Maternal-neonatal immunoregulation in swine. II. Influence of multiparity on de novo immunoglobulin synthesis by piglets

In the first-litter sows lower serum levels were found for all three Ig classes as compared to multiparous sows. The same was true for IgA in lacteal secretions and in piglet serum during the first days of life, while no differences were found for IgG levels. In contrast to these findings, IgM levels were found to be higher in lacteal secretions of first-litter sows and in piglet serum during the first days of life as compared to their counterparts. From three weeks after birth Igs found in piglet serum mainly originate from de novo synthesis. In this period piglets of first litter sows showed a higher IgA level up to the 6th week of life and higher IgG and IgM levels up to the end of the investigation period. Results are discussed in terms of maternal-neonatal immune regulation, focussing on the apparent suppressive role of maternally-derived IgG on total de novo Ig synthesis by suckling piglets.     

Changes in serum immunoglobulin values in kittens after ingestion of colostrum.

Immunoglobulin values were determined in fetal and kitten sera. In the fetal and precolostral kitten sera, only IgG was detected, except in 1 case in which IgM was detected. The IgG, IgA, and IgM were transferred to the kittens through colostrum ingestion with some selectivity. Concentration of the transferred IgG, IgA, and IgM decreased significantly with half-lives of 4.15 +/- 1.29 days, 2.03 +/- 0.33 days, and 2.2 +/- 1.2 days, respectively. As a result of this decrease and increase of de novo immunoglobulin synthesis, IgG, IgA, and IgM were at their lowest values when kittens were 20 to 25 days, 14 to 20 days, and 8 to 10 days old, respectively. After their nadir was reached, IgG values increased gradually, IgA slowly, and IgM rapidly, as a result of de novo immunoglobulin synthesis. When the kittens were 90 days old, their immunoglobulin values were 80% (IgG), 7% (IgA), and 100% (IgM), compared with those of adult cats. These findings suggest that kittens that receive inadequate colostrum from their mothers will be particularly susceptible to infection after they are 5 weeks old.     

Studies on immunoglobulins and trypsin inhibitor in colostrum and milk from sows and in serum of their piglets.

The concentrations of IgG, IgM, IgA and the specific sow colostrum trypsin inhibitor (SCTI) were measured by radial immunodiffusion in colostrum and milk samples from sows and in serum samples from their offspring during the suckling period. A clear time dependence was found for all the measured variates in both whey and serum. Statistically significant positive correlations were found between, on the one hand, concentrations of IgG and IgA, but not IgM, in sera from 39 suckling piglets 1 and 3 days old, and, on the other hand, concentrations of the same immunoglobulins and of the trypsin inhibitor in maternal colostrum (n = 7). Multiple regression analyses showed that at day 1 and day 3 the levels of both IgG and IgA in serum samples from the suckling piglets were positively influenced by both the SCTI and the IgG or IgA contents in maternal colostrum.     

Dynamic changes of immunoglobulin concentrations in pig colostrum and serum around parturition

The aim of the study was the determination of IgA, IgM and IgG concentrations in porcine serum and colostrum, in order to evaluate their variations in the perinatal period, as well as to clarify whether there is a correlation between colostrum intake, initial level of immunoglobulins (Ig) in piglet serum and development of their own immunity. The mean IgA, IgM and IgG concentrations in sow serum 10 days before parturition were 1.58, 6.12 and 39.56 mg/ml, respectively. Seven days later only the IgG level was insignificantly lower (34.94 mg/ml, p = 0.55), while concentrations of IgA and IgM increased to 2.25 and 7.25 mg/ml, respectively (p = 0.23 and 0.62, respectively). The mean initial IgG concentration in colostrum at farrowing was 118.5 mg/ml and differed between sows. The average value of IgA in colostrum at birth was 23.8 mg/ml and decreased to 7.85 mg/ml at 6 hours (h) and to 4.59 mg/ml at 24 h after the onset of farrowing. IgM concentration at birth was 12.1 mg/ml and decreased to 4.23 mg/ml at 24 h postpartum. Positive relationships were found between concentrations of IgM and IgA in serum of piglets at 14 and 56 days of life (r = 0.41 and 0.80, respectively, p < or = 0.05) as well as for IgG concentration in the piglets serum at 7 days and 56 days of age (r = 0.48, p < or = 0.05). The above observations suggest that there is a correlation between the level of Ig in piglet serum in the first days of life and improvement of their own immunity.     

