Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C0017160 (gastroenteritis)
 11,398 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Transmissible gastroenteritis virus, an enteropathogenic coronavirus of swine, is a potent inducer of alpha interferon (IFN-alpha) both in vitro and in vivo. Previous studies have shown that virus-infected fixed cells or viral suspensions were able to induce an early and strong IFN-alpha synthesis by naive lymphocytes. Two monoclonal antibodies directed against the viral membrane glycoprotein M (29,000; formerly E1) were found to markedly inhibit virus-induced IFN production, thus assigning to M protein a potential effector role in this phenomenon (B. Charley and H. Laude, J. Virol. 62:8-11, 1988). The present report describes the selection and characterization of a collection of 125 mutant viruses which escaped complement-mediated neutralization by two IFN induction-blocking anti-M protein monoclonal antibodies. Two of these mutants, designated H92 and dm49-4, were found to exhibit a markedly reduced interferogenic activity. IFN synthesis by lymphocytes incubated with purified suspensions of these mutants was 30- to 300-fold lower than that of the parental virus. The transcription of IFN-alpha genes following induction by each mutant was decreased proportionally, as evidenced by Northern (RNA) blot analysis. The sequence of the M gene of 20 complement-mediated neutralization-resistant mutants, including the 2 defective mutants, was determined by direct sequencing of genome RNA. Thirteen distinct amino acid changes were predicted, all located at positions 6 to 22 from the N terminus of the mature M protein and within the putative ectodomain of the molecule. Two substitutions, Thr-17 to Ile and Ser-19 to Pro, were assumed to generate the defective phenotypes of mutants dm49-4 and H92, respectively. The alteration of an Asn-Ser-Thr sequence in dm49-4 virus led to the synthesis of an M protein devoid of a glycan side chain, which suggests a possible involvement of this structure in IFN induction. Overall, these data supported the view that an interferogenic determinant resides in the N-terminal, exposed part of the molecule and provided further evidence for the direct role of M protein in the induction of IFN-alpha by transmissible gastroenteritis virus. The acronym VIP (viral interferogenic protein) is proposed as a designation for this particular class of proteins.
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PMID:Single amino acid changes in the viral glycoprotein M affect induction of alpha interferon by the coronavirus transmissible gastroenteritis virus. 130 9

Leukocytes were harvested from the peripheral blood, mesenteric lymph node and small intestinal lamina propria from groups of three piglets before, and 1, 2 and 3 weeks after infection with virulent transmissible gastroenteritis virus (TGEV) at 2 weeks of age. The donor piglets developed clinical signs of transmissible gastroenteritis which persisted for up to 3 days, and they developed peak serum titres of TGEV-neutralizing antibodies 2 weeks post-infection. The leukocytes were cultured in the presence of pokeweed mitogen (PWM), various dilutions of purified TGEV, or control media for 3 or 5 days, and the culture supernatants were tested for antiviral activity in MDBK cells challenged with vesicular stomatitis virus. The antiviral activity was characterized as porcine interferon (IFN)-alpha or porcine IFN-tau on the basis of its stability at pH 2.0 and neutralization by anti-human IFN-alpha antibodies. Viability of the leukocytes in culture, determined by trypan blue exclusion, was highest for the peripheral blood leukocytes and lowest for the mesenteric lymph node leukocytes. There were no consistent differences in antiviral activity between cultures incubated for 3 or 5 days. Porcine IFN-alpha was found in the supernatants of the leukocyte cultures stimulated with TGEV antigen, harvested before or after infection of the donor piglets with TGEV. Porcine IFN-tau was demonstrated in the supernatants of the leukocyte cultures stimulated with PWM, more frequently when the leukocytes were harvested post-infection. This was the first demonstration of IFN induction in vitro in leukocytes from porcine gut-associated lymphoid tissue.
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PMID:Interferon induction in porcine leukocytes with transmissible gastroenteritis virus. 134 91

Porcine interferon (POIFN)-alpha prepared in primed peripheral blood leukocyte cultures induced with Newcastle disease virus and POIFN-beta from PK-15 cell cultures induced with polyinosinic:polycytidylic acid were partially purified by precipitation with potassium thiocyanate and anion exchange chromatography. Mean purification factors in terms of units of POIFN per mg of protein, of 37 and 12 were obtained for POIFN-alpha and POIFN-beta respectively. In yield reduction assays in swine testis and pig kidney cell cultures, POIFN-alpha and POIFN-beta had greater antiviral activity against vesicular stomatitis virus than against transmissible gastroenteritis virus (TGEV). The antiviral effects were greater at higher concentrations of interferon (IFN), and when the IFN treatments were continued postinfection. Porcine interferon-beta showed greater antiviral activity against TGEV than POIFN-alpha, but this may have been partly due to cytotoxicity. There were no major differences in the antiviral activities of crude and partially purified IFN preparations. Both types of IFN showed antiviral activity against TGEV in yield reduction assays in porcine intestinal explant and intestinal epithelial cell cultures. Crude POIFN-beta was found to be rapidly cytotoxic, especially in porcine cells, and some fractions of partially purified POIFN-beta were also cytotoxic. The cytotoxicity of POIFN-beta was partially neutralized by antibodies against human IFN-beta, but human IFN-beta was not cytotoxic for porcine or bovine cells.
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PMID:Antiviral activity against transmissible gastroenteritis virus, and cytotoxicity, of natural porcine interferons alpha and beta. 165 3

