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At least 667 records · Page 37Linked to original sources
PubMed1995

Localization of antigenic sites of the S glycoprotein of feline infectious peritonitis virus involved in neutralization and antibody-dependent enhancement.

The S glycoprotein of feline infectious peritonitis virus (FIPV) has been shown to contain the antigenic sites responsible for eliciting both neutralization and antibody-dependent enhancement. To determine the region of S responsible, overlapping DNA fragments spanning the entire S gene were cloned and expressed as fusion proteins by in vitro transcription and translation. Fusion proteins containing relevant epitopes were identified by radioimmunoprecipitation with neutralizing and enhancing FIPV-specific monoclonal antibodies (MAbs). A region spanning residues 509 to 673 reacted with most MAbs tested. Translation in the presence of microsomal membranes did not enhance reactivity, suggesting that glycosylation is not essential for recognition by the MAbs. To localize the antigenic sites further, several MAb-resistant (mar) mutants of FIPV were cloned and sequenced. Amino acid residues that contribute to the neutralizing and enhancing epitopes were localized to two regions, designated A1 and A2, which show partial overlap with the homologous antigenic site A of transmissible gastroenteritis virus. Site A1 contains residues 568 and 591 and is homologous with part of subsite Aa of transmissible gastroenteritis virus. Site A2 contains residues 643, 649, and 656. Double mutations in sites A1 and A2 were found in mar mutants derived from neutralizing and enhancing MAbs 23F4.5 and 18A7.4, while a single mutation in site A2 was found in a mar mutant derived from MAb 24H5.4, which is neutralizing but not enhancing. The data suggest that site A2, which includes residues 643 to 656, is a dominant neutralizing site of FIPV and that sites A1 and A2 may act in concert to induce antibody-dependent enhancement.

Amino Acid Sequence↗
PubMed1994

Three new isolates of porcine respiratory coronavirus with various pathogenicities and spike (S) gene deletions.

Three new isolates of porcine respiratory coronavirus (PRCV) were isolated and partially characterized. These PRCV isolates showed a selective tropism for respiratory tissue and were antigenically related to transmissible gastroenteritis virus. PCR amplification of the 5' half of the spike (S) genes of the three PRCV isolates indicated that a large deletion, characteristic of PRCV, was present. By using cDNA probes specific for the transmissible gastroenteritis virus S gene, the PCR products were shown to be specific in a Southern blot. The three new PRCV isolates were shown to vary in S gene deletion size. In a separate study, these isolates have also been shown to vary in pathogenicity. These new PRCV isolates should serve as important tools in gaining a better understanding of the pathogenesis of coronavirus infections.

Animals↗
PubMed1980

Experimental infection of pigs with a new porcine enteric coronavirus, CV 777.

Cesarean-derived colostrum-deprived and conventionally reared pigs were orally inoculated with the coronavirus-like agent, CV 777, isolate from an outbreak of epizootic diarrhea in swine of all ages. Viral particles detected by electron microscopy in the feces and intestinal contents of inoculated pigs had the typical coronavirus morphology. The present studies provided further evidence that this coronavirus-like agent is different from the two known porcine coronaviruses, transmissible gastroenteritis virus and hemagglutinating encephalomyelitis virus. The experimental infection of pigs with this new agent resulted in vomiting, diarrhea, and dehydration. This coronavirus-like agent was shown to replicate in the epithelial cells covering the small intestinal villi but, unlike transmissible gastroenteritis virus, it also replicated in the epithelial cells covering the large intestinal villi.

Animals↗
PubMed1984

Experimental inoculation of cats with canine coronavirus and subsequent challenge with feline infectious peritonitis virus.

Oronasal inoculation of minimal-disease cats with a virulent field isolate of canine coronavirus elicited a neutralizing antibody response that increased steadily over a two-month period, indicating in vivo amplification of the inoculated dose. A heterologous neutralizing antibody response to transmissible gastroenteritis virus could be detected three weeks after titers to canine coronavirus were first observed and was found to parallel the homologous response at a level approximately one log10 dilution lower. A modest anamnestic response detectable in both assays was observed after a second exposure to canine coronavirus. Cross-reacting antibodies to transmissible gastroenteritis virus were not detected by a kinetics-based enzyme-linked immunosorbent assay (KELA), however, until after cats had received multiple daily doses of canine coronavirus (third exposure). No clinical signs attributable to canine coronavirus were seen in inoculated cats, and virus could not be isolated from fecal or rectal swabs nor identified in fecal specimens by electron microscopy. Both virus-neutralizing and KELA titers were boosted by aerosol challenge with feline infectious peritonitis virus. Antibodies produced in response to canine coronavirus did not sensitize cats to subsequent feline infectious peritonitis virus challenge, but neither did they protect cats against the challenge dose.