Early, microbially driven follicular reactions in the neonatal piglet do not contribute to expansion of the immunoglobulin heavy chain V-D-J repertoire

Selective microbial colonisation of germ-free piglets is reported to result in expansion of immunoglobulin V(H)- and D(H)-segment usage from an initially limited repertoire. Here, the response of the palatine tonsil to microbial colonisation was compared in age-matched conventionally reared and germ-free piglets. At 3 and 5 days after birth an expansion in the B-cell follicle area was observed in the conventional, microbially colonised animals, which was not seen in the germ-free piglets. Consistent with this observation, sequencing of re-arranged heavy chain V-D-J units demonstrated accumulation of point mutations indicating somatic hypermutation in the conventional, microbially colonised piglets but not in the germ-free animals. However, V(H)- and D(H)-segment usage and CDR3 length did not differ between the groups. The results suggest that the follicle reaction observed occurs in response to microbial challenge, involves proliferation and somatic hypermutation of B-cells but does not expand repertoire or generate classical, isotype-switched memory B-cells. We suggest that microbial colonisation of neonatal piglets drives immunological competence in two stages: first, an antigen non-specific, follicular reaction which expands immunological compartments; and second, microbe driven changes in V-segment usage which expand immunological repertoire.     

Experimental fetal infection with bovine viral diarrhea virus. I. Virological and serological studies.

The serological and virological results of an experimental infection of bovine fetuses with bovine viral diarrhea virus are presented. Four fetuses, 120-165 days gestational age, were inoculated in utero with a second passage virus strain. Two fetuses received a sham-inoculum. A humoral immune response in the virus-inoculated fetuses, was demonstrated three weeks later. In three fetuses only IgM and IgG1 were detectable. The serum from the fourth fetus also contained IgG2 and IgA. Bovine viral diarrhea virus-neutralizing antibodies were detected in two fetuses. These two fetuses inoculated at 135-150 days gestational age, represent the youngest reported bovids, giving a specific response in three weeks following an experimental infection with bovine viral diarrhea virus. The fetal sera did not contain heat-labile factors, which could mediate the neutralization. The virus was not reisolated from any of the fetuses, but viral antigen was nevertheless demonstrated by immunocytochemical methods in sections of several of the fetal organs, primarily lymphoid tissues.     

IgA, igG1, IgG2, IgM, and BSA in serum and mammary secretion throughout lactation

Bovine IgG1, IgG2, IgA, and IgM were measured in the serum and lacteal secretions of six cows from 10 days prepartum to 240 days of lactation. Immunoglobulins in lacteal secretions were expressed in units of concentration (mg/ml) as well as in total daily output. All isotypes were selectively accumulated during colostrum formation. The rate of IgG1 accumulation decreased rapidly after calving; this decrease corresponded to a return to normal serum levels of this immunoglobulin. Selective accumulation of IgA > IgM > IgG1 was maintained throughout lactation, but IgG2 showed no selective accumulation beyond 5 days postpartum. In serum, IgA and IgM levels were elevated at parturition and showed a significant decrease postpartum. Increases in serum IgA levels 60 days postpartum corresponded to a rise in lacteal concentration. The concentration of all immunoglobulins increased during late lactation, coincident with a major reduction in milk yield. Six strains of mastitis-causing organisms were cultured during the period of the experiment; however, none resulted in clinical mastitis or showed an effect on immunoglobulin secretion.     

