Total and antigen-specific serum immunoglobulin isotype concentrations in hyperimmunized cattle that have undergone plasmapheresis

The effects of prolonged plasmapheresis of cattle on total and antigen-specific immunoglobulin production were evaluated. Five adult cows were hyperimmunized by repeated IV administration of live, logarithmic-phase Pasteurella haemolytica A1 organisms. Three of the cows underwent plasmapheresis daily for 3 weeks. From 2 cows, serum was only obtained periodically. Anti-P haemolytica antibody was assayed by indirect hemagglutination and a kinetic-augmented, antigen-capture ELISA for capsular polysaccharide and lipopolysaccharide/outer membrane protein antigens. Total serum immunoglobulin concentration was determined for IgM, IgG1, and IgG2 by primary radial immunodiffusion. Anti-P haemolytica A1 activity increased rapidly after immunization. After beginning plasmapheresis, the antigen-specific antibody activities remained nearly constant. In general, antilipopolysaccharide/outer membrane protein activity (in terms of concentration) was higher than anti-capsular polysaccharide activity and was not affected as much by the plasmapheresis. Total serum Ig concentration decreased transiently by a small amount after beginning plasmapheresis.     

Development and evaluation of an enzyme-linked immunosorbent assay for bovine antibody (IgG) to Pasteurella haemolytica

The sensitivity of an indirect enzyme-linked immunosorbent assay (ELISA) for bovine IgG serum antibody to Pasteurella haemolytica was compared with that of an indirect hemagglutination (IHA) test. Pasteurella haemolytica serotypes were grown in a chemically defined cell culture medium, and soluble antigens released into the growth medium were used in the ELISA and IHA test. An ELISA with serotype-1 antigen consistently detected antibody in sera that were positive by IHA test (correlation, 99%). Sera reacting with serotype-1 ELISA antigens also reacted with ELISA antigens prepared from other serotypes. Although ELISA titers averaged 5 log2 units higher than IHA titers, plots of titers determined by the 2 methods were approximately linear. Titer increases detected in paired serum samples by either test were similar. The ELISA was more sensitive than was the IHA in detecting colostral IgG antibody in serum of newborn calves. The ELISA uses a simple, stable antigen preparation and detects antibody to P haemolytica serotypes that commonly infect cattle.     

Serum IgG and IgM antibody response in cattle to antigens of Pasteurella haemolytica

The serum IgG and IgM antibody responses of 48 cattle vaccinated with live Pasteurella haemolytica (LIVE), formalin-killed P. haemolytica in Freund's incomplete adjuvant (FIA), or formalin-killed P. haemolytica in aluminum hydroxide adjuvant (ALH) to a variety of P. haemolytica antigens were evaluated. Enzyme-linked immunosorbent assays (ELISAs) were used to determine the sequential and day 21 IgG and IgM antibody responses to whole P. haemolytica (WB), a capsular carbohydrate-protein subunit (CPS) extracted from the organism, P. haemolytica capsular carbohydrate (CC), and P. haemolytica leukotoxin (LT). LIVE and FIA vaccinates developed generally higher IgG and IgM responses to all antigens compared to ALH vaccinates. LIVE vaccinates developed IgG responses to LT which were significantly higher (P less than 0.05) than all other vaccinates. In contrast, FIA vaccinates developed significantly higher IgG responses to CPS than all other vaccinates. On the basis of the ELISA results, similar or cross reacting antigenic sites were present in preparations containing surface antigens (WB, CPS and CC), but not LT. Disease resistance, as determined by experimental lesions induced in the 48 calves by transthoracic challenge with P. haemolytica, was significantly greater in the LIVE and FIA vaccinates compared with ALH vaccinates. No significant difference in resistance was detected between LIVE and FIA vaccinates. Lesions in ALH vaccinates were not significantly different than those in phosphate-buffered saline (PBS) controls. Increased IgG responses to all antigens were significantly associated with resistance to experimental disease; however, IgG responses to CPS were most highly correlated with resistance. The only IgM response which was significantly correlated with resistance was the response to CPS. These studies indicate that serum IgG antibody responses to various surface antigens of P. haemolytica, as well as LT, can enhance resistance to experimental pneumonic pasteurellosis. Serum IgM responses, however, do not appear to play a major role in resistance to experimental disease.     