Animals↗
PubMed1982

[Detection of antibodies against the virus causing viral gastroenteritis in swine using the modified autoradiography test].

A modified method for autoradiographic determination of antibodies to the virus of transmissible gastroenteritis of swine was developed. It is based on the actual reaction between antigen bound in cells of the infected cell cultures and antibodies in tested sera, which is visualized, by help of rabbit antibodies marked 125J (125J RaSw IgG antibody) to porcine IgG, on a sensitive radiograph and evaluated on the basis of darkening at the point of positive immunological reaction. Specificity of the test and mutual comparability and reproducibility of the results were confirmed by examining the known positive and negative sera and by comparison with the results of the virus-neutralisation test. Out of the 36 examined porcine blood sera the antibodies were proved autoradiographically only in the samples positive also by virus-neutralisation. In experimentally infected pigs, the same dynamics of antibody production was recorded by the two tests. They were, however, demonstrated autoradiographically already by the two tests. They were, however, demonstrated autoradiographically already the eighth day after infection, while by virus neutralisation test as late as 14th day. Their level increased gradually until 35th day after infection.

Animals↗
PubMed1981

Inner structures of some coronaviruses.

When treated with formaldehyde, Tween 80, sodium oleate and Nonidet P-40, avian infectious bronchitis virus, porcine transmissible gastroenteritis virus, neonatal calf diarrhea coronavirus, porcine hemagglutinating encephalomyelitis virus as well as the human coronavirus show similar inner structures by negative staining. The first one is an inner membranous bag. This structure could be evaginated following treatments used and does not show the characteristic projections of coronaviruses. Subsequently, the inner fold could be separated from the outer membrane at the point of junction between these two membranes. Each virus does not react in the same way to the action of the different products. The transmissible gastroenteritis virus appears more sensitive to treatments than other viruses. On the other hand, the hemagglutinating encephalomyelitis virus is the most resistant. The variable sensitivities of these viruses are not related to the type of host-cells. Also, a second internal structure, which is more dense than the viral particle, encircles partially the aperture of the internal tongue-shaped structure and seems to emerge from the viral particle through the aperture of the inner bag.

Coronaviridae↗
PubMed1977

Cell culture propagation of porcine rotavirus (reovirus-like agent).

Two isolates of porcine rotavirus (reovirus-like agent) were isolated and passaged in primary procine kidney cell cultures. Viral infectivity for cells was monitored by immunofluorescence because viral cytopathic effect was moderate. Successful passage of virus in cell culture required that viral suspensions obtained from infected cell cultures be treated with pancreatin prior to inoculation onto cell monolayers. Porcine rotavirus passage in cell culture also was accomplished, using trypsin treatments in lieu of pancreatin treatments. Porcine rotavirus passaged 10 times in cell culture infected gnotobiotic pigs and caused diarrhea. Gnotobiotic pigs that recovered from this infection were resistant to challenge exposure with porcine rotavirus but were susceptible to challenge exposure with transmissible gastroenteritis virus. As determined by immunofluorescent cross reactions, porcine rotavirus was found to be antigenically related to the human and bovine rotaviruses but not to reovirus type 3 or to transmissible gastroenteritis virus.

Animals↗
PubMed1988

Comparison of serologic assays for measurement of antibody response to coronavirus in cats.

Serologic virus neutralization tests, indirect immunofluorescence tests, and ELISA, using tissue culture-adapted feline infectious peritonitis virus (FIPV) or feline enteric coronavirus (FECV) were compared for their ability to distinguish specific virus exposure in cats. Sera of specific-pathogen-free cats inoculated with virulent or modified FIPV or FECV were used to compare the sensitivity and specificity of the homologous assays to a heterologous assay that measures antibody reactivity with transmissible gastroenteritis virus of swine. The geometric means of the serologic titers in FIPV and FECV assays were higher for FIPV- or FECV-infected specific-pathogen-free cats than the geometric means of the transmissible gastroenteritis virus assays for most groups. None of the assays was specific enough to discern the virus to which a cat had been exposed. However, the FIPV virus neutralization test appeared to be more sensitive for detection of an early response to FIPV infection than did the FIPV immunofluorescence test or FIPV-ELISA.

