Weathering the storm: Extreme weather events and their association with PED and PRRS occurrence.

Porcine epidemic diarrhea (PED) and Porcine reproductive and respiratory syndrome (PRRS) are viral diseases that continue to challenge the US swine industry. Despite many known risk factors, unusual circumstances associated with their occurrence continues to be poorly explained. We investigated if extreme weather events (flood, heavy rain, high wind and tornadoes, measured at a county-level) are associated with the occurrence of both diseases up to ten weeks after the occurrence of the weather event using a case control study and logistic regression modeling to control for covariates.

Intrarenal renin-angiotensin system modulates glomerular angiotensin receptors in the rat.

The aim of this study was to test the hypothesis that the intrarenal renin-angiotensin system (RAS) modulates glomerular angiotensin II (ANG II) receptors. In one protocol ANG II receptors were measured 7 days after unilateral denervation of the left kidney in rats. There were 50% more receptors in the glomeruli from denervated compared with innervated kidneys (right, 1,037 +/- 108 vs.

Characteristics of the polyriboinosinic acid:polyribocytidylic acid assay for noncytopathogenic bovine viral diarrhea virus.

The use of polyriboinosinic acid:polyribocytidylic acid (poly I:C) for noncytopathogenic bovine viral diarrhea virus (NC-BVDV) assay (PINBA) was studied. Several viruses were tested for their suitability as test challenge viruses. In addition to vesicular stomatitis virus, which previously was shown to be a suitable challenge virus, bovine enteroviruses also were found to be suitable, whereas infectious bovine rhinotracheitis virus and parainfluenza type 3 virus were only marginally suitable.

Effect of infectious bovine rhinotracheitis virus immunization on viral shedding in challenge-exposed calves treated with dexamethasone.

Calves not vaccinated with infectious bovine rhinotracheitis virus (IBRV) became latently infected when challenge exposed and treated with dexamethasone (DM). Calves that shed IBRV after DM treatment were considered to be latently infected. Vaccination with a temperature-sensitive intranasal vaccine or with formalinized IBRV in Freund's complete adjuvant (IBRV-FCA) protected some, but not all, calves against latent infection--indicating a role for the immune response in preventing latent infection.

Association between route of inoculation with infectious bovine rhinotracheitis virus and site of recrudescence after dexamethasone treatment.

Four calves latently infected with infectious bovine rhinotracheitis virus (IBRV) were used to compare the ease of isolation of virus from neuronal ganglia and from mucosal surfaces. Two calves were slaughtered, and neuronal ganglia (cranial cervical, trigeminal, and 3rd and 4th sacral) were cocultivated on bovine fetal kidney cells. Virus was not isolated.

Evidence for suppression or incomplete maturation of cell-mediated immunity in neonatal calves as determined by delayed-type hypersensitivity responses.

Fifteen bovine fetuses were inoculated in utero 20 to 123 days before birth with a mixture of killed Mycobacterium bovis, tetanus toxoid, and ferritin in Freund's complete adjuvant. On the day of birth (day 0) and when the calves were 21 days of age, the calves were skin-tested to each of the antigens for delayed-type hypersensitivity. Nine delayed-type hypersensitivity responses to the various antigens were obtained at the 0-day test, whereas 28 responses were obtained at the 21-day test.

Viral contamination of bovine fetal lung cultures and bovine fetal serum.

Commercial bovine fetal serum (BFS) and bovine fetal lung (BFL) cells were tested for viruses. The only virus detected in any samples was noncytopathogenic bovine viral diarrhea virus (BVDV). Of 37 BFL cultures initiated, 34 were negative for BVDV, 1 was positive, and 2 were suspicious in that the source of BVDV contamination was not certain.

Factors affecting the production of bovine type I interferon on bovine embryonic lung cells by polyriboinosinic-polyribocytidylic acid.

Variables believed to affect the amount of interferon (IF) produced in bovine embryonic lung cell cultures by polyriboinosinic-polyribocytidylic acid (poly (rI:rC)) were investigated. A concentration of 100 micron of poly (rI:rC)/ml consistently induced substantial amounts of IF. Bovine viral diarrhea virus infection of cultures did not interfere with induction of IF by poly (rI:rC).

Factors affecting the assay of bovine type I interferon on bovine embryonic lung cells.

