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T W Molitor

Publications and source records attributed to T W Molitor.

At least 55 records · Page 3Linked to original sources
PubMed1994

Genetic variation of foot-and-mouth disease virus from field outbreaks to laboratory isolation.

Foot-and-mouth disease virus (FMDV), by nature of its RNA genome, possesses a high rate of mutation during replication. This results in extensive genetic polymorphism of virus populations in nature. The emergence of FMDV variants during replication has been reported. Genetic changes in the viral capsid protein (VP1) gene can result in amino acid changes affecting the immunodominant epitopes of FMDV. The genetic heterogeneity of FMDV in the field and the antigenic variants observed after cell culture isolation has been investigated by PCR sequencing and reactivity with monoclonal antibodies. These methods were applied to viruses causing two different outbreaks of FMD before and after replication in cell culture and in the animal host. The VP1 region of the genome was amplified by PCR and sequenced to reveal variant sequences identified after passage and to determine their presence in the original field tissue. In one case, reactivity with monoclonal antibodies was lost after passage as a result of an amino acid change in the subpopulation. These findings suggest that host cells can select specific virus genetic and antigenic subpopulations during virus isolation and propagation.

Amino Acid Sequence↗
PubMed1994

Experimental porcine reproductive and respiratory syndrome virus infection in one-, four-, and 10-week-old pigs.

One-, 4-, and 10-week-old pigs were exposed to porcine reproductive and respiratory syndrome virus (PRRSV) to determine the effect of age on clinical signs, hematologic alterations, the onset and duration of viremia, routes of virus shedding, antibody production, and microscopic lesions produced by PRRSV isolate ATCC VR-2332. The response to PRRSV infection was similar among age groups. Fever, usually prolonged, and a marked dyspnea with cutaneous erythema when restrained for sample collection were the most consistent clinical signs. Prolonged periocular edema was unique to the 1-week-old pigs. The white blood cell count was decreased on day 4 postexposure (PE) due to decreases in neutrophils and lymphocytes. The virus was isolated from buffy coats at day 1 PE and was isolated from serum, buffy coat, or plasma at each sample collection period through the end of the trial (day 28 PE). Virus was most consistently isolated from lung, lymph node, spleen, and tonsil on day 7 PE and exclusively from lymph node, spleen, and tonsil on day 28 PE. Virus was infrequently isolated from urine and fecal and nasal swabs. Consistent microscopic changes in all age groups included interstitial pneumonia and lymph node hypertrophy and hyperplasia on days 7 and 28 PE, lymph node necrosis on day 7 PE, and subacute mononuclear myocarditis on day 28 PE. Findings presented here indicate that interstitial pneumonia, lymphoid necrosis, and mononuclear myocarditis are characteristic lesions of PRRSV isolate ATCC VR-2332 infection in 1-, 4-, and 10-week-old pigs.

Aging↗
PubMed1994

A modified serum neutralization test for the detection of antibody to porcine reproductive and respiratory syndrome virus in swine sera.

Various conditions were evaluated and modified to improve the sensitivity of the serum neutralization (SN) test for detecting antibody in pigs infected with porcine reproductive and respiratory syndrome virus (PRRSV). Higher SN titers were consistently obtained by the addition of 20% fresh swine serum to the virus diluent and by the use of a permissive cell clone (MARC-145) derived from the MA-104 cell line. Test sera used to assess the SN test were obtained from 2 groups of 3-week-old pigs infected intranasally with PRRSV (MN-1b). Using the modified method, SN antibody was first detected 9-11 days postinoculation (PI), with a peak evident at 11-21 days PI. The antibody subsequently declined, and a second peak was observed between 41 and 45 days PI. The first antibody peak was not observed and the SN antibody was only detectable between 32 and 41 days PI when the test was done with 20% heated swine serum or without supplemental swine serum. The SN antibody during 2-3 weeks PI was found to be sensitive to 2-mercaptoethanol or anti-swine IgM treatment. The SN antibody titers were high when homologous PRRSV isolate was used in the test but were markedly low for heterologous PRRSV isolates. No difference in antibody titers was observed when homologous and heterologous PRRSV isolates were tested by indirect fluorescent antibody assay. These results indicate that the modified SN method is useful in detecting earlier and higher PRRSV antibody and that it can differentiate among PRRSV isolates.

