Protection against experimental salmonellosis in mice and sheep by immunisation with aromatic-dependent Salmonella typhimurium.

Mice immunised by the oral or intraperitoneal route with a live aromatic-dependent strain of Salmonella typhimurium exhibited significantly less protection against oral challenge with 50 LD50 of an ovine isolate of S. typhimurium (12313) than when a bovine isolate with the same O antigens and phage-type as strain 12313 was used as the challenge organism. When challenged with 10 LD50, however, protection against both strains was significantly better than that obtained when mice were vaccinated with killed vaccines (heat-killed, acetone-killed or irradiated) even when the antigenic mass of the killed vaccine was increased by up to 500-fold in an attempt to compensate for the expected limited multiplication of the mutant organism. Sheep immunised with the live mutant strain by either the intramuscular or oral route were protected against oral challenge with the virulent ovine isolate of S. typhimurium; unimmunised sheep died of acute enteritis within 7 days, although there was no evidence of systemic invasion by the challenge organism. After challenge, immunised animals ate more food than the unimmunised controls and suffered only transient, mild diarrhoea. Serum antibody titres against O and H antigens measured by direct or antiglobulin tests were significantly higher in sheep immunised by the intramuscular route than in those immunised orally. Sheep in both immunised groups developed skin swellings within 30 min after intradermal inoculation with purified homologous lipopolysaccharide indicating development of immediate-type hypersensitivity, but only those immunised by the intramuscular route showed significant indurated skin swellings characteristic of delayed-type hypersensitivity 48 and 72 h post-inoculation.(ABSTRACT TRUNCATED AT 250 WORDS)

The antibody-containing cell response in hepatic and intestinal lymph following intraperitoneal and intravenous administration of antigen in different adjuvants.

A comparison was made of the antibody-containing cell (ACC) response in hepatic and intestinal lymph of sheep following intraperitoneal injection of ovalbumin in Freund's complete adjuvant (FCA), Freund's incomplete adjuvant (FIA) or the bland vegetable oil preparation, adjuvant 65. There was a substantial ACC response in intestinal lymph following intraperitoneal injection of ovalbumin in either FCA or FIA. Responses were essentially similar in magnitude and for both adjuvants ACC were distributed mainly among the IgGl, IgA and IgM immunoglobulin classes. In contrast, there was a negligible ACC response in intestinal lymph following injection of antigen in adjuvant 65. The output of ACC in hepatic lymph and the immunoglobulin class distribution of the ACC following intraperitoneal injection of antigen in either FCA or FIA were similar and results were specificity comprising 32% of ACC at the peak of the response. In contrast to results for intestinal lymph, injection of antigen in IgGl- and IgM-specific cells in hepatic lymph. The ACC response was much smaller in magnitude than with the Freund's adjuvants. Intravenous injection of ovalbumin in FIA or adjuvant 65 gave rise to substantial ACC responses in hepatic lymph which contrasted with the barely detectable response in intestinal lymph. Following intravenous administration the great majority of ACC in hepatic lymph were of the IgM class irrespective of adjuvant used although ACC of the IgA class made a transitory appearance.

Immune response of sheep to oral and subcutaneous administration of live aromatic-dependent mutant of Salmonella typhimurium (SL1479).

The major objective of the present study was to determine whether oral immunization with a live aromatic-dependent strain of Salmonella typhimurium (SL1479) was capable of stimulating an intestinal immune response in sheep similar to that induced by combined intraperitoneal injection followed by oral boosting. The results showed that repeated oral immunization was incapable of stimulating an anti-flagella antibody containing cell (ACC) response in the lamina propria of the intestine even though primary oral administration of 5 x 10(9) live SL1479 gave rise to an ACC response in intestinal lymph which was predominantly of the IgM isotype. ACC reached a peak 9-10 days after oral administration when ACC comprised 0.5-1% of total lymphocytes in lymph. An ACC response of similar isotope specificity also occurred in popliteal prefemoral lymph of unprimed sheep following regional subcutaneous injection of SL1479. Oral administration of SL1479 to orally primed sheep did not reinvoke an ACC response in lymph although IgG1-ACC were observed in medullary cords of mesenteric lymph nodes of sheep 6-8 days after the booster dose of SL1479. The results suggest that the protective immunity elicited by oral administration of SL1479 cannot be attributed to induction of a local intestinal antibody production.

Significance of Freund's adjuvant/antigen injection granuloma in the maintenance of serum antibody response.

