Haemolytic assay of bovine serum complement

Calves severely affected by bovine respiratory disease have reduced protection against histone toxicity and exhibit lower complement activity

Bovine respiratory disease (BRD) remains the greatest challenge facing the beef industry. Calves affected by BRD can manifest illness ranging from subclinical infection to acute death. In pathologies similar to BRD, extracellular histones have been implicated as major contributors to lung tissue damage. Histones are basic proteins responsible for DNA organization in cell nuclei, however when released extracellularly during cell injury or via neutrophil activation they become cytotoxic. Cattle suffering severe cases of BRD demonstrate reduced capacity to protect against the cytotoxic effects of histones, however, the protective mechanism(s) of serum remain(s) unknown. Therefore, the objective was to identify components within serum that contribute to protection against histone toxicity. Serum proteins from animals considered protective (P; N = 4) and nonprotective (NP; N = 4) against the toxic effects of histones were precipitated by the addition and incubation of exogenous histones. Proteins that interact with histones from both groups were isolated by sodium dodecyl sulfate-polyacrylamide gel electrophoresis and identified via label free "shotgun" proteomics. Sixteen candidate proteins increased by ≥2-fold change in P vs. NP animals were identified, with several associated with the complement system. A subsequent study was conducted to evaluate complement system activity and serum protective capacity against exogenous histones in feedlot heifers. Serum samples were collected from 118 heifer calves (BW at arrival = 229 ± 2.4 kg) at feedlot arrival. Animals were retrospectively assigned to groups consisting of: calves not requiring treatment with antibiotics for BRD (CONT; N = 80), calves treated once (1TRT; N = 21), calves treated twice (2TRT; N = 5), calves treated thrice (3TRT; N = 3), or calves that died from BRD within 1 wk of entering the feedlot (DA; N = 9). Serum from DA animals was less protective than CONT (P = 0.0005) animals against histone toxicity. Complement activity of DA animals was reduced compared to CONT (P = 0.0044) animals. Additionally, the use of both assays as a ratio resulted in increased ability to detect DA animals. Results suggest that cattle predisposed to severe cases of respiratory disease may have impaired complement activity presumably contributing to reduced protective capacity against histone toxicity.

The genetic influence on serum haemolytic complement levels in cattle

Total serum haemolytic complement (HC) activity has been determined in 130 young bulls of the Norwegian Red Cattle Breed (NRF). A highly significant sire effect (p less than 0.01) on HC with a corresponding heritability of about 0.75 was estimated. Evidence of any simple mode of inheritance is not produced but the distribution patterns of HC indicate influences of relatively few genes.

Conglutinin and immunoconglutinin titers in stressed calves in a feedlot

OBJECTIVE

To determine whether increased conglutinin titers are evident in stressed calves that do not develop respiratory tract disease in feedlots, compared with respiratory tract disease, and to determine the increase in immunoconglutinin titers.

ANIMALS

101 mixed-breed beef calves.

PROCEDURE

Calves were processed at 4 farms of origin and allowed to remain with their dams for another 100 days. Calves from each farm were brought to a centrally located order-buyer barn. In a feedlot, 101 calves were assigned to pens and observed daily for clinical signs of acute respiratory tract disease. When sick calves were detected, they were treated with antibiotics and isolated in a pen for 4 days. Conglutinin and immunoconglutinin titers were determined for all calves.

RESULTS

During the 28-day study, 73 calves developed respiratory tract disease, whereas 28 calves remained healthy. Mean conglutinin titers differed significantly among calves from the 4 farms. Significant differences were not detected in conglutinin titers among calves on the basis of sex, morbidity, or vaccination status against Mannheimia haemolytica at each farm, the order-buyer barn, or the feedlot on days 8, 15, and 28 after arrival. Immunoconglutinin titers in calves differed significantly among farms and morbidity status.

CONCLUSIONS AND CLINICAL RELEVANCE

Mean conglutinin titers in calves do not appear to be associated with the incidence of acute respiratory tract disease; however, increased immunoconglutinin titers appear to be associated with recovery of stressed calves from respiratory tract disease during the first 15 days after arrival in a feedlot.