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.
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PMID:The effect of interferon induction in newborn piglets on the humoral immune response to oral vaccination with transmissible gastroenteritis virus. 169 49

The causative agent (TGEV) of porcine transmissible gastroenteritis belongs to the Coronaviridae, a family of enveloped viruses with a positive, single-stranded RNA genome. Important progress has recently been made concerning the molecular biology of TGEV. The research work of our group has been focused on two main aspects: genome structure and functional domains of the envelope proteins. TGEV genomic RNA is organised into seven regions. The sequence of six of them, i.e. the 3' most 8300 nucleotides, has been established from cDNA clones. Three genes encoding the structural proteins, the peplomer protein E2, the transmembrane protein E1 and the nucleoprotein, have been identified. Additional open reading frames allowed for the prediction of four non-structural polypeptides, the role of which remains to be discovered. The remaining part of the genome (estimated length 20 kb) is thought to encode the polymerase. Expression of TGEV genes involves the production of six subgenomic mRNAs, which together with the virion RNA, form a 3' terminal nested set. The peplomer glycoprotein E2 (220 kDa) is 1431 residues long and highly glycosylated. Several domains were identified, including a C-terminal anchoring region and at least four major antigenic sites, which cluster in the amino half part of the molecule. Two sites containing most of the critical neutralisation determinants are highly conserved among TGEV strains. The glycoprotein E1 (29kDa) is mostly embedded in the membrane and plays a crucial role in the virion architecture. However, a short N-terminal domain protruding out of the particle mediates complement-dependent neutralisation, and induces alpha interferon synthesis, likely through a direct interaction with the lymphocyte membrane.
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PMID:Molecular biology of transmissible gastroenteritis virus. 216 70

We have performed molecular studies on the pig interferon (IFN) system (i) to analyse the role played by endogenous IFN in neonatal viral enteritis such as transmissible gastroenteritis and possibly to obtain, via recombinant DNA technology, a new anti-infectious and immunomodulatory agent in this species, (ii) to characterize the structure and biological functions of the IFN-like antiviral activity produced by the porcine embryo at the time of implantation in the uterus. By probing porcine genomic libraries with human and porcine IFN-alpha probes to isolate related genes, we have shown that the porcine IFN-alpha multigene family included, like several other mammalian species, two subfamilies of related but distinct genes. Class I subfamily contains at least 11 loci, located on chromosome no. 1, among which nine have been cloned and two (potentially functional) sequenced. Class II subfamily, which is specifically expressed by the embryo of ruminants before implantation, contains at least seven loci among which six have been cloned. One of the sequenced class I loci: PoIFN-alpha 1 encodes a 189 amino acids (AA) preprotein. After removal of the sequence encoding the putative signal peptide (23 N-terminal AA) this gene was inserted into an Escherichia coli bicistronic expression vector allowing intracellular synthesis of mature porcine IFN-alpha 1 (methionyl IFN-alpha 1). Expression of the recombinant protein was optimized by insertion of a seven base pairs long random synthetic sequence in the intercistronic region, followed by cloning in E. coli and immunodetection of clones expressing high amounts of recombinant protein. The E. coli strain obtained produced high levels of a 18,000 Da protein exhibiting the same in vitro overall biological properties as leucocyte derived porcine IFN (LeuIFN). However, it had a stronger antiviral effect on porcine cells than LeuIFN. After immunoaffinity purification to a specific activity of 5-10 x 10(7) International Units (IU)/mg of protein, pharmacokinetic and pharmacological studies were realized to determine the in vivo half life of this rIFN-alpha in the pig. These experiments revealed no major toxic effects in newborn (given 5 x 10(6) IU/kg) or adult (1 X 10(6) IU/kg) pigs. A significant pyrogenic effect (+ 1.5 degrees C) was noted only in the adults.
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PMID:Contribution of molecular biology to the study of the porcine interferon system. 220 70

