خيارات البحث
النتائج 1 - 7 من 7
Effect of levamisole on immune function and reproductive performance in first-litter gilts
1988
Purswell, B.J. | Dawe, D.L. | Brown, J. | Williams, D.J.
First-litter commerical cross-bred gilts were treated with levamisole (1.5, 2.5, or 3.5 mg/kg of body weight) weekly during the last 4 weeks of gestation, because similar treatment of dairy heifers had improved postpartum maternal health and neonatal survival. In the gilts, differences in reproductive performance were not found on the basis of pig survival at birth, pig survival at weaning, birth weight, or weaning weight. Also differences between treated and control gilts were not found in response of circulating lymphocytes to mitogen stimulation (phytohemagglutinin A, concanavalin A, and pokeweed mitogen). In all gilts, the lymphocyte response to mitogen stimulation was decreased during the first week after farrowing.
اظهر المزيد [+] اقل [-]Identification of viral antigens that induce antibody responses on exposure to coronaviruses
1988
Ingersoll, J.D. | Wylie, D.E.
Various techniques were used to look for protective, non-cross-reactive antibodies in the sera of cats exposed to virulent feline infectious peritonitis virus (FIPV). Antibodies reactive with feline enteric coronavirus (FECV) from FIPV-exposed cats were adsorbed by several passages over an FECV-Sepharose column. In an ELISA against FECV and FIPV, the activity against both viruses was removed at the same rate; thus, no FIPV-specific antibodies could be identified. By gel electrophoresis-derived ELISA, the responses of cats surviving FIPV exposure were compared with those of cats succumbing to FIPV exposure to determine whether survival could be correlated with an antibody response against a particular virus protein. Results indicated that both groups responded in the same way to the matrix envelope protein and nucleocapsid proteins. Even though the response to peplomer in each group was weak, the survivor group responded better to this protein. Furthermore, the response of this group to the peplomer protein had the highest correlation with virus neutralization titer.
اظهر المزيد [+] اقل [-]Differential effect of T-2 toxin on murine host resistance to three facultative intracellular bacterial pathogens: Listeria monocytogenes, Salmonella typhimurium and Mycobacterium bovis
1988
Ziprin, R.L. | McMurray, D.N.
The effect of T-2 toxin, a radiomimetic immunosuppressive agent, on resistance to the facultative intracellular bacterial pathogens Listeria monocytogenes (strain EGD), Mycobacterium bovis (BCG Copenhagen 1331), and Salmonella typhimurium was determined. Female Swiss ICR mice were given a single dose of T-2 toxin (4 mg/kg of body weight) by gastric gavage. On the seventh day after toxin administration, the mice were infected by intraperitoneal inoculation with L monocytogenes, S typhimurium, or M bovis. Mice given the toxin also were exposed to respirable droplet nuclei containing L monocytogenes or M bovis. The effect of the toxin on the course of infection was monitored by observing mortality or by enumeration of bacteria in te spleen or lungs of infected mice. The toxin increased resistance to infection with L monocytogenes initiated by intraperitoneal inoculation, but reduced resistance to M bovis infection initiated by intraperitoneal inoculation. The toxin had no appreciable effect on the course of salmonellosis or on resistance to infection initiated by inhalation of L monocytogenes or M bovis aerosols. Therefore, it was concluded that T-2 toxin does not necessarily reduce resistance to infection in mice. The toxin's effect on the course of in vivo bacterial infections depends on the nature of the infective agent and the route of inoculation.
اظهر المزيد [+] اقل [-]Evaluation of relationship among three purified antigens from Pasteurella multocida strain P-1059 and of their protective capacities in turkeys
1988
Tsuji, M. | Matsumoto, M.
Three antigens were prepared from Pasteurella multocida strain P-1059, and their immunogenicity and antigenic relationships were investigated. The 3 antigens were a soluble antigen purified from a 2.5% NaCl extract (2.5S), a similar antigen purified from an extract in 0.3% formalin solution containing 0.85% NaCl (FS), and lipopolysaccharide (LPS). The antigens were treated with various chemicals and enzymes to study their antigenic and immunogenic determinants. Antigenic analyses with ELISA inhibition tests indicated that 2.5S and FS were similar LPS-protein complex antigens. The 2.5S and FS antigens induced protective immunity in turkeys with high antibody titers against LPS antigen. Although LPS was a component of 2.5S and FS,LPS itself was poorly immunogenic in turkeys. The antigenicity of protein compounds in 2.5S was deteriorated by protease treatment, which, however, did not significantly diminish the protective immunogenicity. Treatment of 2.5S with sodium periodate, altering its carbohydrate moieties, decreased its immunogenicity. The immunogenicity of 2.5S also was abolished by phenol-water treatment, owing to dissociation of the LPS-protein complex. These findings suggest that a certain form of LPS-protein complex is essential for the induction of immunity against the P multocida infection in turkeys.
اظهر المزيد [+] اقل [-]Studies on the ability of a 98-kilodalton pseudorabies virus diagnostic antigen to detect latent infections induced by low-dose exposure to the virus
1988
Ginley, M.J. | Platt, K.B.
