Brett T Webb's research while affiliated with North Dakota State University and other places

The antiviral activity of interferon (IFN) increases in uterine vein serum (UVS) during early pregnancy in sheep. This antiviral activity in UVS collected on Day 15 of pregnancy is blocked by anti-IFN-tau (IFNT) antibodies. Conceptus-derived IFNT was hypothesized to induce IFN stimulated gene (ISG) expression in endometrium and extra-uterine tissues during pregnancy. To test this hypothesis, blood was collected from ewes on Days 12-16 of the estrous cycle or pregnancy. Serum progesterone was >1.7 ng/ml in pregnant (P) and non-pregnant (NP) ewes until Day 13, then declined to <0.6 ng/ml by Day 15 in NP ewes. A validated IFNT radioimmunoassay (RIA) detected IFNT in uterine flushings (UF) on Days 13-16 and in UVS on Days 15-16 of pregnancy. IFNT detection in UF correlated with paracrine induction of ISGs in the endometrium and occurred prior to the inhibition of estrogen receptor 1 and oxytocin receptor expression in uterine epithelia on Day 14 of pregnancy. Induction of ISG mRNAs in corpus luteum (CL) and liver tissue occurred by Day 14 and in peripheral blood mononuclear cells by Day 15 in P ewes. Expression of mRNAs for IFN signal transducers and ISGs were greater in the CL of P than NP ewes on Day 14. It is concluded that: i) paracrine actions of IFNT coincide with detection of IFNT in UF; ii) endocrine action of IFNT ensues through induction of ISGs in peripheral tissues; and iii) IFNT can be detected in UVS, but not until Days 15-16 of pregnancy, which may be limited by the sensitivity of the IFNT RIA.

Infection of pregnant cows with noncytopathic (ncp) bovine viral diarrhea virus (BVDV) induces rapid innate and adaptive immune responses, resulting in clearance of the virus in less than 3 weeks. Seven to 14 days after inoculation of the cow, ncpBVDV crosses the placenta and induces a fetal viremia. Establishment of persistent infection with ncpBVDV in the fetus has been attributed to the inability to mount an immune response before 90-150 days of gestational age. The result is 'immune tolerance', persistent viral replication and shedding of ncpBVDV. In contrast, we describe the chronic upregulation of fetal Type I interferon (IFN) pathway genes and the induction of IFN-γ pathways in fetuses of cows infected on day 75 of gestation. Persistently infected (PI) fetal IFN-γ concentrations also increased at day 97 at the peak of fetal viremia and IFN-γ mRNA was significantly elevated in fetal thymus, liver and spleen 14-22 days post maternal inoculation. PI fetuses respond to ncpBVDV infection through induction of Type I IFN and IFN-γ activated genes leading to a reduction in ncpBVDV titer. We hypothesize that fetal infection with BVDV persists because of impaired induction of IFN-γ in the face of activated Type I IFN responses. Clarification of the mechanisms involved in the IFN-associated pathways during BVDV fetal infection may lead to better detection methods, antiviral compounds and selection of genetically resistant breeding animals.

A 14-year-old Trakehner gelding was evaluated for recurrent colic, with episodes occurring over 1 year. Signs were consistent with intermittent ascending colon obstruction and hematochezia. Necropsy examination revealed an ulcerated mass extending into the lumen of the right dorsal ascending colon. Gross and histologic appearance and immunoreactivity to c-kit (CD117), desmin, vimentin, and smooth muscle actin, were consistent with a diagnosis of gastrointestinal stromal tumor.