Immune response of pregnant cows to bovine rotavirus immunization

Fifteen pregnant Holstein cows were freely assigned to 3 experimental groups (5 cows in each group). Cows in group I were inoculated IM and intramammarily (IMm) with Ohio Agricultural Research and Development Center (OARDC) tissue culture-propagated modified-live Nebraska calf diarrhea bovine rotavirus with added adjuvant (OARDC vaccine-immunized cows). Group II cows were given IM injections of a commercial modified-live rotavirus-coronavirus vaccine (commercial vaccine-immunized cows), and the remaining 5 cows were noninoculated controls (group III). Rotavirus antibody in colostrum and milk was mainly associated with immunoglobulin (Ig)G1, and less so with IgG2, IgA, and IgM, as analyzed by the enzyme-linked immunosorbent assay (ELISA), using monospecific anti-bovine IgG1, IgG2, IgM, and IgA sera. In serum, the rotavirus antibody was distributed almost equally between IgG1 and IgG2. The same relationships appeared in both immunized and nonvaccinated cows. All OARDC vaccine-injected cows had virus-neutralization (VN) and ELISA IgG1 rotavirus antibody titers in serum and mammary secretions at significantly increased levels (at least 100-fold; P less than 0.05) compared with the titers in groups II (commercial vaccine-immunized cows) and III (controls). Serum, colostrum, and milk antibody titers from these latter 2 groups did not differ statistically. The ELISA IgG2, IgA, and IgM rotavirus antibody titers also were significantly greater in mammary secretions from OARDC vaccine-immunized cows than in groups II and III cows. There was a high correlation between ELISA IgG1 and VN rotavirus antibody titers for all samples tested (r = 0.97, P less than 0.001), but ELISA IgG1 antibody titers were consistently higher than VN titers. The ELISA IgG1 and VN antibody titers of milk samples collected from cows 30 days after parturition were higher from the OARDC vaccine-immunized cows (ELISA IgG1, geometric mean titer (GMT) = 3,511; VN GMT = 1,689) than were titers from the group II cows (ELISA IgG1 GMT = 39; VN GMT = 33) or group III cows (ELISA IgG1 GMT = 21; VN GMT = 19). These results indicate that IM plus IMm immunization of pregnant cows, using modified-live bovine rotavirus with added adjuvant, may significantly enhance serum, colostrum, and milk rotavirus antibody titers, whereas IM vaccinal inoculation of pregnant cows with a commercial modified-live rotavirus-coronavirus vaccine may not.     

Immunoglobulin isotype of specific antibodies in reproductive tract secretions and sera in Tritrichomonas foetus-infected heifers

Four virgin heifers were experimentally inoculated intravaginally with 7 x 10(6) Tritrichomonas foetus, and 2 heifers served as uninfected controls. The durations of infection were 13, 20, 21, and 28 weeks, respectively. An ELISA that used whole T foetus antigen was used to detect anti-T foetus immunoglobulins (IgA, IgG1, IgG2, and IgM) in vaginal, cervical, and uterine secretions, and sera during the course of infection. The vaginal and cervical antibody responses were characterized by significantly increased T foetus-specific IgA and IgG1 at 7 to 9 weeks of infection, whereas uterine IgA and IgG1 responses peaked at 10 to 12 weeks. The antibody response in serum was predominantly of the IgG1 and IgG2 subclasses. In all reproductive tract regions, IgA persisted at least until the time of T foetus clearance, and usually longer. The next most persistent isotype was IgG1, lasting longest in the vagina, then cervix, and for the shortest time in the uterus. In local secretions, IgG2 was seen only transiently, increasing at weeks 13 to 15 in the vagina, and at weeks 10 to 12 in the cervix. Little IgM, relative to that present before infection, was detected in any secretion or serum, although cervical secretions had the greatest amount. Eight to 12 weeks after clearance, the 4 experimental heifers were inoculated intravaginally with 1 x 10(5) T foetus; transient infections (2 to 3 weeks' duration) were established in only 2 of 4 heifers, as determined by culturing of reproductive tract secretions.(ABSTRACT TRUNCATED AT 250 WORDS)     

