Schistosoma japonicum: Immunological response to circulating polysaccharide antigens in rabbits with a light infection

To study the detectability of circulating polysaccharide antigens and the immunological response to such antigens in rabbits with a light Schistosoma japonicum infection, sera of five rabbits infected with 50 cercariae were studied up to 29 weeks post infection (p.i.). While one rabbit developed no worm burden, the other rabbits developed low worm burdens (4 to 16 worms). In the sera of these rabbits, the only polysaccharide antigen demonstrable with immunoelectrophoresis (IEF), was the circulating anodic antigen (CAA). With the enzyme-linked immunosorbent assay (ELISA), CAA was detectable from 5 to 6 weeks p.i. in the sera of the two rabbits with the highest number of worm couples. The lowest CAA level which was detectable in unconcentrated sera from which serum proteins had been removed was 125 ng CAA/ml, corresponding with a worm burden of 4.5 worm/kg body wt. During the entire infection, CAA-specific immune complexes were only demonstrable in very low concentrations. Antibodies against polysaccharide antigens were assessed with immunofluorescent antibody (IFA) on Rossman's fixed sections of adult worms, with the ELISA, and with IEF. Specific IgA, IgG, and IgM antibodies were detectable from 2 to 3 weeks p.i. with IFA and ELISA. These early antibodies were shown to be directed against gut-associated antigens, while antibodies against parenchyma-associated antigens were found later in the infection. With IEF, antibodies against two trichloroacetic acid (TCA)-soluble antigens were detectable, including the major, S. japonicum-specific antigen 2.     

Pathogenesis of CAR bacillus in rabbits, guinea pigs, Syrian hamsters, and mice.

Cilia-associated respiratory (CAR) bacillus isolated from infected mice (designated, CBM) and propagated in embryonated chicken eggs was inoculated intranasally in rabbits (Oryctolagus cuniculus), guinea pigs (Cavia porcellus), hamsters (Mesocricetus auratus) and mice (Mus musculus). Gross and microscopic lesions, localization of CBM antigen in the respiratory tract, development of antibody, and ability to reisolate the CAR bacillus were studied in animals killed at 2-, 4-, or 8-week intervals postinoculation (PI). In rabbits, although no histopathological changes were observed in the respiratory tract, CBM antigen was detected on the ciliated epithelium of the respiratory tract, and serum CBM antibody was also detected 4 and 8 weeks PI. In guinea pigs, no histopathological changes were noted, CBM antigen was detected in the respiratory tract 2 and 4 weeks PI but not 8 weeks PI, and serum CBM antibody was detected 4 and 8 weeks PI. In hamsters, mononuclear cell proliferation in the submucosa of the bronchus and trachea was observed 8 weeks PI. CBM antigen was detected at first in the nasal cavity 2 weeks PI and in the lower respiratory tract 4 and 8 weeks PI and serum CBM antibody was detected 4 and 8 weeks PI. In mice, histopathological changes, CBM antigen and CBM antibody were observed. CBM was reisolated from the tracheal washouts of hamsters and mice 8 weeks PI but not from those of rabbits and guinea pigs. These results confirm and extend previous reports of experimentally-induced CAR bacillus infection in mice, guinea pigs, and rabbits. To this list of susceptible laboratory animals, we now add hamsters.(ABSTRACT TRUNCATED AT 250 WORDS)     

Immunocontraceptive effects on female rabbits infected with recombinant myxoma virus expressing rabbit ZP2 or ZP3

Recombinant myxoma viruses expressing rabbit zona pellucida 2 (rZP2) or rabbit zona pellucida 3 (rZP3) glycoproteins were constructed and tested in domestic rabbits to assess their potential to induce autoimmune infertility. The recombinant virus expressing rZP2 had no effect on fertility or ovarian histology, despite all animals developing antibodies against the rZP2 antigen. However, recombinant viruses expressing rZP3 induced infertility in 70% of animals at the first breeding. Serum antibodies were relatively short-lived, but antibody was bound to zona pellucida of all rabbits from Day 10 onward. There was no obvious correlation between infertility and rZP3 antibody titer. There was a transient inflammatory response in the ovaries of rZP3-immunized rabbits at Day 15 but no T-cell response to rZP3 could be detected at any time. Dysfunctional follicular formation was present in ovaries from rabbits infected with rZP3-expressing viruses 15-40 days postinfection but this had disappeared at later time points. A recombinant myxoma virus expressing a modified rZP3 antigen with the C-terminal hydrophobic putative anchor sequence deleted was also tested. This virus did not induce either infertility or an antibody response against the zona pellucida. Thus, the context of antigen presentation was crucial for an autoimmune response.     