Specific release of 51Cr and the production of interferon (IFN) increased in parallel in a spontaneous cell-mediated cytotoxicity (SCMC) assay in which uninfected PK-15 cells or PK-15 cells persistently infected with transmissible gastroenteritis virus (PK-15-TGE cells) were used as targets, and peripheral blood lymphocytes (PBL) from a young adult pig were used as effector cells. Higher levels of both specific 51Cr release and IFN were obtained in the assays containing PK-15-TGE cells. Co-cultivation of PBL from newborn piglets with PK-15-TGE cells yielded similar levels of IFN to those produced by co-cultivation of adult PBL and PK-15-TGE cells, but lower levels of IFN were produced by co-cultivation with uninfected PK-15 cells. Pretreatment of adult PBL with IFN augmented their SCMC effector activity for both PK-15 and PK-15-TGE cells in the 51Cr release assay. Pretreatment of the PK-15-TGE target cells with IFN did not affect their release of 51Cr in the SCMC reaction, while IFN pretreatment of PK-15 targets protected them against SCMC. In a single cell cytotoxicity assay the effects of IFN pretreatment on the effector adult PBL and on the PK-15 and PK-15-TGE target cells were confirmed, and SCMC incompetent PBL from neonatal piglets were rendered cytotoxic by pretreatment with IFN. PBL from newborn piglets bound to either target cell with the same frequency as PBL from SCMC competent adult pigs, and IFN pretreatment of either effector or target cells had no effect on target-binding frequency.
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PMID:The role of interferon in spontaneous cell-mediated cytotoxicity in pigs. 242 8

High titers of interferon were found in the serum and milk of three sows treated two days after farrowing with polyinosinic:polycytidylic acid complexed with poly-L-lysine and carboxymethylcellulose, but circulating interferon was not found in the piglets suckled by these sows. When two treated sows and their suckling piglets were exposed to infection with transmissible gastroenteritis virus eight hours after treatment, the sows showed no signs of disease, although they developed circulating interferon in response to the virus infection. The piglets suckled by the treated sows developed signs of transmissible gastroenteritis which were identical to those seen in a control litter of piglets suckled by an untreated sow. Piglets treated at two days of age with the polyinosinic:polycytidylic acid complex showed a delay in onset of clinical signs when exposed to infection with transmissible gastroenteritis virus, compared with untreated control piglets. When two sows were treated with the polyinosinic:polycytidylic acid complex before farrowing, neither circulating interferon nor activated natural killer cells were found in the piglets after birth.
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PMID:The effect of interferon induction in parturient sows and newborn piglets on resistance to transmissible gastroenteritis. 245 Jun 28

Three transmissible gastroenteritis (TGE) virus-specific T helper (Th) cell hybridomas have been generated from virus-primed BALB/c mice, by fusion with the thymoma BW5147. The hybridomas responded to purified u.v.-inactivated TGE virus with interleukin production and growth inhibition. TGE virus recognition by the hybridomas was restricted by the major histocompatibility complex: only splenocytes from syngeneic or semi-syngeneic mice were able to recognize the antigen. The three hybridomas were Thy 1.2+, but did not express detectable levels of Lyt 1 or Lyt 2 antigens by fluorescent cell sorting analysis. Only one hybridoma (T.1J.B5) expressed the L3T4 marker. These hybridomas had helper activity, as they were able to reconstitute in vitro the synthesis of TGE virus-specific antibodies by Th cell-depleted spleen cells from immune BALB/c mice. The antibodies that they induced specifically neutralized by 10(3)- to 10(4)-fold the infectivity of TGE virus, ruling out the possibility of inhibition of virus replication by interferon. These hybridomas could be very useful for identifying antigenic domains in TGE virus recognized by Th cells, which cooperate with B cells in the synthesis of neutralizing antibodies.
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PMID:Induction of transmissible gastroenteritis coronavirus-neutralizing antibodies in vitro by virus-specific T helper cell hybridomas. 247 95

The objective of this study was to compare the sensitivity of 11 porcine viruses to the antiviral effects of porcine interferon-alpha in serum from piglets which had been infected 19 h previously with transmissible gastroenteritis virus, and of porcine interferon-beta prepared in PK-15 cells by induction with polyinosinic:polycytidylic acid, in yield reduction assays in pig kidney cells which were treated with interferon before virus challenge, and both before and after virus challenge. The most sensitive virus to both types of interferon was vesicular stomatitis. A porcine isolate of bovine herpesvirus type 1, hemagglutinating encephalomyelitis virus and porcine enterovirus types 1 and 2 were also highly sensitive to interferon-alpha. There was little reduction in the yield of porcine parvovirus or porcine rotavirus, while swinepox, swine influenza and transmissible gastroenteritis viruses were intermediate in their sensitivity to interferon-alpha. In addition to vesicular stomatitis virus, porcine adenovirus type 3, swine influenza, hemagglutinating encephalomyelitis and porcine rotavirus were highly sensitive to interferon-beta, while swinepox, bovine herpesvirus type 1, porcine parvovirus, transmissible gastroenteritis and porcine enteroviruses were less sensitive than the above viruses to interferon-beta, although all showed significant reductions in virus yield.
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PMID:The interferon sensitivity of selected porcine viruses. 249 45


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