Differential complement activation by bovine IgG2 allotypes

Immunoglobulin allotypes and complement (C) are known to be related to susceptibility to infection. Because bovine IgG2 is important in resistance to pyogenic infections and because its two allotypes, IgG2a and IgG2b, differ in sequence in the CH1, hinge, CH2, and CH3 regions, we tested the ability of these allotypes to initiate the bovine C cascade. Bovine IgG2a and IgG2b were standardized according to specific anti guinea pig red blood cell (GPRBC) ELISA activity using anti IgG2 reagents shown essentially unbiased for allotype. Complement activating activity of the allotypes was quantitated in a GPRBC lysis assay. With this system, IgG2b consistently had more than twice the activity in bovine C mediated lysis as compared with IgG2a. The fact that both EDTA and EGTA/Mg almost completely inhibited C mediated lysis of GPRBCs indicated that lysis was due to the classical pathway. Since antibody usually activates C by the classical pathway, this supports the supposition that activation was by the IgG2-GPRBC complexes. Flexibility analyses showed that IgG2b had a more rigid hinge than IgG2a, perhaps partially explaining the greater efficiency of IgG2b in C activation. Other mechanisms may include differences in glycosylation and in the amino acid at position 332. The difference in ability to activate C may mean that animals of the IgG2a allotype could be more susceptible to infection with extracellular pyogenic pathogens which are killed by C or by phagocytes after opsonization with IgG2 and C.

Studies on the haemolytic complement of the dromedary camel (Camelus dromedarius). I. Classical pathway haemolytic activity in serum

Classical pathway haemolytic complement (CPHC) of the dromedary was assayed under standardised conditions. A total of 14 indicator systems of red blood cells (RBC) and haemolysins were investigated. Highest CH50 titre was obtained with rabbit RBC sensitised with goat haemolysin. Among the factors investigated were: ionic strength, Mg2+, Ca2+, ethylenediaminetetraacetic acid (EDTA) concentration, pH, incubation time and temperature. The standard system of titrating the HC levels consisted of rabbit RBC sensitised with goat haemolysin, sucrose veronal buffer (SVBS) pH 7.4, ionic strength 0.14 M and Ca2+ and Mg2+ concentrations of 4.0 x 10(-4) M and 1 x 10(-3) M, respectively. Incubation at 37 degrees C for 120 min gave the highest HC activity. Using these standardised conditions HC levels were determined in 79 camels aged between 3 months and 15 years. Highest mean HC value of 873 +/- 26.6 CH50 units ml-1 were recorded in the age group of 1-5 year old camels and the lowest mean HC value of 598 +/- 120.8 CH50 units ml-1 in the age group of 10-15 year old camels. Adult males in the age group 5-10 years had significantly higher mean HC levels than their female counterparts (P < 0.0001).

Effect of low temperature storage on the haemolytic complement of cattle and sheep

Sera from cattle and sheep stored at -70, -20 and -10 degrees C were examined for haemolytic complement at Days 0, 37, 54, 86, 133 and 245. The decline in complement followed a similar trend, both by classical pathway (CPW) and alternative pathway (APW) assay methods. Both cattle and sheep sera retained 80% of their complement activity till Day 245 at -70 degrees C whereas at -20 degrees C cattle sera had lost 67% and sheep sera 80% of the activity. At -10 degrees C the decline in complement levels was, in general, similar to -20 degrees C. The complement level of sheep sera declined more rapidly than that of cattle. For reliable results, it is suggested that sera of cattle and sheep should be assayed for complement within 4-5 months at -70 degrees C and within a month at -20 or -10 degrees C.