Effect of cutaneous and digestive colonization in the induction of anti -Candida albicans antibodies: Experimental study

Candida albicans colonization induces antibodies, which must be taken into account in the serological diagnosis of candidiasis. In order to determine the degree of this effect, an experimental study in rabbits free of specific anti -Candida antibodies by cutaneous and digestive inoculation has been carried out. The evolution of humoral response was studied over 8 weeks by indirect immunofluorescence (IIF), direct agglutination (DA), counterimmunoelectrophoresis (CIE) and double diffusion (DD).The cutaneous colonization detectable by culture was maintained until the second week in 70% of the animals and the presence of antibodies detectable by IIF and DA was observed after the 2nd week. The highest antibody titre by IFF and DA was 1/64, and was reached in the 5th week, with a tendency to drop in the following weeks. Precipitins were only detected by CIE in 15% of the animals in the 7th week.Elimination of yeast in stools continued only in 20% of the animals in the 2nd week of the experiment. Antibodies were detected by IIF and DA after the 2nd week, with the highest titres detectable by IFF in the 5th week. Precipitant antibodies detectable by CIE appeared in 15% of the animals in the 8th week.     

Modification of swine serum-induced bile duct lesion in BALB/c mice by cyclophosphamide

Effects of cyclophosphamide (CY) on the antibody titer level and incidence and severity of swine serum (SS)-induced bile duct lesion (BDL) were examined. BDL induced by 0.2 ml of SS per head twice a week for 2 weeks was characterized by hyperplasia of biliary epithelial cells, proliferation of mucous glands, and periductal infiltration of eosinophils with mild fibrosis. CY showed no significant influence on the above-mentioned parameters at the dose levels of 140 and 210 mg/kg. On the other hand, CY lowered the antibody titer level and decreased the severity of BDL at the dose level of 280 mg/kg, and it suppressed the antibody response and BDL at the dose level of 280 x 2 mg/kg. Thus the antibody titer level and the severity of BDL were closely related each other.     

Specificity of antigens from pathogenic Aspergillus species. I. Studies with ELISA and immunofluorescence

Studies were made by enzyme linked immunosorbent assay (ELISA) and indirect fluorescent antibody (IFA) tests on the reactivities and specificities of 13 antigens prepared from four species of Aspergillus against antisera from immunized rabbits and 64 sera from patients with aspergillosis, other systemic mycoses and nocardiosis. Although reactions in both serological tests were invariably strongest with homologous antigen: antibody systems, antisera from rabbits immunized with A. fumigatus, Blastomyces dermatitidis, Candida albicans and Paracoccidioides brasiliensis reacted in the ELISA test with all of the Aspergillus antigens. In contrast, cross-reactivity was virtually non-existent with antiserum to Histoplasma capsulatum. Of five antigens prepared from A fumigatus tested by ELISA against human sera from patients with aspergillosis and other nocardial and systemic fungal infections, sensitivities varied from 81 to 100% for sera from 32 patients with aspergillosis, and specificities from 20 to 97% for sera from 30 patients with nocardiosis and other systemic mycoses. Purified A. fumigatus C antigen reacted weakly with sera from eight of these 30 patients, but the reactions were readily distinguishable from those obtained with sera from patients with aspergillosis. At optimal serum dilutions, cross-reactivities of A. fumigatus in the IFA studies were non-existent in the sera from 28 patients with candidosis, coccidioidomycosis, cryptococcosis, histoplasmosis, paracoccidioidomycosis and nocardiosis. Sensitivities of IFA were 94% for patients with aspergilloma and 83% for patients with allergic bronchopulmonary aspergillosis.     

