The preparation of a polyvalent feline calicivirus antiserum.

A polyvalent antiserum capable of neutralizing 82 isolates of feline calicivirus made from cats in various parts of North America was produced by the sequential inoculation of SPF cats at three-week intervals with feline calicivirus strains F-9, 68-2024 and FS, followed by a final booster inoculation two weeks after the third inoculation with all three strains combined. Sera raised against the same strains but individually and then pooled failed to show such broad cross-neutralizing capacity. The polyvalent serum should prove useful for the confirmation of an isolation of feline calicivirus.     

Identification and characterization of rat intestinal lamina propria cells: consequences of microbial colonization.

Germ-free (GF) animals exhibit an abnormally diminished, cell-mediated immune response which can be rapidly normalized by bacterial colonization of the intestine. This conventionalization suggests that the development and/or regulation of the immune system is dependent upon intestinal bacteria or their products. Here we consider the ontogeny of gut-associated lymphoid tissue (GALT) immunocytes by isolating and characterizing the intestinal lamina propria cells (LPC) of GF rats responding to bacterial colonization or an irrelevant protein antigen, and compared to LPC of specific pathogen-free (SPF) rats which were conventionalized (CV) from birth. Isolation of cells was accomplished by successive EDTA washings of small intestine to remove the epithelium, and enzymatic digestion of the tissue generating single-cell suspensions. Resulting cell suspensions were characterized by monoclonal antibodies directed against leukocyte epitopes using flow cytometry. Functional characterization was measured by the tritiated thymidine proliferation assay with concanavalin A (Con A) and lipopolysaccharide (LPS) as co-stimulators. Germ-free and SPF rats had fewer total LPC than CV rats. Antibody staining revealed that GF rats had fewer total leukocytes than CV and SPF rats, and that CV rats had a greater percentage of T-cells and cells positive for the C3 receptor than GF rats. Co-stimulation of LPC with mitogens only increased proliferation of cells from CV rats compared to GF and SPF rats. In addition, spleen cells from CV rats demonstrated significantly enhanced proliferative responses compared to spleen cells from GF rat and were more analogous to spleen cells from SPF rats in their ability to proliferate in vitro, with and without mitogens. We conclude that T-cells and CD35-positive (C3BR+) cells are recruited and/or proliferate in response to intestinal bacteria and/or their products, and that this results in the induction of immune competency.     

Evaluation of protection against colonization of the chicken trachea following administration of Mycoplasma gallisepticum bacterin

Twelve-week-old commercial white leghorn pullets were given one or two doses of an inactivated oil-emulsion Mycoplasma gallisepticum (MG) vaccine or kept as unvaccinated controls. At 24 weeks of age, all groups were challenged intratracheally with one of six dilutions of a low-passage R strain of MG. Three days postchallenge, the tracheas from all chickens were cultured for MG to determine the number of challenge organisms required to initiate infection. The log10 ID50 of chickens vaccinated 0, one, or two times was 2.9, 3.4, and 3.7, respectively, and the minimum infectious dose (the lowest challenge dose to infect a single bird) was 15, 150, and 1500 colony-forming units, respectively. It was concluded that the vaccine provided measurable, though limited, protection against infection under these experimental conditions.     

Partial colonic obstruction following ovariohysterectomy: a report of three cases

Partial extramural obstruction of the descending colon was diagnosed in two dogs and a cat as a complication of elective ovariohysterectomy. In each case, the obstruction was caused by fibrous tissue that encircled or crossed the descending colon, severely restricting the organ's normal mobility and luminal diameter. Clinical signs secondary to obstipation were observed in two cases, five weeks and 27 months after elective ovariohysterectomy. In one dog without clinical signs, the adhesion was an incidental finding during a laparotomy performed nine years after the ovariohysterectomy. The fibrous adhesions were removed surgically in all three cases without additional complications.     

Alteration in testicular cyclic AMP system in the rat following vasectomy.

