Biomedical subjects

D A Halvorson

Publications and source records attributed to D A Halvorson.

At least 55 records · Page 3Linked to original sources

PubMedDate not supplied

Avian pneumovirus infection in Minnesota turkeys: experimental reproduction of the disease.

Avian pneumovirus (APV) is an emerging viral respiratory disease agent of turkeys in Minnesota. Clinical signs of APV infection include open mouth breathing, ocular and nasal discharge, and swelling of infraorbital sinuses. The virus spreads rapidly among flocks of susceptible turkeys and is associated with increased mortality rates. A flock of 11-wk-old turkeys experienced a respiratory problem characterized by coughing, sneezing, swollen sinuses, and nasal discharge. The reverse transcriptase-polymerase chain reaction (RT-PCR) performed on tissues from the nasal turbinates and tracheal tissues was positive for avian pneumovirus. Turbinate tissue was inoculated into chicken embryo fibroblasts, and cytopathic effect was observed after five blind passages. In an attempt to reproduce the disease, 50 microl of this cell culture-propagated virus was instilled into each conjunctival space and nostril of 23-day-old turkey poults. The poults were sacrificed at 2-day intervals for 12 days, and serum, tissues, and tracheal and cloacal swabs were collected. Between days 2 and 10 after exposure, the poults developed ocular and nasal discharge and swollen sinuses. The virus was detected by RT-PCR and virus isolation from the nasal turbinates of poults sacrificed on days 4 and 6 postinoculation. Antibodies to APV were detected by enzyme-linked immunosorbent assay.

Animals↗

PubMedDate not supplied

Susceptibility of an avian pneumovirus isolated from Minnesota turkeys to physical and chemical agents.

Survival characteristics of a Minnesota avian pneumovirus (APV) isolated from a turkey nasoturbinate, propagated in tissue culture, and exposed to various physiochemical treatments were determined. These characteristics included survivability under various conditions. Specifically, APV was viable at temperatures of -70 C and -20 C for over 26 wk, 4 C for less than 12 wk, 20 C for less than 4 wk, 37 C for 48 hr, and 50 C for less than 6 hr. In addition, APV survived 12 freeze/thaw cycles with no loss of activity. With a variable pH for 1 hr, the titer was unaffected between the levels of pH 5 and 9. Several disinfectants, including quaternary ammonia, ethanol, iodophor, a phenol derivative, a biguanide, and bleach, were all effective in reducing the viability of the virus. After 7 days of drying at room temperature, the APV remained viable and was recovered on cell culture.

Animals↗

PubMedDate not supplied

Ornithobacterium rhinotracheale infection in turkeys: immunoprophylaxis studies.

Ornithobacterium rhinotracheale has been shown to cause serious clinical illness and is a significant concern to the turkey industry because of its potential economic impact. In this study, 6-wk-old turkeys were vaccinated intranasally with a live or subcutaneously with a killed O. rhinotracheale vaccine. At 14 or 21 wk of age, the birds were challenged intratracheally with live O. rhinotracheale. Airsacculitis and pneumonia occurred less frequently in vaccinated birds than in unvaccinated birds after challenge with O. rhinotracheale. Ornithobacterium rhinotracheale was recovered from unvaccinated, challenged birds but not from vaccinated, challenged or from unchallenged birds. Thus, turkeys inoculated with live or killed O. rhinotracheale vaccine were protected from pathologic changes.

Air Sacs↗

PubMedDate not supplied

Ornithobacterium rhinotracheale infection in commercial laying-type chickens.

Ornithobacterium rhinotracheale is a gram-negative, rod-shaped, pleomorphic bacterium that has been isolated from flocks of turkeys and broilers from around the world. Infections cause respiratory disease, mortality, and growth suppression, or clinical signs of infection may be absent. In layers, there have been few reports of disease caused by O. rhinotracheale. This is the first report of O. rhinotracheale infection in United States layer flocks.

Animals↗

PubMedDate not supplied

Susceptibility of broiler chicks to infection by avian pneumovirus of turkey origin.

In this paper we present the results of studies on the infectivity of an isolate of avian pneumovirus (APV) from turkeys to broiler chickens. Two-week-old broiler chicks free of antibodies to APV were exposed either by oculonasal or oral route with a cell cultured APV of turkey origin. Chickens from both APV-inoculated groups exhibited clinical signs that included coughing, sneezing, nasal discharge, and watery eyes during 2-8 days postinoculation. Tissue samples from birds in the APV-inoculated group were positive for APV by polymerase chain reaction (PCR) up to 9 days postinoculation. Samples of blood from both oculonasally and orally infected chickens were positive for APV. Intestinal samples from chickens infected with APV orally were positive for the presence of APV on PCR up to 9 days postinoculation. APV was reisolated from samples taken from chickens in both groups inoculated orally and oculonasally. Sera from birds exposed by the oculonasal or by the oral route showed the presence of APV-specific antibodies.

Animals↗

PubMedDate not supplied

Outer membrane proteins for serologic detection of Ornithobacterium rhinotracheale infection in turkeys.