Intestinal and serum antibody response in gnotobiotic piglets to oral immunization with Escherichia coli

The local and systemic immune response to a formolized E. coli oral vaccine was investigated in 13 gnotobiotic piglets. Beginning at ten days of age animals received a daily dose of 10¹⁰ or 10¹¹ bacteria, on ten consecutive days. Intestinal loop tests with one animal of each group on day 26 showed protection which was more pronounced in the animal dosed 10¹⁰ bacteria compared with the other immunized piglet. Immunoglobulin class-specific antibodies to O and K antigens were determined by ELISA technique. In serum no IgG or IgA antibodies were found, whereas IgM-anti O149 antibodies in both immunized groups reached their highest level at day 4 of dosing and decreased thereafter. IgM-anti K88 antibodies were first detected at day 10 of dosing. Both immunized groups had comparable serum levels at days 20 and 30. Also in gut secretion the IgM antibody response was predominant, and higher levels were found in the 10¹⁰ group than in the 10¹¹ group. IgG and IgA antibody response were also detected in secretion.     

The Influence of Sow Colostrum Trypsin Inhibitor on the Immunoglobulin Absorption in Newborn Piglets

The influence of sow colostrum trypsin inhibitor (SCTI) on the immunoglobulin absorption from the gut of 16 newborn colostrum-deprived piglets was investigated in a paired feeding experiment.Three times at 1 h intervals the piglets were fed an experimental diet consisting of sow milk, purified swine serum immunoglobulins containing agglutinins against Bordetella bronchiseptica, and purified SGTI (diet I) or saline (diet II). The serum concentrations of IgG, IgM, IgA, and antibodies for B. bronchiseptica were measured by single radial immunodiffusion and by a tube agglutination procedure and used to evaluate the immunoglobulin absorption. Four and 6 h after the first experimental meal, blood samples from the piglets given SGTI in their diet had a generally higher level of IgG, IgA and aggutinins against B. bronchiseptica than blood samples from the piglets d no SGTI. No real differences were found in the IgM levels. Although the piglets fed no SGTI all showed a considerable immunoglobulin absorption, the SCTI was found to have a statistically significant positive influence on the IgG and IgA absorption.     

Synthesis of immunoglobulin by normal and antigenically stimulated fetal sheep.

The rate of appearance, quantity and immunochemical character of serum immunoglobulins which appear normally during the development of fetal sheep and following the injection of antigens at different stages of gestation have been studied. After 70 days' gestation a percentage of normal fetal sheep synthesise IgM. Although the concentration of IgM in the circulation of these animals was very low, the precentage with IgM increased with fetal age. A few late term fetuses were detected which also had IgG1 in their circulation, although none were detected with IgG2 or IgA. Fetuses injected with antigens before 71 days' gestation only synthesised IgM, while fetuses injected after 79 days' gestation synthesised both IgM and IgG1. Neither IgG2 nor IgA were detected by single-radial immunodiffusion analyses during the first 14 days of primary immune responses to a variety of antigens, although trace amounts of IgG2 were detected late in responses occurring in older fetuses. The immunoglobulins synthesised by antigenically stimulated fetal sheep appeared identical to adult sheep 19S IgM, 7S IgG1 and 7S IgG2 respectively, when analysed by immunoelectrophoresis, isoelectric focusing and G200 Sephadex column chromatography.     

Humoral immune response of the bovine fetus to in utero vaccination with attenuated bovine coronavirus

A fetal response to in utero vaccination with attenuated bovine coronavirus (9 to 49 days before parturition) was determined in 8 calves, 5 vaccinated and 3 controls. Calves were derived by hysterotomy before parturition and were maintained in a closed gnotobiotic environment. The IgA, IgM, and IgG values and coronavirus-neutralizing antibody titers were higher in the sera and intestinal loop fluid from vaccinated calves than in those from control calves. Sections of ileum and ileal lymph nodes from 1-day-old vaccinated calves, when stained with monospecific anti-bovine IgG, IgM, and IgA had numerous positively stained plasma cells. Positive fluorescence was not detected in comparable tissues from controls. When the 8 calves were given virulent coronavirus orally at 6 days of age, vaccinated calves did not become ill, whereas control calves had diarrhea in 19 to 22 hours. All calves were killed at 10 days of age. Control calves had lesions characteristic of coronavirus infection, and intestinal epithelial cells were positive by fluorescent antibody tests. In vaccinated calves, lesions of coronavirus infection were absent, and results of fluorescent antibody tests were negative. Although in utero vaccination with a coronavirus vaccine stimulated immunity in the newborn calf, the frequency of abortions (2 of 14 cows inoculated intra-amniotically) and premature births (4 of 14) precluded practical application.     