Endogenous cyclic AMP levels and the activities of adenylate cyclase, cyclic AMP-dependent and independent protein kinases were examined in testes of mature rats bilaterally vasectomized for one, three and seven months. Although no significant alteration in testicular cyclic AMP was detected one month following vasectomy, marked decreases (by 55% and 32%, respectively) were seen three and seven months postvasectomy. Likewise, vasectomy also resulted in a significant decrease (by 25%) in the activity of testicular adenylate cyclase three and seven months after vasectomy. Although soluble cyclic AMP-dependent protein kinase activity remained unaffected three months postvasectomy, the activity of the cyclic nucleotide-dependent enzyme was significantly increased (by 21%) when compared to the sham-operated controls. Furthermore, while the protein kinase ratio (--cyclic AMP/+cyclic AMP) was decreased in animals vasectomized for three months, the ability of the enzyme to bind (3H) cyclic AMP in vitro was significantly enhanced (18%). Rats vasectomized for seven months showed similar biochemical alterations but the effects of this procedure were more pronounced. Moreover, while short-term vasectomy increased the responsiveness of seminiferous tubular adenylate cyclase to in vitro stimulation by follicle stimulating hormone, the activity of the enzyme was also increased (by 100%) in the presence of luteinizing hormone in vasectomized rats. These data raise the possibility that changes in testicular function seen following vasectomy may be related to the alterations in cyclic AMP metabolism as well as in the sensitivity of testicular adenylate cyclase to regulation by gonadotropins.     

Mycoplasmas: use of polyvalent antisera for identification by indirect immunofluorescence.

It would be an advantage, under many circumstances, to be able to make use of polyvalent antisera in the process of identifying mycoplasmas. As the indirect immunofluorescence test is sufficiently sensitive and also generally accepted as being rather specific, this technique was chosen to investigate whether polyvalent antisera are applicable in routine identification of mycoplasmas. Three polyvalent sera were used, each consisting of 9 or 10 rabbit antisera raised against 29 of the more common species of the genus Mycoplasma. Twenty-six field strains were examined. One strain did not react with any of the 3 polyvalent antisera although it was later identified as M. bovigenitalium. The remaining 25 strains reacted with 1 and only 1 of the polyvalent antisera and were subsequently identified by immunofluorescence utilizing monospecific antisera. Strains of the following species were identified: M. arginini, M. bovigenitalium, M. bovis, M. bovoculi, M. canis, M. capricolum, M. cynos, M. edwardii, M. hominis, M. hyorhinis, M. molare, M. mycoides subsp. mycoides and M. opalescens. It is concluded that polyvalent antisera may be used in identification procedures and thereby permit the use of a limited number of monospecific antisera without preceding biochemical testing.     

Adhesion of bacteria to the cecal mucosal surface of conventional and germ-free chickens infected with Eimeria tenella.

When Salmonella typhimurium and Clostridium perfringens were tested in conventional chickens, larger numbers of S typhimurium and C perfringens adhered to Eimeria tenella-infected ceca than to uninfected ceca. In germ-free chickens, S typhimurium and C perfringens adhered to the E tenella-infected cecal mucosa more than to the uninfected cecal mucosa, but fewer Bacteroides vulgatus and Bifidobacterium thermophilum adhered to the E tenella-infected ceca than to the uninfected ceca. Many bacteria adhered to the lesions caused by E tenella as observed by scanning electron microscopy. On the basis of our findings, we suggest that infection with E tenella upsets the balance of competitive adherence of bacteria, allowing more colonization of S typhimurium and C perfringens.     

Studies on the pathogenesis of swine dysentery. I. Characterization of the lesions in colons and colonic segments inoculated with pure cultures or colonic content containing Treponema hyodysenteriae.

Swine dysentery was induced in pigs and in ligated colonic segments by inoculation of pure cultures of, or colonic contents containing, Treponema hyodysenteriae. The mildest changes, best seen in ligated segments 48 or 72 hours after inoculation, were congestion and leucocytic margination in mucosal capillaries and depletion of mucigen from goblet cells lining the base of the crypts of Lieberkühn. Superficial mucosal necrosis and crypt cell hyperplasia were later changes. Perfusion studies with India ink did not demonstrate occlusive mucosal ischemia in acute swine dysentery. Mucosa with lesions of swine dysentery contained at least 10(5) colony forming units of T. hyodysenteriae per gram. Mucosa without lesions had 10(5) or fewer T. hyodysenteriae per gram. Segments with acute swine dysentery were distended with clear mucoid fluid with electrolyte composition indicative of net colonic secretion. No increase in the concentration of volatile fatty acids was detected in content from intact colons or colonic segments with lesions of acute swine dysentery.     

Staphylococcosis of turkeys. 1. Portal of entry and tissue colonization

Staphylococcus aureus and various coagulase-negative staphylococci were isolated from turkeys with staphylococcosis. Virulent S. aureus adhered well (averaged more than 100 bacteria per tissue cell) in vitro to cells from tissues of the respiratory tract but did not adhere well (averaged fewer than 12 bacteria per tissue cell) to cells from tissues of the alimentary tract. Some avirulent coagulase-negative staphylococci also adhered well to cells from the respiratory tissues. Lungs and livers of turkeys became colonized with virulent S. aureus following experimental aerosol exposure. Tracheas, livers, and hock joints of some market-age turkeys were naturally colonized with S. aureus and various species of coagulase-negative staphylococci.     