Studies on activation and levels of haemolytic complement of buffalo (Bubalus bubalis). II. Alternate complement pathway activity in serum

Buffalo serum caused lysis of unsensitized red blood cells (RBC) of sheep, goat, rabbit and guinea-pig. There was minimal lysis of cattle RBC, and homologous RBC were resistant. Lysis of sheep and goat RBC was the result of natural antibodies as adsorption with respective RBC and addition of 8 mmol ethylene glycolbistetraacetate (EGTA) in diluent completely abrogated the haemolytic activity. The lysis of guinea-pig and rabbit RBC was only partially decreased by these treatments, indicating the presence of alternate complement pathway (ACP) activity in buffalo serum. The guinea-pig RBC were the most sensitive to lysis, and 50% CH titre units above 40 ml-1 of serum were obtained. The haemolytic activity of buffalo C for unsensitized guinea-pig RBC was reduced from 47 CH50 units to an undetectable level by heating at 50 degrees C for 20 min and at 56 degrees C for 4 min. Similarly, treatment with zymosan also inhibited this haemolytic activity. Maximum activation of buffalo ACP occurred in the presence of 4 mmol Mg2+ in the diluent. Using standardized conditions, ACP activity was determined in sera of 98 healthy buffaloes of different age groups from 1 month to 12 years. Even young calves less than three months of age showed considerable ACP activity (45.60 +/- 1.21 CH50 units ml-1) which increased with age. The peak mean values of 79.79 +/- 1.45 CH50 units was recorded in 2 to 4-year-old animals. However, in all the 11 animals above 4 years of age, the haemolytic activity was greatly reduced and was even less than that in 1 to 3-month-old buffalo calves.(ABSTRACT TRUNCATED AT 250 WORDS)

A new hemolytic assay for bovine serum complement and its application during experimental bovine anaplasmosis

A new hemolytic assay for bovine complement is presented. Using this assay we found a significant reduction in bovine serum complement activity during the acute phase of anaplasmosis, and an increase in the sensitivity of the red blood cells (RBC) to bovine complement lysis in vitro. The new hemolytic test is performed with bovine RBC, rabbit anti-bovine RBC serum and bovine serum complement. An isotonic sucrose Tris-buffered saline solution of ionic strength 0.094 and pH 7.2 was found to be adequate for this test. The titres obtained with this new assay, which uses autologous RBC, are comparable with those obtained using the guinea pig RBC assay. The finding of a reduction in bovine serum complement during anaplasmosis may be suggestive of a mechanism responsible for the pathology of this disease.

Classical and alternative pathway haemolytic activities of ovine complement: variations with age and sex

The classical (CH50) and alternative (ACH50) pathway haemolytic activities of sheep complement were measured with microtechniques. Storage of blood at room temperature (instead of 4 degrees C) before centrifugation and usage of sera stored at -70 degrees C were compatible with complement titration. The effects of age and sex were tested in 303 sera obtained from animals aged between 2 weeks and 3.5 years old. ACH50 titres were low during the first 1.5 months of life then increased to reach the level found in adults at the age of 3 months. Conversely, CH50 titres were very high in suckling lambs, decreased up until the age of 3 months and then increased to reach the adult level at 1 year old. In lambs, the haemolytic complement activity was significantly higher in females than in males.

Serum haemolytic complement activity and C3 levels in bovine trypanosomosis under natural conditions of challenge--early indications of individual susceptibility to disease

Twenty-five Baoule (Bos taurus) and 12 Zebu (Bos indicus) cattle, which were part of an experiment aimed at characterizing cattle for resistance to trypanosomosis under natural challenge in Burkina Faso, were monitored for complement levels. Total haemolytic activity of the alternative complement pathway and C3 in sera taken weekly were estimated. The results were analysed in relation to the course of the disease, parasitological data, packed red cell volume (PCV) and body weight. All the animals became infected with Trypanosoma vivax and/or T. congolense. The Zebu had to be treated with Berenil (Diminazene aceturate, Hoechst, W. Germany) after a mean period of 5 weeks of infection, whereas 7 of the 25 Baoule remained in good condition throughout the experiment. The remaining 18 Baoule required treatment after a variable period of infection. There was a decrease in haemolytic complement activity (HC') as well as in C3 levels, which coincided with the first detection of parasites in the blood. The titres in the Zebu fell to 10-20% of pre-infection level within 2-3 weeks and they showed no tendency towards regaining normal levels. The drop in complement in the Baoule was less pronounced and was in most cases followed by an increase approaching normal values. In these animals, the complement level in early infection was found to depend on the intensity of parasite load and on the control potential of each individual. There was a significant correlation between minimum complement activity (min. HC'), minimum C3 (min C3) and minimum PCV (min.PCV) in early infection. These three parameters correlated with individual resistance and might, therefore, be useful criteria for the identification of the most resistant individuals within a trypanotolerant breed.