Animals↗
PubMed1994

Interaction of bovine respiratory syncytial virus with bovine alveolar macrophages in vivo: effects of virus infection upon selected cell functions.

The effect of bovine respiratory syncytial virus (BRSV) upon alveolar macrophage (AM) function was investigated using an in vivo calf inoculation model. Alveolar macrophages were collected sequentially from live calves at multiple time points during the 14 day period following viral inoculation. Alveolar macrophages from bronchoalveolar lavage fluids were purified by density gradient centrifugation (> 95% AM) prior to in vitro evaluation of cell functions. There were significant but variable and inconsistent differences in the functions of AM from the BRSV inoculated calves compared to the control calves. Fc-receptor mediated phagocytosis was either increased or unchanged by BRSV inoculation. Nonopsonized phagocytosis was decreased during the early postinoculation period and later increased. There was a variable effect on AM phagosome lysosome fusion with increased fusion activity on postinoculation days 2 through 5, 7 and 12 but reduced activity on days 6 and 10. The AM respiratory burst, as measured by nitroblue tetrazolium dye reduction, was essentially unaffected with a reduction in activity on day 10 only. In this model, BRSV inoculation of calves primarily resulted in an alteration of the membrane associated phagocytic functions of the alveolar macrophages (p < 0.05).

Animals↗
PubMed1993

Neuroprotective role of IL-4 against activated microglia.

Microglia have been proposed to play a pathogenetic role in immunologically mediated neurodegenerative diseases. In our study, using microglial/neuronal cell cocultures primed with IFN-gamma, we found that both LPS and TNF-alpha triggered neuronal cell injury (impairment of gamma-aminobutyric acid uptake and neuronal loss) via a nitric oxide mechanism. Pretreatment of cell cocultures with IL-4, an immunosuppressive cytokine, prevented, in a dose-dependent manner, neuronal cell injury induced by activated microglia. The mechanism by which IL-4 exerts its neuroprotective effect was found to involve the inhibition of IFN-gamma priming of microglia with a subsequent decrease in the production of TNF-alpha and nitric oxide.

Animals↗
PubMed1993

Cloning, sequencing and regulation of an mRNA encoding porcine interleukin-1 beta.

Interleukin 1 (IL-1) is a cytokine that mediates a variety of immunological responses. We report here the isolation of a porcine IL-1 beta cDNA from an alveolar macrophage library. The complete cDNA sequence is 1458 bp in length and has an open reading frame of 803 bp, encoding a 267-amino-acid (aa) protein with an approximate molecular size of 31 kDa. The porcine IL-1 beta cDNA sequence shows homologies of 82.0, 81.0, 74.0, and 74.0% with the bovine, sheep, human, and murine sequences in the protein coding regions, respectively. Northern blot analysis reveals a single 1.7-kb mRNA species that is differentially regulated by lipopolysaccharide, phorbol myristate acetate, and tumor necrosis factor but is not regulated by human recombinant IL-1. Porcine IL-1 beta is down-regulated by dexamethasone, polymyxin B, and IL-4 in a fashion kinetically similar to the other reported species.

Amino Acid Sequence↗
PubMed1993

Tissue tropisms of porcine parvovirus in swine.

Late-term gestation swine fetuses, similar to adult animals, are able to effectively mount immune response and survive porcine parvovirus (PPV) infection. An exception to this is the Kresse strain of PPV, which causes fetal death in late-term gestation swine fetuses. In an effort to understand the basis for this profound difference in pathogenicity between Kresse strain and the prototype strain of PPV, NADL-8, studies were designed to examine potential difference in sites of replication and quantity of virus produced between Kresse and NADL-8 strains. In order to define the sites of viral replication or sites of viral sequestration in situ hybridization, using digoxigenin-labeled strand-specific oligonucleotide probes, was applied to detect the presence of either double stranded viral DNA (RF) or viral single stranded DNA in tissues of infected fetuses. The presence and the state of viral DNA was confirmed by Southern blot hybridization. Relative amounts of RF-DNA synthesis in each tissue was compared between the two virus strains. Virus replication appeared to be of comparable levels in the livers of both NADL-8 and Kresse infected swine fetuses. Differences between these strains were observed in the brain and spleen; RF-DNA was detected in the brain and spleens of Kresse infected fetuses but not in NADL-8 infected ones. These findings indicate that differences in DNA replication of the PPV strains in selective sites, as well as the quantity of virus produced, may explain the distinction in pathogenesis of these viruses.