Development of transplacental infection depends on the ability of the virus to cross the placenta and replicate within the fetus while counteracting maternal and fetal immune responses. Unfortunately, little is known about this complex process. Non-cytopathic (ncp) strains of bovine viral diarrhea virus (BVDV), a pestivirus in the Flaviviridae family, cause persistent infection in early gestational fetuses (<150 days; persistently infected, PI), but are cleared by immunocompetent animals and late gestational fetuses (>150 days; transiently infected, TI). Evasion of innate immune response and development of immunotolerance to ncp BVDV have been suggested as possible mechanisms for the establishment of the persistent infection. Previously we have observed a robust temporal induction of interferon (IFN) type I (innate immune response) and up regulation of IFN stimulated genes (ISGs) in BVDV TI fetuses. Modest chronic up regulation of ISGs in PI fetuses and calves reflects a stimulated innate immune response during persistent BVDV infection. We hypothesized that establishing persistent fetal BVDV infection is also accompanied by the induction of IFN-gamma (IFN-γ). The aims of the present study were to determine IFN-γ concentration in blood and amniotic fluid from control, TI and PI fetuses during BVDV infection and analyze induction of the IFN-γ downstream pathways in fetal lymphoid tissues. Two experiments with in vivo BVDV infections were completed. In Experiment 1, pregnant heifers were infected with ncp BVDV type 2 on day 75 or 175 of gestation or kept naïve to generate PI, TI and control fetuses, respectively. Fetuses were collected by Cesarean section on day 190. In Experiment 2, fetuses were collected on days 82, 89, 97, 192 and 245 following infection of pregnant heifers on day 75 of gestation. The results were consistent with the hypothesis that ncp BVDV infection induces IFN-γ secretion during acute infection in both TI and PI fetuses and that lymphoid tissues such as spleen, liver and thymus, serve both as possible sources of IFN-γ and target organs for its effects. Notably, IFN-γ induction coincides with a decrease in BVDV RNA concentrations in PI fetal blood and tissues. This is the first report indicating the possible presence of an adaptive immune response in persistent BVDV infections, which may be contributing to the observed reduction of viremia in PI fetuses.

The hypothesis that ovine luteal gene expression differs due to pregnancy status and day of estrous cycle was tested. RNA was isolated from corpora lutea (CL) on Days 12 and 14 of the estrous cycle (NP) or pregnancy (P) and analyzed using the Affymetrix bovine microarray. RNA also was isolated from luteal cells on Day 10 of estrous cycle that were cultured for 24 h with luteolytic (OXT and PGF) hormones and secretory products of the conceptus (IFNT and PGE2). Differential gene expression (>1.5 fold, P < 0.05) was confirmed using semi-quantitative real time PCR (RTPCR). Serum progesterone concentrations decreased from Day 12 to Day 15 in NP ewes (P < 0.05) reflecting luteolysis; and remained > 1.7 ng/ml in P ewes reflecting rescue of the CL. Early luteolysis (Days 12 to 14) was associated with differential expression of 683 genes in the CL, including up-regulation of SERPINE1 and THBS1. Pregnancy on Day 12 (55 genes) and 14 (734 genes) also was associated with differential expression of genes in the CL, many of which were ISGs (i.e., ISG15, MX1) that were induced when culturing luteal cells with IFNT, but not PGE2. Finally, many genes, such as PTX3, IL6, VEGF and LHR were stabilized during pregnancy, and down-regulated during the estrous cycle and in response to culture of luteal cells with luteolytic hormones. In conclusion, pregnancy circumvents luteolytic pathways, and activates or stabilizes genes associated with interferon, chemokine, cell adhesion, cytoskeletal, and angiogenic pathways in the CL.

Transplacental viral infection of the fetus can result in abnormal trabecular and cortical bone modeling in long bones through impaired bone resorption and formation. Although such infections are frequently associated with neonatal fractures in humans and animals, their effect on the biomechanical properties of the developing skeleton remain poorly understood. The goal of this study was to determine the effects of transplacental bovine viral diarrhea virus (BVDV) infection on the biomechanical properties of fetal femora. Pregnant heifers were inoculated intranasally with non-cytopathic BVDV or media alone on day 75 of gestation to produce persistently infected (PI) and control fetuses, respectively, which were then removed on days 192 and 245 of gestation. Histomorphometry, compositional analysis and 'four-point bending until failure' were performed on fetal femora. Altered cortical geometry largely accounted for differences in calculated elastic modulus (PI vs. control, and day 192 vs. day 245) and ultimate stress (day 192 vs. day 245). Fetal infection with BVDV did not significantly impair inherent biomechanical properties of bone but rather resulted in decreased periosteal apposition rates, manifested as smaller femoral mid-diaphyseal diameters. There were no differences between PI and control fetuses in cortical thickness ratio, ash density or calcium/phosphorous content; however, cortical thickness ratio decreased with fetal age. Thus even when cortical thickness ratios are similar, differences in mid-diaphyseal diameter affect the error associated with the calculation of stress and strain by classical beam theory equations.