Monoclonal precipitating antibodies to porcine immunoglobulin M

Fusion of splenic immunocytes from a porcine IgM-immunized BALB/c mouse with SP2/0 mouse myeloma cells resulted in 231 primary hybrids. Culture fluids of the primary hybrids were screened for antibody production by enzyme-linked immunosorbent assay (ELISA) against porcine IgM and by radial immunodiffusion versus porcine serum. Culture fluids of 10 of the primary hybrids were positive in IgM-ELISA and radial immunodiffusion. Six of these primary hybrids (1A11, 1D10, 2D7, 2E2, 3B11, and 5C9) were cloned, and ascitic fluids were produced using cloned primary hybrids. The monoclonal antibodies (Mabs) in ascitic fluids were characterized as to their reactivity with porcine immunoglobulin isotypes. All six Mabs had mouse IgG1, K isotype and were mu-chain specific as they formed single precipitin lines against porcine serum and porcine IgM and no lines against porcine IgG, IgA, and fetal porcine serum in immunodiffusion and immunoelectrophoresis. In indirect ELISA, all Mabs reacted with porcine serum, porcine IgM, and mu-chains but did not react with porcine IgG, IgA, or light chains. All six Mabs were species-specific and recognized either of two antigenic regions of mu-chain. These Mabs have been successfully used to detect IgM-containing cells in tissue sections, to detect IgM in serum, and to quantitate surface membrane IgM-bearing cells in peripheral blood.     

Immunologic responses of calves to aerosolized antigen: humoral response to ovalbumin

The humoral response of cattle to ovalbumin (OA), a nonenvironmental well-defined antigen, was studied. During 9 weeks of aerosolization, weekly serum and nasal secretion concentrations of immunoglobulin (Ig)G1, IgG2, IgM, IgA, and IgE were determined by enzyme-linked immunosorbent assay (ELISA) for OA specific antibody. Data from 3 calves given aerosol OA were compared and contrasted with data from 3 calves given aerosol saline solution and 1 calf given parenteral OA. The presence of cytotropic (skin sensitizing) antibody was evaluated during weeks 6 and 9 by direct skin testing with OA. A humoral response was induced in all 3 calves given aerosol OA. Serum IgG1 and IgG2 titers reached a maximum of 64,000 and 2,000, respectively, in calves given aerosol OA compared with 521,000 and 16,000, respectively, in the calf given parenteral OA. The ELISA did not detect an OA-specific IgM response. In contrast, all 3 calves given aerosol OA had serum IgA concentrations that increased to a peak by week 9. The mean IgA absorbance value for the 3 calves given aerosol OA was slightly greater than 5 times that of the calf given parenteral OA. Similarly, nasal secretions from calves given aerosolized OA had absorbance values that were 15-fold greater than that from the calf given parenteral OA. Calves given aerosol OA had antigen-specific IgE responses during weeks 6 to 8. The ELISA results were compared with results of passive cutaneous anaphylaxis tests. The presence of skin-sensitizing antibody was indicated by positive skin tests in the calves given aerosol OA and the calf given parenteral OA by week 9.     

A longitudinal study of rotavirus antibody titers in swine in a closed specific pathogen-free herd.