Animals↗
PubMed1993

Morphine inhibits the release of tumor necrosis factor in human peripheral blood mononuclear cell cultures.

Opiates modulate a variety of immune responses of peripheral blood mononuclear cells (PBMC). When PBMC were treated with morphine for 24 h, cells released less (P < 0.05) bioactive TNF, a cytokine important in host defense, in the following 24-h incubation period when stimulated with lipopolysaccharide and phytohemagglutinin. Morphine alone did not significantly alter the release of TNF from PBMC cultures. Pretreatment of PBMC cultures for 1 h with naloxone blocked (P < 0.05) the inhibitory effect of morphine on the release of TNF upon stimulation with phytohemagglutinin, but not with lipopolysaccharide, suggesting the involvement of an opioid receptor. The mechanism of morphine-induced suppression of TNF release appears to be counteracted by the effect of this opiate on the release of transforming growth factor (TGF)-beta, since antibodies to this immunoregulatory cytokine further enhanced morphine-related inhibition of TNF release. Taken together, these findings indicate that morphine suppresses the release of bioactive TNF from PBMC and that TGF-beta plays a modulatory role in this inhibitory process.

Adult↗
PubMed1993

Effects of morphine dependence on the pathogenesis of swine herpesvirus infection.

To further understand the effects of opiates on the pathogenesis of infectious disease, naturally occurring pathogens were studied in a swine model. Swine were given morphine for 21-42 days to establish a tolerant, dependent state. On day 7 after morphine initiation, pigs were challenged with swine herpesvirus-1 (SHV-1); on day 14, selected animals were superinfected with Pasteurella multocida. Evaluations were made of the clinical disease, protective effect of SHV-1 vaccination, and pathology. Morphine-dependent animals developed significantly greater virus-induced and secondary bacterial pneumonia. Prior vaccination with SHV-1 was not protective against pneumonia in morphine-dependent pigs. Unexpectedly, clinical signs associated with neurologic disease were less pronounced, and mortality from viral encephalitis was decreased in morphine-treated animals. Collectively, the findings demonstrate that morphine dependence is associated with a marked alteration of the pathogenesis of SHV-1 and that the effects of this opiate on pathogenesis are determined by the specific site of infection.

Animals↗
PubMed1993

Pathogenesis of porcine reproductive and respiratory syndrome virus infection in mid-gestation sows and fetuses.

Two experiments were undertaken to evaluate whether porcine reproductive and respiratory syndrome (PRRS) virus was able to cross the placenta and infect midgestation fetuses following intranasal inoculation of sows and whether PRRS virus directly infected fetuses following in utero inoculation. In experiment 1, eight sows between 45 and 50 days of gestation were intranasally inoculated with PRRS virus (ATCC VR-2332), and four control sows were inoculated with uninfected cell culture lysate. Virus inoculated sows were viremic on postinoculation (PI) days 1, 3, 5, 7 and 9, shed virus in their feces and nasal secretions, and became leukopenic. Sixty-nine of 71 fetuses from principal sows euthanized on PI day 7, 14 or 21 were alive at necropsy and no virus was isolated from any of the fetuses. Two principal sows that farrowed 65 and 67 days PI delivered 25 live piglets and three stillborn fetuses. The PRRS virus was isolated from two live piglets in one litter. In experiment 2, laparotomies were performed on five sows between 40 and 45 days of gestation and fetuses were inoculated in utero with either PRRS virus alone, PRRS virus plus a swine serum containing PRRS antibodies, or uninfected cell culture lysate. Three sows were euthanized on PI day 4 and two sows on PI day 11. Viral replication occurred in fetuses inoculated with virus alone and was enhanced in fetuses inoculated with virus plus antibody. No virus was isolated from control fetuses.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1992

Activated microglia mediate neuronal cell injury via a nitric oxide mechanism.