Effects of Fermented Atractylodes chinensis on Serum Immune and Biochemical Indexes of Weaned Piglets

The aim of this experiment was conducted to study the effects of fermented Atractylodes chinensis on serum immune and biochemical indexes of weaned piglets. Ninety-six Landrace ×Large White weaned piglets with weaning weight (6.0±0.5) kg were randomly allocated to 6 groups with 4 replicates per group and 4 weaned piglets per replicate. The weaned piglets were subjected to the following 6 treatments for 28 days:Control group was fed with the basal diet,groups Ⅰ and Ⅱ were fed with antibiotics and 0.2% unfermented Atractylodes chinensis in basal diet,while groups Ⅲ,Ⅳ and Ⅴ were supplemented 0.1%,0.2% and 0.3% fermentated Atractylodes chinensis in basal diet,respectively. The results showed that the immune and biochemical index of weaned piglets in fermented Atractylodes chinensis group had different degrees of improvement compared with control group and group Ⅰ.In the whole experimental stage,comparing with control group,the serum IgA,IgG,IgM,TP and ALB of weaned piglets in group Ⅳ were increased 10.5%,10.0%,7.8%,21.0% and 15.6%,respectively,and the difference were significant (P < 0.05),and serum ALT content was significantly reduced 20.4% (P < 0.05).Compared with group Ⅰ,the serum IgA,IgG,IgM and TP of weaned piglets in group Ⅳ were increased 7.1%,3.8%,3.8% and 12.6%, respectively,the difference were significant (P < 0.05),while the serum ALB, AST and BUN of group Ⅳ were increased 1.0%, 9.5% and 15.0%, and the difference were not significant (P > 0.05), and serum ALT content was reduced 9.4% compared with the antibiotics group (P > 0.05).     

发酵北苍术对断奶仔猪血清免疫指标和生化指标的影响

试验旨在研究发酵北苍术对断奶仔猪血清免疫指标和生化指标的影响。选取96头体况相近、断奶重为（6.0±0.5）kg的长白猪×大白猪二元杂交仔猪,随机分为6组,每组4个重复,每个重复4头猪。对照组饲喂基础日粮,Ⅰ组为抗生素组,在基础日粮中添加杆菌肽锌＋硫酸黏杆菌素,Ⅱ组在基础日粮中添加0.2%未发酵北苍术,Ⅲ、Ⅳ、Ⅴ组分别在基础日粮中添加0.1%、0.2%、0.3%发酵北苍术,试验期为28 d。结果显示,日粮中添加发酵北苍术组的断奶仔猪的血清各项免疫指标和生化指标较对照组及Ⅰ组均有不同程度的改善,其中Ⅳ组的效果最好。在整个试验阶段（断奶后28 d）,与对照组相比,Ⅳ组断奶仔猪血清中IgA、IgG、IgM、TP和ALB含量分别提高了10.5%、10.0%、7.8%、21.0%和15.6%,差异均显著（P < 0.05）,血清中ALT含量与对照组相比显著降低了20.4%（P < 0.05）;与Ⅰ组相比,Ⅳ组断奶仔猪血清中IgA、IgG、IgM、TP分别提高了7.1%、3.8%、3.8%、12.6%,差异均显著（P < 0.05）,而ALB、AST和BUN含量分别提高了1.0%、9.5%和15.0%,差异均不显著（P > 0.05）,血清中ALT含量与Ⅰ组相比降低了9.4%（P > 0.05）。     

Fetal infections and antibody profiles in pigs naturally infected with porcine circovirus type 2 (PCV2)

