAT for diagnosing leptospirosis.

Degradation of ornithine decarboxylase in mammalian cells is ATP dependent but ubiquitin independent

Ornithine decarboxylase (ODC), a key enzyme in the biosynthesis of polyamines in mammalian cells is characterized by an extremely short half-life. In the present study, ODC degradation was investigated in 653-1 mouse myeloma cells that overproduce ODC and in ts85 cells that are thermosensitive for conjunction of ubiquitin to target proteins. Addition of 2-deoxyglucose and dinitrophenol (agents that efficiently deplete cellular ATP) to the growth medium of these cells inhibited ODC degradation. In contrast, chloroquine and leupeptin, inhibitors of intralysosomal proteolysis, did not affect ODC degradation. Shifting ts85 cells to 42 degrees C (a non-permissive temperature that inhibited conjugation of ubiquitin to target proteins) did not prevent ODC degradation. The ATP-dependent degradation of ODC in 653-1 cells was inhibited substantially by N alpha-tosyl-L-lysine chloromethane (TosPheMeCl), iodoacetamide and o-phenanthroline. These results suggest that ODC degradation occurs via a non-lysosomal. ATP-requiring and ubiquitin-independent cellular proteolytic mechanism, and that serine proteases and enzymes containing sulphydryl groups and metalloenzyme(s) may be involved in this process.

Degradation of ornithine decarboxylase in reticulocyte lysate is ATP-dependent but ubiquitin-independent

Reticulocyte lysate contains all the components of the ubiquitin-dependent proteolytic system. Several proteins are degraded in reticulocyte lysate in a ubiquitin-dependent manner. However, none of the proteins studied has a short intracellular half-life. We have investigated the degradation of ornithine decarboxylase (ODC), one of the most labile proteins in mammalian cells. ODC is efficiently degraded in reticulocyte lysate depleted of the ubiquitin activating enzyme, E1, in fraction II of reticulocyte lysate completely lacking ubiquitin, and in fraction II depleted of the entire complex of enzymes responsible for the ligation of ubiquitin to target proteins. The degradation of ODC is ATP dependent. Therefore, our results demonstrate that in addition to the ubiquitin-dependent proteolytic pathway, reticulocyte lysate contains at least one additional ATP-dependent proteolytic pathway. In vitro synthesized ODC served as a substrate in the present degradation study. Its successful utilization establishes a general strategy for investigating the degradation of short-lived proteins (for which a corresponding cDNA is available), that constitute a very small fraction of cellular proteins and for which purification is difficult or impossible. In contrast to ODC synthesized in vitro, that isolated from cells was not degraded by the reticulocyte lysate degradation system, suggesting that post-translational modifications may be involved in regulating ODC degradation.

Clinical Leptospira interrogans serogroup Australis serovar lora infection in a stud farm in The Netherlands

A Leptospira interrogans serogroup australis serovar lora infection in a stud farm is reported. During three successive years (1984-1986) clinical leptospirosis with a severe often rapid, fatal course was seen in 12 foals. Clinical examination revealed severe respiratory distress, depression and pyrexia. Other symptoms were diarrhea (2), jaundice (1), and an unsteady gait (1). Morphological characteristics of the disease were massive pulmonary haemorrhage and haemorrhagic-thrombotic or extracapillary glomerulonephritis with tubulonephrosis and interstitial oedema. In most foals high or increasing MAT titres to serovar bratislava were found; from one foal Leptospira interrogans serovar lora was isolated. Serological examination of all 56 mares at the farm (August 1986) revealed antibodies to serovar bratislava in 64 per cent of the animals. These findings support the idea that Leptospira interrogans serovar bratislava and closely related strains (in this study serovar lora) may be adapted to and maintained by the horse population.

