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Results for “Transmissible gastroenteritis”

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PubMed1975

[Some properties of strains of the transmissible gastroenteritis virus of swine (TGE) isolated in Bulgaria].

Strains of the swine transmissive gastroenteritis (TGE) virus were isolated for the first time in Bulgaria in 1972. The dynamics was followed up of some strains' propagation in primary cell cultures of kidney tissue and subcultures of the thyroid of pigs. The intracellular virus reached highest titers at the 24--48th hour in the kidney cells, and at the 24--36th hour in the thyroid cells, while the extracellular virus was subjected to inactivation by the 2nd hour after infecting the cultures, by the 4--6th h its titer dropped up to 50 per cent of its initial value, and by the 24th h it was completely inactivated. The viability of the virus was tested after freeze-drying and after it had been stored at 4degreesC and--20degreesC. It was found that chloroform fully inactivates the virus at 4degreesC for 24 hours. The same results were obtained with the use of sodium desoxycholate. The strains isolated in this country form plaques, and with some strains the plaques are of a varying size. Halogenic desoxyuridines (IUDR, BUDR), as well as 8-azoridine do not suppress the multiplication of the tested TGE strains even in high concentrations. Inhibitory effect has 5-bromurazyl which in given concentrations affects the titer of the virus and the size of the plaques formed. Two Bulgarian and two reference strains have lowered their plaque-forming titer by 2 log after being treated with rifamycin-B or rifampicin.

Animals↗

PubMed1994

Entry and release of transmissible gastroenteritis coronavirus are restricted to apical surfaces of polarized epithelial cells.

The transmissible gastroenteritis coronavirus (TGEV) infects the epithelial cells of the intestinal tract of pigs, resulting in a high mortality rate in piglets. This study shows the interaction of TGEV with a porcine epithelial cell line. To determine the site of viral entry, LLC-PK1 cells were grown on permeable filter supports and infected with TGEV from the apical or basolateral side. Initially after plating, the virus was found to enter the cells from both sides. During further development of cell polarity, however, the entry became restricted to the apical membrane. Viral entry could be blocked by a monoclonal antibody to the viral receptor aminopeptidase N. Confocal laser scanning microscopy showed that this receptor protein was present at both the apical and basolateral plasma membrane domains just after plating of the cells but that it became restricted to the apical plasma membrane during culture. To establish the site of viral release, the viral content of the apical and basolateral media of apically infected LLC-PK1 cells was measured by determining the amount of radioactively labelled viral proteins and infectious viral particles. We found that TGEV was preferentially released from the apical plasma membrane. This conclusion was confirmed by electron microscopy, which demonstrated that newly synthesized viral particles attached to the apical membrane. The results support the idea that the rapid lateral spread of TGEV infection over the intestinal epithelia occurs by the preferential release of virus from infected epithelial cells into the gut lumen followed by efficient infection of nearby cells through the apical domain.

Animals↗

PubMed1976

Transmissible gastroenteritis. Mucosal ion transport in acute viral enteritis.

Ion transport in the jejunal mucosa of 14-to 16-day-old piglets with severe diarrhea 40 hr after infection with transmissible gastroenteritis (TGE) virus was studied. In infected pigs Na+ transport failed to respond normally to glucose when studied either in Ussing short-circuited chambers or in suspensions of enterocytes isolated selectively from jejunal villi. Theophylline, 10mM, added to the chambers produced the same brisk electrical responses and increments in net Cl- secretion in tissue from both infected and control groups. A defect in glucose-stimulated Na+ absorption in the acute stage of a viral enteritis has been identified which probably contributes to the impaired lumen-to-extracellular fluid flux of Na+ found previously in the jejunum of intact TGE-infected pigs. The mechanisms causing diarrhea in this invasive viral enteritis differ from those causing toxigenic diarrhea.

Acute Disease↗

PubMed1983

[Simulation as an aid in the study of the course and effects of an infectious animal disease. A prospective study exemplified by transmissible gastroenteritis in a pig breeding farm].