In a newly established closed specific pathogen-free (SPF) swine herd, gilt/sow suckling and weaned pig rotavirus specific antibody titers were followed for three lactations by enzyme-linked immunosorbent assay (ELISA) to gain insight into the dynamics of herd antibody titers to group A rotavirus. Among gilts/sows, serum antirotavirus IgG titers increased during each lactation with a subsequent drop in titer between farrowings. Serum antirotavirus IgM titers declined during each lactation and with subsequent parity. Serum antirotavirus IgA titers remained constant during lactations and among parities. In colostrum and milk, antirotavirus IgA antibody was abundant. Differences in titer were not noticed between gilts and second litter sows but third litter sows had significantly higher titers than the first two groups. Antirotavirus IgG was high in colostrum but nearly nonexistent in milk. This titer did not vary significantly within or among parities. There was a linear regression in the titers of baby pig serum antirotavirus IgG from the post colostral sample through to seven weeks old, after which titer began to increase. No difference in baby pig serum antirotavirus IgG was noted among the three litters. Serum antirotavirus IgA and IgM were undetectable in baby pig sera after 2-3 weeks of age. Coproantibody to rotavirus was sporadically present in pig feces for 2-3 weeks after birth with highest titers in the IgA fraction. We conclude that although it is probable that age resistance of pigs to rotavirus diarrhea occurs, humoral immunity as measured by ELISA rotavirus antibody titers may not be intimately involved in virus clearance since in our studies baby pigs passively received large amounts of antibody but still excreted pathogenic virus. The finding of increasing levels of serum antirotavirus IgG in gilt/sow serum suggest that exposure to antigen of dams occur without significant increases in antirotavirus IgG titers in either colostrum, milk, or baby pig serum.     

Bovine serum and nasal secretion immunoglobulins against Pasteurella haemolytica serotype 1 antigens

Experimental intranasal inoculation of cattle with Pasteurella haemolytica serotype 1 resulted in a group that shed the bacteria in their nasal secretions (colonized) and a group that did not shed (uncolonized). After inoculation, antibody titers in serum and nasal secretions against the total P haemolytica increased significantly, and the proportions of total antibody against specific P haemolytica antigens changed so that the proportion directed against the 94- and 62-kD antigens increased. Prior to inoculation, the proportion of total antibody in the serum against 94- and 62-kD antigens of P haemolytica was higher in calves that remained uncolonized than in those that became colonized with P haemolytica after exposure. Antibody specificity of serum and nasal secretions differed in the relative amounts directed against each P haemolytica antigen. The specificity against P haemolytica antigens differed between IgG and IgA isotypes of serum and nasal secretions, with IgA being directed against fewer antigens than was IgG.     

Measurement of isotype-specific antibody responses to Aujeszky's disease virus in sera and mucosal secretions of pigs.

Enzyme-linked immunosorbent assays (ELISAs) for the detection of porcine IgM, IgA, IgG1 and IgG2 antibodies directed against Aujeszky's disease virus (ADV) are described. ADV-specific IgA and IgM were detected in an antibody capture assay, and ADV-specific IgG1 and IgG2 were detected in an indirect double antibody sandwich assay. A selected set of samples was tested in the four ELISAs and in a 24 h virus neutralization assay. Comparison of the results showed that the ELISAs were isotype-specific, sensitive, and reproducible. Samples with ADV antibody of one isotype showed that ADV-specific IgG1, IgG2 and IgM were able to neutralize the virus in vitro. In vitro neutralization of virus can be enhanced by complement. ADV-specific IgA neutralized virus only weakly. ADV-infected cells activated complement in the absence of antibody. Specific IgG2 and IgM enhanced complement activation. Analysis of the time course of antibody responses after infection or vaccination revealed that the isotype-specific ELISAs are suitable to study the humoral antibody response of pigs to the virus in mucosal secretions. Wild-type virus (strain NIA-3) and an attenuated vaccine strain (Bartha) administered intranasally induced mucosal IgM and IgA responses to the virus. In contrast, a killed vaccine (Nobivac) administered intramuscularly induced only weak mucosal IgM responses. The attenuated vaccine strain primed for a mucosal IgA memory response evoked upon challenge infection with wild-type virus.     