The aim of this study was to describe early infections with porcine circovirus type 2 (PCV2) in naturally infected piglets and the piglets' serologic profiles. A total of 20 sows (15 PCV2-vaccinated and 5 unvaccinated) and 100 newborn piglets were studied. Colostrum and serum of the sows and serum of the presuckling piglets were obtained on the day of parturition. Milk samples were collected on day 20 postpartum. Blood samples were taken and the piglets weighed on days 1, 20, 42, 63, and 84 postpartum. Colostrum and milk were evaluated for infectious PCV2 and for PCV2 total antibody (TA), neutralizing antibody (NA), and IgA. Serum samples were evaluated for PCV2 TA, NA, IgA, IgM, and DNA. The sows had high levels of TA and NA in serum and colostrum; however, 11 and 5, respectively, of the 20 colostrum and milk samples contained infectious PCV2. In the serum, PCV2 DNA and IgM were detected in 17 and 5, respectively, of the 20 sows. Nine piglets were born with PCV2 antibodies, which indicates in utero transmission of PCV2 after the period of immunocompetence (> 70 d of gestation). On day 1 postpartum, PCV2 DNA was detected in 29 of the 100 serum samples from the piglets. There was no difference between the weights of viremic and nonviremic piglets throughout the study. In conclusion, even on farms with sows that have high PCV2 antibody titers, vertical transmission of PCV2 may occur, resulting in piglet infection.     

Helicobacter pylori-specific immunoglobulin synthesis in gnotobiotic piglets: evidence for the induction of mucosal immunity in the stomach

Short term tissue biopsy cultures and paired, sera, bile and gastric and intestinal contents from Helicobacter pylori-infected gnotobiotic piglets were tested for the synthesis of H. pylori-specific immunoglobulin (Ig) isotype production by antigen-specific ELISA from post-infection days (PIDs) 2-28. Serum antibody levels in all three Ig isotypes were elevated from baseline values by PID 14, serum IgM levels reached peak levels on PID 14 and by PID 28 bile was strongly positive for IgA and IgG.Intestinal, but not gastric contents from infected piglets, contained IgA-specific antibody from PID 14 onward. Gastric mucosal epithelia adjacent to areas of inflammation in infected but not uninfected control piglets produced readily detectable amounts of porcine secretory component (SC); IgA-positive plasma cells were identified in gastric submucosa and lamina propria in these areas. Culture fluid supernatants, collected from explanted gastric cardia and antra and intestinal ilea of H. pylori-infected piglets had trace amounts of IgA as early as PID 2 in some animals, and strong IgA reactivity in all by PID 28. Supernatants also contained H. pylori-specific IgG by PID 14. A strong gastric lymph node IgA response contrasted with moderate IgA production in mesenteric lymph nodes and spleen. Mucosal biopsy production of H. pylori-specific IgG was more evenly distributed throughout the lymphoid system. These data support the contention that the Ig response to H. pylori is initiated within the gastric compartment and matures over time to a generalized IgA-dominated mucosal and IgG-dominated nonmucosal humoral immune response.     

Immunohistochemical studies on ontogeny of bovine lymphoid tissues.

Developing lymphoid tissues of bovine fetuses ranging from 70 to 270 days of fetal age were examined by histological and immunohistochemical procedures. In the peripheral blood, surface membrane immunoglobulin bearing cells (B-lymphocytes) and sheep red blood cell rosette forming cells (T-lymphocytes) had already appeared by 70 days of fetal age. In the lymph nodes intracytoplasmic IgM positive cells appeared at 90 days of fetal age. The cells positive for IgG appeared at 150 days of fetal age and IgA positive cells appeared at 180 days of fetal age. The spleen contained intracytoplasmic immunoglobulin positive cells at almost the same time as those in the lymph nodes. In the ileocecal region, IgM positive cells and IgG positive cells were present at 180 days of fetal age and IgA positive cells were present at 210 days of fetal age. The tonsils contained IgM positive cells and IgG positive cells at 240 days of fetal age. In the thymus, terminal deoxynucleotidyl transferase positive cells appeared at 90 days of fetal age.     

The protective effect of two porcine enterovirus vaccines in swine.