Evaluation of a delayed-type hypersensitivity test for the diagnosis of Brucella abortus infection in cattle

The delayed-type hypersensitivity (DTH) test was used to diagnose brucellosis in two cows experimentally induced with brucellosis, and 176 dairy cows from a farm suspected of brucellosis. DTH test results were compared with results of the milk ring test, the serum agglutination test, the complement fixation test and the Coombs test. Cows positive in the DTH test and in one of the other tests were examined bacteriologically. In experimentally infected animals the DTH test was positive 10 days after infection, 1-4 weeks before serologic tests indicated brucellosis. Although the DTH test was positive during the whole experiment, on the one occasion when serologic titres were high, it was negative. Of the 176 dairy cows, 45 were positive in one or more serologic tests. In twelve cows (29%) the diagnosis was inconclusive because they were positive in only one of the serologic tests. In these cases the DTH test confirmed the infection. Three cows with high serologic response tested negative in the DTH test. B. abortus was isolated from 13 of 15 cows examined. We conclude that when serologic results are ambiguous, the DTH test is a useful additional technique for diagnosing brucellosis.

[The occurrence of antibodies to various Leptospira serotypes in swine in The Netherlands in the period 1975-1980]

A total number of 18.675 sera of pigs were examined for the presence of antibodies to various serotypes of Leptospira in the Netherlands during the period from 1975 to 1980. The study showed an average of 21 per cent of positive serological findings. The distribution of these findings amongst the various serotypes of Leptospira was as follows: L. bratislava 39%; L tarassovi 22%; L. ballum 15% and L. icterohaemorrhagiae 12%. The combined other serotypes scored approximately 12%. The percentage of serologically positive animals having a history of abortion was approximately 23%. 23% up to 1978. In 1979, it fell to 11%, and it increased again to 32% in 1980. The common serotypes of Leptospira in sows which aborted were L. bratislava, L. tarassovi, L. ballum and L. icterohaemorrhagiae. L. pomona, L. australis, L. canicola and L. hardjo were rare but were identified in a few cases. It is recommended that measures should be adopted to prevent the introduction of these serotypes.

Serological diagnosis of Erysipelothrix rhusiopathiae: a comparative study between the growth inhibition test and the complement fixation test

A Complement Fixation Test (CFT) was developed for the diagnosis of Erysipelas infections. The results of that work were compared with those of the Growth Inhibition Test (GIT), and they showed that the CFT test was very useful to determine whether an animal had been vaccinated or was still suffering from the disease. The CFT is as reliable as the GIT in detecting recent as well as chronic infections, but its value is limited where animals are examined for their response to a vaccination. The test is quick, easy, and safe to conduct.

[Non-specific positive milk ring test(s) in tank milk and Estrumate in the treatment of cattle (author's transl)]

The fact that non-specific milk ring tests were occasionally observed in tank milk provided the reason for doing a survey to detect the possible cause. Among others, non-specific reactions were found to occur after treatment with Estrumate. A regressing corpus luteum may also give rise to non-specific milk ring tests in animals which have not been treated with Estrumate.

[Contamination and age as factors in the pathogenesis of atrophic rhinitis (author's transl)]

The relationship between contamination with Bordetella bronchiseptica or Pasteurella multocida and the age of the piglets on the one hand and the pathogenesis of atrophic rhinitis on the other, is discussed. Minimal disease-free piglets born and reared on farms on which pigs affected with clinical atrophic rhinitis were present, developed clinical atrophic rhinitis at the age of six weeks. Piglets born in the Central Veterinary Institute (CVI) of sows from herds including pigs affected with atrophic rhinitis and reared under normal CVI conditions, did not develop clinical atrophic rhinitis. These sows are believed to be factors of minor importance in the pathogenesis of clinical atrophic rhinitis in piglets. When minimal disease-free piglets were contaminated during the third or fourth week of life, a slight degree of foreshortening of the upper jaw was observed in three out of nine pigs, the carcase weights of these animals not differing markedly from those of normal swine. When they were contaminated at the age of eight weeks, clinical atrophic rhinitis did not appear. It is essential that young piglets should be protected against atrophic rhinitis during the first few weeks of life.

