Functional properties of the predicted helicase of porcine reproductive and respiratory syndrome virus.

Porcine reproductive and respiratory syndrome virus (PRRSV) is a member of the positive-strand RNA virus family Arteriviridae. Although considerable research has focused on this important pathogen, little is known about the function of most PRRSV proteins. To examine characteristics of putative nonstructural proteins (nsp) encoded in ORF1b, which have been identified by nucleotide similarity to domains of equine arteritis virus, defined genomic regions were cloned and expressed in the pRSET expression system.

Use of lipopolysaccharide (LPS) as a positive control for the evaluation of immunopotentiating drug candidates in experimental avian colibacillosis models.

The aetiologic agent of avian colibacillosis is Escherichia coli. Colibacillosis is a disease that causes mortality and production performance problems in chickens which results in economic losses for the poultry industry. It will be increasingly important for scientists to identify novel solutions that can be implemented which will provide poultry producers with a tool to manage this economically important disease.

Effect of tylosin tartrate (Tylan Soluble) on cellular immune responses in chickens.

Although many antimicrobial agents have been reported to cause immunosuppression in animals, macrolide antibiotics enhance immune function. Tylosin is a macrolide antibiotic approved for the control of mycoplasmosis in poultry. The purpose of this investigation was to determine the effect of tylosin on cellular immune functions in chickens.

Effect of tylosin tartrate on humoral immune responses in chickens.

While many antimicrobial agents have been reported to cause immunosuppression in animals, macrolide antibiotics enhance the immune function. Tylosin tartrate is a macrolide antibiotic approved for the control of mycoplasmosis in poultry. The purpose of this investigation was to determine the effect of tylosin on the humoral immune functions in chickens.

Immunoprophylaxis of Salmonella gallinarum infection by Salmonella enteritidis-immune lymphokines in broiler chicks.

Research on the control of intestinal and tissue colonization of breeder and table-egg producing flocks by invasive Salmonella enteritidis (SE) has focused on the advancement of anti-salmonella feed additives, microbiological strategies, and the development of vaccines. Recent investigations in our laboratories have concentrated on the development of immunoprophylactic measures to control Salmonella infections. We have found an increased resistance to Salmonella enteritidis (SE) organ infectivity in chickens conferred by the prophylactic administration of SE-immune lymphokines (SE-ILK).

Evaluation of Salmonella enteritidis-immune lymphokines on host resistance to Salmonella enterica ser. gallinarum infection in broiler chicks.

The prophylactic treatment of neonatal broiler chicks with lymphokines derived from S. enteritidis-immurazed chickens (SE-ILK) was evaluated for its effect on the birds' resistance to an experimental infection S. enterica ser.

Characterisation of colony-stimulating activity in the avian T cell-derived factor, Salmonella enteritidis-immune lymphokine.

This investigation was designed to characterise the specific cytokine activity from the conditioned medium of concanavalin A-stimulated avian T cells derived from Salmonella enteritidis-immune chickens, S enteritidis-immune lymphokine (ILK). Studies were designed to determine first, whether colony-stimulating activity was present in ILK, second, the type(s) of colonies from the bone marrow that were supported in vitro by the potential colony-stimulating factors in ILK and, third, whether colony-stimulating activity was present in serum from chicks treated with ILK and challenged with S enteritidis, and to use physicochemical treatment as a means of identifying the potential colony-stimulating factor(s) in ILK. Both ILK alone and serum from chicks treated with ILK and challenged with S enteritidis caused significant increases in the number of colony-forming units (CFU) from the bone marrow in vitro.

Efficacy of Salmonella enteritidis (SE)-immune lymphokines from chickens and turkeys on SE liver invasion in one-day-old chicks and turkey poults.

We have shown previously that increased resistance to Salmonella enteritidis (SE) organ infectivity in 1-day-old chicks was conferred by the immunoprophylactic administration of SE-immune lymphokines (SEILK). These lymphokines have been found to be present in the cell culture media of concanavalin A-stimulated splenic lymphocytes obtained from SE-immunized chickens. In the present study we evaluated whether turkeys also produced SEILK and whether these lymphokines could protect 1-day-old chicks and turkey poults against SE liver invasion.

Interaction of dexamethasone and Salmonella enteritidis immune lymphokines on Salmonella enteritidis organ invasion and in vitro polymorphonuclear leukocyte function.

We used an anti-inflammatory dose of dexamethasone (DEX) and Salmonella enteritidis (SE)-immune lymphokines (ILK) followed by oral SE challenge to chicks to determine the effects of these treatments on SE organ invasion and in vitro function of PMNs derived from peripheral blood. Endpoints included percent protection against SE organ invasion, numbers of peripheral blood PMNs, and in vitro PMN adherence, chemotaxis, and SE killing. SE organ invasion was significantly reduced in chicks treated with either ILK alone or DEX + ILK compared to controls.

Characterization of the pattern of inflammatory cell influx in chicks following the intraperitoneal administration of live Salmonella enteritidis and Salmonella enteritidis-immune lymphokines.

We characterized the inflammatory cell influx in day-old chicks induced by the i.p. administration of live Salmonella enteritidis (SE) and lymphokines from concanavalin A-stimulated SE-immune T lymphocytes (ILK).