Activated microglial have been proposed to play a pathogenetic role in immune-mediated neurodegenerative diseases. To test this hypothesis, purified murine neonatal microglial were cocultured with neuronal cells derived from fetal brain. Activation with IFN-gamma and LPS of these cocultures brought about a sharp decrease in uptake of gamma-amino butyric acid and a marked reduction in neuronal cell survival. These effects varied with the density of microglia, the concentrations of the activation signals (IFN-gamma and LPS), and the duration of coculture. Inasmuch as addition of NG-monomethyl-L-arginine blocked these effects, a L-arginine-dependent neurocytotoxic mechanism was implicated. Abundant nitrite, a metabolite of the free radical nitric oxide (NO) derived from L-arginine, was detected in activated microglial/neuronal cell cocultures and in purified microglial cell cultures but not in purified astrocyte or neuronal cell cultures, suggesting that microglial were the principal source of the NO. These findings support the hypothesis that microglia are the source of a neurocytotoxic-free radical, and shed light on an additional mechanism of immune-mediated brain injury.

Amino Acid Oxidoreductases↗
PubMed1992

High- and low-challenge exposure doses used to compare intranasal and intramuscular administration of pseudorabies virus vaccine in passively immune pigs.

We compared 3 modified-live pseudorabies virus (PRV) vaccine strains, administered by the intranasal (IN) or IM routes to 4- to 6-week-old pigs, to determine the effect of high- and low-challenge doses in these vaccinated pigs. At the time of vaccination, all pigs had passively acquired antibodies to PRV. Four experiments were conducted. Four weeks after vaccination, pigs were challenge-exposed IN with virulent virus strain Iowa S62. In experiments 1 and 2, a high challenge exposure dose (10(5.3) TCID50) was used, whereas in experiments 3 and 4, a lower challenge exposure dose (10(2.8) TCID50) was used. This low dose was believed to better simulate field conditions. After challenge exposure, pigs were evaluated for clinical signs of disease, weight gain, serologic response, and viral shedding. When vaccinated pigs were challenge-exposed with a high dose of PRV, the duration of viral shedding was significantly (P less than 0.05) lower, and body weight gain was greater in vaccinated pigs, compared with nonvaccinated challenge-exposed pigs. Pigs vaccinated IN shed PRV for fewer days than pigs vaccinated IM, but this difference was not significant. When vaccinated pigs were challenge-exposed with a low dose, significantly (P less than 0.05) fewer pigs vaccinated IN (51%) shed PRV, compared with pigs vaccinated IM (77%), or nonvaccinated pigs (94%). Additionally, the duration of viral shedding was significantly (P less than 0.05) shorter in pigs vaccinated IN, compared with pigs vaccinated IM or nonvaccinated pigs. The high challenge exposure dose of PRV may have overwhelmed the local immune response and diminished the advantages of the IN route of vaccination.(ABSTRACT TRUNCATED AT 250 WORDS)

Administration, Intranasal↗
PubMed1992

Replication and immunosuppressive effects of Pseudorabies virus on swine peripheral blood mononuclear cells.

The infectivity and potential immunosuppressive effects of Pseudorabies virus (PRV) was evaluated in swine peripheral blood mononuclear cells (PBMC). Virus progeny titers and viral DNA synthesis at various intervals post-inoculation revealed the replication of PRV in both peripheral blood monocytes and lymphocytes; however, replication in lymphocytes was restricted compared with monocytes. PRV infection resulted in the damage and death of monocytes. Although PRV did not appear to affect the viability of the lymphocytes, PRV infection suppressed lymphocyte functions such as proliferation and interleukin-2 (IL-2) synthesis in response to Concanavalin A. This immunosuppression was dependent upon the multiplicity of infection (MOI) of infectious PRV. UV-inactivated PRV was not immunosuppressive. There was no effect of PRV on natural killer (NK) cell activity. The reduction of lymphocyte proliferation by PRV was not reversible by the addition of supernatant containing porcine IL-2 and non-infected monocytes to the infected cultures. The results from these in vitro studies demonstrate that PRV can infect and cause immunosuppressive effects on swine PBMC. These effects may explain the potential role of PRV in predisposing infected pigs to secondary infection and support the hypothesis that PRV can spread systemically by infected PBMC in blood and lymph.