Studies on activation and levels of haemolytic complement of buffalo (Bubalus bubalis). 1. Classical complement pathway

Optimum conditions for haemolytic complement (HC) assay in buffalo serum were standardized. In all, 11 indicator systems of red blood cells (RBC) and haemolysins were investigated. Maximum HC CH50 titre was obtained with rabbit RBC sensitized with goat haemolysin. The effect of pH, Ca2+ and Mg2+ concentration, ionic strength, time and temperature were studied. Of all the variables, ionic strength influenced the HC activity most significantly. The standard system for titrating the HC consisted of rabbit RBC sensitized with goat haemolysin, sucrose-veronal buffer with pH 7.5, ionic strength 0.023 M and Ca2+ and Mg2+ concentrations 6 x 10(-4) and 2 x 10(-3) M, respectively. Incubation at 37 degrees C for 2 h gave highest haemolytic activity. With this protocol 5-7-fold higher HC activity was recorded than with prestandardized conditions. Levels of HC were determined in the sera of 98 buffaloes aged from 1 month to 12 years. The lowest mean CH50 units of 401 +/- 0.35 per ml were recorded in buffalo calves below 3 months of age. The mean HC levels increased with age, reaching peak values of 2349 +/- 62.25 CH50 units/ml in 2-3-year-old buffalo. Animals in the age group 5-12 years had significantly decreased (P less than 0.05) mean HC levels of 1545 +/- 68.94.

Characterization of some parameters of non-specific immunity in beef cattle (II)

Serum protein, immunoglobulins, complement, lysozyme, serum bactericidal activity and blast transformation of peripheral blood lymphocytes were tested in beef cattle in different herds and age groups. These parameters were evaluated in their time-kinetics, in comparison with age-matched groups of dairy cattle. Like dairy calves, beef calves up to 4 months of age were shown to have low levels of serum bactericidal activity and haemolytic complement; besides, a worse profile was detected in serum protein and gamma 2 globulin levels. Al(OH)3 and oil-adjuvanted vaccines had a favourable influence on immunoglobulin and lysozyme synthesis. An acute stressing event like transportation was shown to decrease mitogen-driven lymphocyte stimulation for at least 10 days after arrival.

Characterization of some parameters of non-specific immunity in dairy cattle (I)

The concentrations of serum protein and immunoglobulin, complement, lysozyme, serum bactericidal activity and blast transformation of peripheral blood lymphocytes were assessed in dairy cattle in different herds and age groups. The study aimed at defining fundamental aspects of non-specific defence under the field conditions, related to age/season/management influences. The observed differences in the expression of these parameters are discussed, with regard to their role in the immune defence of calves and their relation to colostrum uptake. The possible use of these parameters in the control of animal welfare is stressed and the possibility is put forward of predicting possible unfavourable interactions with environmental pathogens.

The use of a passive hemolysis system to evaluate the complement activities of six mammalian species

A passive hemolysis assay system was developed which permitted comparisons of the hemolytic activities of complement (C) from six species. This system employs a single antigen and an antiserum raised in one species. Thus, variations resulting from different target antigens and those inherent in using antibodies (of different affinities and isotypes) raised in a variety of species were minimized. Of the erythrocytes (E) examined, those from horses and guinea pigs were most susceptible to lysis, and either would be suitable, as a tentative choice, for measuring C activity of a previously unstudied species. Horse serum had the lowest C activity of any of the sera tested. It lysed certain cells only at high concentrations, and the hemolytic activity dropped off sharply with minimal dilution. The data presented in this paper could also be used for selecting target E for C studies using direct lysis with antibodies raised against the cells.