Fasciola hepatica: IgG and IgA levels in the serum and bile of infected cattle

Bile and serum samples were collected from calves with an implanted cannula throughout a 20-week period of infection with Fasciola hepatica. Using indirect fluorescent antibody labelling and plastic-embedded sections of juvenile and adult flukes as antigens, estimates were made of the relative concentrations of IgG and IgA specific for fluke tegumental and gut antigens in the samples of serum and bile. In serum, antibodies against juvenile (t1) tegument and gut antigens reached peak concentrations 4–6 weeks postinfection and declined slowly thereafter as flukes became established in the bile ducts. IgG against adult tegument (t2) antigens appeared in the serum 6 weeks after infection, but no IgA against t2 was detected. In the bile, both IgG and IgA titres against t1 and gut antigens rose to peak values at 4–6 weeks after infection, but there was no activity against t2 antigen. The Ig levels in bile were considerably lower than in serum. Much more IgA relative to IgG occurred in bile as compared to serum (IgG/IgA ratio in serum was 16–32, in bile 1–2) suggesting a role for IgA in defence at mucosal surfaces. Comparison of the antibody profiles in bile and serum suggested that IgG in the bile was derived from circulating IgG whereas IgA may have been preferentially concentrated in the bile.     

Immunodiagnosis of Candida-infections. I. Sensitivity of the antigens

Attemps were made to prepare a sensitive antigen from C. albicans suitable for detecting humoral antibodies and hypersensitivity in deep-seated candidiasis, in patients at risk of invasive candidiasis and in allergic states caused-by Candida.5343 persons suffering from systemic, bronchial, vaginal candidiasis, bronchial asthma, chronic bronchitis, polyarthritis nodosa, ulcus cruris, malignancy, rhinitis pollinosa, vasomotorica, and non infected miners, farmers and blood donors were investigated on the presence of antibodies and hypersensitivity against 8 different antigen preparations.The extracellular protein and mannan- protein isolated from the cultivation medium of C. albicans proved the most sensitive for specific anticandida antibodies. The mannan, especially the mannan isolated from the cell surface of C. albicans determined best for the allergy.Comparison made of commercial Candidine showed similar activity. The whole cell C. albicans antigen as well as the mixed Candida antigen reacted much weakly.Comparison made of autoantigen, C. albicans and mixed C. albicans antigen proved the highest sensitivity of the autoantigen.     

Production and characterization of antibody against aflatoxin Q1.

Antibodies against aflatoxin Q1 (AFQ1) were obtained from rabbits after immunization of either AFQ1-hemisuccinate or AFQ2a conjugated to bovine serum albumin. Both radioimmunoassay and enzyme-linked immunosorbent assaY (ELISA) were used for the determination of antibody titers and specificities. Antibodies obtained from rabbits after immunization with AFQ1-hemisuccinate-bovine serum albumin had the highest affinity to aflatoxin B1, whereas antibodies obtained from rabbits after immunization with AFQ2a-bovine serum albumin bound most effectively with AFQ2a. AFQ2a antibody was selected for the subsequent direct and indirect ELISA for the detection of AFQ1 in biological fluids. When AFQ2a-peroxidase and AFQ2a antibody were used, direct ELISA was able to detect as low as 2 ppb (ng/ml) of AFQ1 spiked in the urine samples that had been subjected to a Sep-Pak cleanup treatment. In indirect ELISA in which the antigen (AFQ2a-bovine serum albumin) was coated to the solid phase followed by reaction with rabbit antibody and goat anti-rabbit immunoglobulin G-peroxidase conjugate, 50-fold less antibody was used without sacrificing sensitivity. Recoveries of AFQ1 added to urine samples (2 to 40 ppb) were 46.3 to 73% and 65.8 to 85.8% for direct and indirect ELISA, respectively.     

