Histopathology of transmissible gastroenteritis in experimentally infected newborn piglets. II. Lesions in organs other than digestive tract and pathologic feature of TGE.
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Animals↗
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Results for “Transmissible gastroenteritis”
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Transmissible gastroenteritis of swine as a model for the study of enteric disease.
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Animals↗
The effect of cytopathogenic transmissible gastroenteritis-like viruses and-or Escherichia coli on germfree pigs.
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Animals↗
Epizootiologic features of transmissible swine gastroenteritis.
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Age Factors↗
[Identification of transmissible porcine gastroenteritis in Germany. I. Clinical studies].
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Animals↗
[Combined vaccine protecting from transmissible swine gastroenteritis].
An effective system for specific prevention of transmissive swine gastroenteritis (TSG) is based on the use of combined vaccine and combined vaccination. Combined vaccine is a lyophilized preparation for intranasal application and emulsion for intramuscular injection. The former is prepared from natural attenuated respiratory variant of TSG virus and the latter from artificially attenuated TSG virus. Combined vaccination consists in parallel double immunization of females on days 70-75 of gestation intramuscularly and intranasally and on days 90-95 of gestation intramuscularly. Vaccinal lactogenic immunity ensures protection of newborn piglets under experimental and field conditions (protection of 70-80 and 90-95% piglets, respectively). The proposed vaccine preparations and protocols of combined immunization of females during gestation by two methods are an effective and safe method for specific prevention of TSG.
Administration, Intranasal↗
Nucleotide sequence of the E2-peplomer protein gene and partial nucleotide sequence of the upstream polymerase gene of transmissible gas gastroenteritis virus (Miller strain).
The E2-peplomer protein gene of the virulent Miller strain of transmissible gastroenteritis virus (TGEV) was sequenced from cDNA clones and compared to the E2 gene sequence of the avirulent Purdue strain. Sequence comparisons indicate that most amino acid differences occur in the N-terminal half of the E2-peplomer which represents the most exposed region of the protein. In addition, analysis of an incompletely sequenced open reading frame (ORF) to the immediate 5' side of the E2 gene indicates extensive sequence homology with the infectious bronchitis virus (IBV) F2 gene which is thought to encode a RNA polymerase.
Amino Acid Sequence↗
Activation of natural killer cells in newborn piglets by interferon induction.
Natural killer (NK) cell activity in the peripheral blood lymphocytes (PBL) of newborn piglets, normally negligible, was stimulated by in vitro treatment with porcine type I interferon (IFN), and the NK activity of PBL from weaned piglets was augmented by the same treatment. Binding of the PBL to the PK-15 targets used in the single cell cytotoxicity assay for NK activity was not affected by age or by IFN treatment. When newborn piglets were treated with a single intravenous dose at 2 days of age of 0.5 mg/kg of polyinosinic:polycytidylic acid complexed with poly-L-lysine and carboxymethylcellulose (poly ICLC), a synthetic IFN inducer, their IFN levels peaked at 6 h post-induction, and NK activity in their PBL peaked at 24 h post-induction at the level normally found in weaned piglets. The NK activity then declined until 7 days post-induction, when it increased again in a similar manner to that in untreated control piglets. Target-binding of the PBL was not affected by poly ICLC treatment of the piglets. Newborn piglets treated with poly ICLC and subsequently exposed to infection with transmissible gastroenteritis (TGE) virus showed a delay in onset of clinical signs of TGE compared with untreated control piglets. It was concluded that NK cells in newborn piglets can be activated by treatment of the piglets with poly ICLC, and that the presence of active NK cells is associated with some increase in resistance to challenge with TGE virus.
Animals↗
Intragastric administration of Lactobacillus casei expressing transmissible gastroentritis coronavirus spike glycoprotein induced specific antibody production.