Host serum proteins in Taenia saginata metacestode fluid

Taenia saginata cyst fluid was examined for host proteins; IgG1 and IgG2 as well as haemolytic complement activity were detected. Polyacrylamide gel electrophoresis revealed differences in proteinograms among the samples taken from 1-, 4-, and 10-month old cysts. Fluid from older cysts had fewer protein components and showed a weaker antigenic reaction with sera of bovines infected with T. saginata than that of younger cysts. The roles of antibody and complement in initiating degeneration of the parasite are discussed.

Inflammation and mediators of lung injury

This article covers the major pathways involved in acute inflammation in mammals with a particular emphasis on their relevance to the bovine species. It focuses on the potential and proven contributions of these systems to pulmonary defense mechanisms and lung pathology. The article also points out what is known and where gaps in our information exist as well as promising areas for research in the coming years.

Isolation and partial characterization of bovine and equine factor D

Bovine and equine factor D were purified to apparent homogeneity as evidenced by a single protein staining band on 7.5-17.5% SDS-PAGE slab gels under both reducing and non-reducing conditions. An apparent mol. wt of 15,000 for bovine D and 22,500 for equine D were noted after SDS-PAGE gel analysis of both reduced and non-reduced preparations. A single polypeptide chain for both proteins was evidenced by the lack of any change in the electrophoretic mobility under each of these conditions. The bovine and equine D were enriched 3347- and 9447-fold, with a 20 and 29% yield of hemolytic activity, respectively. Functionally, both equine and bovine D would reconstitute a human reagent deficient in D (RD), while human or equine D would substitute for bovine D when using a bovine RD. Neither bovine, equine or human D would, however, reconstitute an equine RD.

Effects of various treatments of bovine complement on its lytic efficacy measured by two different tests

Bovine complement was treated with various agents known to activate or inactivate one or more of the cascade components. The treated complement was then assessed for remaining hemolytic activity by a tube titration test and a radial hemolysis method. Divalent cation chelators (EDTA and EGTA); immune complexes prepared with serum and IgM, IgG1, IgG2, and IgA isotypes; smooth and rough lipopolysaccharides and lipid A; hydrazine; zymosan; cobra venom factor and brown recluse spider venom caused depletion of complement as determined in the tube titration test. Immune complexes (prepared with serum); hydrazine; cobra venom factor; EDTA and smooth lipopolysaccharide caused loss of hemolytic activity in the radial hemolysis test. This evidence suggests that the radial hemolysis test assessed complement consumed by the alternate pathway, while the tube titration method measured classical pathway consumption.

A sensitive microassay for the determination of hemolytic complement activity in bovine milk

A 51Cr release microhemolytic complement assay is described to detect hemolytic complement activity in bovine milk. 51Cr-labeled guinea-pig erythrocytes (GPRBC), which have been sensitized with a subagglutinating amount of rabbit anti-GPRBC, are placed in microtiter plates. Pooled bovine sera as source of complement to achieve about 50% of 51Cr release were added to each well prior to the addition of the samples on the test. Determination of CH100 titer was obtained by difference of counting between heated and unheated diluted whey samples from a standard linear regression. Comparative hemolytic values throughout lactation were established for the first time and confirmed the improved sensitivity of the assay.

Conglutination and haemolysis of unsensitized human erythrocytes by bovine serum complement

Unsensitized human erythrocytes (E) were haemolyzed by bovine serum to a titre of 1:16-1:32. In the single dilution beyond the haemolytic endpoint, the cells were conglutinated. In dilutions in which haemolysis occurred, cells were conglutinated before being lyzed. With no or minimal haemolysis, conglutination to 1:32-1:64 occurred in tests using insulin-absorbed serum, serum heated at 50 degrees C for 30 min and in tests incubated at 4 degrees C for 30 min. In two-stage tests, EDTA and Mg2+-EGTA prevented bovine C sensitization of human E for conglutination by bovine serum heated at 56 degrees C for 30 min. EDTA prevented haemolysis, but haemolysis to 1:16-1:32 occurred with serum dilutions containing Mg2+-EGTA. Haemolytic activity was restored to serum heated at 50 degrees C by a factor B-containing fraction. Conglutination and haemolysis were blocked by heating serum at 56 degrees C for 30 min and were reduced to low titres by absorbing serum with zymosan. These results strongly suggest that the conglutination reaction involved the classical activation pathway whereas the haemolytic reaction involved the alternative activation pathway. Thus, with dilutions of untreated or treated bovine serum, two C-dependent reactions and the pathways involved can be demonstrated by using unsensitized human E as an indicator system.