Rapid enzyme-linked immunosorbent assay (ELISA) for detection of IgG antibodies to Candida albicans

A rapid enzyme-linked immunosorbent assay (ELISA) where the performance time was shortened to 4h was compared with counter-immunoelectrophoresis (CIE) and a standard ELISA procedure for the detection of IgG antibodies to Candida albicans in 61 patients with suspected invasive candidosis. Using a C. albicans cytoplasmic antigen the rapid ELISA compared well with CIE and the standard ELISA. Seventeen sera that reacted with two concentrations of C. albicans antigen in CIE were also positive in both forms of ELISA. Four sera that were CIE-negative were positive in the standard ELISA and three were also positive in the rapid ELISA. The rapid ELISA provides a sensitive and reproducible test for routine serological investigation of different forms of candidosis.     

Production and characterization of antibody against aflatoxin Q1

Antibodies against aflatoxin Q1 (AFQ1) were obtained from rabbits after immunization of either AFQ1-hemisuccinate or AFQ2a conjugated to bovine serum albumin. Both radioimmunoassay and enzyme-linked immunosorbent assaY (ELISA) were used for the determination of antibody titers and specificities. Antibodies obtained from rabbits after immunization with AFQ1-hemisuccinate-bovine serum albumin had the highest affinity to aflatoxin B1, whereas antibodies obtained from rabbits after immunization with AFQ2a-bovine serum albumin bound most effectively with AFQ2a. AFQ2a antibody was selected for the subsequent direct and indirect ELISA for the detection of AFQ1 in biological fluids. When AFQ2a-peroxidase and AFQ2a antibody were used, direct ELISA was able to detect as low as 2 ppb (ng/ml) of AFQ1 spiked in the urine samples that had been subjected to a Sep-Pak cleanup treatment. In indirect ELISA in which the antigen (AFQ2a-bovine serum albumin) was coated to the solid phase followed by reaction with rabbit antibody and goat anti-rabbit immunoglobulin G-peroxidase conjugate, 50-fold less antibody was used without sacrificing sensitivity. Recoveries of AFQ1 added to urine samples (2 to 40 ppb) were 46.3 to 73% and 65.8 to 85.8% for direct and indirect ELISA, respectively.     

Antigen-antibody complexes produced in chickens tolerant to bovine serum albumin.

A radioimmunoassay for circulating soluble antigen-antibody complexes is described. The assay detects complexes either in antigen or antibody excess. Soluble complexes were found in the sera of chickens tolerant to bovine serum albumin (BSA). The complexes appeared in the serum as soon as 7 days following neonatal induction of tolerance. The amount of complexes reached a peak between 1 to 2 weeks of age and disappeared by 6 weeks when responsiveness returned. The complexes were found in the bottom third of a 10 to 40% sucrose density gradient and by analytical ultracentrifugation indicated a size of 22.8S. If tolerant chickens were challenged with BSA at 2, 4 or 6 weeks, the disappearance of complexes was not accelerated, and a proportion of the previously tolerant chickens exhibited a heightened antibody response.     

Antigen detection in primary HIV infection

Serial blood samples were obtained from 21 homosexuals who had developed symptomatic primary infection with human immunodeficiency virus (HIV) after a median incubation time of 14 days. During the first two weeks after the onset of illness HIV antigen (p24) was detected in the blood by enzyme linked immunosorbent assay (ELISA). During the second and third weeks after the onset of illness p24 antibody was detected by Western blot assay and antigen concentrations rapidly decreased to undetectable values. Dissociation of antigen-antibody complexes showed complexed antigen during the phase of declining concentrations of free antigen. Neither free nor complexed antigen was detected in any serum samples for several months thereafter, which suggested that failure to detect HIV antigen reflected low or absent synthesis of viral protein rather than masking of antigen by antibodies. Reappearance of HIV antigen with a fall in p24 antibody concentration was observed in a few patients six months or more after the onset of disease.The combined use of antigen and antibody assays made it possible to obtain evidence of infection with HIV in all of the 95 serum samples tested, illustrating the usefulness of these assays for diagnosing infection with HIV in its early stages.     