The possibilities of applying simulation in a study on the occurrence and effects of infectious animal disease are reported. For this purpose a model of transmissible gastroenteritis (TGE) was designed on a pig-multiplying farm. Using this model, the effects of certain management policies on the financial loss caused by TGE were quantified. It is concluded that computer simulation may be of great help in studying animal disease. It may result in better understanding of the manner in which a disease will exert its effects on the farm or on the population. Moreover, it offers an opportunity of predicting the effects of alternative procedures in prevention and control.

Animal Husbandry↗

PubMed1990

Expression of the porcine transmissible gastroenteritis coronavirus M protein.

Cloned cDNA encoding the M protein of the porcine transmissible gastroenteritis coronavirus (TGEV) was introduced into a vaccinia virus to examine the function of the amino-terminal signal peptide. The M protein expressed by the recombinant virus was targeted to the Golgi region of infected cells, as is the M protein in cells infected with TGEV. The protein appeared not to undergo processing other than glycosylation. However, the vaccinia-expressed M protein was slightly larger than the protein found in TGEV-infected cells, suggesting that a difference in modification exists between the proteins.

Animals↗

PubMed1988

Induction of alpha interferon by transmissible gastroenteritis coronavirus: role of transmembrane glycoprotein E1.

Epithelial cells infected with the coronavirus transmissible gastroenteritis virus (TGEV) and fixed by glutaraldehyde induced a high alpha interferon (IFN-alpha) production in nonimmune porcine as well as human or bovine peripheral blood mononuclear cells (PBMC). IFN-alpha was detected as early as 3 h after exposure of PBMC to infected cells and at producer/inducer cell ratios as low as 1/1. Two of four monoclonal antibodies directed against the viral transmembrane glycoprotein E1 could block the IFN-inducing capacity of both TGEV-infected cells and viral particles. On the other hand, IFN-alpha induction was not markedly affected by monoclonal antibodies directed against other E1 epitopes, against peplomer glycoprotein E2, or against nucleocapsid protein. Thus, these findings strongly imply that IFN induction by TGEV results from interactions between an outer membrane domain of E1 and the PBMC membrane.

Animals↗

PubMed1990

The effect of interferon induction in newborn piglets on the humoral immune response to oral vaccination with transmissible gastroenteritis virus.

Groups of newborn piglets were vaccinated orally with a modified live transmissible gastroenteritis (TGE) virus vaccine at 3 days and 13 days of age, and treated with the synthetic interferon (IFN) inducer polyinosinic:polycytidylic acid (poly ICLC) at 2, 3 or 4 days of age. Control groups consisted of piglets which were vaccinated but not treated with poly ICLC, as well as piglets which were treated with poly ICLC but not vaccinated. Significantly higher mean IFN titres were produced in response to induction at 3 or 4 days of age than at 2 days, and the mean IFN titre of the vaccinated piglets treated with poly ICLC at 3 days of age was significantly higher than in the unvaccinated piglets which were treated at the same time. The mean TGE virus neutralizing antibody titres in the vaccinated piglets which were treated with poly ICLC on the day before vaccination were significantly lower than the mean titres in the untreated vaccinated piglets 10 and 14 days after the first dose of vaccine. The mean titres in the vaccinated piglets which were treated with poly ICLC at 3 or 4 days of age did not differ significantly from those in the untreated vaccinated piglets. The piglets which were treated with poly ICLC on the day after vaccination developed severe diarrhoea which persisted for 5-7 days.

Animals↗

PubMed1994

Molecular characterization of attenuated vaccine strains of transmissible gastroenteritis virus.