The effect of low-dose challenge of immunity with pseudorabies virus (PRV) on subunit-vaccinated pigs was studied in 2 experiments. In the first experiment, we studied the effect of challenge dose on the antibody response to an early excreted 98-kilodalton PRV-glycoprotein that was used as a diagnostic antigen in the ELISA. In the second experiment, we studied the effect of low doses of virus on the establishment of latent infections in subunit-vaccinated pigs. The relationship of virus exposure dose and vaccine dose to the response of pigs to diagnostic antigen was studied in 18 pigs. Two groups of 3 pigs were vaccinated with a total of 200 micrograms of a lectin-derived PRV subunit vaccine over a 5-week period. Two groups of 3pigs were similarly vaccinated with a total of 100 micrograms. Two groups of 3 pigs served as nonvaccinated controls. One group of pigs from each of the preceding categories was intranasally exposed to 10(6.0) and 10(2.7) plaque-forming units (PFU) of virus. Antibody to diagnostic antigen was detected by the ELISA and radioimmunoprecipitation 3 to 7 days earlier in pigs exposed to 10(6.0) PFU, demonstrating that the size of the virus challenge dose affects the antibody response to diagnostic antigen. The establishment of latent infections by low PRV doses and the ability to detect these infections was studied in 10 subunit-vaccinated pigs. Each pig was intranasally exposed to 10(2.3) PFU of virus (day 0). The serum virus-neutralizing antib ody titer of these pigs increased to their highest level 14 to 21 days after exposure and then steadily decreased through day 113, indicating absence of viral recrudescence. All pigs were treated with dexamethasone for 4 consecutive days, beginning on day 113. Latent infections were identified in 8 of 10 pigs on the basis of recovery of virus and/or 2 log2 or greater increases in serum virus-neutralizing titer. Antibody to diagnostic antigen was initially detected in the 8 latently infected pigs on day 14 or 21 and continued to be detected through days 21, 46, 53, 110, and 113 in 1, 2, 1, 1, and 3 pigs, respectively. The antibody titer to diagnostic antigen increased in 6 of the 8 latently infected pigs after dexamethasone treatment. However, antibody to diagnostic antigen was not detected by ELISA in the remaining 2 latently infected pigs, despite increases in serum virus-neutralizing titers in both pigs and the recovery of reactivated virus from one pig. The failure to consistently detect antibody to diagnostic antigen in latently infected pigs suggests that diagnostic tests using nonvaccine diagnostic antigen may be suitable only for detecting infections in vaccinated herds, but not in individual pigs.
اظهر المزيد [+] اقل [-]Cellular defense of the avian respiratory system: effects of Pasteurella multocida on respiratory burst activity of avian respiratory tract phagocytes
1988
Ochs, D.L. | Toth, T.E. | Pyle, R.H. | Siegel, P.B.
The respiratory tract of healthy chickens contain few free-residing phagocytic cells. Intratracheal inoculation with Pasteurella multocida stimulated a significant (P < 0.05) migration of cells to the lungs and air sacs of White Rock chickens within 2 hours after inoculation. We found the maximal number of avian respiratory tract phagocytes (22.9 +/- 14.0 x 10(6)) at 8 hours after inoculation. Flow cytometric analysis of these cells revealed 2 populations on the basis of cell-size and cellular granularity. One of these was similar in size and granularity to those of blood heterophils. Only this population was capable of generating oxidative metabolites in response to phorbol myristate acetate. The ability of the heterophils to produce hydrogen peroxide, measured as the oxidation of intracellularly loaded 2', 7'-dichlorofluorescein, decreased with time after inoculation. These results suggest that the migration of heterophils, which are capable of high levels of oxidative metabolism, to the lungs and air sacs may be an important defense mechanism of poultry against bacterial infections of the respiratory tract.
اظهر المزيد [+] اقل [-]Effects of an orally administered live Escherichia coli pilus vaccine on duration of lacteal immunity to enterotoxigenic Escherichia coli in swine
1988
Moon, H.W. | Rogers, D.G. | Rose, R.
Primigravid swine were vaccinated orally with a live enterotoxigenic Escherichia coli (ETEC) strain that produces pilus antigen K99. The titers of K99 antibody in colostrum and milk of vaccinates remained higher than those of nonvaccinated controls through the first lactation after vaccination (4 weeks). Some control swine had low titers of K99 antibody in colostrum or developed low titers of K99 antibody in milk during lactation. Lacteal K99 antibody titers of vaccinates dropped to control levels during the second lactation, 6 months after vaccination. Pigs suckling vaccinates and controls were equally susceptible to challenge exposure to K99+ ETEC during the second lactation. Orally vaccinated swine given a parenteral booster vaccination (with killed K99+ ETEC) during their second gestation had K99 antibody in milk through their second lactation. During the second lactation, these orally vaccinated parenterally revaccinated swine had higher titers of K99 antibody in postcolostral milk than did nonvaccinated controls, controls given only the parenteral booster injection, or controls vaccinated parenterally during both gestations.
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