A comparative study of the disease in cattle caused by Theileria parva or T. lawrencei: II. Hematology, clinical chemistry, coagulation studies and complement

Theileria lawrencei tick-derived stabilate infection of 8 cattle resulted in the development of panleukopenia and hypoproteinemia. In addition to these changes, T. parva infection caused mild normocytic, normochromic, non-responsive anemia at either of two dose rates. Disseminated intravascular coagulation, as indicate by positive protamine paracoagulation tests, prolonged prothrombin and partial thromboplastin times, and thrombocytopenia, developed in cattle infected with either of the Theileria spp., and was probably an important intermediary mechanism leading to death. Infection of calves with a high dose of T. parva stabilate resulted in more rapid onset of clinico-pathologic changes than did the low dose infection. Theileria lawrencei infection produced a severe, acute syndrome, the clinico-pathologic alterations of which varied in time of onset and severity between those of the T. parva high dose and low dose groups.

Ethylenediaminetetraacetic acid (disodium salt)-labile bovine immunoglobulin M Fc binding to Brucella abortus: a cause of nonspecific agglutination

It was demonstrated by a radioimmunoassay procedure that Brucella abortus agglutinins from noninfected cattle sera, absorbed to B. abortus antigen and eluted with ethylenediaminetetraacetic acid (EDTA), was immunoglobulin M that bound to that bacterium by its Fc portion. The EDTA-eluted immunoglobulin M agglutinated intact B. abortus cells but not erythrocytes treated with B. abortus lipopolysaccharide. The specificity of the EDTA-eluted immunoglobulin was for B. abortus, although a small titer to Yersinia enterocolitica serotype O:9 was observed. In contrast, immunoglobulin M purified from the serum of a cow injected 7 days previously with heat-killed B. abortus bound to the antigen by its Fab portion, was not labile to EDTA treatment, cross-reacted extensively with Y. enterocolitica serotype O:9, and agglutinated various other bacterial antigens and normal erythrocytes.

Laboratory techniques of veterinary clinical immunology: a review

Laboratory tests currently used or easily applicable in veterinary clinical immunology were reviewed in the following three categories: (1) tests detecting disorders in humoral immune response: serum protein screening tests, gammaglobulin estimation and complement testing; (2) tests detecting disorders in cellular immune response: phagocyte function tests and lymphocyte function tests; (3) tests detecting autoimmune disorders: detection of antinuclear antibodies, rheumatoid factor, autoimmune hemolytic diseases, and autoimmune organ and tissue disorders. The principles of the tests and the interpretations of the results are presented with the appropriate references.

Hemolytic assay for goat (caprine) and swine (porcine) complement

Optimal conditions for assaying hemolytic complement of goat (caprine) and swine (porcine) sera were determined. Effects of the following were tested: pH, ionic strength, calcium and magnesium ion concentrations, time and temperature of incubation, and ethylenediamine tetracetate concentration. Guinea pig erythrocytes sensitized with goat or cattle antibodies were the most sensitive target cells for goat complement. Sheep and cattle erythrocytes sensitized with rabbit hemolysin were the best target cells for swine complement. Barbital buffer, pH 7.3, ionic strength of 90 nmM relative salt concentration, containing 0.5 mM CaCl2 and 1 mM MgCl2 was the best for swine complement assay. Goat complement lysed best in a barbital buffer, pH 8, ionic strength of 90 to 120 mM of relative salt concentration, in presence of 0.5 mM CaCl2 and 1 mM MgCl2. The optimal incubation temperature was 37 degrees C for both complements. The complement dependent lysis required 75 minutes to reach its maximum. Ethylenediamine tetracetate in 4 mM concentration completely inhibited lysis by both species complements. The CH50 for goat sera varied between 18 and 75 per ml, in swine sera between 75 and 210 per ml.