Animals↗
PubMed1981

Possible factors influencing immunoglobulin A concentration in swine colostrum.

The immunoglobulin (Ig) A concentration in swine colostrum was determined by the single radial immunodiffusion method, using 157 samples collected from the same number of farm-raised sows in the Yamaguchi Prefecture of Japan during 1976 and 1977. The mean IgA value was 12.26 +/- 3.30 mg/ml, and the maximum and minimum values were 28.14 mg/ml and 5.63 mg/ml, respectively. To determine factors influencing the IgA concentration in swine colostrum, the following items were analyzed in the present study: season, district, breed, number of parturitions, udder section from which samples were collected, kind of feed, vaccinations of swine (erysipelas live-organism vaccine, hog cholera live-virus vaccine, Japanese encephalitis live-virus vaccine, and transmissible gastroenteritis live-virus vaccine), type of farming, and number of sows raised on a farm. Relationships between the IgA concentration in swine colostrum and each of these 12 items were analyzed. Of the 12 items, breed and number of parturitions were the most influential on the IgA concentration in colostra of farm-raised sows. Season, district, and vaccination with transmissible gastroenteritis live-virus vaccine were moderately influential. Udder section, kind of feed, vaccinations of swine (erysipelas live-organism vaccine, hog cholera live-virus vaccine, and Japanese encephalitis live-virus vaccine), type of farming, and number of farm-raised sows were slightly influential. The multiple correlation coefficient obtained was 0.5887 (P greater than 0.05).

Animal Feed↗
PubMed1981

Possible factors influencing the immunoglobulin M concentration in swine colostrum.

The immunoglobulin (Ig) M concentration in swine colostrum was determined by the single radial immunodiffusion method, using 157 samples collected from the same number of farm-raised sows in Yamaguchi Prefecture of Japan during 1976 and 1977. The mean IgM value was 4.16 +/- 1.11 mg/ml, and the maximum and minimum values were 7.74 mg/ml and 1.50 mg/ml, respectively. To elucidate the possible factors influencing the IgM concentration in swine colostrum, the following 12 items were surveyed in the present study: season, district, breed, age, udder section (mamma) from which colostral samples were collected, kind of feed, 4 vaccinations (swine erysipelas live-organism vaccine, hog cholera live-virus vaccine, Japanese encephalitis live-virus vaccine, and transmissible gastroenteritis live-virus vaccine), type of farming, and number of sows raised on a farm. Relationships between the IgM concentration in swine colostrum and each item were analyzed. Of the 12 items, 3 items--season, breed, and vaccination of swine erysipelas live-organism vaccine--were the most influential on the IgM concentration in colostra of farm-raised sows. Five items--district, age, kind of feed, vaccination with transmissible gastroenteritis live-virus vaccine, and number of sows raised on a farm--were moderately influential. The remaining items--udder section, vaccinations with hog cholera live-virus vaccine and Japanese encephalitis live-virus vaccine, and type of farming--were poorly influential. The multiple correlation coefficient obtained here was 0.5605 (P greater than 0.05).

Age Factors↗
PubMed1967

Experimental sprue-like small intestinal lesions in pigs.

The virus of transmissible gastroenteritis produced sprue-like lesions in the small intestines of young pigs. These lesions were characterized by villous shortening, fusing and blunting in the jejunum and ileum. There was decreased height of the brush border and morphologic alteration of the villous epithelial cells from simple columnar to a variable cuboidal type. Accompanying these microscopic lesions were histochemical changes characterized by decreased staining intensity of acid phosphatase, alkaline phosphatase, adenosine triphosphatase, leucine aminopeptidase, succinic dehydrogenase and malic dehydrogenase in the affected intestinal mucosa. The clinical nature of transmissible gastroenteritis in the pig together with the histopathologic and histochemical changes may provide a useful experimental model for obtaining additional basic information on enteric disturbances.

Acid Phosphatase↗
PubMed1998

Feline aminopeptidase N is a receptor for all group I coronaviruses.