A modified milk ring test for detecting Brucella agglutinins in bulk tank coolers

The Milk Ring Test (MRT) can be used to detect Brucella antibodies in tank milk if the following points are considered: (1) Before testing, the milk must be stored at least 72 hours at 6 degrees C. (2) To obtain a reliable reaction one must use 8 ml milk and 0.8 ml antigen, instead of 1 ml milk and 0,05 ml antigen. (3) The 4 vol.% antigen appears to be more sensitive than the 5 vol.% antigen. (4) A standard negative milk sample should be included in a batch to be examined. It can help to determine doubtful results. (5) For further determination of a doubtful result obtained from the 1 ml milk reaction, 3 ml milk and 0.05 ml antigen can be used.

Vaccination with Bordetella bronchiseptica vaccine on a farm with atrophic rhinitis: an evaluation of a field experiment

On a farm where Atrophic rhinitis (AR) occurred the animals were vaccinated with a Bordetella bronchiseptica vaccine. The immune state of the sows was checked and also the effect of this vaccination on the antibody titre of the piglets. Groups of pregnant sows were vaccinated once or twice before the partus, another group of sows only had their piglets vaccinated and a third group were used as control. The serum titres of the sows were low, not higher than 1:100 before vaccination. A double vaccination of the pregnant sows induced the piglets to produce antibodies in a sufficiently high titre during the first 7 weeks of life. Vaccination only against Bordetella bronchiseptica did not protect the piglets against AR. Piglets of the vaccinated sows showed two types of titre progress. It is not recommended to vaccinate the piglets only. The rapid plate agglutination was found extremely useful for the early diagnosis of Bordetella bronchiseptica infection.

[Measures to be adopted in the prevention and treatment of atrophic rhinitis in piglets under field conditions (author's transl)]

The following measures designed for the prevention of Atrophic rhinitis (AR) were compared. (1) Adopting the all in - all out system in separate farrowing quarters. The variation in age between piglets in a single farrowing house was confined to one to two weeks. (2) Treating the piglets with a combined preparation of penicillin, chloramphenicol, oxytetracycline hydrochloride or sulphonamides on the third, sixth and twelfth days of life. (3) Administering immune sera to piglets. (4) Vaccinating sows and piglets with Bordetella bronchiseptica vaccine and piggery--specific Pasteurella multocida vaccine. The various forms of treatment had a beneficial effect on the clinical picture in every case of Atrophic rhinitis. Moreover, the dosage of the antibiotic oxytetracycline hydrochloride as well as the titre of the immune serum were found to be factors in the prevention of AR. The pressure of infection with Bordetella bronchiseptica and/or Pasteurella multocida is a factor of major importance in the pathogenesis of clinically apparent AR in piglets under eight weeks. Maintaining infection at a low level is the main object in the control of AR. The more so as the knowledge available today does not make it possible to free piggeries from Bordetella bronchiseptica and Pasteurella multocida.

[Shortening of the upper jaw (brachygnathia superior) as a clinical feature of atrophic rhinitis in approximately eight-week-old piglets (author's transl)]

Determining the degree of shortening of the upper jaw is described as an effective and simple method by which piglets affected with severe atrophic rhinitis may be identified as early as the eighth week of life. A positive high correlation (r2 = 0.61) between shortening of the upper jaw and atrophy of the ventral conchae was found to be present in pigs at this age. Clinical and pathological studies of 2,000 heads of swine of various ages revealed changes of the conchae and nasal bones as well as shortening of the upper jaw in animals affected with atrophic rhinitis. Over 99 per cent of the affected animals showed changes of the conchae at an age of eight weeks. In 95 per cent of the cases, the nasal bones were also involved. In 92 per cent of the animals showing lesions of the conchae, which were pigs of two herds, the shortening of the upper jaw was given a grading of one or higher. In view of these findings, the piglets were selected for severe shorting of the upper jaw and deviation of the axis of the head. The losses caused by atrophic rhinitis were reduced to nil on these fattening farms.