On the biological role of a proteolytic-enzyme inhibitor from the ectoparasitic tick Boophilus microplus

The tick Boophilus microplus contains a protein that inhibits a range of proteolytic enzymes. Variations in the concentration of this protein throughtout the life cycle were followed by measuring simultaneously the inhibition of trypsin and chymotrypsin and reaction with an antiserum to the purified inhibitor. The protein is present in large amounts in eggs and in unfed larvae, but its concentration falls very rapidly after the start of the parasitic stage of the life cycle. This, together with previous evidence, suggests that the inhibitor is important both in eggs and in the initial establishment of the parasite on its host. The activity of the protein towards several enzymes has been measured as an indication of its possible function. Bovine trypsin, chymotrypsin and plasmin and pig pancreatic kallikrein are all inhibited. The protein also affects the blood-coagulation system at several points, since it prolongs both activated-partial-thromboplastin time and prothrombin time. It inhibits the complement-dependent lysis of erythrocytes, but is without significant effect on mitogen-induced lymphocyte stimulation. Thus the inhibitor could have several effects on the host that would be beneficial to the parasite.

Hemolytic complement and serum C3 levels in Zebu cattle infected with Trypanosoma congolense and Trypanosoma vivax and the effect of trypanocidal treatment

Total hemolytic complement and C3 levels were found to drop to 6.25% and 50% of preinfection levels, respectively, during trypanosome infections. Chemotherapeutic elimination of the trypanosomes with Berenil led to recovery of preinfection levels within 7 days and 11 days when cattle infected with Trypanosome congolense and Trypanosoma vivax, respectively, were treated 37 days after onset of infection. Recovery was slower in T. vivax-infected cattle treated on day 50. Berenil treatment had no effect on complement levels in control animals. The possible causes and implications of these low complement levels in bovine trypanosomiasis are discussed.

Changes in the haemolytic activity of serum complement during acute Babesia bovis infection in cattle

The haemolytic activity of serum complement was measured in cattle during acute Babesia bovis infection. The level fell significantly on day 5 post infection (p.i.) and was not detectable by day 10 p.i. After clinical recovery between days 15 and 20 p.i. haemolytic activity was again detected in serum and gradually returned to the pre-infection level. The components of both classical and alternative pathways were involved in complement depletion and factors such as protease secretion by the parasites, antigen-antibody reactions, and the release of haemoglobin were implicated as causes of the decline. The absence of complement activity during the acute phase of the disease may interfere with immune mechanisms at a critical time for the host.

Classical and alternate complement pathway activities in paired dairy cow--newborn calf sera

Hemolytic assays were used to compare alternate and classical C pathway activities in sera obtained from clinically normal newborn dairy calves and their mothers at the time of delivery. Mean alternate and classical CH50 concentrations in sera from newborn calves were both significantly lower than in their dams (P less than 0.001). The titer of alternate C pathway activity, expressed as CH50 units/ml, in sera from 17 calves was 12.9 +/- 5.5, whereas for the cows it was 25.8 +/- 6.2. The ratio of cow: calf serum alternate CH50 titers averaged 2.25 +/- 0.80 and ranged from 0.88 to 4.14. Classical CH50 titers were 78.0 +/- 42.7 units/ml in calf sera and 246.0 +/- 44.5 in cow sera. The ratio of cow: calf serum classical CH50 titers averaged 3.71 +/- 1.49 and ranged from 1.19 to 6.87. The wide range of values, noted for both the alternate and classical C pathways, within maternal and neonatal groups was assumed to reflect the biologic variability of complement levels in bovine serum. The possible relationships between deficient levels of alternate and classical CH50 activity in newborn calves and their susceptibility to infections is discussed.