酸化剂在养鸡业中的应用及前景

预防疾病发生的一条重要措施就是确保饲料干净,尽可能不被病原菌污染。有机酸对大肠杆菌、沙门氏菌等有害微生物抑制作用效果良好,在饲料中添加有机酸,能够抑制饲料中大量有害微生物的生长,从而维持家禽消化道中微生物菌群的正常平衡,使得家禽的生产性能得到最大程度地提高。作为有机酸、无机酸制成的无毒无副作用的酸化剂,近年来国内外对其进行广泛性研究、制作,并作为添加剂应用来保护鸡群的胃肠健康,取得了良好的效果。1酸化剂的作用机理酸化剂的作用机理为:具有抑杀胃肠道有害细菌,促进有益菌生长、繁殖,降低病理性腹泻的发生率,降低胃…     

Immunization of chickens and turkeys against avian influenza with monovalent and polyvalent oil emulsion vaccines.

Chickens and turkeys vaccinated with inactivated virus oil-emulsion vaccines containing different concentrations of either 1 (monovalent) or 4 (polyvalent) strains of avian influenza virus (AIV) were challenged-exposed with virulent AIV A/chicken/Scotland/59 or A/turkey/Ontario/7732/66. Four of 6 vaccines protected completely against postexposure mortality. Vaccine valency did not alter the serologic and challenge-exposure responses of chickens vaccinated with AIV A/turkey/Wisconsin/68, which was the virus component common to both monovalent and polyvalent vaccines. The magnitude of the serologic responses and protection against challenge-exposure were dependent on the concentration of virus in the vaccines. These data indicate that control of virulent AIV in chickens and turkeys by vaccination with inactivated vaccines may be feasible.     

Expression of mucins on the mucosal surface of lungs of 4-week-old pigs

The aim of this study was to determine the immunoreactivity of normal small bronchial, bronchiolar, respiratory bronchiolar, and interalveolar epithelium using antibodies to six mucins: MUC1, MUC2, MUC4, MUC5AC, MUC5B, and MUC6. The large, gel-forming secreted mucins MUC2, MUC5AC, and MUC5B were widely expressed in the lower respiratory tract. The results of this study demonstrate that these secreted mucins form a gel to cover and protect the mucosal surface in the lower respiratory tract of pigs.     

Coronavirus infections in the laboratory rat: degree of cross protection following immunization with a heterologous strain.

One hundred and twenty-one specific pathogen-free male Wistar rats eight to ten weeks of age were used to evaluate the efficacy of Parker's rat coronavirus (PRC) in affording cross protection on subsequent challenge with virulent sialodacryoadenitis (SDA) virus. Sixty-two animals were inoculated intranasally on day 0 and 21 days later with approximately 10(2) median tissue culture infective doses (TCID50) of the tenth passage of PRC replicated in L-2 cells. Animals were selected at random postvaccination to evaluate the safety and efficacy of PRC by histopathology, immunohistochemistry and serology. At three and six months postvaccination (PV), vaccinated and seronegative control rats were inoculated intranasally with approximately 10(3) TCID50 doses of virulent SDA virus. Challenged rats were then killed at 6, 10 and 14 days postchallenge and necropsied. Evaluations were based on lesion indices in lacrimal and salivary glands and respiratory tract, the presence of viral antigen by immunohistochemistry, and antibody response. Lesions were observed in rats killed PV, but in general, they were significantly reduced compared with those present in seronegative animals post-exposure to virulent SDA virus (p < or = 0.05). However, they were still considered to be an unacceptable level for a routine vaccination procedure. Potvaccination antibody titers to rat coronavirus were evident in all animals tested at three or six months prior to challenge with SDA virus.(ABSTRACT TRUNCATED AT 250 WORDS)     

Influencing the immune parameters in germ-free piglets by administration of seal oil with increased content of omega-3 PUFA.

Oral administration of oil with an increased content of omega-3 polyunsaturated fatty acids to germ-free piglets resulted in a significant increase in the total values of CD4, CD8 lymphocytes, B lymphocytes, and monocytes, in peripheral blood in comparison with the controls. The metabolic activities of phagocytes as well as the polyclonal activation of lymphocytes were not significantly influenced. The level of growth factor was significantly higher, as determined on the basis of somatomedin in the blood serum. Biochemical indices showed a significant increase in the level of eicosapentaenoic and docosahexaenoic acids in blood serum and the decrease in the level of arachidonic acid at the same time.