Previous studies in our laboratory demonstrated that 2 attenuated strains of transmissible gastroenteritis virus (TGEV) contain deletions affecting messenger (m) RNAs 2, 3, or 4. In this report, we have compared mRNAs of four modified-live virus vaccines for TGEV with the virulent Miller PP3 isolate to determine whether any transcriptional patterns are shared among attenuated strains. Using northern blot analysis, all vaccine viruses expressed mRNAs indistinguishable in size from those of Miller PP3. However, using S1 nuclease protection experiments, alterations in the regions of the genome from which mRNAs 2 and 3 are transcribed were detected in 2 of the vaccine strains. When genomic cDNA fragments derived from the coding region for mRNA 2 were sequenced, a 6-nucleotide deletion, also found in the attenuated strain Purdue-115, was discovered. The product of mRNA 2, a spike glycoprotein, was visualized by western blotting for each vaccine strain, and no profound differences in mobility were detected relative to Miller PP3. Alterations in the region of the genome from which mRNA 3 is transcribed appear to be identical or very similar to sequence alterations already described in this region for Purdue-115, one of which is likely to alter the polypeptide product of mRNA 3. Insertions or deletions in mRNAs 2 or 3 may contribute to attenuation but are not a prerequisite for this phenotype. The S1 nuclease protection analysis is a sensitive tool for differentiating particular strains of TGEV.

Blotting, Northern↗

PubMed2002

In vitro and in vivo expression of foreign genes by transmissible gastroenteritis coronavirus-derived minigenomes.

A helper-dependent expression system based on transmissible gastroenteritis coronavirus (TGEV) has been developed using a minigenome of 3.9 kb (M39). Expression of the reporter gene beta-glucuronidase (GUS) (2-8 microg per 10(6) cells) and the porcine respiratory and reproductive syndrome virus (PRRSV) ORF5 (1-2 microg per 10(6) cells) has been shown using a TGEV-derived minigenome. GUS expression levels increased about eightfold with the m.o.i. and were maintained for more than eight passages in cell culture. Nevertheless, instability of the GUS and ORF5 subgenomic mRNAs was observed from passages five and four, respectively. About a quarter of the cells in culture expressing the helper virus also produced the reporter gene as determined by studying GUS mRNA production by in situ hybridization or immunodetection to visualize the protein synthesized. Expression of GUS was detected in the lungs, but not in the gut, of swine immunized with the virus vector. Around a quarter of lung cells showing replication of the helper virus were also positive for the reporter gene. Interestingly, strong humoral immune responses to both GUS and PRRSV ORF5 were induced in swine with this virus vector. The large cloning capacity and the tissue specificity of the TGEV-derived minigenomes suggest that these virus vectors are very promising for vaccine development.

Animals↗

PubMed2001

Partial passive protection with two monoclonal antibodies and frequency of feeding of hyperimmune anti-transmissible gastroenteritis virus (TGEV) serum for protection of three-day-old piglets from a TGEV challenge infection.

Passive protection experiments were conducted to determine the frequency and amounts of hyperimmune antiserum needed to block a transmissible gastroenteritis virus (TGEV) challenge infection and to identify monoclonal antibodies that are partially protective against TGEV. Hyperimmune antiserum or monoclonal antibodies were added to milk at each feeding or at selected feedings when the amount of antiserum was reduced. Three-day-old piglets were challenged with virulent virus that had been preincubated with antiserum or monoclonal antibodies. The results indicated that supplementing antiserum every other day was not efficacious for protection. Supplementing even small quantities of hyperimmune antiserum (0.5 ml) at least once a day in most cases was sufficient for piglet survival but did not prevent morbidity. Increasing the amount (>2 ml) and providing antiserum 3 times/day completely blocked the TGEV challenge infection. Two monoclonal antibodies were discovered that also provided passive protection for baby pigs. One monoclonal antibody, 5G1, had a high neutralizing titer, and the other, 6C4, was more effective in neutralizing and binding to virulent TGEV than to attenuated TGEVs. Both of these monoclonal antibodies were partially effective as supplements in milk for passive protection. Furthermore, these monoclonal antibodies were useful for boosting the efficacy of TGEV-neutralizing colostrum, which by itself was ineffective. These results show that other antigenic sites, different from the 4-well characterized epitopes on the S glycoprotein of TGEV, also are important for passive protection.