The virus neutralizing substance in the gastrointestinal tract of swine vaccinated in different ways with porcine enterovirus strain T80 was characterized by tests for enhancement and absorption of virus neutralizing activity by class specific antiporcine Ig antisera. The gastrointestinal virus neutralizing activity of piglets which were vaccinated with live virus orally resided predominantly in the IgA class, although some activity was present also in the IgM and IgG classes. The serum virus neutralizing activity of this group was present in all three classes but primarily in the IgG class. The IgA in the serum of this group was presumably of gut origin. However, in piglets vaccinated with live virus intramuscularly, with formaldehyde-inactivated virus orally or intramuscularly or with ethylenimine-inactivated virus by both oral and subcutaneous routes, both serum and gastrointestinal virus neutralizing activity were attributable predominantly to antibodies of the IgG and IgM classes. None possessed serum IgA. There was evidence also for the presence of Ig fragments in some gastrointestinal extracts.     

Evaluation of systemic and secretory IgA concentrations and immunohistochemical stains for IgA-containing B cells in mucosal tissues of an Irish setter with selective IgA deficiency

Immunoglobulin A is the predominant secretory antibody at mucosal surfaces. In the dog, immunoglobulin A deficiency (IgAD) is characterized by low to absent serum IgA and normal to elevated serum immunoglobulin G (IgG) and immunoglobulin M (IgM) concentrations. However, studies comparing serum and secretory IgA in dogs have often documented a poor correlation, suggesting that serum concentrations should not be used to estimate mucosal secretion of this antibody. This report demonstrates the concurrent use of serum IgA, IgG, and IgM; secretory IgA (from bronchoalveolar lavage fluid); and immunohistochemical stains on bronchial and duodenal mucosa for IgA-containing B cells in a young Irish setter with recurrent respiratory and gastrointestinal signs.     

Secretion of Salmonella-specific antibodies in the oviducts of hens experimentally infected with Salmonella enteritidis

The production and secretion of Salmonella enteritidis whole cell antigen-specific antibodies in the oviducts and in the serum of laying hens experimentally infected with Salmonella enteritidis, was analyzed by ELISA. The dynamics of the antibody levels in the oviducts were identical to that in the serum. Subclasses of antibodies (IgA, IgG, and IgM) in the infected hens were found to increase significantly (p < 0.01) compared to those in the control uninfected hens throughout the experiment. IgG and IgM levels in both oviducts and in sera reached to a peak by 14 days post-inoculation, and remained elevated throughout. The secretion of IgA seemed to be transient since the IgA levels increased to a peak 7 days after both primary and secondary inoculations, and declined rapidly. The elevated levels of antibodies were followed by partial clearance of Salmonella organisms from the oviducts. The present results indicate a significant local immune reaction against the Salmonella infection and suggest an association of the local antibodies with the clearance of Salmonella from the oviducts at least partially.     

Early development of immune system in pigs

Prenatal and early postnatal immune system development has been studied in minipigs. First leukocytes were observed in the yolk sac and fetal liver (FL) on the 17th day of gestation, the majority of them being SWC3(+). The colonization of the thymus (TH) with leukocytes was observed 21 days later. Two waves of fetal TH colonization with pro-T cells were deduced from the frequency of thymocyte subsets. Thymic B cells and immunoglobulin-secreting cells (Ig-SC) were studied by flow cytometry and ELISPOT, respectively. When the total numbers of fetal Ig-SC were compared, the TH was identified as the main source of natural antibodies and the only site of IgA and IgG synthesis. In germ-free animals, the TH also represented the major site of IgG and IgA production and the number of Ig-SC was not influenced by colonization with microflora. FL and bone marrow were identified as primary B lymphopoietic sites. The phenotype of B precursors was characterized and pre-B II cells were shown to be the dominant mononuclear fraction between DG50 and DG105. In the periphery, relative proportions of lymphocyte subsets were determined. Studies in gnotobiotic piglets have revealed that the appearance of CD4(+)CD8(+) T cells and CD2(-) B cells is absolutely dependent on the contact of immune system with live viruses and bacteria, respectively.