Antibody class and complement requirement of neutralizing antibodies in the primary and secondary antibody response of cattle to infectious bovine rhinotracheitis virus vaccine

Calves responded to a single intramuscular injection of an attenuated strain of infectious bovine rhinotracheitis virus by producing IgM followed by IgG antibody. Both IgM and IgG antibody produced during the first month were primarily complement-requiring neutralizing antibody (CRNAb), especially IgM antibody. After a month, IgG had replaced IgM as the predominant immunoglobulin, and titers with and without complement (C') decreased in both IgG and IgM fractions. The largest decrease was in the IgM CRNAb fraction. Seven days after a second injection given on day 196, calves responded with an anamnestic IgG response in which CRNAb titers were 1 or 2 two-fold dilutions higher than non-CRNAb titers. One calf developed an IgM response similar to its primary response, whereas inhibition of the IgM response occurred in the other 3 calves which had much lower IgM antibody titers than those attained in the primary response. Twenty-eight days after the second injection the titers of IgG were the same or only a 2-fold dilution less than their 7-day secondary titers, whereas IgM titers generally decreased considerably more than this. Guinea pig and rabbit sera were equally effective as C' sources in potentiating CRNAb, whereas bovine serum was a poor C' source.

Separation of six bovine complement components and one inactivator (1, 2)

Six components (C1, C5, C6, C7, C8 and C9) of bovine complement and one inactivator (C3 in) could be separated from bovine serum. Bovine C1 was separated by precipitation at low molarity (0.03 M of relative salt concentration) other components by DEAE-cellulose chromatography using 0.005 M sodium phosphate buffer, pH 7.5, as a base for solvents having the relative salt concentration adjusted by addition of NaCl from 0.03 to 0.3 M. The separated bovine complement components could be tested using intermediates formed from sheep erythrocytes, rabbit hemolysin, guinea pig C1 and remaining human complement components. C2, C3 and C4 of bovine origin remained undetected either because of incompatibility with the intermediates used or interference of inhibitors or inactivators.

Chicken (Gallus gallus) hemolytic complement: optimal conditions for its titration

The effect of pH, ionic strength, cation concentration, ethylenediaminetetraacetic acid trisodium salt (Na3EDTA), time and temperature were studied to determine the optimal conditions for titrating the hemolytic complement (C) activity in sera of chicken (Gallus gallus). Swine erythrocytes (E) sensitized with rabbit antibodies were the most sensitive, while chicken serum had a smaller amount of "natural" antibody against them than against red blood cells from other five species tested. The highest titers of chicken C, when tested with swine sensitized E, were detected when isotonic NaCl-barbital buffer was used as diluent, having the ionic strength of 0.15, conductance of 11 millimhos/cm at 20 degrees C. However, maximal chicken C titers detected with sensitized rabbit E were obtained at ionic strength of 0.07 to 0.11 depending on pH. A final concentration of 1 X 10(-3) M of Mg2+ and 3 X 10(-4) M of Ca2+ and pH 8 were optimal in both cases. The temperature of 30 degrees C and time of 60 minutes were appropriate to reveal the maximal titers..

Immunoglobulin classes and biological functions of Campylobacter (Vibrio) fetus antibodies in serum and cervicovaginal mucus

Serum and cervicovaginal mucus (CVM) antibodies from heifers after genital infection or systemic immunization with Campylobacter (Vibrio) fetus were classified according to their immunoglobulin class, antigenic specificities, and biological functions. Only immunoglobulin (Ig) A antibodies, specific both for O and superficial, heat-labile, whole-cell (W) antigens, were detected in CVM of convalescent animals. After systemic immunization, antibodies in serum were directed principally to W antigens and were located in IgG(1), IgG(2), and IgM classes; CVM antibodies of the same specificity were detected only in the IgG subclasses. Functional tests revealed that antibodies of W specificity, whether of the IgA or IgG class, were capable of immobilizing the organism. However, IgG antibodies immobilized with clumping, whereas IgA antibodies immobilized single organisms within the 3-min period. None of the antibody preparations was bactericidal in the presence of homologous complement when the infecting strain was used as the target organism, but a bactericidal effect was observed when the target strain was rough and non-encapsulated. Both serum and CVM from systemically immunized animals opsonized C. fetus organisms, but CVM from locally immunized animals containing IgA antibodies was not opsonic. It is hypothesized that functions of immobilization for IgA and IgG and of opsonization for IgG are important features of protective immunity in venereal vibriosis.