Reversibility of the effects of chronic paternal exposure to cyclophosphamide on pregnancy outcome in rats

Low-dose chronic treatment of the male rat with the antitumor drug cyclophosphamide causes a time- and dose-dependent increase in pre- and post-implantation loss in the untreated females to which he is mated. The objective of the present study was to determine whether such effects are reversed, and if so at what time after cessation of drug treatment. Adult male Sprague-Dawley rats were gavage fed daily, 6 times per week for 9 weeks, with saline (control) or with 1 of 3 doses of cyclophosphamide, 1.4, 3.4 or 5.1 mg/kg/day. After the 9 weeks of treatment and at 2-week intervals thereafter, each male was mated with 2 females in proestrus. The females were caesarian sectioned 20 days later and pregnancy outcome assessed. After 9 weeks of drug treatment, pre-implantation loss increased more than 3-fold from 6% in the control group to 21% in the 5.1 mg/kg/day cyclophosphamide treatment group. Post-implantation loss increased in a dose dependent fashion from 5% in the control group to 74% in the 5.1 mg/kg/day cyclosphosphamide treatment group. Pre-implantation loss rapidly decreased upon cessation of treatment with cyclophosphamide: within 2 weeks it had returned to within the control range. Within just 2 weeks after termination of drug treatment in the 5.1 mg/kg/day cyclophosphamide treatment group, post-implantation loss decreased by half to 44%; it had decreased to 11% by 4 weeks and then was maintained at 4-6% thereafter. In the 3.4 mg/kg/day cyclophosphamide treatment group, post-implantation loss returned to the control range by 4 weeks. Thus, the effects of paternally administered cyclophosphamide on progeny outcome are reversible. The timing of reversal suggests that the effects on pre-implantation loss are due to a drug effect on spermatozoa either in the epididymis or near the time of spermiation while those on post-implantation loss are due to an additional effect on spermatids in the seminiferous tubules.     

Adoptive suppression of granuloma formation by T lymphocytes and by lymphoid cells sensitive to cyclophosphamide.

Egg-induced granulomas formed in mice with chronic Schistosoma mansoni infection are smaller than those which develop during early (8-week) infection. Adoptive transfer of spleen cells from chronically infected mice (15–25 week), which displayed modulated granulomas, to 6-week-infected recipients effectively suppressed active granuloma formation in the recipients by 8 weeks after infection. Pretreatment of these suppressive spleen cells with anti-Thy 1.2 serum and complement eliminated their suppressive capacity. Administration of cyclophosphamide (CY) (20 mg/kg, 3 times/week for 3 weeks) to 12- to 15-week-infected mice reversed modulation of granuloma formation resulting in larger granulomas at 15 weeks. This abrogation of suppression was reflected in the spleens of the CY-treated mice, as seen by the inability of their spleen cells to adoptively transfer suppression to 6-week-infected mice. This regimen of CY treatment did not significantly alter anti-schistosome egg antigen hemagglutinating antibody titers. It is reasoned that the modulation of granuloma formation observed during chronic schistosomiasis mansoni is in part dependent upon a T lymphocyte and a CY-sensitive spleen cell.     

Experimental infection of wild‐caught European rabbits (Oryctolagus cuniculus) with Sarcoptes scabiei from a naturally infected wild rabbit

Scabies was recently reported for the first time in the European wild rabbit, Oryctolagus cuniculus (Lagomorpha: Leporidae). We experimentally exposed 10 seronegative wild‐caught rabbits to skin from a mangy wild rabbit. Serological, physiological, parasitological and histopathological changes were recorded. Three rabbits developed antibodies at 2–5 weeks post‐infection (w.p.i.), two of which then developed lesions at 7 w.p.i. One of these had a small area of alopecia on the hind limb that healed naturally within 1 week; the other developed more extensive lesions restricted to the hind limbs (as typically observed in wild rabbits) that lasted until the rabbit died (12.5 w.p.i.). The third rabbit died of trauma 5 w.p.i. before developing any lesions. Antibodies in the healed rabbit disappeared from serum at 8 w.p.i., whereas antibody levels in the sick rabbit increased until its death. Disseminated intravascular coagulation and hepatic necrosis, probably arising from a concomitant infection with rabbit haemorrhagic disease virus, were the likely final cause of death in this rabbit. The mangy rabbit that served as a donor died of a multifocal fibrinosuppurative pneumonia that may have been secondary to the skin bacterial pyoderma.     