Ornithobacterium rhinotracheale (ORT) is a bacterium responsible for a respiratory disease in turkeys and chickens and has been identified as one of the emerging respiratory bacterial pathogens. The clinical signs and lesions caused by ORT are very similar to those caused by other respiratory infectious agents; therefore, an accurate diagnostic test is necessary to identify the infection. In this study, we have investigated the use of outer membrane proteins of ORT in an indirect enzyme-linked immunosorbent assay (ELISA) to detect the exposure to ORT infection. Outer membrane proteins of ORT were extracted and used as an antigen in ELISA to detect infection in turkeys exposed to different serotypes of ORT. The ELISA results were compared with the conventional serum plate agglutination test. The agglutination test detected specific antibodies for ORT in 65% of experimentally infected turkeys during the first 2 wk of infection. The ELISA detected up to 100% of infected birds for 8 wk postinfection. The results suggest that ELISA is able to detect the exposure to ORT in later stages of the infection and this assay can be used in serologic surveillance of ORT infection for poultry in the field.

Animals↗

PubMedDate not supplied

Vaccination of turkeys with an avian pneumovirus isolate from the United States.

Four-week-old poults obtained from avian pneumovirus (APV) antibody-free parents were vaccinated with different serial 10-fold dilutions of cell culture-propagated APV vaccine. The birds were vaccinated with 50 microl into each conjunctival space and nostril (total of 200 microl). Each poult of each group was vaccinated in groups that received doses of 4 x 10(4), 4 x 10(3), 4 x 10(2), 4 x 10(1), or 4 x 10(0) 50% tissue culture infective dose (TCID50) of APV vaccine, respectively. Respiratory signs were seen between 3 and 12 days postvaccination (PV) in the poults that were vaccinated with 4 x 10(4), 4 x 10(3), and 4 x 10(2) TCID50, respectively. In these groups, APV was detected from swabs collected at 5 days PV and seroconversion was detected at 2 wk PV. The groups that were originally vaccinated with 4 x 10(1) and 4 x 10(0) TCID50 developed mild clinical signs after vaccination, but neither virus nor antibody was detected PV. At 2 wk PV (6 wk of age), birds from each group, along with five unvaccinated controls, were challenged with APV. Upon challenge, the 4 x 10(4) and 4 x 10(3) TCID50 groups were protected against development of clinical signs and were resistant to reinfection. The group previously vaccinated with 4 x 10(2) TCID50 developed clinical signs after challenge that were considerably milder than those seen in the groups that had previously been vaccinated with lower doses or no virus. Even though 4 x 10(2) TCID50 vaccine dose administered by intranasal ocular route resulted in infection, incomplete protection resulted with this pivotal dose. Upon challenge, the 4 x 10(1) and 4 x 10(0) TCID50 groups exhibited milder disease signs than those seen in the challenged unvaccinated controls. In these groups, APV was detected in preparations of swabs collected at 5 days postchallenge (PC) and seroconversion was detected at 2 wk PC. These results indicate that the dose of APV vaccine that causes protection is higher than that required to produce infection.

Animals↗

PubMedDate not supplied

Seroprevalence of Ornithobacterium rhinotracheale infection in commercial laying hens in the north central region of the United States.

This study was the first to examine the seroprevalence of Ornithobacterium rhinotracheale (ORT) within a commercial egg layer population. Serum samples collected from egg production companies were examined by serum plate agglutination test (SPAT) and outer membrane protein-based enzyme-linked immunosorbent assay (ELISA). Results show that 90% of layer flocks were positive by SPAT and 100% by ELISA. Of the pullet flocks examined, 43% and 52% were positive by SPAT and ELISA, respectively. Our study indicates that the prevalence of ORT antibody is high in the commercial layer population, suggesting that this respiratory pathogen can easily spread through multiple-age layer farms from older flocks to newly housed pullet flocks.

Agglutination Tests↗

PubMedDate not supplied

Influenza in commercial broiler breeders.

Influenza was detected in a flock of broiler breeders during routine serological monitoring. Although there were no clinical signs, egg production may have been affected in hens on one story of a two-story breeder house. Intensive measures were taken to avoid transmission to other farms. Two months after the flock was found to be serologically positive, sentinel hens were placed in the flock, and they became serologically positive 1 month later. In spite of this evidence for virus being present in the flock, no detectable transmission to any other farm occurred.

Animals↗

PubMedDate not supplied

Serological response in broiler chicks to different commercial Newcastle disease and infectious bronchitis vaccines.

Broiler chicks were administered vaccines against Newcastle disease and infectious bronchitis (both Arkansas and Massachusetts strains) at 2 weeks of age as either primary or secondary vaccinations. The vaccine was administered as a spray at 2 weeks of age to chicks that had received Newcastle disease vaccine alone, bronchitis vaccine alone, both vaccines in combination, or no vaccine at day 1 in the hatchery. The Newcastle disease hemagglutination-inhibition response was significantly lower in chicks receiving Newcastle disease vaccine as a secondary vaccine at 2 weeks than in those receiving the vaccine as a primary vaccination at that age. In contrast, the bronchitis hemagglutination-inhibition response was significantly higher in chicks receiving bronchitis vaccine as a secondary vaccination at 2 weeks than in those receiving the vaccine as a primary vaccination at that age.