An experimental system involving injections of ovalbumin (OVA) and ferritin (FER) in Freund's incomplete adjuvant (FIA) into the right and left flank skin folds of sheep was used to study the influence of the FIA/antigen depot and the draining lymph node in maintaining an antibody response. Excision of the injection granuloma and draining lymph node from one side 2-3 months after injections resulted in a profound decrease in serum antibody titres. This response was observed in all eight sheep in the experimental group. In five of eight animals in another experiment, excision of the injection sites had no appreciable effect on antigen-specific antibody titres when compared with antibody specific for antigen on the intact side of the sheep. In the remaining three animals, excision of the injection site did cause some fall in titre. Radiotracer studies revealed that about one-third of the original [125I]OVA/FIA injected was present in the granuloma 20 weeks after injection. Lymphatic cannulation approaches were used to study the responsiveness of the lymph node draining an FIA/antigen granuloma established 12 weeks earlier and showed that increments of 1-2 mg OVA in saline administered adjacent to the granuloma at 6-7 day intervals gave rise to strong anti-OVA containing cell (AOCC) responses in lymph. There were 2-6-fold increases in serum antibody titre in response to 3-5 doses of OVA or FER (1-2 mg) in saline injected adjacent to the FIA/antigen injection site (which had been administered 14-16 weeks previously). It is concluded that the release rate of antigen from a FIA/antigen depot is insufficient to sustain maximal antibody levels in blood serum.

The influence of systemic immunisation during mammary involution on subsequent antibody production in the mammary gland.

The primary purpose of the experiments reported in this paper was to determine whether a powerful systemic antigenic stimulus, given at the time of mammary involution, would affect the level of specific antibody in milk secreted during the ensuing lactation. The results showed that a single systemic administration of antigen with adjuvant, during mammary involution, is an efficient means of inducing high titres of specific antibody in milk in the subsequent lactation. Furthermore, such antibody belongs mainly to the IgA and IgM classes of immunoglobulin. These results suggest that the antibody is produced locally in the mammary gland by sensitised cells of the lymphocyte-plasma cell series, which infiltrate the tissue during the early stages of mammary involution and then become sessile.

Antibody responses to neonatal immunisation in calves.

Antibody responses were measured in colostrum-fed (CF) and colostrum-deprived (CD) calves immunised at ages varying from birth to four months using a variety of antigens with and without adjuvant. In addition immunoglobulin production in CD calves over the same period was compared with that of CF calves. A marked unresponsiveness to antigens injected at birth was observed if maternal antibody specific for the antigen used was present in the circulation. However, significant responses to all antigens tested occurred in CD calves and also in CF calves immunised with an antigen (egg albumin) to which there was no maternal antibody. Since these responses were not as great as those in older calves immunised similarly it is clear that age was influencing the response. It was also found that subsequent responsiveness was not significantly enhanced or impaired by neonatal exposure to antigen. With respect to immunoglobulin production the results conclusively demonstrated that endogenous production occurred much earlier in CD calves than CF calves and even after 128 days the serum concentrations of IgG1 and IgA in CD calves exceeded those for CF calves. Thus it appears that the most important consideration in immunological responsiveness of neonates is not so much immaturity of the lymphoid system as the effects of maternal antibody on the cells in that system.

The immune system on the ruminant mammary gland and its role in the control of mastitis.

Immunoglobulins in mammary secretion are derived from blood serum or are made locally by cells of the lymphocyte-plasma cell series situated close to the glandular epithelium. The major immunoglobulin in colostrum and milk of ruminants, IgG1, is derived from the blood and is transferred into secretion selectively relative to IgG2, probably by a mechanism requiring specific receptor sites on the basal of intercellular membrane of the glandular epithelium. Acute inflammation causes suppression of selective transfer of IgG1, but there is a marked increase in the transfer of proteins, such as IgG2 and serum albumin, which enter secretion nonselectively. Infusion of antigen into the mammary gland of ruminants some weeks before parturition induces a persisting local production of antibody, most of which is associated with IgA and IgM. IgA cells in the mammary gland probably originate in the intestine, and prior antigenic stimulation of the gut may be required for maximal IgA antibody responses in the gland. Local immunization with staphylococcal vaccines gives a measurable degree of protection against staphylococcal challenge. Systemic immunization with viable staphylococci leading to subcutaneous abscess formation elicits significant protection to subsequent mammary challenge which is attributable, at least in part, to specific antibody of the IgG2 class cytophilic to polymorphs.

The flow and lipoid composition of thoracic duct lymph in the grazing cow.

1. A technique is described for the collection of thoracic duct lymph from the grazing cow.2. The effects of continuing drainage of lymph were overcome by establishing an exteriorized lymphatico-venous shunt from which lymph and blood samples were obtained when required. The shunt functioned satisfactorily for periods of 10, 14 and 28 days in the three cows.3. The rate of lymph flow and concentration of lipids in the lymph were low during and immediately after the operation. Higher sustained levels of flow of 1.37 +/- 0.43 (S.D.), 1.88 +/- 0.40 (S.D.) and 1.90 +/- 0.45 (S.D.) 1./hr, for the dry and two lactating cows respectively, were observed during the period 3-9 days after the operation.4. More than 200% of the volume and 100% of the protein of the blood plasma compartment passed through the thoracic duct each day.5. Chlyomicron triglyceride comprised 50-70% and phospholipid 20% of the total lipid in lymph.6. The results indicated that at least 200 and 400 g of esterified fatty acid were transported daily in the lymph of the dry and lactating cows respectively.