Administration, Oral↗

PubMed1973

Age dependent resistance to transmissible gastroenteritis of swine (TGE). II. Coronavirus titer in tissues of pigs after exposure.

Coronavirus titers were compared in various tissues of three-day old and 21-day old pigs after exposure to the virus of transmissible gastroenteritis (TGE). Pigs in both groups that did not die from TGE were necropsied at intervals from one to 15 days post-exposure, and their tissues assayed for viral content. Viral titers were much higher in the small intestines of the younger pigs. Viral isolations were obtained from several tissues of the younger pigs but only from the small intestines of pigs infected at 21 days of age. Levels of viral neutralizing antibodies in the serums of both age groups were comparable at similar post-exposure intervals.

Age Factors↗

PubMed1973

Transmissible gastroenteritis in feeder swine: clinical, immunofluorescence and histopathological obervations.

Eight feeder swine (four to six months of age) were inoculated orally with 200,000 to 500,000 pig infectious doses (PID) of the Purdue strain of transmissible gastroenteritis (TGE) virus. Biopsies obtained from their small intestines were examined histopathologically and by fluorescent antibody tissue section technique at intervals that included 24, 48, 72 and 96 hours postexposure, and similar examinations were carried out at necropsy 168 hours postexposure. Evidence of virus infection was demonstrated in all segments of the small intestine except the upper duodenum and the viral antigen was found only in the cytoplasm of the absorptive cells covering the villi. Although six of the eight pigs failed to show clinical signs of TGE, typical microscopic lesions of villous atrophy with replacement of columnar absorptive cells by cuboidal cells were observed in seven pigs, and TGE virus antigen was demonstrated in the intestinal cells of four of eight pigs during the first week postexposure. The infection was usually mild to moderate and focal in the pigs without clinical signs of the disease and more severe and extensive in the pigs with clinical signs of the disease variable in severity. It was concluded that TGE virus probably replicated in all feeder swine exposed, and that the presence or absence of clinical signs of TGE in these pigs was related to the severity and extent of the villous atrophy and columnar cell replacement induced in their small intestines.

Administration, Oral↗

PubMed1994

Pseudorabies and transmissible gastroenteritis: a serological survey in South Africa.

Two specific and sensitive, indirect enzyme-linked immunosorbent assays (ELISAs) utilizing a protein G-peroxidase conjugate were developed to detect antibodies to the pseudorabies virus (PRV) and the transmissible gastroenteritis virus (TGEV) in pig sera. Sera from 5,337 pigs, obtained from various abattoirs in South Africa, were tested with both ELISAs. No serological evidence of infection with either PRV or TGEV was found in any of the pigs tested.

Animals↗

PubMed1988

Pathophysiology of diarrhoea induced by a combined infection with transmissible gastroenteritis virus and enterotoxigenic Escherichia coli in newly-weaned piglets and the effect of flurbiprofen treatment.

In newly-weaned 3-4 week old piglets (n = 29) diarrhoea (100%) and vomiting (65%) were induced by inoculation with transmissible gastroenteritis virus and enterotoxigenic E. coli strains (0(149):K91:K88ac; LT, STa and STb enterotoxin positive). This combined infection resulted in pronounced mortality within 7 days. During this period the piglets had decreases in body weight, arterial pressure and leucocyte count and increases in heart rate and in total plasma protein concentration. The plasma pH and lactic acid concentration decreased, whereas the values for pO2, pCO2 and frequency of respiration did not change significantly. No significant changes in the serum concentrations of potassium, chloride or calcium were observed, whereas sodium concentration revealed a transient increase. In shocked and dying piglets an increase in haematocrit was observed, whereas base excess and bicarbonate concentration decreased. Flurbiprofen, a potent non-steroidal anti-inflammatory drug, administered intramuscularly on 3 successive days following the combined infection at a dosage of 1 mg/kg/12 h was without beneficial effect on diarrhoea or mortality.