Lactobacillus casei strain Shirota was selected as a bacterial carrier for the development of live mucosal vaccines against coronavirus. A 75 kDa fragment of transmissible gastroenteritis coronavirus (TGEV) spike glycoprotein S was used as the model coronavirus antigen. The S glycoprotein was cloned into a Lactobacillus/E. coli shuttle vector (pLP500) where expression and secretion of the glycoprotein S from the recombinant lactobacilli was detected via immunoblotting. Oral immunization of BALB/c mice with recombinant LcS that constitutively expresses the 75 kDa fragment of the glycoprotein S, induced both local mucosal and systemic immune responses against TGEV. Maximum titers of IgG (8.38+/-0.19 ng/ml of serum) and IgA (64.82+/-2.9 ng/ml of intestinal water) were attained 32 days post oral inturbation. The induced antibodies demonstrated neutralizing effects on TGEV infection.
Administration, Oral↗
Comparison of a fimbrial versus an autotransporter display system for viral epitopes on an attenuated Salmonella vaccine vector.
Attenuated Salmonella have been used as vectors to deliver foreign antigens as live vaccines. We have previously developed an efficient surface-display system by genetically engineering 987P fimbriae to present transmissible gastroenteritis virus (TGEV) C and A epitopes for the induction of anti-TGEV antibodies with a Salmonella vaccine vector. Here, this system was compared with an autotransporter protein surface display system. The TGEV C and A epitopes were fused to the passenger domain of the MisL autotransporter of Salmonella. Expression of both the MisL- and 987P subunit FasA-fusions to the TGEV epitopes were under the control of in vivo-induced promoters. Expression of the TGEV epitopes from the Salmonella typhimurium CS4552 (crp cya asd pgtE) vaccine strain was greater when the epitopes were fused to MisL than when they were fused to the 987P FasA subunit. However, when BALB/c mice were orally immunized with the Salmonella vector expressing the TGEV epitopes from either one of the fusion constructs or both together, the highest level of anti-TGEV antibody was obtained with the 987P-TGEV immunogen-displaying vector. This result suggested that better immune responses towards specific epitopes could be obtained by using a polymeric display system such as fimbriae.
Animals↗
Mucosal immunity: an overview and studies of enteric and respiratory coronavirus infections in a swine model of enteric disease.
Based on the tenet of a common mucosal immune system, antigenic stimulation at one mucosal site results in the distribution of antigen-specific IgA precursor cells to distant mucosal sites. However, recent studies suggest that functional compartmentalization and limited reciprocity may exist within some components of the common mucosal immune system. Although oral immunization is often very effective in inducing immunity to respiratory pathogens, the converse (respiratory immunization to prevent enteric diseases) may not be as effective. To address this question and to study interactions between the bronchus-associated (BALT) and gut-associated (GALT) lymphoid tissues related to protective immunity, we used as a model two antigenically related porcine coronaviruses which replicate primarily in the intestine (transmissible gastroenteritis virus, TGEV) or respiratory tract (porcine respiratory coronavirus, PRCV). The tissue distribution and magnitude of the antibody secreting cell (ASC) responses (measured by ELISPOT) and cell-mediated immune responses (measured by lymphoproliferative assays, LPA) coincided with the viral tissue tropisms. Immunization via GALT (gut infection with TGEV) elicited high numbers of IgA ASC and high LPA responses in GALT (gut lamina propria, LP or mesenteric lymph nodes, MLN), but lower responses in BALT (bronchial lymph nodes, BLN) and induced complete protection against enteric TGEV challenge. In contrast immunization via BALT (respiratory infection with PRCV) elicited systemic type responses (high numbers of IgG ASC in the BLN), but few ASC and low LPA responses in the gut LP or MLN and induced only partial protection against enteric TGEV challenge. Thus administration of vaccines intranasally may not be optimally effective for inducing intestinal immunity in contrast to the reported efficacy of oral vaccines for inducing respiratory immunity.
Administration, Intranasal↗
Delivery of subunit vaccines in maize seed.