Administration, Inhalation↗

PubMedDate not supplied

Isolation of H13N2 influenza A virus from turkeys and surface water.

This is the first report of the isolation of H13N2 avian influenza virus (AIV) subtype from domestic turkeys. This subtype was also isolated from nearby surface water. The observation of large numbers of gulls in close association with turkeys on range before the virus isolations suggests that this virus subtype was transmitted from gulls to range turkeys. Turkey flocks infected by this virus subtype did not show any clinical signs of the disease, although seroconversion did occur. The H13N2 isolates were found to be non-pathogenic in chickens.

Animals↗

PubMedDate not supplied

A highly fatal vascular disease of broiler breeder chickens.

A broiler breeder operation experienced a sudden outbreak of high mortality in nine different houses of breeders at eight different locations. In the first house to be affected, the losses were mainly in the females, but later flocks had losses up to 6.4%, mainly in the males. Affected chickens ranged in age from 7 to 22.5 weeks. Multifocal areas of necrosis and vasculitis were found in skin, muscle, and internal organs. No involvement of the brain was identified, but many of the birds had uveitis. The outbreak lasted 3 weeks and ended without treatment. Neither infectious agents nor mycotoxins were identified.

Animals↗

PubMedDate not supplied

Pasteurella haemolytica as a co-pathogen in pullets and laying hens.

Pasteurella haemolytica was isolated from internal organs of laying hens and pullets of four flocks in which five incidents of increased mortality had occurred. There was inflammation of the trachea in all cases, and infectious laryngotracheitis virus was identified in three of the incidents. Rapid response to antimicrobial therapy was seen in two out of three outbreaks in the pullets. P. haemolytica was regarded as a significant secondary invader in these cases.

Animals↗

PubMedDate not supplied

Perirenal hemorrhage syndrome in market turkey toms: effect of management factors.

Differences in the overall mortality rates and mortality due to perirenal hemorrhage syndrome (PHS) were compared in large white Nicholas tom turkeys. The study evaluated the effects of 1) four different light and temperature treatments; 2) three feed additives proposed to have anti-stress effects (reserpine, acetylsalicylic acid, and increased calcium); 3) toe-clipping on mortality, various disease conditions, and production parameters. Mortality varied from 0.60% to 3.57% among groups. Increased room temperature (21 C), toe-clipping, step-up/step-down lighting, and dietary reserpine reduced the incidence of PHS as compared with lower room temperature (13 C), no toe-clipping, intermittent lighting (2 hours light, 4 hours dark), and no dietary reserpine. Dietary aspirin or elevated calcium levels had no effect on PHS incidence. Overall mortality was greatest in the warmer rooms.

Animal Husbandry↗

PubMedDate not supplied

Loss of cell-associated Marek's disease vaccine titer during thawing, reconstitution, and use.

Tests of the effects of mismanagement practices observed in hatcheries showed that very subtle deviations from the explicit directions accompanying Marek's vaccine can cause dramatic losses of vaccine potency. Such mismanagement was found to result in 14 to 97% loss of vaccine titer. It appears that procedures used in hatcheries for the handling of cell-associated Marek's vaccine should be closely monitored on a continuous basis to prevent a gradual drift from correct handling.

Animals↗

PubMedDate not supplied

An adsorption-elution technique for the recovery of influenza virus from water.

A virus adsorption-elution (viradel) procedure was modified and evaluated for the concentration of influenza virus from water. Influent pH, flow rate, eluent pH and composition, and a second-step concentration method were evaluated. The viradel procedure in combination with a chicken erythrocyte adsorption technique resulted in up to 3200-fold concentration of influenza virus from 100 liters of tap water.

Adsorption↗

PubMedDate not supplied

Effect of time and temperature on growth of Salmonella enteritidis in experimentally inoculated eggs.

Influence of time and temperature on Salmonella enteritidis multiplication in experimentally injected eggs was examined. There was an increase in the number of S. enteritidis with the increase in temperature of egg storage. There was less increase of S. enteritidis in eggs stored at 4 degrees C than in eggs held at temperatures higher than 4 degrees C (P less than 0.05). These results suggest a possible method for monitoring commercial eggs for the presence of S. enteritidis. It was concluded that the chances of recovery of S. enteritidis can be increased 10(6)-fold or more by holding the eggs at temperatures of 21 or 27 degrees C for more than 20 days and culturing their contents.

Animals↗

PubMedDate not supplied

A broad-spectrum avian influenza subtype antigen for indirect enzyme-linked immunosorbent assay.

A broad-spectrum viral antigen for the detection of avian-influenza-virus-specific antibodies, using the indirect enzyme-linked immunosorbent assay (ELISA), was identified. Purified and disrupted antigens were used, which helped to increase the sensitivity of the assay. All of the antigens tested were able to detect antibodies to homologous and heterologous viruses to varying degrees. The H9N2 antigen was the best single antigen to use in the ELISA to screen for avian influenza virus antibodies. It detected antibodies against six viruses as early as day 4 postinfection.

Animals↗