Systemic and pulmonary antibody responses of calves to Pasteurella haemolytica after intrapulmonary inoculation.

Systemic and pulmonary antibody responses of calves to Pasteurella haemolytica were evaluated by measuring immunoglobulin production in blood for 9 days and in pulmonary lavage fluid for 7 days after intrapulmonary inoculation. Clinical signs, pulmonary lesions, pulmonary and systemic inflammatory response, and amount of antigen in lavage fluid were used to evaluate the response of calves to challenge with P haemolytica. The pulmonary response consisted of production of IgG, IgE, and IgM antibodies to P haemolytica antigens and a 17- to 68-fold increase of cells in lavage fluid 8 hours after inoculation, with a gradual decrease toward normal. Antibodies of the IgM isotype to P haemolytica were demonstrated as early as 8 hours through 7 days after inoculation in 3 of 3 calves. Of the anti-P haemolytica isotypes, IgM was found in the highest concentration. In all of the inoculated calves, IgE was found 1 to 2 days after inoculation, and IgG was found in 2 of 3 inoculated calves from day 1 through 7 after inoculation. Detection of IgG correlated with smaller pulmonary lesions. Immunoglobulin A was not detected in lavage fluid. Serum was evaluated for IgG and IgM antibody response to P haemolytica. Specific IgM was detectable 5 days after inoculation, and IgG was detectable 7 days after inoculation. Pasteurella haemolytica antigens were not detected in serum or plasma. A transient increase in neutrophil count was found 8 hours after inoculation, with return to baseline values by 24 hours after inoculation.(ABSTRACT TRUNCATED AT 250 WORDS)     

Isotype-specific ELISAs for the detection of antibodies to bovine respiratory syncytial virus

Isotype-specific ELISAs for the detection of antibodies to bovine respiratory syncytial virus (BRSV) are described. BRSV-specific IgG1 and IgG2 were determined in indirect double antibody sandwich assays. For IgA and IgM antibody capture assays were used. The isotype specificity of the assays was confirmed by the observation that samples with a high titre of BRSV-specific antibodies of particular isotype were negative in the assays for the other isotypes and vice versa. Comparison of the results obtained in the ELISAs and in the virus neutralisation test showed that acute phase antibodies were more efficiently detected in the latter. It also showed that the presence of BRSV-specific IgA was not correlated with neutralising activity in vitro. The serum antibody response of BRSV-infected seronegative calves from the field consisted of a nearly simultaneous increase of IgM, IgA and IgG1-antibodies in the acute phase of the disease, while the IgG2-response followed at various intervals thereafter. In young animals with maternal antibodies a different pattern was found. There was no increase in IgG1 and IgG2, but six of eight animals showed a weak IgM response and two of these six calves also showed a weak and short lasting IgA response. Because maternal antibodies are insufficiently effective in protecting calves against BRSV, the presence of such antibodies at mucosal surfaces was investigated. Maternal immunity was found to be restricted to IgG1 antibodies in serum. This agrees with the failure of maternal antibodies to protect mucosal surfaces against BRSV infection.     

雏鸡感染毒害艾美耳球虫后血清免疫球蛋白含量的动态变化

采用间接ELISA法检测雏鸡初次及二次感染毒害艾美耳球虫(Eimerianecatrix)后血清免疫球蛋白含量的动态变化。结果表明,雏鸡初次感染E.necatrix 后10 d~ 14 d血清IgG, IgM, IgA 含量开始增加,16 d~18 d达到峰值;雏鸡二次攻击性感染E.necatrix 后2 d~7 d,其血清的上述3种免疫球蛋白含量均不同程度低于初次感染雏鸡,随后开始回升,至10 d~14 d明显高于相应对照及初次感染雏鸡。血清抗体,特别是IgG介导的体液免疫,在雏鸡抵抗E.necatrix初次及二次感染中发挥了重要作用。     

Serum antibody response to soluble extract of the third-larval stage of Ostertagia ostertagi in cattle

Serum IgG, IgM, and IgA antibody responses against L₃ antigens of Ostertagia ostertagi were monitored by enzyme-linked immunosorbent assay (ELISA) after one, two or multiple sequential inoculations of this nematode in calves. Following the first infection, antibody levels did not change. After a second inoculation, IgG increased significantly (P < 0.05) after 2 months. IgG was not significantly increased 1 month after challenge inoculation. IgM and IgA antibody levels did not change following the first or second inoculations of L₃. IgG antibody levels rose only slightly following multiple sequential inoculations with infectious L₃.