In ovo administration of Salmonella enteritidis-immune lymphokines confers protection to neonatal chicks against Salmonella enteritidis organ infectivity.

We previously reported that the prophylactic, intraperitoneal administration of supernatants from concanavalin A-stimulated T cells derived from Salmonella enteritidis (SE)-immune White Leghorn hens (i.e., SE-immune lymphokines or ILK), conferred protection to neonatal White Leghorn chicks against SE organ invasion.

In vivo activation of heterophil function in chickens following injection with Salmonella enteritidis-immune lymphokines.

We have previously shown that increased resistance to Salmonella enteritidis organ infectivity in day-old chicks was conferred by the immunoprophylactic administration of S. enteritidis-immune lymphokines (ILK). This resistance was associated with a significant increase in the number of circulating heterophils 4 h after ILK injection.

Comparison of prophylactic and therapeutic efficacy of Salmonella enteritidis-immune lymphokines against Salmonella enteritidis organ invasion in neonatal Leghorn chicks.

Investigations in our laboratories have indicated that when Salmonella enteritidis (SE)-immune lymphokines--supernatants from concanavalin-A-stimulated T cells derived from SE-immune adult chickens--were administered intraperitoneally to 1-day-old chicks before SE challenge, they conferred protection against SE organ invasion within 24 hr. This resistance mediated by SE-immune lymphokines was associated with a concomitant increase in peripheral blood polymorphonuclear leukocytes that peaked 4 hr after SE challenge. In the present study, we evaluated efficacy of SE-immune lymphokines in protecting chicks against SE organ invasion and alterations in peripheral blood polymorphonuclear leukocyte counts.

Dynamics of avian inflammatory response to Salmonella-immune lymphokines. Changes in avian blood leukocyte populations.

Investigations in our laboratories have indicated that an increased resistance to SE organ infectivity in chicks was conferred by the immunoprophylactic administration of SE-immune lymphokines (SE-ILK). This resistance was associated with an increase in the lamina propria thickness due to a marked infiltration of inflammatory polymorphonuclear cells (PMNs). In the present study, we determined whether the hematological profile of SE-ILK-treated chicks might reflect changes that are associated with the protection against organ invasion by SE.

Genus-specific detection of salmonellae in equine feces by use of the polymerase chain reaction.

Members of the genus Salmonella were identified in feces from horses, using the polymerase chain reaction (PCR) and genus-specific oligonucleotide primers. Feces from healthy horses were determined to be culture-negative for Salmonella spp. Fecal samples were inoculated with known numbers of colony-forming units (CFU) of S anatum, S derby, S enteritidis, S heidelberg, S newport, and S typhimurium.

Comparison of the polymerase chain reaction using genus-specific oligonucleotide primers and microbiologic culture for the detection of Salmonella in drag-swabs from poultry houses.

Drag-swab samples were collected from 18 poultry houses at 9 broiler farms. Fifty drag-swab samples were tested for Salmonella by microbiologic culture using selective enrichment and the polymerase chain reaction (PCR) with oligonucleotide primers specific for all members of the genus Salmonella. Drag-swab samples were tested for Salmonella using PCR before and after enrichment.

Detection of Salmonella enteritidis in feces from poultry using booster polymerase chain reaction and oligonucleotide primers specific for all members of the genus Salmonella.

Salmonella enteritidis was identified in feces from hens using the polymerase chain reaction (PCR) and oligonucleotide primers specific for all members of the genus Salmonella. Feces from specific-pathogen-free Leghorn hens were determined to be negative for Salmonella by microbiological culture and by the PCR. Fecal samples were inoculated with known numbers of colony-forming units of S.

Heterophils are decisive components in the early responses of chickens to Salmonella enteritidis infections.

Chickens injected with 5-fluorouracil (5-FU) were found to have a three- to nine-fold reduction in circulating heterophils without a reduction in the number of circulating mononuclear cells. A 50% organ invasive dose (ID50) for orally and intravenously administered Salmonella enteritidis (SE) was established in the heteropenic chickens. When challenged orally, about 150-fold fewer SE cells were required for organ invasion in the 5-FU-treated chickens; whereas an intravenous challenge of the heteropenic chickens required about 4000-fold fewer bacteria for organ invasion than found in the control birds.

Salmonella enteritidis immune leukocyte-stimulated soluble factors: effects on increased resistance to Salmonella organ invasion in day-old Leghorn chicks.

Cytokines, derived from either concanavalin A-stimulated Salmonella enteritidis-immune chicken T lymphocytes [SE-immune Lymphocyte Stimulated Soluble Factor (LSSF)] or lipopolysaccharide-stimulated SE-immune chicken macrophages [SE-immune Macrophage Stimulated Soluble Factor (MSSF)], were evaluated for their ability to increase resistance to SE organ invasion in day-old Leghorn chicks. In Trial 1, day of hatch chicks were injected i.p.

Genus-specific detection of salmonellae using the polymerase chain reaction (PCR).

Oligonucleotide primers for the polymerase chain reaction (PCR) that enable genus-specific detection of members of the genus Salmonella were developed. The primers amplify a 496-bp genetic sequence of members of the genus Salmonella. Amplification of DNA extracted from all other genera of the family Enterobacteriaceae and various other gram-positive aerobic and anaerobic bacteria yielded negative results.