One preparation of interferon (IF) on 7-day-old bovine embryonic lung cultures free of bovine viral diarrhea virus had titers ranging from 20 to 10,240 in plaque-reduction tests, using bovine vesicular stomatitis virus. Factors believed to contribute to this variation were investigated. Although titers differed on different cell strains, different passages, and on cultures of different ages, variations between the two assays definitely could not be established as a function of these factors.

Kinetics of detection of blastogenic responses of neonatal calves inoculated in utero with tetanus toxoid, killed Mycobacterium bovis, and killed Brucella abortus.

Nine pregnant cows were laparotomized and their fetuses were immunized with tetanus toxoid, killed Brucella abortus, and killed Mycobacterium bovis. Blastogenesis assays and total leukocyte and differential counts were done when the calves were 1, 2, 3, 7, 14, 21, 28, and 60 days of age. Initial blastogenesis responses to antigens, phytohemagglutinin, and concanavalin A were not positive as frequently as were the responses obtained when the calves were 2 to 3 weeks of age.

Cell-mediated and humoral immune responses of cattle to Brucella abortus, Mycobacterium bovis, and tetanus toxoid: evaluation of immunization and assay techniques.

A concentration of 2.5 X 10(-5) M 2-mercaptoethanol (2-ME) added to the medium in lymphocyte blastogenesis assays increased both the uptake of [3H]thymidine in unstimulated lymphocyte cultures and the probability of detecting antigen-sensitized cattle. The use of 2-ME did not cause lymphocytes from unsensitized cattle to react positively in blastogenesis assays.

Bovine respiratory syncytial virus infection of bovine embryonic lung cultures: enhancement of infectivity with diethylaminoethyl-dextran and virus-infected cells.

The effects of incorporating diethylaminoethyl-dextran (DEAE-D) in the inoculum with bovine respiratory syncytial virus (BRSV) on the infectivity of BRSV was evaluated. A concentration of 40 microgram DEAE-D/ml provided maximal enhancement of infection as determined by the time of onset of cytopathic effect (CPE), the percentage of cells infected by the inoculum, and the amount of virus produced. When DEAE-D was used in the inoculum, the CPE appeared a day earlier, the percentage of cells infected by the inoculum, as determined by the fluorescent antibody test, was increased 11 times, and the viral titer was increased 2 times as compared to results obtained without DEAE-D.

Bovine respiratory syncytial virus infection of bovine embryonic lung cultures: a kinetic study by the fluorescent antibody technique.

Development of fluorescence in bovine embryonic lung cells infected with bovine respiratory syncytial virus (BRSV) was studied by the fluorescent antibody (FA) test. Similar patterns of fluorescence were seen with the direct FA test, in which the immunoglobulin G fraction of antiserum to BRSV was conjugated with fluorescein isothiocyanate and used; and the indirect test, in which antiserum to the Long strain of respiratory syncytial virus and fluorescein isothiocyanate-conjugated anti-rabbit immunoglobulin G were used. In different trials, fluorescence was first detected between 16 and 18 hours after inoculation with BRSV.

Susceptibility of bovine macrophage and tracheal-ring cultures to bovine viruses.

Cultures of macrophages initiated from peripheral blood monocytes and organ cultures of tracheal rings were tested for their susceptibility to bovine viruses. With several notable exceptions, viruses cytopathogenic for bovine embryonic lung cultures were cytopathogenic for macrophages. Although cowpox virus replicated in macrophages, pseudocowpox did not, and although pseudorabies virus replicated within macrophages, infectious bovine rhinotracheitis and DN-599 herpesviruses did not.

Bovine immunoglobulin G subclass receptor sites on bovine macrophages.

Macrophage cultures were initiated from bovine peripheral blood monocytes. The following antiserums were prepared: rabbit immunoglobulin (Ig) M anti-sheep erythrocyte (RBC) serum, bovine IgG1 anti-rabbit Ig serum, and bovine IgG2 anti-rabbit Ig serum. Erythrocytes treated singly with any of these serums failed to mediate attachment of RBC to macrophages.

Bovine peripheral blood monocyte cultures: growth characteristics and cellular receptors for immunoglobulin G and complement.

Bovine peripheral blood monocytes were cultured in vitro for as long as 60 days. Although mitotic figures were not observed, the amount of cytoplasm was observed to increase; most cultures developed multinucleated cells, some containing as many as 200 nuclei. In multinucleated cells, the nuclei were peripherally distributed around a cytoplasmic matrix and surrounded by an undulating membrane.