Results indicate that calves with ostertagiasis have very weak serum antibody responses to L₃, and these appear to be of little value in detection of the infection in these animals.     

Demonstration and quantitation of immunoglobulins in bovine serum, follicular fluid, and uterine and vaginal secretions with reference to bovine viral diarrhea and infectious bovine rhinotracheitis.

Immunoglobulin concentrations (IgG, IgM, and IgA) in bovine serum, follicular fluid, and uterine and vaginal secretions were determined. The specificities of IgG, IgM, and IgA for virus-neutralizing antibody against bovine viral diarrhea (BVD) and infectious bovine rhinotracheitis (IBR) viruses were also examined. High concentrations of IgG were present in both serum and follicular fluid. The IgG, IgM, and IgA concentrations were low in uterine and vaginal secretions. There was more IgG in the uterus during estrus than at any other time. Virus-neutralizing antibodies against BVD and IBR in serum of cows were mainly the IgG class. There was positive correlation between serum and follicular fluid virus-neutralizing antibody titers fro BVD and IBR. These antibodies may provide some protection for recently ovulated ova.     

Comparison of Latex Agglutination, Indirect Hemagglutination, and ELISA Techniques for the Detection of Toxoplasma gondii-specific Antibodies in the Serum of Cats

The primary purpose of this study was to determine whether commercially available latex agglutination and indirect hemagglutination kits for the detection of Toxoplasma gondii-specific antibodies were capable of detecting T. gondii-specific immunoglobulin M (IgM) in the serum of cats. Serum samples from 35 cats containing either T. gondii-specific IgM, T. gondii-specific immunoglobulin G (IgG), or both were collected. Each serum sample was assayed using a latex agglutination kit, an indirect hemagglutination kit, an enzyme-linked immunosorbent assay (ELISA) for the detection of T. gondii-specific IgG, and an ELISA for the detection of T. gondii-specific IgM. When serum samples containing only T. gondii-specific IgM as determined by ELISA were assayed, the latex agglutination kit and the indirect hemagglutination kit detected antibodies in 33.3% and 13.3%, respectively. When T. gondii-specific IgG was present in a serum sample, the results from the latex agglutination kit, the indirect hemagglutination kit, and the IgG-ELISA were similar; however, there was a wide variation in titer magnitude results between the three assays. It was concluded that the latex agglutination kit and the indirect hemagglutination kit did not adequately detect T. gondii-specific IgM in feline serum.     

Change of antibody levels to ferritin in the sera of foals after birth: Possible passive transfer of maternal anti‐ferritin autoantibody via colostrum and age‐related anti‐ferritin autoantibody production

Antibody (immunoglobulin G (IgG), IgM or IgA) levels relative to ferritin in six foal sera (three male and three female) after birth (day 0 and 2, 6, 10, 20, 28, 36, 40, 52 and 56 weeks of age) were semi‐quantitatively measured with normalization with antibody activity to ferritin in one adult horse serum. After addition of horse spleen ferritin to the serum sample, the complex formed between antibodies to ferritin in the serum and ferritin was co‐immunoprecipitated using antibody to horse spleen ferritin. Antibody classes of the co‐immnoprecipitate were detected with antibodies specific for horse IgG, IgM or IgA heavy chain. Six adult horse serum samples were found to have ferritin‐binding activities in all immunoglobulin classes examined. Although ferritin antibody activities (IgG, IgM and IgA) were scant in the foal sera before sucking colostrum (day 0), their activities increased at 2 weeks of age. IgG antibodies showed a biphasic response and IgM antibody activity increased up to 40 weeks of age. Antibody (IgG, IgM and IgA) activities to ferritin in three colostrum samples were significantly higher than in adult horse serum samples. These results demonstrate that antibody to ferritin in foal serum is derived from colostrum after birth and is produced thereafter.     