Animals↗
PubMed1992

Functional alterations of swine peripheral blood mononuclear cells by methadone.

In vitro exposure of the synthetic opiate drug methadone allowed evaluation of putative immunomodulatory activities of swine peripheral blood mononuclear cells. Respiratory burst, an index of microbicidal activity, was suppressed by methadone in a dose-dependent manner following exposure for 48 h. The suppression was blocked by the opiate antagonist naloxone. Another macrophage function phagosome-lysosome fusion was impaired by exposure to methadone. A primary lymphocyte-mediated function natural killer cell activity was also affected. In contrast, the macrophage function antibody-mediated phagocytosis was not affected. Because the functions affected by methadone are critical to host defenses against pathogenic organisms, our findings suggest that opiate-mediated immunomodulation merits further study. Moreover, our studies suggest that swine may provide an ideal model for the investigation of opiate-mediated suppression of immune cell functions.

Animals↗
PubMed1992

A monoclonal antibody which recognizes cell surface antigen and inhibits porcine parvovirus replication.

Monoclonal antibody technologies were applied to the study of early events in porcine parvovirus (PPV) infections in vitro. Balb/c mice were immunized with whole swine testicle cells and hybridomas were produced following fusion with myeloma cells. Resultant clones were screened firstly in an ELISA system, to detect monoclonal antibody recognition of swine testicle cells, and secondly, in a fluorescent antibody test to detect monoclonal antibody which inhibited production of PPV antigen. One clone, 1H11, which satisfied these screening requirements, recognized proteins present in cell lines both permissive and non-permissive for porcine parvovirus replication and inhibited the production of virus progeny of several PPV isolates. A linear staining pattern of cross-linked plasma membranes, indicative of monoclonal antibody binding at the cell membrane, was demonstrated by indirect immunofluorescence assays. In immunoblotting experiments, 1H11 recognized a polypeptide of approximately 40 kDa in size, present in both permissive and non-permissive cell lines.

Animals↗
PubMed1992

Acute and chronic morphine administration in swine.

Functional responses to acute and chronic morphine administration in domestic swine were examined and correlated with pharmacokinetic profiles. Acute effects of morphine sulfate were monitored in pigs for 24 h and the chronic actions of morphine alkaloid were monitored for 21 days. Serum morphine levels, nociception, locomotor activity, respiratory rate, body temperature, and body weight were monitored during all studies. To assess nociception in a large laboratory animal, a portable thermal stimulating device was constructed. Morphine sulfate administered IV and SC had a half-life of approximately 1 h whereas delayed-release morphine alkaloid delivered SC had a half-life of 28 h. The degree of antinociception paralleled decline in blood morphine levels for both SC- and IV-administered animals. Tolerance occurred to both antinociception as well as weight gain despite morphine levels remaining constant over the 21-day period. Morphine dependence was demonstrated by precipitation of an abstinence syndrome using naloxone. Animals in withdrawal displayed consistent signs, including wet-dog shakes, posture changes, vocalization, and salivation. Collectively, these results indicate that swine may be reliably employed as a model to study the actions of morphine and opiate-like compounds.

Analgesics↗
PubMed1992

Cytokine release from microglia: differential inhibition by pentoxifylline and dexamethasone.

Cytokines have been implicated in the pathogenesis of gram-negative bacterial meningitis. The effects of pentoxifylline and dexamethasone on the release of tumor necrosis factor (TNF), interleukin (IL)-1, and IL-6 from primary murine microglial cell cultures were explored using bioassays. When added concomitantly with lipopolysaccharide, pentoxifylline blocked the release of TNF and IL-1 but not IL-6, while dexamethasone inhibited the release of TNF and IL-6. After a 2-h exposure of microglia to lipopolysaccharide, pentoxifylline but not dexamethasone still inhibited the release of TNF. Release of TNF was enhanced 20-fold by priming of the microglia with interferon-gamma; only pentoxifylline blocked the priming effect of interferon-gamma on TNF release. These results demonstrate that pentoxifylline and dexamethasone differentially regulate the release of cytokines in microglial cell cultures and provide potential insight into their role in the treatment of gram-negative bacterial meningitis.

Animals↗