The corpus luteum (CL) releases progesterone, which acts on the endometrium to induce release of histotroph that supports the free-floating conceptus and prepares for epithelial-chorial placentation. Two steroidogenic cell types, which are classified based on size, contribute to serum progesterone concentrations. Large luteal cells produce the bulk of progesterone because of constitutively active protein kinase A. Small luteal cells also contribute to serum progesterone concentrations through release of progesterone in response to luteotrophic stimuli. The CL is maintained in ruminants until endometrial-derived prostaglandin F2 alpha (PGF) initiates functional and structural regression. The decline in serum progesterone and loss of negative feedback on the hypothalamus and anterior pituitary sets up hormonal responses resulting in a new estrous cycle that is characterized by estrus, ovulation and formation of a new CL. If a conceptus is present, interferon tau (IFNT) is released from the conceptus, which binds receptors in the endometrium and prevents up-regulation of estrogen receptor (ESR1) and consequently oxytocin (OXT) receptor (OXTR). As a consequence, pulses of PGF are disrupted which results in rescue of the CL from luteolysis. In addition to these paracrine actions, early pregnancy also has direct endocrine action on the CL through inducing IFN-stimulated genes (ISGs) in the CL and resistance of the CL to PGF. Endocrine actions of IFNT have been described through detection of IFNT in uterine vein blood, induction of several ISGs in the CL during pregnancy, and following both in vivo (via miniosmotic pumps) and in vitro (in cultured small, large, and mixed luteal cells) delivery of recombinant ovine (ro) IFNT. These endocrine actions of IFNT might be applied to reducing embryo mortality and associated economic consequences in ruminants.

During 2007-09, we necropsied striped skunks (Mephitis mephitis) from Colorado, USA. Eight of 51 (16%) had severe infections with the subcutaneous filarid nematode Filaria taxideae, and four of the infected skunks (50%) had dermatitis that was histologically associated with parasite ova in the skin.

An 8-month-old female Saint Bernard dog was presented with gait abnormalities consistent with a left-lateralizing cervical myelopathy. Imaging revealed a large, irregular soft tissue and mineral mass at the level of C1 and C2. The lesion was successfully excised, and histopathology was performed, revealing evidence of both multiple cartilaginous exostoses and calcinosis circumscripta. To the authors' knowledge, this is the first report comparing features using magnetic resonance imaging, computed tomography, and radiography. Additionally, multiple cartilaginous exostoses have not previously been reported to occur in combination with calcinosis circumscripta.

Paracrine release of ovine interferon tau (oIFNT) from the conceptus alters release of endometrial prostaglandin F2 alpha (PGF) and prevents luteolysis. Endocrine release of oIFNT into the uterine vein occurs by Day 15 of pregnancy and may impart resistance of the corpus luteum (CL) to PGF. It was hypothesized that infusion of recombinant oIFNT (roIFNT) into the uterine or jugular veins on Day 10 of the estrous cycle would protect the corpus luteum (CL) against exogenous PGF-induced luteolysis. Osmotic pumps were surgically installed in 24 ewes to deliver BSA (n = 12) or roIFNT (n = 12; 200 µg/day) for 24 h into the uterine vein. Six ewes in each treatment group received a single injection of PGF (4 mg/58 kg body weight) 12 h following pump installation. In a second experiment, BSA or roIFNT was delivered at 20 or 200 µg/day into the uterine vein or 200 µg/day into the jugular vein for 72 h in 30 ewes. One half of these ewes received an injection of PGF 24 h following pump installation. Concentrations of progesterone in serum declined in BSA-treated ewes injected with PGF, but were sustained in all ewes infused with 20 µg/day of IFNT into the uterine vein and 200 µg of roIFNT into the jugular vein followed 24 h later with injection of PGF. All concentrations of roIFNT and modes of delivery (uterine or jugular vein) increased luteal concentrations of IFN-stimulated gene (i.e., ISG15) mRNA. Infusion of 200 μg of IFNT over 24 h induced greater mRNA concentrations for cell survival genes, such as, BCL2-like 1 (BCL2L1 or Bcl-xL), serine/threonine kinase (AKT) and X-linked inhibitor of apoptosis (XIAP) and decreased prostaglandin F receptor (PTGFR) mRNA concentrations when compared to controls. It is concluded that endocrine delivery of roIFNT, regardless of route (uterine or jugular vein), effectively protects CL from the luteolytic actions of PGF by mechanisms that involve ISGs and stabilization of cell survival genes.