The use of recombinant gene technologies by the vaccine industry has revolutionized the way antigens are generated, and has provided safer, more effective means of protecting animals and humans against bacterial and viral pathogens. Viral and bacterial antigens for recombinant subunit vaccines have been produced in a variety of organisms. Transgenic plants are now recognized as legitimate sources for these proteins, especially in the developing area of oral vaccines, because antigens have been shown to be correctly processed in plants into forms that elicit immune responses when fed to animals or humans. Antigens expressed in maize (Zea mays) are particularly attractive since they can be deposited in the natural storage vessel, the corn seed, and can be conveniently delivered to any organism that consumes grain. We have previously demonstrated high level expression of the B-subunit of Escherichia coli heat-labile enterotoxin and the spike protein of swine transmissible gastroenteritis in corn, and have demonstrated that these antigens delivered in the seed elicit protective immune responses. Here we provide additional data to support the potency, efficacy, and stability of recombinant subunit vaccines delivered in maize seed.
Administration, Oral↗
Commercialization of plant-based vaccines from research and development to manufacturing.
The benefits of using plant-based oral vaccines are discussed. Transgenic maize expressing an antigen of transmissible gastroenteritis virus (TGEV) is reported as a model to demonstrate efficacy. Young pigs that were fed the TGEV corn orally were protected against challenge with virulent TGEV. Additional parameters important in providing a reliable and consistent supply of plant-based vaccines are discussed. Finally, vaccines developed in maize are evaluated for their potential to contaminate either the food supply or the environment.
Animals↗
A sero-epizootiological study of porcine respiratory coronavirus in Belgian swine.
A porcine respiratory coronavirus (PRCV), antigenically closely related to transmissible gastroenteritis virus (TGEV), appeared in the European swine population in 1984. The present serological study was performed to obtain insight into the epizootiology of PRCV and of TGEV. PRCV-induced neutralizing antibodies were found in 90.6 per cent of the 160 sera collected from sows at slaughter, demonstrating the enzootic appearance of PRCV in the Belgian swine population. A serological study of fattening swine on 33 farms revealed that 11 farms situated in an area with a high farm density (all farms within 4 km2) and 11 on 22 closed breeding-fattening farms situated in areas with a low farm density (only one to four farms per 12 km2) were infected with PRCV throughout the year, whereas the other 11 closed breeding-fattening farms were temporarily free of PRCV. PRCV disappeared from the farms mainly in spring and summer. All the 11 farms became reinfected in autumn or winter, indicating that PRCV is regularly reintroduced in farms in the colder seasons. There was no correlation between the herd size and the temporary disappearance of PRCV from farms. It was observed on some farms that PRCV could infect pigs shortly after weaning in the presence of declining maternal antibodies, indicating that PRCV can persist on a farm by regularly infecting newly weaned pigs. TGEV-specific antibodies were found in 7.6 per cent of the 160 sera from the slaughterhouse sows. TGEV-specific antibodies were also detected in sera from fattening swine of 5 of the above mentioned 33 farms. TGEV-outbreaks were not observed on these farms.(ABSTRACT TRUNCATED AT 250 WORDS)
Animals↗
Construction, characterization, and immunogenicity of an attenuated Salmonella enterica serovar typhimurium pgtE vaccine expressing fimbriae with integrated viral epitopes from the spiC promoter.
Transmissible gastroenteritis virus (TGEV) is a porcine coronavirus that causes diarrhea, leading to near 100% mortality in neonatal piglets with corresponding devastating economic consequences. For the protection of neonatal and older animals, oral live vaccines present the attractive property of inducing desired mucosal immune responses, including colostral antibodies in sows--an effective means to passively protect suckling piglets. Newly attenuated Salmonella vaccine constructs expressing TGEV S protein epitopes were studied and evaluated for improved humoral immune response to TGEV. The macrophage-inducible Salmonella ssaH and spiC/ssaB promoters were compared for their ability to express the TGEV C and A epitopes in the context of the heterologous 987P fimbriae on Salmonella vaccines. Compared to the ssaH promoter, the Salmonella cya crp vector elicited significantly higher levels of mucosal and systemic antibodies in orally immunized mice when the chimeric fimbriae were expressed from the spiC promoter. The Salmonella spiC promoter construct induced the highest level of chimeric fimbriae after being taken up by the J774A.1 macrophagelike cells. The Salmonella cya crp vaccine vector was shown to incorporate into 987P partially degraded chimeric subunits lacking the TGEV epitopes. In contrast, its isogenic pgtE mutant produced fimbriae consisting exclusively of intact chimeric subunits. Mice immunized orally with the Salmonella pgtE vaccine expressing chimeric fimbriae from the spiC promoter elicited significantly higher systemic and mucosal antibody titers against the TGEV epitopes compared to the parental vaccine. This study indicates that the Salmonella cya crp pgtE vector and the spiC promoter can be used successfully to improve immune responses toward heterologous antigens.