Human coronavirus HCV-229E and porcine transmissible gastroenteritis virus (TGEV), both members of coronavirus group I, use aminopeptidase N (APN) as their cellular receptors. These viruses show marked species specificity in receptor utilization as they can only use APN of their respective species to initiate virus infection. Feline and canine coronaviruses are also group I coronaviruses. To determine whether feline APN could serve as a receptor for feline coronaviruses (FCoVs), we cloned the cDNA encoding feline APN (fAPN) by PCR from feline cells and stably expressed it in FCoV-resistant mouse or hamster cells. These became susceptible to infection with either of several biotypes of FCoVs. The expression of recombinant fAPN also made hamster and mouse cells susceptible to infection with other group I coronaviruses, including several canine coronavirus strains, transmissible gastroenteritis virus (TGEV), and human coronavirus HCV-229E. Thus, fAPN served as a functional receptor for each of these coronaviruses in group I. As expected, fAPN could not serve as a receptor for mouse hepatitis virus (MHV), a group II coronavirus which uses murine biliary glycoproteins as receptors. Thus, fAPN acts as a common receptor for coronaviruses in group I, in marked contrast to human and porcine APN glycoproteins which serve as receptors only for human and porcine coronaviruses, respectively. These observations suggest that cats could serve as a "mixing vessel" in which simultaneous infection with several group I coronaviruses could lead to recombination of viral genomes.

3T3 Cells↗
PubMed1976

[The course of viral gastroenteritis of swine in Czechoslovakia during the period of 1971 to 1973 and its economic consequences].

Transmissible gastroenteritis of swine (TGE) was studied in detail for three years; over-all survey on epizootologic and commercial properties of this disease was thus obtained. Occurrence of TGE, its seasonal character, indices of morbidity, mortality and lethality were evaluated statistically. The morbidity rate dropped in 1973 from 68% to 41% in comparison with the year 1972, as well as the mortality rate decreased -- from 23% to 6% and as to the lethality rate -- from 34% to 14%. In the year 1972 (1973) 437.50 (275.21) animals were infected on an average per one focus of the disease, 146.88 (37.71) animals died among infected pigs and 13.84 (5.86) pigs were compulsorily slaughtered. Commercial losses amounted to 82 482 Kc per one vaccinated focus in 1972, and to 60 213 Kc per one non-vaccinated focus (irrespective of the costs of vaccination -- 70 755 Kc). In 1973 commercial losses were 7650 Kc on an average in vaccinated focuses, 41 000 Kc in non-vaccinated focuses (regardless of the costs of vaccination -- 14 797 Kc). Commercial effectiveness reflects in fewer natural focuses of the disease and in lower morbidity; the savings are 4.30 Kc per 1 Kc of investment costs.

Animals↗
PubMed1997

Rapid in situ hybridization technique for the detection of ribonucleic acids in tissues using radiolabelled and fluorescein-labelled riboprobes.

In situ hybridization (ISH) is a useful diagnostic and research tool, but is also time consuming. This study was conducted to determine if a rate enhancement hybridization (REH) buffer, developed for membrane hybridization, could be used to decrease hybridization time for ISH. Tissue from swine with an enteric disease produced by a swine coronavirus, transmissible gastroenteritis virus (TGEV), was used as a model to standardize hybridization conditions for a rapid ISH technique. Small intestinal sections from pigs experimentally and naturally infected with TGEV were hybridized for various times at 52 degrees C and 70 degrees C with a radiolabelled or a fluorescein-labelled RNA probe in a standard hybridization or a REH buffer. Viral RNA was detected in intestines from as early as 30 min of hybridization by using both buffers with the radiolabelled probe; however, the signal was stronger with the REH buffer. With the fluorescein-labelled probe, viral RNA was detected in virus-infected cells of the intestines after 30 min of hybridization by using the REH buffer. Signal intensity was greater with the REH buffer than with the standard hybridization buffer when compared at each hybridization time and hybridization temperature using both radiolabelled and fluorescein-labelled probes. With the REH buffer, hybridization signal intensity was greater at 70 degrees C than at 52 degrees C for both probes. The best results were obtained when small intestinal sections were hybridized at 70 degrees C for 2 h using a radiolabelled or a fluorescein-labelled probe diluted in the REH buffer. The fluorescein-labelled RNA probe with REH buffer resulted in a minimal non-specific signal when compared with the radiolabelled probe. These studies demonstrated that the REH buffer can be used to decrease the time of ISH for the detection of viral RNA. This rapid ISH technique should have broad applications in the utilization of probe technology in diagnostics and research for the detection of target ribonucleic acids in situ

Animals↗
PubMed1978

A new coronavirus-like particle associated with diarrhea in swine.