Evidence of bovine immunoglobulin G1 (IgG1) protease activity in partially purified culture supernate of Pasteurella haemolytica A1.

In the bovine respiratory tract, IgG1 is a major secretory immunoglobulin (Ig), and both IgG1 and IgG2 are believed to be important in defense against pneumonic pasteurellosis (shipping fever) in calves. Here we provide evidence for hydrolysis of IgG1 in the presence of partially purified culture supernate (ppCS) from the respiratory pathogen Pasteurella haemolytica A1. Bovine IgG1 was hydrolysed sequentially into three distinct bands (approximately 39, 12, and 7 kDa respectively). Furthermore, partial hydrolysis of bovine IgG2 was observed, but neither bovine IgA nor IgM were affected by incubation with ppCS. These findings suggest that the production of an IgG1-specific protease by P. haemolytica A1 may be a virulence mechanism contributing to the pathogenesis of bovine pneumonic pasteurellosis.     

Four-layer enzyme immunoassay (EIA) detection of differences in IgG, IgM and IgA antibody response to Aujeszky's disease virus in infected and vaccinated pigs

The use of the four-layer enzyme immunoassay (EIA) for the detection of IgG, IgM and IgA antibodies against Aujeszky's disease virus in blood and oropharyngeal swabs of infected and vaccinated pigs is described. Mean antibody titres obtained using the four-layer EIA were 6.1 and 3829 times higher compared with the indirect enzyme-linked immunosorbent assay (ELISA) and virus neutralization (VN) test, respectively. The VN test detected mainly IgG antibodies, while the IgM antibodies did not react. Using the EIA, the first antiviral antibodies in sera were demonstrated on Days 5-7 after infection or vaccination. Up to the 7th day, demonstrable antibodies were almost exclusively of the IgM class. In infected pigs high titres of IgM antibodies were still detected on Day 18, while in vaccinated animals they were absent by this time. Antibodies of the IgG class appeared in infected pigs sooner (Day 7) than in vaccinated pigs (Day 10) and reached higher mean titres. Antibodies of the IgA class were demonstrable from Day 10 only in samples from infected pigs. Similar antibody dynamics and distribution were detected in oropharyngeal swabs, except that the IgG and IgM titres were roughly 100 times lower than in sera. However, titres of IgA antibodies in oropharyngeal swabs were two times higher than in sera. The greatest differences between both groups of animals were recorded on Day 18; in the infected pigs, IgG, IgM and IgA antibodies were present in sera and oropharyngeal swabs at that time, while in vaccinated pigs only IgG antibodies were demonstrable. The effect of infection and vaccination on the pattern of the immune response as well as the importance of the detection of individual immunoglobulin classes for the specificity of the enzyme immunoassay are discussed.     

Immunoglobulin class response to canine distemper virus in gnotobiotic dogs

Serial serum samples from 27 gnotobiotic dogs infected with R252-canine distemper virus (CDV) were tested for anti-viral IgG, IgM and IgA immunoglobulins using an enzyme-linked immunosorbent assay (ELISA). The results were compared retrospectively to clinicopathological course of disease and to previously reported patterns of complement-fixing and virus neutralizing antibody titers determined in these same sera. Virus-specific IgA was never detected in the sera. High levels of IgG correlated with recovery from disease, whereas the antiviral IgM levels were equivalent in both persistently infected animals and those animals which recovered from disease. The inability to sustain a significant antiviral antibody response in either IgM or IgG classes was characteristic of dogs with fatal encephalitis. The data suggests that IgG is the most important Ig class for recovery from disease.