The use of lyophilized Schistosoma mansoni eggs as antigenic particles in a radioimmunoassay

Lyophilized eggs of Schistosoma mansoni, when incubated briefly with serum from infected mice, bind antibodies, as made evident by subsequent binding of fluorescein labelled anti-IgG or 125I-labelled Protein A. On the basis of these findings, a radioimmunoassay was devised which employs whole lyophilized eggs (500 or 250 eggs/serum sample) as antigenic particles and 125I-labelled Protein A as a probe for antibody binding. Only 10 microliters of serum are required to obtain 90% of the maximal binding. Kinetic studies indicated that 70% of the maximal seropositivity develops in mice between five and six weeks after a light infection, reaches a maximum at eight weeks and fluctuates around a high plateau thereafter. Pre-incubation of the test serum with soluble egg antigen (SEA) considerably inhibits antibody binding to the eggs, suggesting that SEA-like antigens participate in the reaction.     

Enzyme-linked immunosorbent assay of antigens from Candida albicans circulating in infected mice and rabbits: The role of mannan

Various antisera raised either to antigens ofCandida albicans or to sub-lethal infections of blastospores (convalescent sera) were tested for their efficacy in diagnosing systemic disease in artifically infected animals. Globulin from convalescent serum, when conjugated with alkaline phosphatase and used in enzyme-linked immunosorbent assays (ELISA), was the only antiserum type which detected circulatingCandida-related antigen in the serum of infected animals. Conjugates made from anti-mannan, anti-blastospore or antimycelial globulin did not detect antigen. Mannan did not appear to be related to an antigen produced in sera of experimentally infected mice. The significance of these results in the diagnosis of systemic candidosis is discussed.     

Ontogenetic development of antibody formation in response to different doses of gram-negative microorganisms in young rabbits

Rabbits at different stages of development were immunized with different doses of heatinactivated suspension ofEscherichia coli 086 andSalmonella paratyphi B. The dynamics and the site of formation of bactericidal and haemolytic antibodies during the primary reaction was investigated. An increase and an acceleration of antibody formation after increasing the dose of antigen was found in the serum and at the cellular level. The magnitude of the response and the rate of the reaction were directly proportional to the age of the experimental rabbits. The site of antibody formation depends on the character, route of administration, antigen dose and age of rabbits. After intraperitoneal and also after intravenous immunization withEscherichia coli andSalmonella paratyphi B antigens the site of antibody production in 15-day-old rabbits was the lymphatic tissue of the intestine, the appendix, and mesenteric lymph nodes. As the antigen dose was increased and the age of rabbits rose, i.e. in correlation with the increase of the antibody response, antibody formation shifted to the spleen which is the chief site of antibody production following immunization by these bacterial antigens from the first month of life of rabbits. In contrast with this type of antigen, after intraperitoneal or intravenous immunization with sheep erythrocytes of new-born or older rabbits antibody formation was concentrated in the spleen. The development of the immunological competence and the significance of intestinal lymphatic tissue as one of peripheral type is discussed.     

A dot-immunobinding assay for the serodiagnosis of Pasteurella multocida infection in laboratory rabbits

A dot-immunobinding assay was developed to detect serum IgG specific for lipopolysaccharide of rabbit isolates of P. multocida. The assay detected serum IgG as early as 1 week after experimental subclinical nasal infection, whereas 8 weeks were required to detect antibody by a gel diffusion precipitin test. The assay was more reliable than nasal cultures, in that up to 46% of 16 weekly nasal washings of some infected rabbits failed to yield P. multocida. The bacterial antigen (proteinase k digested cell lysate) used in the assay reacted with IgG that did not cross-react with lipopolysaccharide antigens of B. bronchiseptica, P. pneumotropica or P. hemolytica. The assay is sensitive and specific, easily performed, cost effective, requires no special laboratory instruments and provides a permanent easily stored record.