Adhesins, Escherichia coli↗
Comparison of serologic testing and slaughter evaluation for assessing the effects of subclinical infection on growth in pigs.
OBJECTIVE: To compare serologic testing with slaughter evaluation in assessing effects of subclinical infection on average daily weight gain (ADG) in pigs. DESIGN: Cohort study. ANIMALS: 18 cohorts (30 to 35 pigs/cohort) of pigs on/farms. PROCEDURE: Blood samples were collected, and pigs were weighed at 8, 16, and 24 weeks of age. Sera were tested for antibodies to porcine reproductive and respiratory syndrome virus (PRRSV), swine influenza virus (SIV), transmissible gastroenteritis virus (TGEV), pseudorabies virus, Mycoplasma hyopneumoniae, and Actinobacillus pleuropneumoniae. At slaughter, skin, nasal turbinates, lungs, and liver were examined. Associations between ADG and results of serologic testing and slaughter evaluation were examined by use of multiple linear regression. RESULTS: Pathogens that had a significant effect on any given farm during any given year and the magnitude of that effect varied. However, at 16 and 24 weeks of age, a higher antibody titer was consistently associated with a lower ADG. Mean differences in ADG between seropositive and seronegative pigs were 18 g/d (0.04 lb/d) for SIV, 40 g/d (0.09 lb/d) for PRRSV, 38 g/d (0.08 lb/d) for M hyopneumoniae, and 116 g/d (0.26 lb/d) for TGEV. Of the evaluations performed at slaughter, only detection of lung lesions was consistently associated with a decrease in ADG. CONCLUSIONS AND CLINICAL RELEVANCE: Results suggest that subclinical infection with any of a variety of pathogens commonly found in swine herds was associated with a decrease in ADG. Serologic testing was more effective than slaughter evaluation in assessing the impact of subclinical infection on ADG in these pigs.
Actinobacillus Infections↗
[Use of the direct immunofluorescence method for determination of the TGE viral antigen in swine].
Followed up were the appearance and accumulation of the transmissive gastroenteritis (TGE) virus antigen in infected cells of pig kidney and thyroid. Used were specific conjugates, such introduced by the authors and some imported from Czechoslovakia. The cell cultures were infected with strains of the TGE virus, isolated in Bulgaria or supplied from Czechoslovakia. It was found that the Bulgarian strains were the same as those from Czechoslovakia and the United States. A viral antigen was found as early as the sixth hour following the infection of the cell cultures and it appeared under the form of cytoplasmatic yellow-green fluorescence. By the 12th, and up to the 18th hour the number of the specifically fluorescing cells as well as the intensity of fluorescence itself increased. Highest values in this respect were noticed in the interval between the 36th and 48th hour after the cultures had been infected.
Animals↗
[Use of gamma-globulins from the peritoneal fluid of cats with infectious peritonitis for the immunofluorescence demonstration of the TGE antigen].
Peritoneal exudate of a cat affected with feline infectious peritonitis (FIP) was used to isolate an IgG-globulin, employing affinity chromatography, and conjugate it with fluorescein isothiocyanate. The conjugate was tested on cross sections of the small intestine of a pig infected with strain Miller-3 of the transmissive gastroenteritis (TGE) virus, simultaneously with an anti-TGE conjugate of an SPF pig. Identical results were obtained with both conjugates, however, the anti-FIP conjugate had a several-times higher titer. Discussed are the possibilities and advantages of using the anti-FIP conjugate in the immunofluorescence demonstration of the TGE virus antigen.
Animals↗