Coronavirus-like particles were detected by electron microscopy in the intestinal contents of pigs during a diarrhea outbreak on 4 swine breeding farms. Diarrhea was reproduced in experimental pigs with one of the isolates, designated CV777, which was found to be distinct from the 2 known porcine coronaviruses, transmissible gastroenteritis virus and hemagglutinating encephalomyelitis virus.

Animals↗
PubMed2006

Porcine innate and adaptative immune responses to influenza and coronavirus infections.

Both innate and adaptative immune responses contribute to the control of infectious diseases, including by limiting the spreading of zoonotic diseases from animal reservoirs to humans. Pigs represent an important animal reservoir for influenza virus infection of human populations and are also naturally infected by coronaviruses, an important group of viruses, which includes the recently emerged severe acute respiratory syndrome (SARS) virus. Studies on both innate and adaptative immune responses of pigs to influenza virus and coronaviruses contribute, therefore, to a better control of these infections in their natural hosts and will be briefly reviewed in this article. Pro-inflammatory cytokines, including type I interferon (IFN), tumor necrosis factor-alpha (TNF-alpha), and interleukin-6 (IL-6), were found in lung secretions of influenza virus infected pigs, and correlated with the intensity of clinical signs, whereas prior vaccination against influenza strongly reduced the production of infectious virus and cytokines in the lungs upon challenge, which was associated with clinical protection. An early type I IFN production was also found in coronavirus infected pigs, including at mucosal sites. IFN induction by coronavirus is shown to involve interaction between a viral glycoprotein and a leukocyte subset, likely equivalent to plasmacytoid dendritic cells, present in the mucosae and associated lymphoid tissues. Given the IFN mediated antiviral and immunomodulatory effects, the use of IFN or IFN inducers may prove an efficient strategy for a better control of influenza virus and coronavirus infections in pigs. Because influenza and coronaviruses target mucosal surfaces, adaptative immune responses have to be characterized at mucosal sites. Thus, nasal and pulmonary antibody responses were analyzed in influenza virus infected or vaccinated pigs showing short-lived, but potentially protective local IgA and IgG antibody (Ab) responses. Interestingly, primary influenza virus infection induced long-lived increase of lung CD8(+) T cells and local lymphoproliferative responses. Pigs infected by a respiratory coronavirus (PRCV) showed virus-specific IgG Ab-secreting cells in the bronchial lymph nodes, whereas the transmissible gastroenteritis coronavirus (TGEV) induced more IgA Ab-secreting cells in gut tissues, which illustrates the importance of the route of antigen administration for inducing local immune effector mechanisms. Porcine viral infections provide, therefore, valuable models for evaluating the immune parameters that are important for controlling transmission of important viral zoonotic infections.

Animals↗
PubMed1976

Viral gastroenteritis: recent progress, remaining problems.

Infants and young children are particularly susceptible to a recently identified viral enteritis which is highly contagious and seems both common and universal. In this disease, virus invades the upper intestinal epithelium, causing acute diarrhoea with early fever and vomiting. We studied a similar disease in pigs, infecting three-week-old animals with transmissible gastroenteritis virus (TGE), which also invades the upper intestinal epithelium. In this model, diarrhoea is massive 16-40 hours after infection, when stools contain increased electrolytes but no excess of sugar. In the jejunum of intact pigs at the 40-hour stage we found altered Na+ and water flux, decreased mucosal activities of disaccharidases and Na+, K+-ATPase, but normal adenylate cyclase activity. At the same stage the response of Na+ flux to glucose was blunted in jejunal epithelium studied in Ussing short-circuit chambers and in suspensions of villous cells; Cl- flux responded normally to theophylline, and thymidine kinase and sucrase activities of cells isolated from jejunal villi were similar to those found in crypt cells. Probably by 40 hours after infection most virus has been shed from the mucosa. Viral diarrhoea clearly differs from enterotoxigenic diarrhoea. Consideration of its pathogenesis must take into account the dynamic nature of the mucosal epithelium and the factors governing differentiation of enterocytes as they migrate from crypt to villus. Sufficient information is available now to characterize one specific and apparently prevalent viral enteritis in man and to identify additional viral enteritides. There is hope that preventative therapy can be developed. Our understanding of the mechanisms of viral diarrhoea is limited, but the availability of an animal model and the promise of others makes us optimistic that these deficiencies can be remedied. Greater understanding of the pathogenesis of viral diarrhoea should better the active therapy of affected infants and children.

Animals↗