Animals↗

PubMed1974

Transmissible gastroenteritis in feeder pigs: observations on the jejunal epithelium of normal feeder pigs and feeder pigs infected with TGE virus.

Light and electron microscopy findings in the jejunal mucosa of the normal feeder pig and feeder pigs infected with transmissible gastroenteritis (TGE) virus are reported. Villi in the mid jejunum of the normal feeder pig were elongated, finger shaped and covered with a layer of columnar absorptive cells with a well developed and regular brush border. Severe lesions of villous atrophy were present in all jejunal segments of feeder swine killed 96 hours post infection with TGE virus. Atrophic villi were covered by flat to cuboidal cells with a poorly developed brush border in some areas. In other segments, cells varied in appearance from sub-columnar to columnar type of near normal appearance. The ultrastructure of the jejunal absorptive cells in the normal feeder pig was found to be similar to that described for the jejunal cells of other adult mammals. There were no significant indications of high pinocytotic activity. The epithelial cells covering the atrophic villi of TGE infected pigs had a fine structure similar to that described for the crypt cells, ranging in appearance from very immature to moderately differentiated cells. Microvilli were very short, decreased markedly in number and irregular in arrangement. The terminal web was poorly developed. Strands of rough endoplasmic reticulum were markedly diminished and an increase in free ribosomes was noted. The significance of these observations in explaining pathogenesis of TGE in feeder pigs is discussed.

Administration, Oral↗

PubMed1977

Transmissible gastroenteritis: sodium transport and the intestinal epithelium during the course of viral enteritis.

Sodium transport, mucosal structure, and epithelial enzymes were studied in piglets killed 10, 25, 40, 72, or 144 hr after infection with a standard dose of transmissible gastroenteritis virus. Glucose-stimulated Na transport measured in short-circuited jejunal epithelium and suspensions of villous enterocytes became progressively more abnormal during the first 40 hr, but recovered completely by 144 hr. As Na transport deteriorated, jejunal mucosal villi shortened and crypts deepened; cells isolated from the villi became more crypt-like in their enzyme profile, with high levels of thymidine kinase and low levels of sucrase activity 40 hr after infection. At 40 hr, when diarrhea is severe, little if any virus has been found in the epithelium. Our data suggest that the relatively undifferentiated crypt type enterocytes on the villi constitute an important determinant of altered Na transport and diarrhea in this invasive viral enteritis.

Animals↗

PubMed1970

Transmissible gastroenteritis (TGE) of swine: the possible role of dogs in the epizootiology of TGE.

Nine of 11 six-to-eight-week-old beagle puppies from a colony started from hysterectomy-derived breeding stock developed a serological response to a transmissible gastroenteritis (TGE)-associated virus following exposure to TGE-infected pig intestinal tissue. The virus was not isolated on swine testis (ST) cells from dog rectal swabs, except in one instance; however, when composites of rectal swabs from all 11 dogs taken seven days and fourteen days postexposure were fed to piglets, they developed signs of TGE and died within seven days. This TGE-associated virus was readily isolated on ST cells from the rectal swabs of the exposed piglets.

Animals↗

PubMed1987

[Influence of concanavalin A on the attachment of the coronavirus of transmissible gastroenteritis in cell cultures].

Effect of Concanavalin (ConA) on attachment of three strains of Transmissible Gastroenteritis coronavirus (TGE) of swine was investigated in cell culture. Whatever the virus strain, reduction of virus plaques number is observed when viral suspension is incubated with cells together or after addition of ConA. Intensity of inhibition is related with ConA concentration. ConA treatment of preinfected cell cultures has no effect on plaque formation. Addition of alpha-methyl-D-mannoside inhibits the ConA activity. Treatment of cells with metaperiodate has no effect on plaque formation and ConA activity. Our results suggest that ConA inhibits formation of plaques by TGE coronavirus.

Cells, Cultured↗